It all started with the fact that I wanted to do a project and involve my grandson in it. I have a lot of engineering experience behind me, so I did not look for simple projects, and so, one day watching TV, I saw a boat that was moving due to the propeller. "Cool stuff!" - I thought, and began to wool the vastness of the Internet in search of at least some information.
We took the motor from an old lawn mower, and bought the layout itself (it costs $ 30). It is good because it requires only one motor, while most of these boats require two engines. From the same company, we bought the propeller, propeller hub, air cushion cloth, epoxy, fiberglass and screws (they all sell in one set). The rest of the materials are pretty commonplace and can be bought at any hardware store. The final budget slightly exceeded $ 600.
Step 1: Materials
From materials you will need: foam, plywood, whale from Universal Hovercraft (~ $ 500). The kit contains all the little things you need to complete the project: blueprint, fiberglass, propeller, propeller hub, air cushion fabric, glue, epoxy, bushings, etc. As I wrote in the description, about $ 600 was spent on all materials.
Step 2: making the wireframe
We take polystyrene (thickness 5 cm) and cut out a rectangle 1.5 by 2 meters from it. These dimensions will provide a buoyancy of ~ 270 kg. If 270 kg seems small, you can take another sheet of the same type and attach it to the bottom. Use a jigsaw to cut two holes: one for the incoming air flow and the other for inflating the pillow.
Step 3: Cover with glass fiber
The lower part of the case must be waterproof, for this we cover it with fiberglass and epoxy. In order for everything to dry properly, without irregularities and roughness, you need to get rid of air bubbles that may arise. For this, you can use an industrial vacuum cleaner. Cover the fiberglass with a layer of film, then cover with a blanket. The cover is needed to prevent the blanket from sticking to the fiber. Then cover the blanket with another layer of film and glue it to the floor with adhesive tape. We make a small cut, put the trunk of the vacuum cleaner into it and turn it on. We leave in this position for a couple of hours, when the procedure is completed, the plastic can be scraped off the fiberglass without any effort, it will not stick to it.
Step 4: The bottom of the case is ready
The lower part of the case is ready, and now it looks something like the photo.
Step 5: making the pipe
The pipe is made of styrofoam, 2.5 cm thick. It is difficult to describe the whole process, but in the plan it is detailed, we did not have any problems at this stage. I will only note that the plywood disc is temporary, and will be removed in the following steps.
Step 6: motor holder
The design is not tricky, it is constructed from plywood and bars. Fits exactly in the center of the boat hull. Fastened with glue and screws.
Step 7: propeller
The propeller can be purchased in two types: finished and semi-finished. A ready-made product is usually much more expensive, and buying a semi-finished product can save a lot. And so we did.
The closer the propeller blades are to the edges of the air outlet, the more efficiently the latter works. Once you've decided on the clearance, you can grind the blades. As soon as the grinding is completed, it is imperative to balance the blades so that there are no vibrations in the future. If one of the blades weighs more than the other, then the weight needs to be leveled, but not by cutting the ends, and grinding. Once the balance is found, a couple of coats of paint can be applied to keep it in balance. For safety, it is advisable to paint the tips of the blades white.
Step 8: air chamber
The air chamber separates the flow of incoming and outgoing air. Made from 3mm plywood.
Step 9: Installing the air chamber
The air chamber is attached with glue, but you can also use fiberglass, I prefer to always use fiber.
Step 10: guides
The guides are made from 1mm plywood. To give them strength, cover with one layer of fiberglass. It is not very visible in the photo, but you can still see that both guides are connected together at the bottom with an aluminum strip, this is done so that they work synchronously.
Step 11: shape the boat, add the side panels
The outlines of the shape / contour are made on the bottom, after which a wooden plank is attached to the outlines along the outlines. Plywood of 3 mm bends well, and lays down right in the shape we need. Next, we attach and glue a 2 cm beam along the upper edge of the plywood sides. Add the crossbeam and set the handle to act as the rudder. To it we attach the cables extending from the guide blades installed earlier. Now you can paint the boat, preferably several layers. We chose a white color, with it, even with prolonged direct rays of the sun, the body practically does not heat up.
I must say that she swims briskly, and it pleases, but the steering surprised me. At medium speeds, turns are obtained, but at high speed, the boat first skids to the side, and then, by inertia, it moves back for a while. Although I got used to it a little, I realized that tilting the body towards the turn and slightly slowing down the gas can significantly reduce this effect. It is difficult to say the exact speed, because the boat does not have a speedometer, but it feels quite good, and after the boat there is still a decent track and waves.
On the day of the test, the boat was tested by about 10 people, the heaviest weighed about 140 kg, and it withstood it, although it certainly did not work out to squeeze the speed that was available to us. With a weight of up to 100 kg, the boat goes briskly.
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The construction of a vehicle that would allow movement both on land and on water was preceded by an acquaintance with the history of the discovery and creation of original amphibians - hovercraft(WUA), study of their basic structure, comparison of various designs and schemes.
To this end, I visited many Internet sites of enthusiasts and creators of WUAs (including foreign ones), and got acquainted with some of them on the spot.
In the end, the English "Hovercraft" ("soaring ship" - as the WUA is called in Great Britain), built and tested by enthusiasts there, took the prototype of the planned boat. Our most interesting domestic machines of this type were mostly created for law enforcement agencies, and in recent years - for commercial purposes, had large dimensions, and therefore were not suitable for amateur manufacturing.
My hovercraft (I call it "Aerojeep") is a three-seater: the pilot and passengers are arranged in a T-shape, like on a tricycle: the pilot is in front in the middle, and the passengers are next to each other, next to each other. The machine is single-engine, with a split air flow, for which a special panel is installed in its annular channel slightly below its center.
| Hovercraft technical data | |
|---|---|
| Overall dimensions, mm: | |
| length | 3950 |
| width | 2400 |
| height | 1380 |
| Engine power, hp with. | 31 |
| Weight, kg | 150 |
| Carrying capacity, kg | 220 |
| Fuel capacity, l | 12 |
| Fuel consumption, l / h | 6 |
| Overcoming obstacles: | |
| rise, deg. | 20 |
| wave, m | 0,5 |
| Cruising speed, km / h: | |
| on water | 50 |
| on the ground | 54 |
| on ice | 60 |
It consists of three main parts: a propeller-driven installation with a transmission, a fiberglass body and a "skirt" - a flexible enclosure of the lower part of the body - so to speak, a "pillowcase" of an air cushion.
 1 - segment (dense tissue); 2 - mooring cleat (3 pcs.); 3 - wind visor; 4 - side plate for fastening the segments; 5 - handle (2 pcs.); 6 - propeller guard; 7 - annular channel; 8 - rudder (2 pcs.); 9 - steering wheel control lever; 10 - access hatch to the gas tank and battery; 11 - pilot's seat; 12 - passenger sofa; 13 - engine casing; 14 - engine; 15 - outer shell; 16 - filler (foam); 17 - inner shell; 18 - dividing panel; 19 - propeller; 20 - propeller bushing; 21 - drive toothed belt; 22 - assembly for attaching the lower part of the segment. enlarge, 2238x1557, 464 KB |
Hovercraft hull
It is double: fiberglass, consists of an inner and an outer shell.
The outer shell has a rather simple configuration - it is only inclined (about 50 ° to the horizontal) sides without a bottom - flat almost over the entire width and slightly curved in the upper part of it. The bow is rounded, and the rear looks like an inclined transom. In the upper part, along the perimeter of the outer shell, oblong holes-grooves are cut, and at the bottom, outside, a cable covering the shell is fixed in eye-bolts for attaching the lower parts of the segments to it.
The configuration of the inner shell is more complicated than the outer one, since it has almost all the elements of a small vessel (say, a boat or a boat): sides, bottom, curved gunwales, a small deck in the bow (only the upper part of the transom is missing in the stern), while as one piece. In addition, in the middle of the cockpit along it, a separately molded tunnel with a can under the driver's seat is glued to the bottom. It houses a fuel tank and a battery, as well as a "gas" cable and a rudder control cable.
In the aft part of the inner shell, a kind of hut is arranged, raised and open in front. It serves as the base of the annular channel for the propeller, and its bulkhead deck serves as an air flow divider, part of which (supporting flow) is directed into the shaft opening, and the other part to create a propulsive thrust force.
All elements of the case: the inner and outer shells, the tunnel and the annular channel, were glued on matrices made of glass mat with a thickness of about 2 mm on polyester resin. Of course, these resins are inferior to vinyl ester and epoxy resins in adhesion, filtration level, shrinkage, and the release of harmful substances during drying, but they have an undeniable price advantage - they are much cheaper, which is important. For those who intend to use such resins, let me remind you that the room where the work is carried out must have good ventilation and a temperature of at least 22 ° C.
The matrices were made in advance using a master model from the same glass mats on the same polyester resin, only the thickness of their walls was larger and amounted to 7-8 mm (for the case shells - about 4 mm). Before gluing the elements from the working surface of the matrix, all roughness and galls were carefully removed, and it was covered three times with wax diluted in turpentine and polished. After that, a thin layer (up to 0.5 mm) of gelcoat (colored varnish) of the selected yellow color was applied to the surface with a spray gun (or roller).
After it had dried, the process of gluing the shell began using the following technology. First, using a roller, the wax surface of the matrix and the side of the glass mat with smaller pores are coated with resin, and then the mat is placed on the matrix and rolled until the air is completely removed from under the layer (if necessary, you can make a small cut in the mat). In the same way, the subsequent layers of glass mats are laid to the required thickness (4-5 mm), with the installation, where necessary, of embedded parts (metal and wood). Excessive flaps at the edges are cut off when gluing "wet".
After the resin has hardened, the shell is easily removed from the matrix and processed: the edges are turned, grooves are cut, holes are drilled.
To ensure the unsinkability of the "Aerodzhip", pieces of foam (for example, furniture) are glued to the inner shell, leaving only the channels for the passage of air around the entire perimeter free. The pieces of foam are glued together with resin, and are attached to the inner shell with strips of glass mat, also oiled with resin.
After the outer and inner shells are made separately, they are docked, fastened with clamps and self-tapping screws, and then joined (glued) along the perimeter with strips of the same glass mat coated with polyester resin, 40-50 mm wide, from which the shells themselves were made. After that, the body is left until the resin has completely polymerized.
A day later, a duralumin strip with a section of 30x2 mm is attached to the upper junction of the shells along the perimeter with rivets, setting it vertically (the tongues of the segments are fixed on it). Wooden runners with dimensions of 1500x90x20 mm (length x width x height) are glued to the bottom of the bottom at a distance of 160 mm from the edge. One layer of glass mat is glued on top of the runners. In the same way, only from the inside of the shell, in the aft part of the cockpit, is a base made of a wooden plate for the engine.
It is worth noting that using the same technology as the outer and inner shells were made, smaller elements were also glued: the inner and outer shell of the diffuser, rudders, gas tank, engine cover, wind damper, tunnel and driver's seat. For those who are just starting to work with fiberglass, I recommend preparing the manufacture of a boat from these small elements. The total mass of the fiberglass body with diffuser and rudders is about 80 kg.
Of course, the manufacture of such a hull can also be entrusted to specialists - firms producing fiberglass boats and boats. Fortunately, there are many of them in Russia, and the costs will be commensurate. However, in the process of self-manufacturing, it will be possible to gain the necessary experience and the ability to model and create various elements and structures from fiberglass in the future.
Propeller-driven installation of an air cushion boat
It includes an engine, a propeller and a transmission that transfers torque from the first to the second.
The engine is used by BRIGGS & STATTION, produced in Japan under an American license: 2-cylinder, V-shaped, four-stroke, 31 hp. with. at 3600 rpm. Its guaranteed service life is 600 thousand hours. Starting is carried out by an electric starter, from the battery, and the spark plugs are powered by a magneto.
The engine is mounted on the bottom of the Aerojip body, and the propeller hub axis is fixed at both ends on brackets in the center of the diffuser, raised above the body. The transmission of torque from the motor output shaft to the hub is carried out by a toothed belt. The driven and driving pulleys, like the belt, are toothed.
Although the mass of the engine is not so great (about 56 kg), its location on the bottom significantly lowers the center of gravity of the boat, which has a positive effect on the stability and maneuverability of the vehicle, especially this one - "aeronautical".
Exhaust gas is led out into the lower air stream.
Instead of the installed Japanese one, you can also use suitable domestic engines, for example, from the Buran, Lynx snowmobiles and others. By the way, engines with a capacity of about 22 hp are quite suitable for a one- or two-seater WUA. with.
The propeller is six-bladed, with a fixed pitch (set on land by the angle of attack) of the blades.
 1 - walls; 2 - cover with a tongue. |
The annular channel of the propeller should also be attributed to an integral part of the propeller-driven installation, although its base (lower sector) is made integral with the inner shell of the body. The annular channel, like the body, is also composite, glued from the outer and inner shells. Just in the place where the lower sector joins it with the upper one, a fiberglass dividing panel is arranged: it divides the air flow created by the propeller (and, on the contrary, connects the walls of the lower sector along a chord).
The engine, located at the transom in the cockpit (behind the back of the passenger seat), is closed from above with a fiberglass hood, and the propeller, in addition to the diffuser, is also a wire grille in front.
The soft elastic cushion of the air cushion boat (skirt) consists of separate, but identical segments, cut and sewn from dense lightweight fabric. It is desirable that the fabric is water-repellent, does not harden in the cold and does not allow air to pass through. I used Finnish Vinyplan material, but a domestic fabric such as percale is quite suitable. The pattern of the segment is simple, and you can even sew it manually.
Each segment is attached to the body as follows. The tongue is thrown over the side vertical strip, with an overlap of 1.5 cm; on it - the tongue of the adjacent segment, and both of them in the place of the overlap are fixed on the bar with a special clip of the "crocodile" type, only without teeth. And so along the entire perimeter of the "Aerodzip". For reliability, you can also put the clip in the middle of the tongue. The two lower corners of the segment with the help of nylon clamps are suspended freely on a cable that wraps around the lower part of the outer shell of the body.
Such a composite skirt design allows you to easily replace a failed segment, which will take 5-10 minutes. To the point it will be said that the structure turns out to be efficient in case of failure of up to 7% of the segments. In total, there are up to 60 of them on the skirt.
Movement principle hovercraft next. After starting the engine and idling, the machine remains in place. As the number of revolutions increases, the propeller begins to drive a more powerful air flow. Part of it (large) creates propulsive force and propels the boat forward. The other part of the flow goes under the dividing panel into the side air ducts of the body (free space between the shells to the very nose), and then through the holes-grooves in the outer shell evenly enters the segments. This flow, simultaneously with the start of movement, creates an air cushion under the bottom, raising the vehicle above the underlying surface (whether it is soil, snow or water) by several centimeters.
Rotation of the "Aerojip" is carried out by two rudders, deflecting the "forward" air flow to the side. The rudders are controlled from a motorcycle-type two-armed steering column lever, through a Bowden cable running along the starboard side between the shells to one of the rudders. Another rudder is connected to the first rigid rod.
On the left handle of the two-armed lever, the carburetor throttle control lever is also fixed (analogue of the throttle handle).
To operate a hovercraft, it must be registered with the local state small craft inspectorate (GIMS) and receive a ship ticket. To obtain a certificate for the right to drive a boat, you also need to take a course in driving.
However, even on these courses, there are still far from everywhere instructors for piloting hovercraft. Therefore, each pilot has to master the management of the WUA independently, literally bit by bit, gaining the appropriate experience.
Hovercraft is a vehicle capable of traveling both on water and on land. Such a vehicle is not at all difficult to make with your own hands.
This is a device where the functions of a car and a boat are combined. The result is a hovercraft (hovercraft) with unique cross-country characteristics, without loss of speed when moving through the water due to the fact that the hull of the vessel does not move through the water, but over its surface. This made it possible to move through the water much faster, due to the fact that the frictional force of the water masses does not provide any resistance.
Although the hovercraft has a number of advantages, its field of application is not so widespread. The fact is that this device can not move on any surface without any problems. It needs soft sandy or dirt soil, without stones or other obstacles. The presence of asphalt and other hard surfaces can damage the bottom of the boat, which creates an air cushion when moving. In this regard, "hovercraft" are used where you need to swim more and ride less. If on the contrary, it is better to use the services of an amphibious vehicle with wheels. The ideal conditions for their use are difficult-to-pass swampy places, where no other transport, apart from a hovercraft (hovercraft), will be able to pass. Therefore, SVPs have not become so widespread, although rescuers from some countries, such as Canada, for example, use such transport. According to some reports, SVPs are in service with NATO countries.
How to purchase such transport or how to make it yourself?
Hovercraft is an expensive form of transport, the average price of which reaches 700 thousand rubles. Transport of the "scooter" type costs 10 times cheaper. But at the same time, one should take into account the fact that factory-made transport is always of better quality, compared to homemade ones. And the reliability of the vehicle is higher. In addition, factory models are accompanied by factory warranties, which cannot be said about structures assembled in garages.
Factory models have always been focused on a narrowly professional direction associated either with fishing, or hunting, or with special services. As for home-made SVPs, they are extremely rare and there are reasons for this.
These reasons include:
- Quite high cost as well as expensive service. The main elements of the apparatus wear out quickly, which requires their replacement. Moreover, each such repair will result in a pretty penny. Only a rich person will allow himself to buy such a device, and even then he will think once again whether it is worth contacting him. The fact is that such workshops are as rare as the vehicle itself. Therefore, it is more profitable to purchase a jet ski or ATV for moving on water.
- A working product creates a lot of noise, so you can only move around with headphones.
- When moving against the wind, the speed drops significantly and the fuel consumption increases significantly. Therefore, home-made SVPs are rather a demonstration of their professional abilities. The ship not only needs to be able to manage, but also to be able to repair it, without significant expenditure of funds.
DIY SVP manufacturing process
Firstly, it is not so easy to assemble a good SVP at home. To do this, you need to have the ability, desire and professional skills. A technical education will not hurt either. If the last condition is absent, then it is better to refuse to build the apparatus, otherwise you can crash on it at the very first test.
All work begins with sketches, which are then transformed into working drawings. When creating sketches, it should be remembered that this apparatus should be as streamlined as possible so as not to create unnecessary resistance when moving. At this stage, one should take into account the fact that this is, in practice, an air vehicle, although it is very low to the surface of the earth. If all the conditions are taken into account, then you can begin to develop drawings.
The figure shows a sketch of the SVP of the Canadian Rescue Service.
Technical data of the device
Typically, all hovercraft are capable of a decent speed that no boat can. This is when you consider that the boat and the hovercraft have the same mass and engine power.
At the same time, the proposed model of a single-seat hovercraft is designed for a pilot weighing from 100 to 120 kilograms.
As for driving a vehicle, it is quite specific and, in comparison with driving a regular motor boat, does not fit in any way. The specificity is associated not only with the presence of high speed, but also with the way of movement.
The main nuance is associated with the fact that when cornering, especially at high speeds, the ship skids heavily. To minimize this factor, it is necessary to lean to the side when cornering. But these are short-term difficulties. Over time, the control technique is mastered and on the SVP one can show miracles of maneuverability.
What materials are needed?
Basically, you will need plywood, polystyrene and a special construction kit from Universal Hovercraft, which includes everything you need to assemble the vehicle yourself. The kit includes insulation, screws, air cushion cloth, special glue and more. This set can be ordered on the official website, paying 500 bucks for it. The kit also includes several options for drawings for the assembly of the SVP apparatus.
Since the drawings are already available, the shape of the ship should be tied to the finished drawing. But if you have a technical education, then, most likely, a ship will be built that is not similar to any of the options.
The bottom of the vessel is made of foam, 5-7 cm thick. If you need an apparatus for transporting more than one passenger, then another such sheet of foam is attached from below. After that, two holes are made in the bottom: one is intended for the air flow, and the second is for providing the cushion with air. Holes are cut with an electric jigsaw.
At the next stage, the lower part of the vehicle is sealed from moisture. For this, fiberglass is taken and glued to the foam with epoxy glue. In this case, irregularities and air bubbles can form on the surface. To get rid of them, the surface is covered with polyethylene, and on top is also a blanket. Then, another layer of film is laid on the blanket, after which it is fixed to the base with tape. It is better to blow air out of this “sandwich” using a vacuum cleaner. After 2 or 3 hours, the epoxy will harden and the bottom will be ready for further work.
The top of the hull can be of any shape, but take into account the laws of aerodynamics. After that, they start attaching the pillow. The most important thing is that air flows into it without loss.
The motor tube should be made of styrofoam. The main thing here is to guess with the dimensions: if the pipe is too large, then the thrust that is necessary to lift the hovercraft will not work. Then you should pay attention to the mount of the motor. The motor holder is a kind of stool consisting of 3 legs attached to the bottom. The engine is installed on top of this "stool".
What kind of engine do you need?
There are two options: the first option is to use a Universal Hovercraft engine, or use any suitable engine. It can be a chainsaw engine, the power of which is quite enough for a homemade device. If you want to get a more powerful device, then you should take a more powerful engine.
It is advisable to use factory-made blades (those in the kit), since they require careful balancing and it is quite difficult to do this at home. If this is not done, the unbalanced blades will destroy the entire engine.
How reliable can an SVP be?
As practice shows, factory hovercraft (SVP) have to be repaired about once every six months. But these problems are insignificant and do not require serious costs. Basically, the pillow and the air supply system fail. In fact, the likelihood that a homemade device will fall apart during operation is very small if the "hovercraft" is assembled correctly and correctly. For this to happen, you need to hit an obstacle at high speed. Despite this, the airbag is still able to protect the device from serious damage.
Rescuers working on such devices in Canada repair them quickly and competently. As for the pillow, it can really be repaired in a conventional garage.
Such a model will be reliable if:
- The materials and parts used were of proper quality.
- The device has a new engine.
- All connections and fasteners are secure.
- The manufacturer has all the necessary skills.
If the SVP is made as a toy for a child, then in this case it is desirable that the data of a good designer are present. Although this is not an indicator for putting children behind the wheel of this vehicle. This is not a car or a boat. Managing an SVP is not as easy as it seems.
Taking this factor into account, you need to immediately start making a two-seater version in order to control the actions of the one who will sit behind the wheel.
We owe the final design, as well as the informal name of our craft, to a colleague from the Vedomosti newspaper. Seeing one of the test "take-offs" in the parking lot of the publishing house, she exclaimed: "Yes, this is Baba Yaga's stupa!" Such a comparison made us incredibly happy: after all, we were just looking for a way to equip our hovercraft with a rudder and a brake, and the way was found by itself - we gave the pilot a broom!
This looks like one of the dumbest crafts we've ever made. But, if you think about it, it is a very spectacular physical experiment: it turns out that a weak air flow from a hand blower, designed to sweep weightless dead leaves from paths, is able to lift a person above the ground and easily move him through space. Despite its very impressive appearance, building such a boat is as easy as shelling pears: with strict adherence to the instructions, it will require only a couple of hours of dust-free work.
Using a rope and a marker, draw a 120 cm circle on the plywood sheet and cut out the bottom with a jigsaw. Make a second circle immediately.
Align the two circles and drill a 100mm hole through them using a crown. Save the wooden discs removed from the crown, one of which will serve as the center "button" of the air cushion.
Spread the shower curtain on the table, place the bottom on top and secure the plastic with a furniture stapler. Cut off the excess polyethylene, stepping back a couple of centimeters from the staples.
Tape the hem of the skirt with reinforced tape in two rows with 50 percent overlap. This will make the skirt airtight and avoid air loss.
Mark the central part of the skirt: in the middle there will be a "button", and around it six holes 5 cm in diameter. Cut the holes with a breadboard knife.
Carefully glue the central part of the skirt, including the holes, with reinforced tape. Apply 50% overlap tapes, apply two layers of duct tape. Re-cut the holes with a breadboard knife and screw on the center "button" with self-tapping screws. The skirt is ready.
Flip the bottom over and screw the second plywood circle onto it. 12mm plywood is easy to handle, but not rigid enough to withstand the required loads without deforming. Two layers of such plywood will fit just right. Place plumbing insulation around the edges of the circle and secure with a stapler. It will serve as a decorative bumper.
Use 100mm ventilation duct cuffs and elbows to connect the blower to the skirt. Secure the engine with brackets and braces.
Helicopter and washer
Contrary to popular belief, the boat does not rely on a 10-centimeter layer of compressed air at all, otherwise it would already be a helicopter. An air cushion is like an inflatable mattress. The plastic film, which is tightened on the bottom of the apparatus, is filled with air, stretched and turns into a kind of inflatable circle.
The film adheres very tightly to the road surface, forming a wide contact patch (practically over the entire bottom area) with a hole in the center. Pressurized air comes out of this hole. Over the entire contact area between the film and the road, a thin layer of air is formed, along which the device glides easily in any direction. Thanks to the inflatable skirt, even a small amount of air is enough for a good glide, so our stupa is much more like an air hockey puck than a helicopter.
Wind upskirt
Usually we do not print precise drawings in the "master class" heading and we strongly recommend that readers connect their creative imagination to the process, experimenting with the design as much as possible. But this is not the case. Several attempts to deviate slightly from the popular recipe cost the editors a couple of days of extra work. Do not repeat our mistakes - strictly follow the instructions.
The boat should be round like a flying saucer. A ship resting on the thinnest layer of air needs an ideal balance: at the slightest defect in the weight distribution, all the air will come out from the underloaded side, and the heavier side will fall on the ground with all its weight. The symmetrical round bottom helps the pilot to easily find balance by slightly changing the position of the body.
To make the bottom, take 12mm plywood, use a rope and a marker to draw a circle with a diameter of 120cm and cut out the part with an electric jigsaw. The skirt is made of a polyethylene shower curtain. The choice of the curtain is perhaps the most crucial stage at which the fate of the future craft is being decided. The polyethylene should be as thick as possible, but strictly uniform and in no case reinforced with fabric or decorative tapes. Oilcloth, tarpaulin and other airtight fabrics are not suitable for building a hovercraft.
In pursuit of the durability of the skirt, we made our first mistake: the poorly stretched oilcloth tablecloth could not snuggle tightly to the road and form a wide contact patch. The area of the small "speck" was not enough to make the heavy machine slide.
Leaving an allowance to let more air under a tight skirt is not an option. When inflated, such a pillow will form folds that will release air and prevent the formation of a uniform film. But the polyethylene tightly pressed to the bottom, stretching when air is injected, forms a perfectly smooth bubble that tightly fits any irregularities in the road.
Scotch is the head of everything
Making a skirt is easy. It is necessary to spread the polyethylene on a workbench, cover it with a round plywood blank with a pre-drilled air supply hole on top, and carefully fix the skirt with a furniture stapler. Even the simplest mechanical (non-electrical) stapler with 8 mm staples can handle the task.
Reinforced tape is a very important element of the skirt. It strengthens it where necessary, while maintaining the elasticity of the rest of the areas. Pay particular attention to the polyethylene reinforcement under the center "button" and in the area of the air holes. Apply the tape with 50% overlap and in two layers. The polyethylene must be clean, otherwise the tape may come off.
The lack of reinforcement in the central section was the cause of a funny accident. The skirt was torn at the "button" area, and our pillow turned from a "donut" into a semicircular bubble. The pilot, with eyes widening in surprise, ascended a good half a meter above the ground and after a couple of moments fell down - the skirt finally burst and released all the air. It was this incident that led us to the mistaken idea of using oilcloth instead of a shower curtain.
Another misconception that befell us during the construction of the boat was the belief that there is never too much power. We got hold of a large Hitachi RB65EF backpack blower with an engine capacity of 65 cc. This animal machine has one great advantage: it is equipped with a corrugated hose, with which it is very easy to connect the fan to the skirt. But the power of 2.9 kW is a clear overkill. The polyethylene skirt should be given just enough air to lift the machine 5-10 cm above the ground. If you overdo it with gas, the polyethylene will not withstand the pressure and will tear. This is exactly what happened with our first car. So rest assured that if you have any blower at your disposal, it will be suitable for the project.
Full speed ahead!
Typically, hovercraft have at least two propellers: one sustainer, which propels the vehicle forward, and one fan, which blows air under the skirt. How will our "flying saucer" move forward, and can we get by with one blower?
This question tormented us exactly until the first successful tests. It turned out that the skirt glides on the surface so well that even the slightest change in balance is enough for the device to move by itself in one direction or another. For this reason, it is only necessary to install the seat on the machine on the move in order to properly balance the machine, and only then screw the legs to the bottom.
We tried the second blower as a propulsion engine, but the result was not impressive: the narrow nozzle gives a fast flow, but the volume of air passing through it is not enough to create the slightest noticeable thrust. What you really need when driving is a brake. Baba Yaga's broom is ideal for this role.
He called himself a ship - climb into the water
Unfortunately, our editorial office, and with it the workshop, is located in the stone jungle, far from even the most modest bodies of water. Therefore, we were unable to launch our apparatus into the water. But theoretically everything should work! If building a boat becomes your summer cottage entertainment on a hot summer day, test its seaworthiness and share with us your story of your successes. Of course, you need to take the boat out into the water from a gentle bank on a cruising throttle, with a fully inflated skirt. Drowning cannot be allowed - immersion in water means the inevitable death of the blower from a water hammer.
