Imagine the situation: to heat a room at home or cook food, you need to quickly build a simple wood-burning stove. Fuel quality and consumption are secondary. A suitable option is a homemade rocket stove made from scrap materials. We invite you to familiarize yourself with the design of the heater and the assembly process at home.

Design and principle of operation

The rocket stove shown in the diagram consists of the following main elements:

• a bunker for storing firewood of a vertical or inclined design;
• horizontal combustion chamber;
• pipe with lining - afterburner (the second common name is riser);
• a metal cap that plays the role of an air heat exchanger;
• blower;
• chimney channel.

In operation, the stove uses 2 principles: the occurrence of natural draft inside the vertical section and the combustion of wood (pyrolysis) gases. The first is realized due to the heating of the firebox and waste combustion products tending to rise through the afterburner channel. The released pyrolysis gases burn out in it.

Reference. The name rocket or jet stove is associated precisely with the principle of operation - a powerful natural draft arises in the vertical channel, causing intense combustion in the firebox and the release of heat.

The stove operation algorithm is as follows:

1. Firewood loaded into the bunker is ignited from below. The air supply is provided through the blower hatch.
2. During the combustion process, flue gases heat the insulated walls of the afterburner and rush under a thin metal hood, where they give off most of the heat to the room air.
3. With a sufficient amount of secondary air, pyrolysis gases have time to burn inside the riser, releasing additional heat.
4. Combustion products are discharged directly into the chimney or first sent into the smoke circulation of the stove bench.

Options for portable stoves "Robinson"

In a simplified camping version, the stove is made without a hood and insulation. Accordingly, secondary gases do not burn completely, since they have time to fly out into the chimney. A small-sized portable heater, called “Robinson”, is designed for instant cooking food on fuel of any quality and degree of humidity.

Requirements for element sizes

The main heat exchange element of the rocket stove is a metal cap; the intensity of heating a room in the house depends on its size. In stationary structures made of brick, a 200-liter barrel with a diameter of 60 cm is usually used. Portable versions are made from standard gas cylinders Ø300 mm.

Diagram of a rocket heater with a stove bench

Accordingly, the remaining dimensions depend on the dimensions of the barrel - diameter and cross-sectional area:

• the height of the cap is provided to be 1.5-2 times the diameter;
• the cross-sectional area of ​​the afterburner is 5-6.5% of the diameter of the barrel;
• the length of the riser is made such that there is a minimum gap of 7 cm between the upper cut of the pipe and the cover;
• the internal size of the firebox is equal to the cross-section of the afterburner, the ash duct is half as large;
• chimney diameter is 1.5-2 times larger than the afterburner cross-section, height is at least 4 m.

To make it easier for you to calculate the diameters of pipes and linings, we present a drawing for various options for rocket furnaces - from a cylinder, a barrel and old buckets (the riser is made of a round or profile pipe).

We make a stove - a rocket

The easiest way to make a light camp stove, shown in the drawing, is to find it in the household following materials:

• round steel pipe with a diameter of 133-150 mm and a length of 0.5 m;
• profile pipe 14 x 20 cm, length 0.4 m;
• sheet of metal 2-3 mm thick for grates;
• rod Ø8-10 mm for legs;
• scraps of iron for the stand.

A vertical round pipe is welded to the profile at an angle of 45°, then eyes for the legs are attached to the body (they should be easily removed). A grate is placed inside the inclined firebox, and a lid is attached to the outside. To make it easier to clean the ash below, it is advisable to install a second door.

Advice. Be sure to weld a stand to the upper edge of the fire channel - gases must penetrate between the bottom of the dish and the body, otherwise “rocket” thrust will not occur.

Drawing of an improved version of the portable stove

The design of the furnace can be improved by organizing the supply of secondary air inside the flame tube. Modernization will increase the efficiency and duration of firewood burning. Drill holes on both sides on both sides, covering them with rocket “nozzles” according to the presented drawing. How this stove functions is demonstrated in the video:

From a gas cylinder

The following materials will be used to make a do-it-yourself rocket stove:

• pipes round section transverse dimensions 70 and 150 mm; with a wall thickness of 4 mm;
• square corrugated pipe 150-200 mm in diameter;
• chimney pipe Ø10-15 cm;
• low-carbon steel (grade St20) sheet;
• dense basalt wool (80-120 kg/m3) or bulk fire-resistant materials, for example, vermiculite or perlite gravel.

To begin, cut the rolled metal into blanks in accordance with the drawing. Then you need to saw off the lid of the propane tank, after unscrewing the valve and filling the tank to the top with water. The tool is an ordinary grinder with a metal circle.

Further assembly technology is as follows:

The master will tell you in detail about the manufacture of a rocket stove from a cylinder in the video:

Made of brick

The simplest rocket stove for cooking can be built from bricks without using mortar, as shown in the diagram with the order. Such a structure can be easily disassembled and moved if necessary.

The rocket stove with a stove bench must be placed on a foundation made of concrete or rubble stone. Material – ceramic or refractory brick, sand-clay or fireclay mortar, respectively. The finished base is covered with roofing felt for the purpose of waterproofing, then a continuous first row of bricks is laid. The further work order looks like this:

Important. The construction is carried out in compliance with the rules of stove masonry, described.

The length of the smoke channels inside the stove is limited by the draft in the rocket stove and the external chimney. It is better to keep the total length of the flue ducts within 4 m. To prevent the heater from smoking back into the room, raise the top chimney to a height of 5 m, counting from the grate. How to build a brick stove - a rocket without a barrel, watch the video:

In conclusion - the pros and cons of the stove

Such structures are indeed made quickly, and the contractor does not necessarily have to be highly qualified. The first and main advantage of rocket-type furnaces is their simplicity and undemanding use of materials. In addition, they accept a variety of fuels well - raw firewood, branches, brushwood, and so on.

Now about the negative points:

For the above reasons, a rocket heater is extremely inconvenient for a garage, where it is necessary to heat the room quite quickly. But the hiking option is indispensable in nature at any time of the year.

Design engineer with more than 8 years of experience in construction.
Graduated from the East Ukrainian National University. Vladimir Dal with a degree in Electronics Industry Equipment in 2011.

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Despite such a loud name, a rocket stove, of course, has nothing in common with rocket and space technology. And it doesn’t run on jet fuel at all. The stove received this name for the stream of flame escaping from the top pipe of the camping structures and the sound reminiscent of the roar of an engine.

Let us immediately clarify that the stove will produce a strong sound only if the operating rules are violated - the roar of the engine occurs when excess air enters the firebox. Normally, the rocket stove will make a quiet rustling sound. It runs on wood and other fuels and is highly efficient.

The rocket stove came to us from the USA and is still little known even to professional stove makers, although it definitely deserves attention.

Operating principle of a rocket stove:

• Direct combustion. Fuel gases flow freely through the furnace channels without being stimulated by the draft created by the chimney.
• Flue gases, which are always released when burning wood, are burned. This is called pyrolysis.

The simplest jet furnace will consist of two pipes, one of which goes horizontally and the other goes up. You can use one curved pipe if you have such an opportunity, otherwise welding work is required.

The fuel in the rocket stove is placed directly into the pipe. In this case, the hot gases will tend to escape upward along the vertical section. At the end of the pipe you can place a container that will be used for cooking or boiling water. There must be a gap between the container and the pipe so that combustion products can freely come out.

What else do you need to know about jet furnace:

• It is both cooking and heating.
• It is quite possible to equip the “Rocket” with a stove bench, approximately like in a Russian stove, but such a design will be much less cumbersome.
• The operating time on one fuel fill in a rocket stove is approximately six hours, and it retains heat for up to 12 hours if the metal structure is finished with adobe plaster.
• Initially, the rocket stove was intended for use outdoors, in field conditions. Portable metal structures still occupy first place in popularity, but stationary stoves have also appeared that work on the same principle, made of brick or clay.

Pros of the rocket stove:

• The design itself is simple, you can do it yourself, the materials are available.
• Ability to use different types of fuel. In such a stove, even low-quality fuel, damp thin branches, and so on will burn.
• Energy independence.
• High operating efficiency, lower fuel consumption.

Cons of a jet stove:

• It will have to be controlled manually. It is necessary to constantly monitor and regulate the combustion process.
• Some elements of the rocket furnace can become very hot, especially for the simplest metal structures. That is, there is a great danger of burns when touched; you should be especially careful and keep children away from the rocket stove.
• It will not work to use a stove of this design in a bathhouse, since it is simply not able to quickly heat the room to the required temperature.

Now you can find the simplest diagrams of how to build a rocket stove out of 20 bricks with your own hands without mortar in literally three minutes anywhere. The first row will be solid, with a horizontal protrusion, the second will have a hole above the protrusion for loading fuel, the remaining three rows will be a pipe. It will be warm; you can simply place a cauldron or pan on top.

However, in more complex and efficient options, flue gases are passed under the stove bench, for example, through special channels. The second option is to install a water circuit on a simple rocket stove.

These are examples of biodesign of stoves that work on the “rocket” principle, but are much more complex and modernized, with stove beds. The construction of such clay ovens is carried out by the German company Lehm und Feuer.

We state that a rocket stove has many advantages, including ease of installation, the ability to use it in the field or in the summer in the yard for cooking various dishes on live fire. You just need to understand the operating principles and design features.

A do-it-yourself rocket stove, the drawings of which most home craftsmen would probably like to have in their archives, can, in principle, be made even within one day, since its design is not at all complicated. If you have skills in working with tools, reading drawings, necessary materials, then making a simple stove of this type will not be difficult. It should be noted that it can be made from a variety of materials that are at hand, but much will depend on where the stove is planned to be installed. The rocket stove has a slightly different operating principle from other heating devices, and can be either stationary or portable.

Stationary rocket stoves are installed inside the house along the walls or on a designated area for cooking in the courtyard of the house. If the stove is installed indoors, it can heat a room up to 50 square meters. m.

Portable versions of the rocket stove are usually very small in size and can easily fit in the trunk of a car. Therefore, when going out, for example, to a picnic or to the dacha, such a stove will help you boil water and cook lunch. Moreover, the fuel consumption in the rocket stove is quite small; even dry branches, splinters or tufts of grass can be used as fuel.

The principle of operation of a rocket-type stove

Despite the simplicity of the rocket stove design, its design uses two operating principles that the developers borrowed from other types of solid fuel stoves. So for her efficient work The following principles are taken:

• The principle of free circulation of gases released from fuel through the created stove channels, without the forced creation of chimney draft.
• The principle of afterburning pyrolysis gases released during fuel combustion in the mode of insufficient oxygen supply.

In the simplest designs of rocket stoves, which are used only for cooking, only the first principle of operation can operate, since in them it is quite difficult to create the necessary conditions for the flow of pyrolysis and the organization of afterburning of gases.

To understand the designs and understand how they work, you need to consider some of them one by one.

The simplest design of a rocket stove

To begin with, it is worth considering the simplest design of a direct combustion rocket stove. As a rule, such devices are used only for heating water or for cooking, and exclusively outdoors. As can be seen from the figure below, these are two sections of pipe connected by a bend at a right angle.

The firebox for this furnace design is the horizontal part of the pipe, and fuel is placed in it. Often the firebox has a vertical loading - in this case, three elements are used to make the simplest stove - these are two pipes of different heights, installed vertically and connected from below by a common horizontal channel. The lower pipe will serve as a firebox. To make a stationary version of the simplest design scheme, a brick is often used, installed on a heat-resistant mortar.

To achieve higher efficiency, the furnace was improved, and additional elements appeared, for example, the pipe began to be installed in a housing, which increases the heating of the structure.

1 – outer metal body of the furnace.

2 – pipe – combustion chamber.

3 – a channel formed by a jumper under the fuel chamber and intended for the free passage of air into the combustion area.

4 – the space between the pipe (riser) and the body, densely filled with a heat-insulating composition, for example, ash.

The furnace is heated as follows. A light combustible material, such as paper, is first placed in the firebox, and when it flares up, wood chips or other main fuel are thrown into the fire. As a result of the intense combustion process, hot gases are formed, rising through the vertical channel of the pipe and escaping outside. A container for boiling water or cooking food is installed on the open section of the pipe.

An important condition for the intensity of fuel combustion is the creation of a gap between the pipe and the installed container. If its hole is completely blocked, then combustion inside the structure will stop, since there will be no draft that supplies air to the combustion area and lifts the heated gases upward. To avoid problems with this, a removable or stationary stand for the container is installed on the upper edge of the pipe.

This diagram shows simple design, on the loading opening of which a door is installed. And to create draft, a special channel is provided, which is formed by the lower wall of the combustion chamber and a plate welded at a distance of 7-10 mm from it. Even if the firebox door is completely closed, the air supply will not stop. In this scheme, the second principle is already beginning to work - without active access of oxygen to burning wood, the process of pyrolysis can begin, and the continuous supply of “secondary” air will contribute to the afterburning of the released gases. But for a full-fledged process, one more important condition is still missing - high-quality thermal insulation of the secondary combustion chamber, since the combustion process of gases requires certain temperature conditions.

1 – air channel in the combustion chamber, through which air is blown when the firebox door is closed;

2 - zone of the most active heat exchange;

3 – upward flow of hot gases.

Video: a version of the simplest rocket furnace from an old cylinder

Improved rocket furnace design

The design, intended for both cooking and heating the room, is equipped not only with a combustion door and a second body, which serves as a good external heat exchanger, but also with an upper hob. Such a rocket stove can already be installed inside the house, and the chimney pipe from it is led outside. After such a modernization of the furnace, its efficiency increases significantly, since the device acquires many useful properties:

• Due to the second outer casing and insulating heat-resistant materials that thermally insulate the main pipe of the furnace (riser), hermetically sealing the upper part of the structure, the heated air maintains a high temperature for much longer.

• A channel for supplying secondary air was installed in the lower part of the housing, successfully providing the necessary air supply, for which simplest design an open firebox was used.
• The flue pipe in a closed design is not located at the top, as in a simple rocket stove, but at the lower rear part of the body. Thanks to this, the heated air does not go directly into the chimney, but is able to circulate through the internal channels of the device, heating, first of all, the hob, and then diverging inside the housing, ensuring its heating. In turn, the outer casing gives off heat to the air around it.

This diagram clearly shows the entire process of operation of the stove: in the fuel bunker (item 1), preliminary combustion of fuel (item 2) occurs in the insufficient air supply mode “A” - this is regulated by a damper (item 3). The resulting hot pyrolysis gases enter the end of the horizontal fire channel (item 5), where they are burned. This process takes place thanks to good thermal insulation and the continuous supply of “secondary” air “B” through a specially designed channel (item 4).

Next, hot air rushes into the internal pipe of the structure, called the riser (item 7), rises along it to the “ceiling” of the housing, which is the hob (item 10), providing its high-temperature heating. Then the gas flow passes through the space between the riser and the outer drum housing (item 6), heating the housing for further heat exchange with the air in the room. Then the gases go down and only after that they go into the chimney pipe (pos. 11).

In order to achieve maximum heat transfer from the fuel and provide the necessary conditions for complete combustion of pyrolysis gases, it is important to maintain the highest and most stable temperature in the riser channel (item 7). To do this, the riser pipe is enclosed in another pipe of a larger diameter - the shell (item 8 ), and the space between them is tightly packed with a heat-resistant mineral composition (item 9), which will serve as thermal insulation (a kind of lining). For these purposes, for example, a mixture of kiln masonry clay with fireclay sand (in a 1:1 ratio) can be used. Some craftsmen prefer to simply fill this space very tightly with sifted sand.

Increasing the efficiency of heat extraction in rocket stoves

To increase the efficiency of the rocket stove, other designs with more efficient heat extraction were developed, both for using the device outdoors and for indoor use - for heating rooms or heating water.

Stove-oven

For cooking or preparing food for the winter, stoves are made according to the principle described above, but with an expanded hob, which allows you to install several containers at once.

In this model of a rocket stove, a vertical pipe with a top-loading firebox built into it, which has a door, is located under the cooking surface. Therefore, hot air heats it directly, and in order for the entire panel to be hot, heated gases, collecting under the panel, are directed into a horizontal channel passing under its entire surface and connected to a vertical section of the chimney.

Additionally, the structure is equipped with legs, which makes it stable and reliable. It should be noted that when such a stove is not used for its intended purpose, it can be used as an ordinary garden table.

In addition to this outdoor model, several types of structures have been developed for indoor use to effectively heat rooms or heat water.

Rocket stove with water circuit

A rocket furnace with a water circuit consists of the following elements:

• The stove is installed on a solid concrete base to avoid distortions and deformation of structures.
• The lower part of the structure, which includes the combustion chamber (item 2) and the fire channel, is laid out of fireclay bricks (item 1). The firebox has a vertical loading. At the bottom there is an ash pan (item 3) with a side door for regular cleaning of the stove from accumulated ash.

• The vertical channel (riser) (item 4) is made of a steel pipe, which is covered with a thick layer of thermal insulation (item 5) and an outer metal casing.
• A heat exchanger assembly with a water jacket in the walls (pos. 6) and horizontal plates that create a kind of labyrinth (pos. 7) to ensure maximum heat exchange area and time is hermetically fixed on top of the outer casing.

Attempts are being made to install a water register in this location. However, as practice shows, this approach is impractical - the temperatures here due to the afterburning of pyrolysis gases are very high, and the pipe register has every chance of quickly burning out.

• Hot air, passing through the heat exchanger, bending around the metal plates, heats the entire massive block, and the metal gives off heat to the water circulating through the water jacket.
• Next, the cooled gas flow goes into the chimney pipe (pos. 8).
• Water circulation occurs through a heat accumulator (item 9), which may well be made from an old boiler or other closed container with valves for connecting cold water and intake hot water. The option of connecting a heating radiator is not excluded, although, in truth, such a stove is unlikely to justify itself in such a role.
• Hot water from the heat storage tank through a pipe connected to it (item 10) can be directed to water intake points for domestic needs.

Such a rocket stove is perfect for installation in a country house or in a private house, where it is possible to connect such a heat storage tank to an autonomous water supply system. The stove will help to significantly reduce the cost of heating water and heating, since this model does not require a large amount of solid fuel or connecting it to any additional energy sources.

Rocket stove with bench

Another way to effectively use a rocket stove is to equip a fairly massive structure with a heated bench. It should be noted that such a bed can take the form of a bed or sofa, successfully replacing these pieces of furniture, since by laying a mattress on its surface, you can comfortably settle down for a day or night rest. The bed can be made of brickwork or stones and clay mass.

The design of this version of the rocket stove consists of the following components and elements:

• A lid-closable firebox with vertical fuel loading with a secondary air intake chamber located in its lower part.
• The furnace goes into a horizontally located fire channel, at the end of which the pyrolysis gas is burned.
• The hot gas flow rises through a vertical channel (riser) to the hermetically sealed “ceiling” of the housing, where it transfers part of the thermal energy to the horizontal plate - the hob. Then, under the pressure of hotter gases following, it diverges into heat exchange channels, giving off heat to the surfaces of the drum, and falls down.
• At the bottom of the stove there is an entrance to horizontal pipe channels that run under the entire surface of the stove bench. Moreover, in this space one, two or more turns of corrugated pipe can be laid in the form of a coil, through which hot air circulates, heating the bed. This heat exchange pipeline is connected at the end to a chimney pipe led outside through the wall of the house.

• It should be noted that if the bench is made of brick, the channels can also be laid out of this material, without the use of metal corrugated pipes.
• The heated stove and bed, releasing heat into the room, will themselves serve as a kind of “battery”, capable of heating an area of ​​up to 50 m2.

The metal drum of the furnace can be made of a barrel, gas cylinder or other durable containers, and also made of brick. Usually the material is chosen by the craftsmen themselves according to the financial opportunity and ease of use.

A rocket stove with a brick bench looks neater and is somewhat easier to install than a clay version, but the cost of materials will be about the same.

Video: one more original solution increasing the heating efficiency of the rocket furnace

We build a rocket stove with a stove bench out of brick

What is needed for the job?

The brick heating structure proposed for execution is designed on the principle of a rocket stove. The size of the structure with standard brick parameters (250×120×65 mm) will be 2540×1030×1620 mm.

It should be noted that the design is divided into three parts:

• The oven itself – its size is 505? 1620? 580 mm;
• Firebox – 390?250?400 mm;
• Bed 1905×755×620 mm + 120 mm headrest.

To lay the stove you will need the following materials:

• Red brick – 435 pcs.;
• Blower door 140×140 mm – 1 pc.;
• Cleaning door 140×140 mm – 1 pc.;
• A fire door is desirable (250×120 mm - 1 piece), otherwise there is a risk of smoke in the room.
• Hob 505×580 mm – 1 pc.;
• Rear metal shelf panel 370×365 mm – 1 pc.;
• Asbestos sheet 2.5-3 mm thick to create a gasket between metal elements and brick.
• Chimney pipe, 150 mm in diameter, with a 90? outlet.
• clay and sand for mortar or a ready-made heat-resistant mixture. It should be noted here that for 100 bricks laid flat, with a joint width of 5 mm, 20 liters of mortar will be required.

The design of this rocket stove with vertical loading is quite simple, trouble-free and efficient in operation, but only if its masonry is done with high quality, in full accordance with the order.

If you have no experience as a mason or stove maker, but great desire To install such a heating device yourself, you should play it safe, and first lay the structure “dry”, without mortar. This process will help you figure out the location of the bricks in each row.

In addition, to ensure that the seams are the same width, it is recommended to prepare gauge wooden or plastic slats for masonry, which will be laid on the previous row before laying the next one. Once the solution has set, it will be easy to remove them.

Under the laying of such a stove it is necessary to have a flat and solid foundation. Despite the fact that the design is quite compact and its weight is not as great as, for example, a Russian stove, a floor laid with thin boards will not be suitable for its installation. In the case where the floor, although wooden, is very durable, before starting laying under the future stove, it is necessary to lay and secure a heat-resistant material, for example, asbestos 5 mm thick.

Order of a brick rocket stove with a stove bench:

Illustration	Brief description of the operation performed
	The first row is laid out solid, and the brick must lie in exact accordance with the pattern shown in the diagram - this will give strength to the entire base. For masonry you will need 62 red bricks. The diagram clearly shows the connection of all three sections of the furnace. The corners on the side bricks of the firebox facade are cut off or rounded - this way the structure will look neat.
	Second row. At this stage of the work, internal smoke exhaust channels are laid through which gases heated in the firebox will pass, giving off heat to the bricks of the stove bench. The channels connect to the combustion chamber, which also begins to form in this row. The first brick of the wall separating the two channels under the stove bench is cut diagonally - this “nook” will collect unburnt combustion products, and the cleaning door installed opposite the bevel will allow you to easily clean it. To lay a row you will need 44 bricks.
	On the second row, the doors of the blower and cleaning chambers are mounted, which are necessary for periodically tidying up the ash chamber and internal horizontal channels. The doors are secured with wire, which is twisted onto the ears of the cast iron elements and then inserted into the masonry seams.
	Third row. It almost completely repeats the configuration of the second row, but, of course, taking into account the laying in a bandage, and therefore it will also require 44 bricks.
	Fourth row. At this stage, the channels running inside the couch are blocked with a continuous layer of brick. A firebox opening is left, and a channel is formed that will heat the hob and discharge combustion products into the chimney pipe. In addition, a rotating horizontal channel is blocked from above, which removes heated air under the stove bench. To lay a row you need to prepare 59 bricks.
	Fifth row. The next stage is covering the bed with a second cross layer of brick. The smoke exhaust ducts and firebox also continue to be removed. 60 bricks are prepared for a row.
	Sixth row. The first row of the headrest of the couch is laid out, and the part of the stove on which the hob will be installed begins to rise. It still has smoke exhaust ducts. A row requires 17 bricks.
	Seventh row. The laying of the headrest is completed, for which bricks cut diagonally are used. The second row of the base under the hob rises. Laying will require 18 bricks.
	Eighth row. The furnace structure with three channels is being laid. You will need 14 bricks.
	The ninth and tenth rows are similar to the previous, eighth, they are laid out according to the same pattern, alternately, intertwined. 14 bricks are used for each row.
	11th row. Continuation of masonry according to the scheme. This row will take 13 bricks.
	12th row. At this stage, a hole is formed for installing the chimney pipe. The hole supplied under the stove is equipped with a brick cut obliquely for a smoother flow of heated air into the adjacent channel leading to the lower horizontal channels located in the stove bench. 11 bricks were used per row.
	13th row. A base for the slab is formed, and the central and side channels are combined. It is through this that hot air will flow under the stove, and then flow into the vertical channel leading under the stove bench. 10 bricks are laid.
	13th row. On the same row, the base for laying the hob is prepared. To do this, a heat-resistant material - asbestos - is laid around the perimeter of the space in which two vertical channels were combined.
	13th row. Then, a solid metal plate is laid on the asbestos pad. In this case, it is not recommended to install a hob with opening burners, since when they open, smoke may enter the room.
	14th row. The opening for the chimney pipe is closed and the wall separating it is raised. hob from the bedding area. Only 5 bricks are used for a row.
	15th row. This row raising the wall will also require 5 bricks.
	15th row. On the same row, in continuation of the back wall, next to hob a metal shelf is fixed, which can be used as a cutting board. It is attached to brackets.
	15th row. The picture diagram shows well how a hob can be used. In this case, the pan is placed exactly on that section of the stove that will warm up first, since a hot air flow will pass under it.
	After completing all the work described in the order, a chimney pipe is built into the hole at the back of the stove, which is led out to the street.
	From the back, the design also looks quite neat, so it can be installed either near the wall or in the middle of the room. This stove is perfect for heating a country house. If the stove and chimney are decorated with finishing materials, then the structure can become an original addition, and a very functional one, for any private home. As you can see, the corner formed under the cutting shelf is very convenient for drying and storing firewood.
	To fully examine the structure, you need to see its projection from the end side.
	And the last picture clearly shows what should happen as a result of the work done, if you look at the stove from the side of the stove bench.

In conclusion, I would like to especially note that the design of a rocket furnace can be called one of the simplest and most accessible for self-made, compared to other heating devices. Therefore, if a similar goal has been set - to acquire a stove in the house, but there is clearly not enough experience in such work, then it is best to choose this option, since when building it, it is difficult to make a mistake in the configuration of its internal channels.

Simple and cheap design The rocket stove began its march around the world from North America, where it is still very popular in rural areas. It is known on all continents, including distant Australia. The heating unit captivates amateur enthusiasts with its simplicity and energy efficiency, which, combined with its low cost, makes it extremely attractive for manufacturing at home. Of course, with a jet furnace big house not to heat, but in a country house or in a small garden house it will be more than appropriate. Surprisingly, but true - only a few people know about this amazing design. And this is in a country where cold weather lasts longer than six months! Today we will fill this gap and tell you everything we know about the warm and cozy “rocket”, including the smallest details making it yourself and the subtleties of its operation.

Jet stove - what is it?

The home heat that comes from a jet stove cannot be provided by any modern heater.

A jet stove, or, as it is also called, a rocket stove, actually has nothing in common with modern technologies. The only thing that makes this heating unit look like a space vehicle is the intense flow of flame and the humming associated with improper operation. Nevertheless, it cannot be said that the rocket stove is a completely backward device in technical terms. Despite its simple design, it uses the most advanced methods of burning solid fuels:

• pyrolytic combustion of gases released during dry distillation of solid fuel;
• movement of gaseous products through the furnace channels, which does not require forced ejection due to draft.

This is what a simple jet-powered stove looks like

The simplest “rocket” is a curved piece of large diameter pipe. Firewood or other fuel is placed in a short horizontal section and set on fire. At first, the heating device works like an ordinary potbelly stove, but this is only until the temperature of the longer vertical part, which acts as a chimney, rises. The red-hot metal promotes the re-ignition of flammable substances and the appearance of a vacuum at the top point of the chimney. Due to increased draft, the air flow to the firewood increases, which significantly increases the burning intensity. In order to achieve even greater efficiency from this original device, the firebox opening is equipped with a door. When the cross-section of the air channel decreases, the supply of oxygen to the firewood stops and its pyrolytic decomposition into gaseous hydrocarbons begins. But in such a simple installation they will not burn completely - for this you will need to set up a separate area for afterburning the flue gases. By the way, it is this, as well as the thermal insulation of the chimney, that allows more complex “rockets” to successfully compete with other solid fuel units. As for the simplest design we are considering, it is often used for cooking or heating food. All that is required for this is to equip a convenient platform for a pot or kettle on the vertical section of the stove.

Geography of application of rocket heating units

Being a simple and convenient heating and cooking unit, the rocket stove is widely used in both mobile and stationary versions. Most often it is used:

• for heating residential premises;
• as equipment for drying fruits;
• for heating greenhouses;
• to ensure normal working conditions in workshops or garages;
• to maintain above-zero temperatures in warehouses, utility rooms, etc.

Thanks to its simplicity, unpretentiousness and reliability, the jet heater enjoys well-deserved respect among fishermen and hunters, car rally enthusiasts and survivalists. There is even a special version, the purpose of which is indicated by the name - “Robinson”.

Advantages and disadvantages of the rocket stove

Despite its simple design, the rocket stove has many advantages:

• efficiency level at the level of the best examples of modern heating equipment operating on solid fuel;
• efficiency - to achieve the required temperature, the reactive unit will consume four times less firewood than a traditional oven design;
• heating temperature above 1000 °C;
• the ability to use any type of solid fuel, including dry plant waste, cones, pine needles and shavings;
• complete combustion and environmental friendliness - during operation, the flame temperature increases so much that the soot ignites. Rocket stove smoke consists primarily of water vapor and carbon dioxide;
• possibility of additional fuel loading for continuous operation of the heating device;
• simplicity and reliability;
• the presence of portable structures intended for mobile use.

The heating unit is not without its drawbacks. Operation of the device is associated with the risk of penetration into the home carbon monoxide. The stove cannot be used for heating big house, and attempts to install a water heat exchanger in the combustion zone lead to a decrease in thermal power and disruption of normal operation. The disadvantages include the low aesthetic value of the design, which, however, is a very ambiguous statement, since for lovers of ethno-style, the design of the stove is a real find.

Types of jet heating devices. Choosing a design for self-production

Craftsmen have developed several designs of rocket stoves suitable for mobile or stationary use:

• portable units made of metal pipes, cans or buckets;
• jet heating devices from a gas cylinder;
• ovens built from fireclay bricks and metal containers;
• heating heat generators with a stove bench.

The most difficult to manufacture are the structures, the construction of which requires the skills of a mason. However, if you have detailed diagrams of serial layouts, even a novice home craftsman can handle this work.

Portable rocket stove

Portable rocket stoves are mass-produced by industry

Hiking options are represented by the simplest designs, which are based on the same pipe bent or welded from individual sections. The improvements affected only the installation of a partition for arranging the ash pit, in which a slot is made for air leakage. Often the lower part of the loading chamber is equipped with a grate to supply air directly to the combustion zone. The opening for storing firewood is equipped with a door, which subsequently regulates the air supply.

The requirements for a mobile design also extend to convenience during cooking, so the upper section of the chimney must be equipped with a stand for metal utensils.

Gas cylinder unit

The use of a gas cylinder is the next step in the development of jet heating devices. A more complex design can significantly increase the thermal power and efficiency of the furnace. Everything you need to make the installation is household gas cylinder or a barrel for fuel and lubricants, sections of thick-walled steel pipes and a metal sheet 3–5 mm thick.

A rocket stove made from a gas cylinder can be used to heat small utility rooms

If you have a piece of steel pipe with thick walls and a diameter of more than 30 cm, a rocket stove can be made from it. This option will allow you to avoid labor-intensive operations associated with disassembling the factory gas tank.

How such a design works can be seen in the diagram below. Firewood loaded into the firebox burns due to the flow of air through the loading window. Afterburning of combustible gases occurs in a pipe installed inside the cylinder due to the supply of secondary air. To enhance the effect, the inner chamber is insulated, which makes it possible to raise the temperature inside above 1000 °C. Hot gases hit the bell as they move and enter the outer chamber, the walls of which act as a heat exchanger. Having given up their energy, the combustion products are discharged through a chimney cut into the lower part on the back side of the cylinder.

To create the draft necessary for stable operation of the rocket stove, the top of the chimney is raised at least 4 m relative to the loading window.

Combined rocket stove made of brick and metal barrel

The use of fireclay bricks for arranging the firebox and internal chambers of a jet heating device transforms the “rocket” into the category of stationary structures. The high heat capacity of the materials used allows heat to be accumulated and released within several hours, which is why such units are often installed in residential premises.

Furnace structure with refractory lining of the working area

Jet stove with stove bench

Like other solid fuel stoves, the "rocket" has the disadvantage that most of the heat is lost through the chimney. Despite this, certain advantages of its design make it easy to get rid of this disadvantage. The thing is that the unit was called reactive for a reason, but because of the high rate of excision of burning gases. This feature can be turned into a benefit by significantly increasing the length of the smoke exhaust channels.

Scheme of a jet stove with a stove bench

This idea found its implementation in massive stationary structures with a couch in the shape of a sofa or bed. It is successfully made from brick or rubble stone, decorated with a plastic mass of clay and sawdust. Thanks to the high heat capacity of the materials used, the stove can retain heat all night, which, combined with high efficiency, makes the heating unit very attractive for installation in residential premises.

When choosing a design for manufacturing at home, you need to take into account the features of its operation. As a camping option, choose a mobile unit - it will be enough to warm up, dry clothes and cook lunch. In order to occasionally heat small technical rooms, a portable structure made from a gas cylinder is used. If you need to heat a small country house or cottage, then best option than a jet heating unit with a stove bench simply does not exist.

We build a rocket oven with our own hands

The design proposed for self-production is the elite of rocket heating devices. After construction, it will delight the owner for a long time with comfort and cozy warmth, even in the most severe frost. As you might have guessed, we are talking about a unit with a stove bench. Despite the fact that such a design is the most complex, the diagrams, instructions and descriptions we presented will allow you to build a stove in just 2-3 days.

Device and principle of operation

A rocket furnace consists of several chambers and channels. The bunker for loading firewood is made of fireclay bricks and is equipped with an opening in the lower part for air supply. It has a refractory lining and a channel that connects the firebox with a vertical flue (fire pipe or riser). A metal barrel is used as the casing of the rocket furnace, inside of which the afterburning chamber is lined with magnesite or fireclay bricks. The heat exchanger of the heating unit is not only a steel container, but also long horizontal channels of the stove bench made of galvanized steel pipes or bricks.

The processes occurring inside a stationary reactive furnace resemble the operation of pyrolysis heating units

There is no need to use refractory materials to construct heat exchange channels. A well-burnt red brick is sufficient.

The body of the stove and trestle beds is formed from sandbags, stone or brick fragments and coated with a clay composition. The good heat-storing ability of finishing materials allows the structure to release heat within several hours after the firewood has completely burned out. To remove combustion products, a high chimney is used, which can pass both indoors and outdoors.

The high performance of the “rocket” is explained by the method of fuel combustion, which tends not so much to direct-flow heating units as to pyrolysis boilers. The operation of the furnace is accompanied by the active release of gas components, which are burned in the riser. The cap helps reduce the flow rate of hot gases, otherwise they simply would not have time to oxidize. By the way, heating the upper part of the flame tube creates a vacuum at its end, due to which active combustion of the fuel occurs. In this case, the following appears in the riser: heat that even soot ignites. Nevertheless, at the point of transition from the vertical channel to the horizontal heat exchanger, experts recommend installing an ash pan, equipping its chamber with a small door to allow periodic maintenance.

Calculation of basic parameters, drawing

Giving exact dimensions There is no need for a rocket stove with a stove bench - its dimensions and configuration completely depend on the characteristics of the room. The presented method for calculating parameters, based on the use of the proportions of all parts of the rocket furnace, will be quite sufficient to design a high-performance, efficient unit.

To perform the calculation, it is enough to know the diameter D and height H of the external heat exchange casing (drum).

1. The height of the flame tube is at least 1.3H.
2. The gap between the riser and the cap is 0.1–0.15H.
3. External clay coating is carried out no higher than 1/3H.
4. The thickness of the heat-accumulating layer should be no more than 1/3D.
5. The cross section of the flame tube is 0.25–0.3D.
6. The height of the ash pan is up to 10% of the vertical dimensions of the casing.
7. The cross-section of the blower should be 50% smaller than the riser area.
8. The thickness of the adobe cushion above the heat exchanger is at least 1/4D.
9. The chimney height is more than 4 m.
10. The length of the horizontal heat exchanger is calculated based on the volume of the drum. If a standard fuel barrel is used, it can reach 6–8 m.

As you can see, it is not difficult to determine the dimensions of all elements of the furnace, especially since its design allows for some liberties in terms of dimensions and configuration.

For perfectionists and those who are afraid to experiment, we present a drawing of a heating unit, drawn to scale on a marked sheet of paper. If necessary, taking exact dimensions from it will not be difficult.

Drawing of a stationary jet heating installation

Materials and tools

The construction of a jet furnace does not require any special equipment. The only power tools required during the work process are a welding machine and an angle grinder, and even then just for a few minutes - to separate the barrel lid and configure the heat exchanger pipes. Any owner can also find everything else:

• trowel (trowel);
• bushhammer;
• building level and plumb line;
• roulette;
• container for preparing the solution;
• bayonet shovel;
• tamping;
• buckets;
• concrete trowel.

Although the design of the “rocket” is undemanding in terms of materials, you will still have to buy some of them. Here is a list of what will be needed during the construction process:

• refractory bricks of any type;
• metal barrel for making a casing;
• a pipe Ø30–40 cm, which will hold the thermal insulation coating of the vertical channel. You can use the housing from an old water heater, a suitable capacity of an industrial receiver or a hydraulic accumulator;
• galvanized steel pipes with a diameter of more than 25 cm, which will be needed as a heat exchanger;
• a steel pipe for arranging a chimney with a diameter of 150 mm and an elbow for its outlet at 90°;
• ash pan hatch;
• blower door;
• a special heat-resistant mixture for preparing the solution (can be replaced with sand and clay);
• perlite for thermal insulation of the riser;
• Red brick;
• rubble stone or brick waste;
• sawdust or chaff.

Since the barrel will be only partially embedded in the oven, it will have to be painted to increase the aesthetic value of the unit. To do this, you will additionally need a metal brush, a solvent to degrease the metal surface, a primer and any heat-resistant paint.

Site selection and other preparatory activities

When determining the construction site, you should take into account the requirements that apply to all designs of solid fuel stoves with an open flame:

• the area of ​​the room in which it is planned to install a jet heating device with a sunbed must be at least 16 m2;
• the absence of logs (floor beams) under the stove body will greatly simplify installation;
• there should be no wooden rafters or ceilings above the fireplace;
• if part of the chimney passes through the ceiling, then the stove is installed closer to the central part of the house. In this case, the pipe can be secured near the ridge;
• You should not install a heating structure close to the outer contour of the building - precious heat will go outside. It is better to attach the unit to one of the internal walls;
• It is not recommended to build a jet device near wooden walls and partitions. In this case, separate accommodation is chosen.

It is also important how convenient it will be to light the rocket stove and throw firewood into it. To do this, the firebox is placed towards the entrance, providing at least 1 m of free space in front of it.

One of the many options for installing a stove in the middle of the room

In a small room, it is convenient to place a rocket stove in the corner, with the loading hopper oriented in one direction and the lounger in the other.

Having chosen a place, they begin to prepare it for future construction. If the room has a wooden floor, then the part of it that will be under the stove is removed. After this, a shallow pit is dug, the bottom of which is compacted using a tamper.

In addition, it is necessary to prepare a metal barrel for installation. To do this, cut off its cover along the contour. In this case, part of the thickening in the form of a metal hoop is left to ensure the rigidity of the base of the casing. Most likely, the fuel container will be dirty and rusty, so it is better to clean it before installation.

The last thing to do before starting construction is to prepare the solution. It is best to use a special heat-resistant composition, which can be bought in construction stores, but you can get by with a simple mixture of sand and clay in a ratio of 1:1 or 1:2, depending on the fat content of the latter. Water will be needed up to ¼ of the volume of dry ingredients - the output should be a composition reminiscent of thick sour cream.

Instructions for the progress of work

As already mentioned, to make a rocket stove with a stove bench, it will take much more effort and time than when making a metal unit. It will help make the task easier and reduce time step-by-step instruction with illustrations of all stages of construction.

1. The place where the firebox will be formed is deepened by 10 cm and laid out with refractory bricks, after which formwork is installed along the contour of the furnace. To strengthen the foundation, it is necessary to install reinforcement from construction mesh, fittings Ø10–20 mm or scraps of metal pipes and angles.

   

   Arrangement of formwork

2. Lay out the base of the working chamber according to the level.

   

   The base of the loading chamber is lined with refractory bricks

3. The structure is poured with concrete. Further work can begin immediately after the solution has set. As a rule, one day is enough for this.

   

   Pouring the foundation

4. The base of the jet furnace and the combustion chamber are formed from refractory bricks laid in a continuous pattern.

   

   Rocket stove base

5. Several rows of masonry raise the side walls of the structure.

   

   The walls are formed using fireclay bricks installed on the edge

6. The lower channel of the heat-generating rocket is being equipped.
7. The combustion chamber is covered with a row of bricks laid transversely in such a way as to leave two openings open - the firebox and the riser (vertical channel).

   

   Method of covering the horizontal part of the working chamber

8. An old casing from a storage boiler is prepared for installation. To do this, the device is cut off on both sides to obtain a large-diameter pipe.

   

   Furnace parts prepared for installation

9. The lower part of the fuel and lubricants container is equipped with a flange into which the horizontal heat exchanger pipe will fit. Welds must be continuous to ensure tightness and, accordingly, safety of the structure.

   

   Installation of the lower pipe is carried out by welding

10. After the outlet pipe is cut into the barrel, it is cleaned of rust, coated with a primer and several layers of heat-resistant paint.
11. A side outlet is welded to the horizontal chimney, acting as an ash pit. To clean it, the channel is equipped with a sealed flange.
12. A fire tube is made of fireclay bricks. The shape of its internal channel is a square with a side of 18 cm. During work, be sure to control the vertical position of the structure using a plumb line or a building level.

    

    The height of the vertical channel depends on the size of the outer drum

13. A casing is installed on the flame tube, after which the gaps between the metal container and the walls of the vertical channel are filled with perlite. To avoid spillage of thermal insulation on the floor, the lower part of the riser is carefully sealed using a clay mixture.

    

    Riser thermal insulation method

14. The firebox cap is made. You can use a cut-off part of the water heater as it, providing it with a comfortable handle.
15. The furnace body is formed using brick or stone masonry. For this purpose, you can also use sandbags placed at the base of the vertical channel.

    

    The oven body can be lined with sandbags

    The unassuming spring appearance is hidden with the help of adobe coating. To make it, up to 50% of large particles are added to the clay solution. sawdust or chaff (chaff).

    

    Coating the furnace body

    Additives in a clay mixture perform the same role as crushed stone in concrete. They are needed so that during drying and subsequent work with variable thermal loads, the surface of the furnace does not crack.

16. The perlite backfill on top also needs to be sealed with coating.
17. The front part of the oven is formed. To do this, lay out the outline of the stove using any suitable method (brick or stone masonry, sandbags, adobe). The inner part is filled with crushed stone, and the upper part is given the required form using adobe mixture.
18. An outer casing made of metal barrel, orienting the container with the lower pipe towards the bed. The lower part of the container is sealed with clay.

    

    Installation of a casing - a metal barrel

19. Using a corrugated pipe, a channel is led to the firebox, which connects the firebox to the external atmosphere. If it is not installed, the stove will consume warm air from the room, which will be replaced by cold masses coming from outside. On the side of the firebox, the channel will need to be closed as soon as the firewood is completely burned out. This will not allow air from the street to penetrate into the heat exchange channels.

    

    Duct for supplying air from outside the building

20. To check the operation of the rocket stove, the first kindling is carried out, during which they make sure that the gases freely exit into the horizontal chimney.
21. Heat exchanger pipes are connected to the lower pipe, which are installed on a base formed of red brick.
22. The chimney is being installed. All connections of parts of horizontal and vertical channels are sealed using asbestos cord and fire-resistant coating.
23. Using the same method as in the manufacture of the stove body, give the required configuration to the stove bench.

    

    Fully formed oven with bench

24. The barrel can be completely covered with adobe, leaving only the horizontal platform open, which is convenient to use for heating food.
25. The chimney brought outside is equipped with a condensate and tar trap, and the upper cut is protected from precipitation using a cap.

    

    The outer part of the chimney is equipped with a liquid trap

Tests of the rocket furnace are carried out only after the adobe coating has completely dried. Otherwise, the decorative coating may crack.

View of the finished rocket stove with a stove bench

For safe operation of a rocket stove, the room must be equipped with carbon monoxide sensors.

Modernization of rocket heat generator

To expand the scope of reactive heating stoves, they are being modified, increasing the convenience and versatility of the design. In mobile structures, the platform intended for cooking is often replaced with a full-fledged stove. It is convenient to use such a hob in your own backyard for household purposes - for preparing food for pets or during the period of preserving food for the winter. A special feature of this type of rocket furnace is a wide and flat horizontal channel into which hot gases from the nozzle are directed. Passing under the surface of the stove, they heat it red-hot, after which they go into the vertical chimney. Comfortable legs give the structure stability, and the original shape allows the unit to be used as a stand or table when it is not in use for its intended purpose.

Jet stove with stove - necessary thing on a country plot

A liquid heat exchanger cannot be installed in the flame tube of a jet furnace, but this does not mean that it cannot be used as a heat generator in a water heating system. To do this, the “rocket” is equipped with a kind of circuit of radiator plates, which create a kind of labyrinth in the afterburning zone. Thanks to their heating, heat is removed from the afterburning chamber to the water jacket. The efficiency of the unit depends on the area and heat capacity of the plates, so they are made in the form of massive metal strips with an area of ​​up to ¾ of the cross-section of the fire channel. It must be said that such a heat exchanger is best used to produce hot water using the rocket stove itself in the traditional way.

Diagram of a rocket unit equipped with a water circuit

The rocket stove with a convector has an original design. To increase heat transfer, vertical tubes are mounted on the surface of the outer casing, performing the same role as the air channels of the buleryan. Cold air is trapped at the bottom of the tube heat exchangers and is heated as it moves upward. This ensures forced convection, which further increases the thermal efficiency of the installation.

Rocket heat generator casing equipped with a convector

Features of using reactive furnaces

Being a long-burning system, the rocket stove requires preheating before use. As a rule, in mobile installations no one complies with this requirement - they consume little fuel, and the potbelly stove itself is most often used on the principle of “it works, and that’s okay.” In stationary structures, warming up the furnace before starting is extremely important, since with a cold flame tube there can be no question of afterburning. The wood will burn without giving off heat, and the chimney will very quickly become covered with soot, tar and creosote.

The stove is heated using wood chips, paper or shavings, which are loaded into the firebox and set on fire. Reaching operating mode is judged by a humming sound in the heat channel. A loud sound indicates ineffective operation of the unit. As soon as the hum begins to subside, you need to start adding the main fuel. The vent should be completely open for the first 10–15 minutes. Then the air supply is reduced, focusing on the sound of the stove - it should “rustle” or “whisper”. After the wood burns out, the air duct of the firebox is covered to prevent heat from escaping from the room. Once every 2-3 days, ash is removed using a metal scoop and poker.

Maintenance of the jet stove is carried out no more than once a season. To do this, open the ash pan door, through which the remaining soot is removed. If necessary, clean the smoke channel using the hatch of its trap. I must say that correct operation jet heater never leads to smoke in the room. All that is required of the owner is to follow the recommendations for using the “rocket” and not neglect safety rules.

DIY rocket stove: subtleties and nuances of construction (video)

Unique specifications, almost zero cost and availability of materials for construction cover all the disadvantages of the jet furnace. If you wish, you can build a full-fledged heating device over the weekend, including arranging a comfortable couch. “Rocket” is also convenient because it does not require highly qualified stove-maker, and in its external design it allows the implementation of even the most unusual design concept.

Let's say right away: the rocket stove is a simple and convenient heating and cooking device using wood fuel with good, but not exceptional parameters. Its popularity is explained not only by its catchy name, but moreover by the fact that it can be made with one’s own hands and not by a stove maker or even a mason; if necessary - literally in 15-20 minutes.

And also because, by investing a little more work, you can get a wonderful bed in your home without resorting to building a complex, expensive and bulky Russian or bell-type stove. Moreover, the very principle of the design of the rocket stove gives greater freedom to design and the manifestation of creativity.

Rocket stove - wood fuel device

But what is perhaps more remarkable is the “jet furnace” for the huge number of, at times, completely absurd inventions associated with it. Here, for example, are a few pearls snatched at random:

• “The principle of operation of the furnace is the same as that of the MIG-25 ramjet engine.” Yes, the MIG-25 and its descendant MIG-31 did not even sit down in the bushes near the ramjet engine (ramjet engine), as they say. The 25th and 31st are powered by double-circuit turbojet engines (turbojet engines), four of which later pulled the Tu-144 and still power other vehicles. And any stove with any jet engine (RE) is technical antipodes, see below.
• "Reverse jet thrust furnace." Is the stove flying tail first, or what?
• “How will she blow through such a pipe?” A non-pressurized oven does not blow into the chimney. On the contrary, the chimney draws from it, to natural craving. The higher the pipe, the better the pull.
• “The rocket stove is a combination of a Dutch bell stove (sic!) with a Russian stove bench.” Firstly, there is a contradiction in the definition: a Dutch oven is a channel oven, and any bell-type oven is anything but a Dutch oven. Secondly, the bed of a Russian stove warms up completely differently than a rocket stove.

Note: in fact, the rocket stove was so nicknamed because in the wrong firing mode (more on that later), it makes a loud whistling hum. A properly tuned rocket stove whispers or rustles.

These and similar inconsistencies, understandably, confuse and prevent you from making a rocket stove properly. So let's figure out what the truth is about the rocket stove, and how to use this truth correctly so that this really good stove shows all its advantages.

Furnace or rocket?

For complete clarity, we still need to figure out why a stove cannot be a rocket, and a rocket cannot be a stove. Any RD is the same as an internal combustion engine, only the escaping gases themselves act as pistons, connecting rods with a crank and transmission. In a piston internal combustion engine, already at the moment of combustion, the high temperature of the working fluid creates a lot of pressure, which pushes the piston, and it moves all the mechanics. The movement of the piston is active, the working fluid pushes it to where it itself tends to expand.

When fuel is burned in the combustion chamber of the thruster, the thermal potential energy of the working fluid is immediately converted into kinetic energy, like that of a load falling from a height: since the outlet for hot gases is open to the nozzle, they rush there. In the RD, the pressure plays a subordinate role and nowhere exceeds the first tens of atmospheres; this, for any conceivable nozzle cross-section, is not enough to accelerate the migar to 2.5 M or launch a satellite into orbit. According to the law of conservation of momentum (amount of motion), the aircraft with a taxiway receives a push in reverse side(recoil impulse), this is jet thrust, i.e. thrust from recoil, reaction. In a turbofan engine, the second circuit creates an invisible air shell around the jet stream. As a result, the recoil impulse is, as it were, contracted in the direction of the thrust vector, so a turbofan engine is much more economical than a simple turbofan engine.

In a stove there is no conversion of energy types into each other, therefore it is not an engine. The stove simply distributes potential thermal energy properly in space and time. From the point of view of the furnace, an ideal RD has an efficiency = 0%, because it only pulls due to fuel. From the point of view of the jet engine, the stove has an efficiency of 0%, it only dissipates heat and does not draw at all. On the contrary, if the pressure in the chimney rises to or above atmospheric pressure (and without this, where will the jet thrust or active force come from?), the stove will at least smoke, or even poison the residents or start a fire. The draft in the chimney is without pressurization, i.e. without external energy consumption, it is ensured due to the temperature difference along its height. Potential energy here, again, is not converted into any other energy.

Note: in a rocket RD, fuel and oxidizer are supplied to the combustion chamber from the tanks, or they are refueled directly into it if the RD is powered by solid fuel. In a turbojet engine (TRE), the oxidizer is atmospheric air– is pumped into the combustion chamber by a compressor driven by a turbine in the exhaust gas flow, the rotation of which consumes some of the energy of the jet stream. In a turboprop engine (TVD), the turbine is designed so that it selects 80-90% of the jet power, which is transmitted to the propeller and compressor. In a ramjet engine (ramjet), the air supply to the combustion chamber is ensured by hypersonic speed pressure. A lot of experiments have been carried out on ramjet engines, but there have been no production aircraft with them, there are none, and there are no plans to do so, as ramjet engines are too capricious and unreliable.

Kan or not Kan?

Among the myths about the rocket stove, there are some that are not entirely absurd, and even somewhat justified. One of these misconceptions is the identification of the “racket” with the Chinese kan.

The author had the opportunity to visit the Amur region in winter, in the Blagoveshchensk region, as a child. Even then there were a lot of Chinese living in the villages there, fleeing in all directions from the cultural revolution of the Great Chairman Mao and his completely frostbitten Red Guards.

Winter in those parts is not like Moscow, frost of -40 is common. And what amazed and aroused interest in stoves in general was how Chinese fanzas were heated by canals. Firewood is transported to Russian villages by carts, and smoke comes out of the chimneys in a column. And all the same, in a hut made of logs not the size of a child’s girth, by morning the corners from the inside were frozen. And the fanza is built like a country house (see picture), the windows are covered with fish bladder or even rice paper, bunches of wood chips or twigs are placed in the can, but the room is always warm.

However, there are no subtle thermal engineering wisdom in the can. This is an ordinary one, only small, kitchen stove with a lower exit into the chimney, and most of the chimney itself is a long horizontal channel, a hog, on which a stove bench is located. The chimney, for fire safety reasons, is outside the building.

The effectiveness of the can is determined primarily by the thermal curtain it creates: the couch goes around, if not the entire perimeter from the inside, except for the door, then certainly 3 walls. Which once again confirms: the design and parameters of the stove must be linked to those of the heated room.

Note: the Korean ondol stove operates on the principle of a warm floor - a very low stove occupies almost the entire area of ​​the room.

Secondly, in the very cold, the Kans were drowned with argal - the dried droppings of ruminant animals, domestic and wild. Its calorific value is quite high, but argal burns slowly. In fact, an argal fire is already a long-burning stove.

It is not the Russian custom to constantly stick twigs into the oven, and our men disdained to cook food in cattle feces. But travelers of the past highly valued argal as a fuel; they collected it along the way and took it with them, carefully protecting it from getting wet. N. M. Przhevalsky in one of his letters stated that without argal he would not have been able to conduct his expeditions in Central Asia without losses. And the British, who disdained argal, had 1/3-1/4 of the detachments’ personnel returning to base. True, he was recruited from sepoys, Indian soldiers in English service, and pandits - spies recruited from the local population. One way or another, the highlight of the rocket stove is not at all the bed on the hog. To get to it, you will have to learn to think like an American: all the primary sources on the rocket furnace are from there, and utter speculation is generated only and only by misunderstanding.

How to deal with rockets?

With our view of things, it is necessary to study the original technical documentation of rocket stoves with caution, but not at all because of inches-millimeters, liters-gallons and the intricacies of American technical jargon. Although they also mean a lot.

Note: a textbook example is “Naked conductor runs under the carriage.” Literary translation - a naked conductor runs under the carriage. And in the original Petroleum Engineer article, this meant “Bare wire runs under the crane trolley.”

The rocket stove was invented by members of survival societies - people with a unique way of thinking, even by American standards. In addition, they were not bound by any standards and norms, but, like all Americans, they automatically always converted everything into money, taking into account their own benefit; a person with a different worldview simply will not get along in America. And instinctive self-interest inevitably gives rise to egocentrism. He by no means excludes good deeds, but not out of spiritual impulse, but with the expectation of dividends. Not in this life, so in that one.

Note: How afraid the average citizen of the greatest empire in history is of everything can only be understood by talking to them long enough. And sociopsychologists go out of their way to convince you that living in fear is normal and even cool. The rationale is clear: intimidated biomass is easily predictable and manageable.

Without heating and cooking, of course, you cannot survive. What is a stove for? For the time being, survivors were content with camp stoves. But then, according to the Americans themselves, in 1985-86. they were greatly impressed by two films that were released with a short interval and triumphantly went around all the screens of the world: the Soviet science fiction parody of the entire human race “Kin-dza-dza” and the Hollywood “The Day After”, about the global nuclear war.

The survivors realized that after the nuclear winter there would be no extreme romance, but there would be the planet Plyuk in the Kin-dza-dza galaxy. The newly-minted plukans will have to be content with “ka-tse” in small quantities, bad, expensive and difficult to obtain. Yes, in case anyone hasn’t watched “Kin-dza-dza” - ka-tse in Plyukan style, a match, a measure of wealth, prestige and power. It was necessary to come up with your own furnace; none of the existing ones are designed for post-nuclear blast.

Americans are very often endowed with a sharp mind, but a deep mind is found as a rare exception. A completely normal US citizen with an IQ above average may sincerely not understand how it is that someone else does not get what he himself has already “caught up with” and how someone else may not like what suits him.

If an American has already understood the essence of the idea, then he brings the product to its possible perfection - what if a buyer is found, you can’t sell raw iron. But technical documentation, which looks beautiful and neat, can be drawn up extremely carelessly, or even deliberately distorted. What's wrong with this, this is my know-how. Maybe I'll sell it to someone. Either there will be a trick or not, but for now know-how costs money. In America, such an attitude to business is considered quite honest and worthy, but there, a clinical alcoholic at work as a stopper would never miss a job and wouldn’t take a couple of bolts home for the farm. That, in general, is what all of America stands for.

And Russian breadth of soul is also a double-edged sword. Most often, just from the sketch, our master immediately understands how this thing works, but in the details he turns out to be careless and overly trusting of the source code: how is it for a fellow craftsman to deceive his own man. If something isn’t there, well, it’s not necessary. It seems clear how everything is spinning there - my hands are already itching. And then, perhaps, until it comes to the hammer, chisel and accompanying literature, still counting and counting. Moreover, important points can be omitted, veiled or deliberately incorrect.

Note: an American acquaintance once asked the author of this article - how did we, really stupid ones, choose the very smart Reagan as president? And you, who are really smart, tolerate a slobbering senile with dyed eyebrows in the Kremlin? True, then in America no one in a bad dream would have dreamed that in the next century a black citizen with a Muslim name would be installed in the Oval Office, and his first lady would dig up a vegetable garden near the White House and begin to grow turnips there. Times is changing, as Bob Dylan once sang for a completely different reason...

Sources of misunderstandings

There is such a thing in technology - the square-cube law. Simply, when the size of something changes, its surface area changes by the square, and its volume changes by the cube. Most often this means changing the overall dimensions of the product according to the principle of geometric similarity, i.e. You can't just keep the proportions. In relation to solid fuel stoves, the square-cube law is doubly valid, because the fuel also obeys it: it releases heat from the surface, and its reserve is contained in the volume.

Note: a consequence of the square-cube law - any specific stove design has a certain permissible range of its size and power, within which the specified parameters are ensured.

Why, for example, can’t you make a potbelly stove the size of a refrigerator and with a power of about 50-60 kilowatts? Because a potbelly stove, in order for it to provide any heat, must itself be heated inside to at least 400-450 degrees. And in order to warm up the volume of the refrigerator to such a temperature at a given heat transfer, you need as much firewood or coal as will not fit in it. A mini-potbelly stove will also be of no use: the heat will escape through the outer surface of the stove, which has grown relative to its volume, and the fuel will not release more of it than it can.

The square-cube law applies threefold to the rocket stove, because she is “polished” in an American professional way. With our kondachka it is better to stay away from her. For example, here in Fig. an American development, which, judging by its demand, many of our craftsmen take as a prototype.

Original drawing of a mobile rocket oven

The fact that the exact type of fire clay is not indicated here will be sorted out by ours. But, to be honest, who noticed that, judging by the absence of an external chimney and the presence of transportation holes (carrying pipe), this stove is mobile with an open firebox? And most importantly - the fact that her drum used a 20-gallon barrel with a diameter of 17 inches (431 mm with change)?

Judging by the designs from the RuNet - no one at all. They take this thing and adjust it according to the principle of geometric similarity to a domestic 200-liter barrel with a diameter of 590 mm on the outside. Many people think of setting up a ash pit, but the bunker is left open. The exact proportions of vermiculite and perlite for lining the riser and molding the furnace body (core) are not specified? We make the lining homogeneous, although from what follows it will be clear that it should consist of an insulating and accumulating part. As a result, the stove roars, it only eats dry fuel, and a lot of it, and before the end of the season it becomes covered in smoke inside.

How was the rocket stove born?

So, without science fiction and futurology, the survivalists needed a stove to heat the house, working with high efficiency on low-quality random wood fuel: wet wood chips, twigs, bark. Which, in addition, will need to be reloaded without stopping the furnace. And it most likely won’t be possible to dry it in a woodshed. Heat transfer after heating is needed for at least 6 hours to get enough sleep; getting burned in your sleep on Plyuk is no better than in America. Additional conditions: the design of the furnace should not contain complex metal products, non-metallic materials and components that require production equipment for manufacturing, and the furnace itself must be accessible for construction by an unskilled worker without the use of power tools and complex technologies. Of course, no supercharging, electronics or other energy dependencies.

They immediately took a bed from the kana, but what about the fuel? For a bell-type furnace, it requires high quality. Long-burning stoves even operate on sawdust, but only dry ones, and do not allow stopping with additional loading. They were nevertheless taken as a basis; the high efficiency achieved was very attractive in simple ways. But in attempts to make “long stoves” work on bad fuel, another circumstance became clear.

What is wood gas?

The high efficiency of long-burning furnaces is achieved largely due to the afterburning of pyrolysis gases. Pyrolysis is the thermal decomposition of solid fuel into volatile combustible substances. As it turned out (and the survivors have their own research centers with highly qualified specialists), the pyrolysis of wood fuel, especially wet wood, continues for quite a long time in the gas phase, i.e. The pyrolysis gases that have just been released from the wood still require quite a lot of heat to form a mixture that can burn out completely. This mixture was called wood gas.

Note: in RuNet, woodgas has created further confusion, because... in American vernacular gas can mean any fuel, cf. eg gas station - gas station, gas station. When translating primary sources without knowing American technical knowledge, it turned out that woodgas is simply wood fuel.

Before that, no one had seen wood gas: in conventional stoves it is formed immediately in the firebox, due to the excess energy of flaming combustion. The designers of long-burning furnaces came to the conclusion that the primary air needs to be heated, and the exhaust gases must be retained in a significant volume over a large mass of fuel, simply by trial and error, so they also overlooked wood gas.

This was not the case when burning bundles of twigs: here the draft immediately pulled the primary pyrolysis gases into the chimney. Wood gas could have formed in it at some distance from the firebox, but by that time the primary mixture had cooled, pyrolysis stopped, and heavy radicals from the gas settled on the walls of the chimney as soot. Which quickly tightened the channel completely; Hobbyists who build rocket stoves at random are familiar with this phenomenon. But the survival researchers eventually realized what was going on, and still made the necessary stove.

Who are you, the Rocket Stove?

There is an unspoken rule in technology: if it seems that it is impossible to create a device according to the given requirements, then read, smart guy, school books. That is, go back to basics. In this case, to the basics of thermodynamics. Survivors do not suffer from sick pride; they turned to the basics. And they found the main operating principle of their furnace, which has no analogues in others: slow adiabatic afterburning of pyrolysis gases in a weak flow. In long-burning furnaces, afterburning is equilibrium isothermal, requiring a large buffer volume subject to the square-cube law and an energy reserve in it. In pyrolysis gases in the afterburner expand almost adiabatically, but almost into the free volume. And now we are learning to think like an American.

How does a rocket stove work?

A diagram of the final fruit of the survivors' labors is shown on the left side of Fig. Fuel is loaded vertically into the bunker (Fuel Magazine) and burns, gradually settling down. Air enters the combustion zone through the ash pan (Air Intake). The blower should provide excess air so that it is enough for afterburning. But not excessive so that cold air did not cool the primary mixture. With vertical loading of fuel and a blind hopper lid, the flame itself acts as a regulator, although not very effective: when it gets too hot, it pushes out the air.

Construction of rocket furnaces

Then things begin to become non-trivial. We need to heat up a large oven with good efficiency. The square-cube law does not allow it: the meager heat will immediately dissipate so much that pyrolysis will not reach the end, and the thermal gradient from the inside to the outside will not be enough to transfer heat into the room; everything will whistle down the pipe. This law is harmful, you can’t break it in the forehead. Okay, let's look at the basics to see if there is anything there that is beyond his control.

Well, yes, there is. The same adiabatic process, i.e. thermodynamic without heat exchange with the environment. There is no heat exchange - the squares rest, and the cubes can be reduced either to a thimble or to a skyscraper.

Let's imagine a volume of gas completely isolated from everything else. Let's say energy is released in it. Then the temperature and pressure will begin to increase until the energy release stops and freeze at a new level. Great, we have completely burned the fuel, hot flue gases can be released into a heat exchanger or heat accumulator. But how to do this without technical difficulties? And most importantly, how to supply air for afterburning without violating the adiabatics?

And we will make the adiabatic process nonequilibrium. How? Let the primary gases immediately from the combustion source go into a pipe covered with high-quality insulation with a low intrinsic heat capacity (Insulation). Let’s call this pipe a fire tube or a combustion tunnel (Burn Tunnel), but we won’t sign it (know-how! If you don’t catch up, give us money for drawings and consultations! Without theory, of course. Who sells fixed capital at retail.) On the diagram, so that not accused of “opacity”, let’s denote it with flame.

Along the length of the flame tube, the adiabatic index changes (this is a nonequilibrium process): the temperature first drops slightly (wood gas is formed), then increases sharply, and the gas burns out. You can release it into the accumulator, but we forgot - what gases will be pulled through the flame tube? Supercharging means energy dependence, and there will not be an exact adiabatic, but something mixed with an isobar, i.e. efficiency will drop.

Then we will lengthen the pipe by half, maintaining the insulation, so that the heat does not go away in vain. We bend the “idle” half up, making the insulation on it weaker; We’ll think about how to preserve the heat seeping through it a little later. In a vertical pipe there will be a temperature difference in height, and, therefore, draft. And a good one: the thrust force depends on the temperature difference, and with an average temperature in the flame tube of about 1000 degrees, it is not difficult to achieve a difference of 100 at a height of about 1 m. So, while we have made a small, economical stove-stove, now we need to think about how to use its heat.

Yes, it doesn’t hurt to further encrypt it. If we call the vertical part of the flame tube the primary or internal chimney(Primary or Internal Vent), then they will guess the main idea, we are not the smartest in the world. Well... let's call the primary chimney the most common technical term for vertical pipelines with rising current – ​​riser. Purely American: correct and unclear.

Now let's remember about heat transfer after heating. Those. we need a cheap, always available and very capacious heat accumulator. There is nothing to invent here; adobe (Thermal Mass) was invented by the primitives. But it is not fire-resistant, it does not hold more than 250 degrees, and at the mouth of the riser we have about 900.

It is not difficult to convert high-potential heat into medium-potential heat without losses: you need to give the gas the opportunity to expand in an isolated volume. But, if you leave the expansion adiabatic, then the volume needed is too large. This means it is material and labor intensive.

I had to go back to basics again: immediately after leaving the riser, let the gases expand at constant pressure, isobarically. This requires heat removal to the outside, about 5-10% of the thermal power, but it will not be lost and will even be useful for quickly warming up the room during the morning fire. And further along the flow of gases – cooling is isochoric (in a constant volume); Thus, almost all the heat will go into the battery.

How to do this technically? Let's cover the riser with a thin-walled iron drum (Steel Drum), which will also prevent heat loss from the riser. The “drum” turns out to be a bit high (the riser sticks out a lot), but it doesn’t matter: we will coat it 2/3 of the height with the same adobe. We attach a stove bench with an airtight chimney (Airtight Duct), an external chimney (Exhaust Vent), and the stove is almost ready.

Note: the riser and the drum covering it look like a stove hood above an upward-extended heil. But the thermodynamics here, as we see, are completely different. It is useless to try to improve a bell-type stove by building on it - only extra material and work will go away, and the stove will not get any better.

It remains to solve the problem of cleaning the channel in the bed. To do this, the Chinese have to break down the kan from time to time and wall it up again, but we are not in the 1st century. BC. We live when kan was invented. We will install a secondary ash pit (Secondary Airtight Ash Pit) with a sealed cleaning door immediately after the drum. Due to the sharp expansion and cooling of the flue gases in it, everything in them that has not burned out immediately condenses and settles. This ensures the cleanliness of the external chimney for years.

Note: the secondary cleaning will have to be opened once or twice a year, so you don’t have to bother with the valve loops. Let's just make a lid from a metal sheet with screws and a mineral cardboard gasket.

Small rocket

The next task of the designers was to create a small continuous combustion stove on the same principle for cooking food in the warm season. During the heating season, the drum cover (Optional Cooking Surface) of a large oven is suitable for cooking; it heats up to about 400 degrees. The small rocket stove had to be portable, but it was permissible to make it with an open firebox, because When it’s warm, you can cook outdoors or under a canopy.

Here the designers took revenge on the square-cube law by making it work for themselves: they combined the fuel bunker with the blower, see Fig. at the beginning of the section on the right. This cannot be done in a large furnace; precise adjustment of the furnace mode as the fuel settles (see below) will be impossible.

Here, the volume of incoming primary air (Primary Air) turns out to be small relative to the area of ​​heat release and the air can no longer cool the primary mixture until pyrolysis stops. Its supply is regulated by a slot in the hopper lid (Cover Lid). The hopper, inclined at 45 degrees, optimizes the automatic adjustment of oven power for standard culinary procedures, but it is more difficult to make.

Secondary air for afterburning wood gas in a small stove enters through additional holes in the mouth of the riser or simply leaks under the burner if a cooking vessel is placed on it. If the small stove is close to the maximum size (about 450 mm in diameter), then for complete afterburning you may need an Optional Secondary Woodgas Frame).

Note: it is impossible to supply secondary air to the mouth of the riser of a large furnace through holes in the drum (which would increase the efficiency of the furnace). Although the pressure in the entire gas and smoke path is lower than atmospheric, as it should be in a furnace, due to strong turbulence, flue gases will be emitted into the room. This is where their kinetic energy, which is harmful to the furnace, comes into play; This is perhaps the only thing that a rocket stove has in common with a jet engine.

The small rocket stove revolutionized the class of camping stoves, especially camping stoves. A wood chip stove (Bond stove in the West) will help you cook a stew or wait out a snowstorm in a one- or two-person tent, but it won’t save a group caught in a spring hike by belated bad weather. A small rocket stove is only slightly larger; it can be quickly made out of nothing, but is capable of developing power up to 7-8 kW. However, we’ll talk about rocket stoves made from just about anything later.

Also, the small rocket stove gave rise to many improvements. For example, Gabriel Apostol provided it with a separate blower and a wide bunker. The result was a stove suitable for constructing a compact and fairly powerful water heater, see the video below. The large rocket oven was also modified, we will talk about this a little at the end, but for now we will focus on more significant things.

Video: water heater based on a rocket stove designed by Gabriel Apostol

How to sink a rocket?

A rocket stove with long-burning stoves have a common property: they need to be launched only at warm pipe. For a small one this is unimportant, but a large one on a cold chimney will only burn fuel in vain. Therefore, before loading standard fuel into the bunker after a long break in the firebox and kindling, a large rocket stove needs to be accelerated - fired with paper, straw, dry shavings, etc., they are placed in an open ash pit. The end of acceleration is judged by a change in the tone of the furnace hum or its subsidence. Then you can load fuel into the bunker, and it will ignite automatically from the booster fuel.

The rocket stove, unfortunately, is not one of the stoves that is completely self-adjusting to fuel quality and external conditions. At the beginning of combustion of standard fuel, the ash door or hopper lid in a small furnace is opened completely. When the stove starts to hum loudly, cover it “to the point of a whisper.” Further, during the combustion process, it is necessary to gradually cover the access of air, guided by the sound of the stove. Suddenly the air damper slammed shut for 3-5 minutes - no big deal, if you open it, the stove will light up again.

Why such difficulties? As the fuel burns, the flow of air into the combustion zone increases. When there is too much air, the furnace explodes, but do not rejoice: now the excess air cools the primary gas mixture, and the sound intensifies because the stable vortex in the riser is knocked into a chaotic lump. Pyrolysis in the gas phase is interrupted, no wood gases are formed, the furnace consumes too much fuel, and a deposit of soot cemented with bituminous particles settles in the riser. Firstly, this is a fire hazard, but most likely it won’t lead to a fire; the riser channel will quickly become completely overgrown with carbon deposits. How to clean it if you have a non-removable drum cover?

In a large furnace, a spontaneous change of mode occurs abruptly, when the top of the sticks drops to the bottom edge of the hopper, and in a small furnace - gradually, as the fuel mass settles. Because when cooking on the stove experienced housewife does not leave it for a long time, the designers considered it possible, for the sake of compactness, to combine a bunker with a blower in it.

This trick will not work with a large stove: the high riser pulls very hard, and the air gap needs to be so thin (and it also needs to be adjusted) that it is impossible to achieve a stable stove mode. It’s easier with a separate blower: it’s easier for the air to flow around the sides of a mass of fuel that is round in cross-section, and a flame that gets too hot pushes it there. The stove turns out to be self-regulating to some extent; however, within very small limits, so you still have to manipulate the blower door from time to time.

Note: it is impossible to make a bunker for a large oven for the sake of simplicity without a tight lid, as is often done. Due to the unregulated additional air flow through the fuel mass, it is unlikely to be possible to achieve stable operation of the furnace.

Materials, sizes and proportions, lining

Now let's see what a homemade rocket stove should look like from the materials available to us. Here, too, we need to be careful: not everything that is at hand in America is what we have, and vice versa.

Of what?

For a large stove with a stove bench, more or less reliable experimental data is available for products with a drum from a 55-gallon drum with a diameter of 24 inches. 55 gallons is 208-odd liters, and 24 inches is almost exactly 607 mm, so our 200-liter is quite suitable without additional conversion. While maintaining the oven parameters, the diameter of the drum can be halved, to 300 mm, which makes it possible to make it from 400-450 mm tin buckets or a household gas cylinder.

The ash pit, bunker, firebox and riser will use pipes of different sizes, see below, round or profile. This way it will be possible to make an insulating lining of the firebox from a mixture of equal parts of oven clay and crushed fireclay, without resorting to brickwork; We’ll talk about the riser lining in more detail below. Combustion in a rocket furnace is weak, therefore the thermochemistry of gases is gentle and the thickness of the steel of all metal parts, except for the gas pipeline in the stove bench, is from 2 mm; the latter can be made from a thin-walled metal corrugated sheet, here the flue gases are already completely exhausted both in terms of chemistry and temperature.

For external coating, the best heat accumulator is adobe. If the dimensions indicated below are observed, the heat transfer of a rocket stove in adobe after combustion can reach 12 hours or more. The remaining parts (doors, covers) are made of galvanized metal, aluminum, etc., with sealing gaskets made of mineral cardboard. Conventional stove fittings are not suitable, it is difficult to ensure their tightness, and a cracked rocket stove will not work properly.

Note: it is advisable to equip the rocket stove with a view in the external chimney. Although the gas view in the high riser locks the common smoke path tightly, strong wind the outside can suck the heat out of the bed prematurely.

Dimensions and proportions

The basic calculated values ​​to which the rest are tied are the drum diameter D and its internal cross-sectional area S. Everything else, based on the size of the available iron, is determined as follows:

1. Drum height H – 1.5-2D.
2. Drum coating height – 2/3H; For the sake of design, the edge of the coating can be made oblique and curved, then 2/3H must be maintained on average.
3. The thickness of the drum coating is 1/3D.
4. Riser cross-sectional area – 4.5-6.5% of S; It's better to stay within 5-6% of S.
5. The height of the riser is the larger the better, but the gap between its edge and the drum tire must be at least 70 mm; its minimum value is determined by the viscosity of the flue gases.
6. The length of the flame tube is equal to the height of the riser.
7. The cross-sectional area of ​​the flame tube (fire duct) is equal to that of the riser. It is better to make the fire duct from a square corrugated pipe, so the furnace mode will be more stable.
8. The cross-sectional area of ​​the blower is 0.5 of its own firebox and riser. A more stable furnace mode and its smooth adjustment will be provided by a rectangular corrugated pipe with sides 2:1, laid flat.
9. The volume of the secondary ash pan is from 5% of the original volume of the drum (excluding the volume of the riser) for a stove from a barrel to 10% of the same for a stove from a cylinder. Interpolation for intermediate drum sizes is linear.
10. The cross-sectional area of ​​the external chimney is 1.5-2S.
11. The thickness of the adobe cushion under the external chimney is 50-70 mm; if the channel is round, it is counted from its lowest point. If the bed is on wooden floors, the pillow under the chimney can be halved.
12. The height of the coating of the stove bench above the external chimney is from 0.25D for a 600 mm drum to 0.5D for a 300 mm drum. You can do less, but then the heat transfer after heating will be shorter.
13. The height of the external chimney is from 4 m.
14. The permissible length of the gas duct in the bed - see next. section

The maximum thermal power of a rocket stove made from a barrel is approximately 25 kW, and a stove made from a gas cylinder is about 15 kW. The power can be adjusted only by the size of the fuel load. By supplying air, the oven is put into operation, and nothing more!

Note: in the original survivalist stoves, the riser cross-section was taken at 10-15% S based on very wet fuel. Then, there, in America, rocket stoves with a bench for bungalows appeared, designed for air-dry fuel and more economical. In them, the riser cross-section is reduced to the recommended ones and here it is 5-6% S.

Riser lining

The efficiency of a rocket stove largely depends on the thermal insulation of the riser. But American lining materials, alas, are not available to us. In terms of reserves of high-quality refractories, the United States has no equal; there they are considered strategic raw materials and are sold even to trusted allies with caution.

From our available materials according to heating engineering, they can be replaced with light fireclay bricks of the ShL brand and ordinary self-excavated river sand with a large admixture of alumina, correctly laid, see below. However, these materials are porous; in the oven they will quickly become saturated with carbon deposits. Then the oven will roar with any air supply, with all that follows. Therefore, we need to surround the riser lining with a metal shell, and the end of the lining must be covered with oven clay.

Lining diagrams for 3 types of furnaces are shown in Fig. The point here is that as the size of the drum decreases, the share of its direct heat transfer through the bottom and unlined part increases according to the square-cube law. Therefore, while maintaining the desired thermal gradient in the riser, the lining power can be reduced. This makes it possible to correspondingly increase the relative cross-section of the annular lowering of the flue gases in the drum.

Schemes of riser lining in rocket furnaces

For what? Firstly, the requirements for the external chimney are reduced, because The external rod now pulls better. And since it pulls better, then the permissible length of the hog in the bed drops more slowly than the size of the stove. As a result, if a stove from a barrel heats a stove bench with a length of up to 6 m, then a stove made from a cylinder is half as long - 4 m.

How to line with sand?

If the riser lining is fireclay, then the residual cavities are simply filled in construction sand. There is no need to carefully prepare a river self-dug for lining entirely from sand; just select large debris. But they pour it in layers, in 5-7 layers. Each layer is compacted and sprayed until a crust forms. Then the entire backfill is dried for a week, the top edge is covered with clay, as already mentioned, and the construction of the furnace continues.

Balloon rocket

From the above, it is clear that it is more profitable to make a rocket stove from a gas cylinder: less work, fewer unsightly parts in sight, and the stove warms up almost the same. Thermal curtain or a warm floor in the Siberian frost will heat a room of 50 square meters with a power of 10-12 kW. m or more, so here, too, a balloon rocket turns out to be more profitable; a large barrel will rarely have to be launched at full power with maximum efficiency.

The craftsmen apparently understood this too; at least some. For example, here in Fig. – drawings of a balloon furnace-rocket. On the right is the original; the author seems to have wisely understood the initial developments and, in general, everything turned out right for him. On the left are the necessary improvements taking into account the use of air-dry fuel and heating the bed.

Drawings of a rocket stove from a gas cylinder

A fruitful idea is a separate supply of heated secondary air. The furnace will be more economical and the fire tube can be made shorter. The cross-sectional area of ​​its air duct is about 10% of the riser cross-section. The oven always operates with the secondary completely open. First, the mode is set by the primary valve; Precisely adjust with the hopper lid. At the end of the firebox, the stove will roar, but here it’s not so scary; to clean the riser, the author of the design provides a removable drum cover. It, of course, must have a seal.

Rockets made from anything

Canning

Scheme of a rocket stove made from cans

Tourists, hunters and fishermen (many of them members of survival societies) soon adapted the small rocket stove into a camp stove made from empty tins. It was possible to reduce the influence of the square-cube to a minimum by using horizontal fuel supply, see the diagram on the right. True, at the cost of some inconvenience: the sticks need to be pushed inward as they burn out. But the furnace mode began to hold fast. How? Due to the automatic redistribution of air flows through the plenum and over/through the fuel. The power of a can rocket stove lies in the range of 0.5-5 kW depending on the size of the stove and is regulated by approximately three times the amount of fuel loading. The basic proportions are also simple:

• The diameter of the combustion chamber (combustion chamber) is 60-120 mm.
• The height of the combustion chamber is 3-5 times its diameter.
• The cross-section of the blower is 0.5 from its own combustion chamber.
• The thickness of the thermal insulation layer is not less than the diameter of the combustion chamber.

These proportions are very approximate: changing them by half does not prevent the stove from working, and efficiency on a hike is not so important. If the insulation is made of wet sandy loam, as described above, the joints of the parts can simply be coated with clay (left position in the figure below). Then, after 1-2 fires, the stove will acquire strength that allows it to be transported without special precautions. But in general, any of the available non-combustible materials will do the insulation, trace. two pos. A burner of any design must provide free air flow, 3rd position. Welded from steel sheet rocket stove (right position) with sand insulation is twice as light and more economical than a potbelly stove the same power.

Compact rocket stoves

Brick

Rocket stove made from broken bricks

We won’t talk about large stationary rocket furnaces: all the original thermodynamics are in tatters in them, and they are deprived of one of the main advantages of the original furnace - ease of construction. We'll tell you a little about rocket stoves made from brick, clay or stone fragments, which can be made in 5-20 minutes when you don't have tins at hand.

Here, for example (see the video below), is a thermodynamically complete rocket oven made of 16 bricks laid dry. The voice acting is in English, but everything is clear even without words. A similar one can be built from fragments of brick (see figure), cobblestones, or sculpted from clay. A stove made from rich earth is enough for one time. The efficiency of all of them is not so great, the height of the combustion chamber is too small, but it is enough for pilaf or to quickly warm up.

Video: rocket oven made of 16 bricks (eng)

New material

Diagram of the Shirokov-Khramtsov furnace

Among the domestic developments, the Shirokov-Khramtsov rocket stove deserves attention (see figure on the right). The authors, not caring about survival in the splash, used a modern material - heat-resistant concrete, adjusting all the thermodynamics to it. The components of reinforced concrete are not cheap; a concrete mixer is needed for mixing. But its thermal conductivity is much lower than that of most other refractories. The new rocket stove began to work more stable, and it became possible to release some of the heat outside in the form of infrared radiation through heat-resistant glass. The result was a rocket stove - a fireplace.

Do rockets fly in a bathhouse?

Wouldn't a rocket stove be suitable for a sauna? It seems like you can build a heater on the drum cover. Or a flow one instead of a bed.

Unfortunately, the rocket stove is not suitable for a bathhouse. To get light steam, the sauna stove must immediately warm up the walls with thermal (IR) radiation, and then, or a little later, the air by convection. To do this, the oven must be a compact source of infrared and a convection center. Convection from a rocket furnace is distributed, and it provides little IR at all; the very principle of its design excludes significant losses due to radiation.

In conclusion: to the rocket makers

IN successful designs For rocket stoves, there is still more intuition than precise calculation. Therefore, good luck to you too! – the rocket stove is a fertile field for craftsmen with a creative streak. Published

P.S. And remember, just by changing your consciousness, we are changing the world together! © econet