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Do-it-yourself hovercraft snowmobile. Making hovercraft, hovercraft

The high speed characteristics and amphibious capabilities of hovercraft (AHVs), as well as the relative simplicity of their designs, attract the attention of amateur designers. AT last years many small WUAs appeared, built independently and used for sports, tourism or business trips.

In some countries, such as the UK, USA and Canada, serial industrial production small WUAs; ready-made devices or sets of parts for self-assembly are offered.

A typical sports WUA is compact, simple in design, has independent lifting and propulsion systems, and easily moves both above ground and above water. These are predominantly single-seat vehicles with carburetor motorcycle or light air-cooled automobile engines.

Tourist WUAs are more complex in design. Usually they are two- or four-seater, designed for relatively long journeys and, accordingly, have trunks, large-capacity fuel tanks, and devices to protect passengers from bad weather.

For economic purposes, small platforms are used, adapted to transport mainly agricultural goods over rough and swampy terrain.

Main characteristics

Amateur WUAs are characterized by the main dimensions, weight, diameter of the supercharger and propeller, distance from the center of mass of the WUA to the center of its aerodynamic drag.

In table. 1 compares the most important technical data of the most popular English amateur WUAs. The table allows you to navigate in a wide range of values of individual parameters and use them for comparative analysis with your own projects.

The lightest WUAs have a mass of about 100 kg, the heaviest - more than 1000 kg. Naturally, the smaller the mass of the apparatus, the less engine power is required for its movement, or the higher performance can be achieved with the same power consumption.

Below are the most typical data on the mass of individual components that make up the total mass of an amateur WUA: a carburetor engine with air-cooled- 20-70 kg; axial blower. (pump) - 15 kg, centrifugal pump- 20 kg; propeller - 6-8 kg; motor frame - 5-8 kg; transmission - 5-8 kg; propeller nozzle ring - 3-5 kg; controls - 5-7 kg; body - 50-80 kg; fuel tanks and gas lines - 5-8 kg; seat - 5 kg.

The total carrying capacity is determined by calculation depending on the number of passengers, the given amount of cargo carried, the fuel and oil reserves necessary to ensure the required cruising range.

In parallel with the calculation of the mass of the AWP, an accurate calculation of the position of the center of gravity is required, since the driving performance, stability and controllability of the vehicle depend on this. The main condition is that the resultant of the air cushion support forces pass through the common center of gravity (CG) of the apparatus. At the same time, it should be taken into account that all masses that change their value during operation (such as, for example, fuel, passengers, cargo) must be placed close to the CG of the device so as not to cause it to move.

The center of gravity of the apparatus is determined by calculation according to the drawing of the lateral projection of the apparatus, where the centers of gravity of individual units, structural units of passengers and cargo are applied (Fig. 1). Knowing the masses G i and the coordinates (relative to the coordinate axes) x i and y i of their centers of gravity, it is possible to determine the position of the CG of the entire apparatus by the formulas:

The designed amateur WUA must meet certain operational, design and technological requirements. The basis for creating a project and construction of a new type of WUA are, first of all, the initial data and specifications, which determine the type of apparatus, its purpose, gross weight, carrying capacity, dimensions, type of main power plant, running characteristics and specific features.

From tourist and sports WUAs, as, indeed, from other types of amateur WUAs, ease of manufacture, the use of easily accessible materials and assemblies in the design, as well as complete safety of operation are required.

Speaking about driving characteristics, they mean the height of the AWP and the ability to overcome obstacles associated with this quality, maximum speed and throttle response, as well as the length of the braking distance, stability, controllability, and cruising range.

In the WUA design, the hull shape plays a fundamental role (Fig. 2), which is a compromise between:

a) round in terms of contours, which are characterized the best parameters air cushion at the time of hovering in place;
b) drop-shaped contours, which is preferable from the point of view of reducing aerodynamic drag during movement;
c) a pointed nose (“beak-shaped”) hull shape, which is optimal from a hydrodynamic point of view during movement on a rough water surface;
d) the form that is optimal for operational purposes.

The ratios between the length and width of the bodies of amateur WUAs vary within L:B=1.5÷2.0.

Using statistical data on existing structures that correspond to the newly created type of WUA, the designer must establish:

weight of apparatus G, kg;
air cushion area S, m 2 ;
length, width and outline of the hull in plan;
lifting system engine power N v.p. , kW;
traction motor power N dv, KW.

These data allow you to calculate the specific indicators:

pressure in the air cushion P v.p. =G:S;
specific power of the lifting system q v.p. = G:N c.p. .
specific power of the traction motor q dv = G:N dv, and also start developing the configuration of the AWP.

The principle of creating an air cushion, superchargers

Most often, in the construction of amateur WUAs, two schemes for the formation of an air cushion are used: chamber and nozzle.

In the chamber circuit, which is most often used in simple designs, the volume flow of air passing through the air path of the apparatus is equal to the volume flow of air of the blower

where:
F is the area of the perimeter of the gap between the support surface and the lower edge of the apparatus body, through which air exits from under the apparatus, m 2 ; it can be defined as the product of the perimeter of the air cushion fence P and the gap h e between the fence and the supporting surface; usually h 2 = 0.7÷0.8h, where h is the hovering height of the apparatus, m;

υ - speed of air outflow from under the device; with sufficient accuracy, it can be calculated by the formula:

where P c.p. - air cushion pressure, Pa; g - free fall acceleration, m/s 2 ; y - air density, kg / m 3.

The power required to create an air cushion in a chamber circuit is determined by the approximate formula:

where P c.p. - pressure after the supercharger (in the receiver), Pa; η n - the efficiency of the supercharger.

Air cushion pressure and air flow are the main parameters of an air cushion. Their values depend primarily on the dimensions of the apparatus, i.e., on the mass and bearing surface, on the hovering height, speed of movement, the method of creating an air cushion and resistance in the air path.

The most economical air-cushion vehicles are large-sized or large bearing surfaces for which the minimum pressure in the cushion allows a sufficiently large load capacity to be obtained. However, independent construction of a large-sized apparatus is associated with difficulties in transportation and storage, and is also limited by the financial capabilities of an amateur designer. With a decrease in the size of the WUA, a significant increase in air cushion pressure is required and, accordingly, an increase in power consumption.

In turn, negative phenomena depend on the pressure in the air cushion and the rate of air flow from under the apparatus: splashing while moving over water and dusting when moving over a sandy surface or loose snow.

Apparently, the successful design of the WUA is, in a certain sense, a compromise between the contradictory dependencies described above.

To reduce the power consumption for the passage of air through the air channel from the supercharger into the cavity of the pillow, it must have a minimum aerodynamic resistance (Fig. 3). The power losses that are inevitable during the passage of air through the channels of the air path are of two kinds: the loss due to the movement of air in straight channels of constant cross section and local losses due to the expansion and bending of the channels.

In the air path of small amateur WUAs, losses due to the movement of air flows along straight channels of constant cross section are relatively small due to the insignificant length of these channels, as well as the thoroughness of their surface treatment. These losses can be estimated using the formula:

where: λ is the coefficient of pressure loss per channel length, calculated according to the graph shown in fig. 4, depending on the Reynolds number Re=(υ d): v, υ - air velocity in the channel, m/s; l - channel length, m; d - channel diameter, m (if the channel has a different round section, then d is the diameter of the area-equivalent cross section cylindrical channel); v - coefficient of kinematic viscosity of air, m 2 / s.

Local power losses associated with a strong increase or decrease in the cross section of the channels and significant changes in the direction of the air flow, as well as losses for air intake into the supercharger, nozzles and rudders, are the main costs of the supercharger power.

Here ζ m is the coefficient of local losses, depending on the Reynolds number, which is determined by the geometric parameters of the source of losses and the speed of air passage (Fig. 5-8).

The supercharger in the AUA must create a certain air pressure in the air cushion, taking into account the power consumption to overcome the resistance of the channels to the air flow. In some cases, part of the air flow is also used to form a horizontal thrust of the apparatus in order to ensure movement.

The total pressure generated by the supercharger is the sum of the static and dynamic pressures:

Depending on the type of WUA, the area of the air cushion, the height of the apparatus and the magnitude of the losses, the constituent components p sυ and p dυ vary. This determines the choice of type and performance of superchargers.

In the chamber scheme of the air cushion, the static pressure p sυ required to create lift can be equated to the static pressure behind the supercharger, the power of which is determined by the formula above.

When calculating the required power of an AVP blower with a flexible air cushion guard (nozzle circuit), the static pressure downstream of the blower can be calculated using the approximate formula:

where: R v.p. - pressure in the air cushion under the bottom of the apparatus, kg/m 2 ; kp - pressure drop coefficient between the air cushion and the channels (receiver), equal to k p = P p: P v.p. (P p - pressure in the air channels behind the supercharger). The value of k p ranges from 1.25÷1.5.

The blower air volume flow can be calculated using the formula:

The regulation of the performance (flow rate) of the AVP blowers is most often carried out - by changing the rotational speed or (less often) by throttling the air flow in the channels with the help of rotary dampers located in them.

After the required power of the supercharger is calculated, it is necessary to find an engine for it; most often, hobbyists use motorcycle engines if power up to 22 kW is required. In this case, 0.7-0.8 of the maximum engine power indicated in the motorcycle passport is taken as the calculated power. It is necessary to provide for intensive cooling of the engine and thorough cleaning of the air entering through the carburetor. It is also important to obtain a unit with a minimum mass, which is the sum of the mass of the engine, the transmission between the supercharger and the engine, as well as the mass of the supercharger itself.

Depending on the type of WUA, engines with a displacement of 50 to 750 cm 3 are used.

In amateur WUAs, both axial superchargers and centrifugal superchargers are used equally. Axial superchargers are intended for small and simple structures, centrifugal - for AVP with significant pressure in the air cushion.

Axial superchargers typically have four or more vanes (Figure 9). They are usually made of wood (four-blade) or metal (superchargers with a large number of blades). If they are made of aluminum alloys, then the rotors can be cast, and welding can also be applied; it is possible to make them of welded structure from steel sheet. The pressure range generated by axial four-blade superchargers is 600-800 Pa (about 1000 Pa with a large number blades); The efficiency of these superchargers reaches 90%.

Centrifugal blowers are made of a welded metal structure or molded from fiberglass. The blades are made bent from a thin sheet or with a profiled cross section. Centrifugal superchargers create pressure up to 3000 Pa, and their efficiency reaches 83%.

Choice of traction complex

Propulsors that create horizontal thrust can be divided mainly into three types: air, water and wheeled (Fig. 10).

Air propulsion means an aircraft-type propeller with or without a nozzle ring, an axial or centrifugal supercharger, as well as an air-jet propulsion. In the simplest designs, horizontal thrust can sometimes be created by tilting the AWP and using the resulting horizontal component of the force of the air flow flowing from the air cushion. The air mover is convenient for amphibious vehicles that do not have contact with the supporting surface.

If we are talking about WUAs that move only above the surface of the water, then you can use a propeller or a water jet propulsion. Compared to air propulsion, these propulsion units allow you to get much more thrust per kilowatt of power expended.

The approximate value of the thrust developed by various propellers can be estimated from the data shown in Fig. eleven.

When choosing elements of a propeller, one should take into account all types of resistance that occur during the movement of the WUA. Aerodynamic drag is calculated by the formula

The water resistance due to the formation of waves when the WUA moves through the water can be calculated by the formula

where:

V - WUA movement speed, m/s; G - WUA mass, kg; L is the length of the air cushion, m; ρ is the density of water, kg s 2 /m 4 (at a sea water temperature of +4 ° C it is 104, river water - 102);

C x - coefficient of aerodynamic resistance, depending on the shape of the device; is determined by blowing WUA models in wind tunnels. Approximately, you can take C x =0.3÷0.5;

S - cross-sectional area of the WUA - its projection on a plane perpendicular to the direction of movement, m 2 ;

E - wave resistance coefficient, depending on the AWP speed (Froude number Fr=V:√g·L) and the ratio of air cushion dimensions L:B (Fig. 12).

As an example, in Table. 2 shows the calculation of resistance depending on the speed of movement for a device with a length of L = 2.83 m and B = 1.41 m.

Knowing the resistance to movement of the apparatus, it is possible to calculate the engine power required to ensure its movement at a given speed (in this example, 120 km / h), assuming the efficiency of the propeller η p equal to 0.6, and the efficiency of transmission from the engine to the propeller η p \u003d 0 ,nine:
As an air propulsor for amateur WUAs, a two-blade propeller is most often used (Fig. 13).

The blank for such a screw can be glued from plywood, ash or pine plates. The edge as well as the ends of the blades, which are mechanically affected by solid particles or sand sucked in together with the air flow, are protected by brass sheet fittings.

Four-bladed propellers are also used. The number of blades depends on the operating conditions and the purpose of the propeller - for development. high speed or creating a significant traction force at the time of launch. A two-blade propeller with wide blades can also provide sufficient thrust. Thrust is generally increased if the propeller runs in a profiled nozzle ring.

The finished screw must be balanced, mainly statically, before being mounted on the motor shaft. Otherwise, it will vibrate when it rotates, which may cause damage to the entire machine. Balancing with an accuracy of 1 g is quite sufficient for amateurs. In addition to balancing the screw, its runout relative to the axis of rotation is checked.

General layout

One of the main tasks of the designer is to connect all the aggregates into one functional whole. When designing the apparatus, the designer is obliged to provide a place for the crew, placement of units of the lifting and propulsion systems within the hull. At the same time, it is important to use the designs of already known WUAs as a prototype. On fig. Figures 14 and 15 show structural diagrams of two typical amateur-built WUAs.

In most WUAs, the body is a load-bearing element, a single structure. It contains the units of the main power plant, air channels, control devices and the driver's cab. The driver's cabs are located in the bow or central part of the apparatus, depending on where the supercharger is located - behind the cab or in front of it. If the WUA is multi-seat, the cabin is usually located in the middle part of the vehicle, which makes it possible to operate it with a different number of people on board without changing the alignment.

In small amateur WUAs, the driver's seat is most often open, protected in front by a windshield. In devices more complex design(tourist type) cabins are covered with a transparent plastic dome. To accommodate the necessary equipment and supplies, the volumes available on the sides of the cabin and under the seats are used.

With air engines, the control of the AVP is carried out using either rudders placed in the air stream behind the propeller, or guide devices fixed in the air stream flowing from the air-jet propulsion unit. The control of the device from the driver's seat can be of an aviation type - using the handles or levers of the steering wheel, or, as in a car, the steering wheel and pedals.

In amateur WUAs, two main types of fuel systems are used; with gravity fuel supply and with an automotive or aircraft-type gasoline pump. Fuel system components such as valves, filters, oil system together with tanks (if a four-stroke engine is used), oil coolers, filters, water cooling system (if it is a water-cooled engine) - they are usually selected from existing aviation or automotive parts.

Exhaust gases from the engine are always discharged to the rear of the vehicle and never to the pillow. To reduce the noise generated during the operation of WUAs, especially near settlements, automobile-type silencers are used.

In the simplest designs, the lower part of the body serves as a chassis. The role of the chassis can be performed by wooden skids (or skids), which take on the load when in contact with the surface. In tourist WUAs, which are heavier than sports WUAs, wheeled chassis are mounted, which facilitate the movement of WUAs during stops. Usually two wheels are used, mounted on the sides or along the longitudinal axis of the WUA. The wheels have contact with the surface only after the cessation of the lifting system, when the AUA touches the surface.

Materials and manufacturing technology

High-quality pine lumber, similar to those used in the aircraft industry, as well as birch plywood, ash, beech and linden wood are used for the manufacture of wooden structure WUAs. For gluing wood, a waterproof glue with high physical and mechanical properties is used.

For flexible fences, technical fabrics are mainly used; they must be exceptionally durable, resistant to atmospheric influences and humidity, as well as friction. In Poland, fire-resistant fabric covered with plastic-like PVC is most often used.

It is important to perform the correct cutting and ensure that the panels are carefully connected to each other, as well as fastening them to the device. To fasten the shell of the flexible fence to the body, metal strips are used, which, by means of bolts, evenly press the fabric against the body of the apparatus.

When designing the form of a flexible air cushion fence, one should not forget about Pascal's law, which states that air pressure is distributed in all directions with the same force. Therefore, the shell of the flexible barrier in the inflated state must be in the form of a cylinder or a sphere, or a combination thereof.

Housing design and strength

Forces are transferred to the WUA hull from the load carried by the vehicle, the weight of the mechanisms of the power plant, etc., as well as loads from external forces, impacts of the bottom against the wave and pressure in the air cushion. Basic structure The hull of an amateur WUA is most often a flat pontoon, which is supported by pressure in an air cushion, and in the swimming mode ensures the buoyancy of the hull. The hull is affected by concentrated forces, bending and torsional moments from the engines (Fig. 16), as well as gyroscopic moments from the rotating parts of the mechanisms that occur during the AWP maneuvering.

The most widely used are two constructive types of buildings for amateur WUAs (or their combinations):

truss construction, when the overall strength of the hull is ensured by flat or spatial trusses, and the skin is intended only to hold air in the air path and create buoyancy volumes;
with load-bearing plating, when the overall strength of the hull is provided by the outer plating, working in conjunction with the longitudinal and transverse framing.

An example of a WUA with combined scheme hull design is a sports apparatus "Caliban-3" (Fig. 17), built by amateurs in England and Canada. The central pontoon, consisting of a longitudinal and transverse set with a load-bearing plating, provides the overall strength of the hull and buoyancy, and the side parts form air ducts (side receivers), which are made with a light plating attached to the transverse set.

The design of the cab and its glazing should ensure the possibility of a quick exit of the driver and passengers from the cab, especially in the event of an accident or fire. The location of the windows should provide the driver with a good view: the observation line should be within the limits from 15 ° down to 45 ° up from the horizontal line; side view must be at least 90 ° on each side.

Power transmission to propeller and supercharger

The simplest for amateur manufacturing are V-belt and chain drives. However, a chain drive is used only to drive propellers or superchargers whose rotation axes are located horizontally, and even then only if it is possible to select the appropriate motorcycle sprockets, since their manufacture is quite difficult.

In the case of a V-belt drive, to ensure the durability of the belts, the pulley diameters should be chosen as maximum, however, the circumferential speed of the belts should not exceed 25 m/s.

The design of the lifting complex and flexible fencing

The lifting complex consists of an injection unit, air channels, a receiver and a flexible air cushion guard (in nozzle schemes). The channels through which air is supplied from the blower to the flexible enclosure must be designed taking into account the requirements of aerodynamics and ensure minimal pressure loss.

Flexible fences of amateur WUAs usually have a simplified form and design. On fig. 18 shows examples of design schemes of flexible barriers and a method for checking the shape of a flexible barrier after it has been mounted on the body of the apparatus. Fences of this type have good elasticity, and due to the rounded shape they do not cling to the unevenness of the supporting surface.

The calculation of superchargers, both axial and centrifugal, is rather complicated and can only be performed using special literature.

The steering device, as a rule, consists of a steering wheel or pedals, a system of levers (or cable wiring) connected to a vertical rudder, and sometimes to a horizontal rudder - an elevator.

The control can be made in the form of an automobile or motorcycle steering wheel. Considering, however, the specifics of the design and operation of the WUA as an aircraft, the aviation design of the controls in the form of a lever or pedals is more often used. In its simplest form (Fig. 19), when the handle is tilted sideways, the movement is transmitted by means of a lever fixed on the pipe to the elements of the steering cable wiring and then to the rudder. The movements of the handle back and forth, possible due to its hinged fastening, are transmitted through the pusher, passing inside the tube, to the wiring of the elevator.

With pedal control, regardless of its scheme, it is necessary to provide for the possibility of moving either the seat or the pedals for adjustment in accordance with individual features driver. Levers are most often made of duralumin, transmission pipes are attached to the body with brackets. The movement of the levers is limited by openings in the cutouts in the guides mounted on the sides of the apparatus.

An example of the design of the rudder in the case of its placement in the air flow thrown by the propeller is shown in Fig. 20.

The rudders can either be fully rotatable or consist of two parts - fixed (stabilizer) and rotatable (rudder blade) with different percentages of the chords of these parts. Rudder profiles of any type must be symmetrical. The rudder stabilizer is usually fixed to the body; the main bearing element of the stabilizer is the spar, to which the rudder blade is hinged. Elevators, very rare in amateur WUAs, are constructed on the same principles and sometimes even exactly the same as the rudders.

Structural elements that transmit movement from controls to steering wheels and engine throttles usually consist of levers, rods, cables, etc. With the help of rods, as a rule, forces are transmitted in both directions, while cables work only for traction. Most often, amateur WUAs use combined systems - with cables and pushers.

Editorial

More and more close attention lovers of water-motor sports and tourism enjoy hovercraft. With a relatively low power consumption, they allow you to achieve high speeds; shallow and impassable rivers are accessible to them; hovercraft can hover above the ground and above the ice.

For the first time, we introduced readers to the issues of designing small SVPs back in the 4th issue (1965), placing an article by Yu. A. Budnitsky “Soaring Ships”. In was published short essay development of foreign SVPs, including a description of a number of sports and pleasure modern 1- and 2-seater SVPs. The editors introduced the experience of independent construction of such an apparatus by Riga resident O. O. Petersons in. The publication of this amateur design aroused especially great interest among our readers. Many of them wanted to build the same amphibian and asked for the necessary literature.

This year the publishing house "Sudostroenie" publishes a book by the Polish engineer Jerzy Ben "Models and amateur hovercraft". In it you will find a presentation of the fundamentals of the theory of the formation of an air cushion and the mechanics of movement on it. The author gives the calculated ratios that are necessary for the independent design of the simplest SVP, introduces trends and development prospects of this type courts. The book contains many examples of designs of amateur hovercraft (AHVs) built in the UK, Canada, USA, France, Poland. The book is addressed to a wide range of fans of self-construction of ships, ship modellers, water motorists. Its text is richly illustrated with drawings, drawings and photographs.

The journal publishes an abridged translation of a chapter from this book.

The four most popular foreign SVPs

American hovercraft Airskat-240

Double sports SVP with a transverse symmetrical arrangement of seats. Mechanical installation - automob. dv. "Volkswagen" with a power of 38 kW, driving an axial four-bladed supercharger and a two-bladed propeller in the ring. The control of the SVP along the course is carried out using a lever connected to a system of rudders placed in the stream behind the propeller. Electrical equipment 12 V. Engine start - electric starter. The dimensions of the device are 4.4x1.98x1.42 m. The air cushion area is 7.8 m 2; propeller diameter 1.16 m, gross weight - 463 kg, maximum speed on water 64 km / h.

American SVP firm "Skimmers Incorporated"

A kind of single SVP scooter. The body design is based on the idea of using a car camera. Two-cylinder motorcycle motor with a power of 4.4 kW. The dimensions of the device are 2.9x1.8x0.9 m. The air cushion area is 4.0 m 2; gross weight - 181 kg. The maximum speed is 29 km/h.

English hovercraft "Air Ryder"

This two-seat sports apparatus is one of the most popular among amateur shipbuilders. The axial supercharger is driven by a motorcycle, dv. working volume 250 cm 3 . Propeller - two-blade, wooden; powered by a separate 24 kW motor. Electrical equipment with a voltage of 12 V with an aircraft battery. Engine start - electric starter. The apparatus has dimensions of 3.81x1.98x2.23 m; ground clearance 0.03 m; rise 0.077 m; pillow area 6.5 m 2; empty weight 181 kg. Develops a speed of 57 km / h on water, 80 km / h on land; overcomes slopes up to 15 °.

Table 1. shows the data of a single modification of the device.

English SVP "Hovercat"

Light tourist boat for five or six people. There are two modifications: "MK-1" and "MK-2". The centrifugal supercharger with a diameter of 1.1 m is driven by a car. dv. "Volkswagen" with a working volume of 1584 cm 3 and consumes power of 34 kW at 3600 rpm.

In the MK-1 modification, movement is carried out using a propeller with a diameter of 1.98 m, driven by a second engine of the same type.

In the MK-2 modification, a car was used for horizontal thrust. dv. "Porsche 912" with a volume of 1582 cm 3 and a power of 67 kW. The apparatus is controlled by means of aerodynamic rudders placed in the stream behind the propeller. Electrical equipment with a voltage of 12 V. The dimensions of the apparatus are 8.28x3.93x2.23 m. The air cushion area is 32 m 2, the gross weight of the apparatus is 2040 kg, the speed of movement of the modification "MK-1" is 47 km / h, "MK-2" - 55 km/h

Notes

1. A simplified method for selecting a propeller according to known value resistance, rotational speed and translational speed is given in.

2. Calculations of V-belt and chain drives can be performed using the standards generally accepted in domestic engineering.

The prototype of the presented amphibious vehicle was an air-cushion vehicle (AVP) called "Aerojeep", the publication of which was in the magazine. Like the previous machine, the new machine is single-engine, single-rotor with distributed air flow. This model is also a triple, with the location of the pilot and passengers in a T-shaped pattern: the pilot is in front in the middle, and the passengers are on the sides, behind. Although nothing prevents the fourth passenger from sitting behind the driver, the length of the seat and the power of the propeller installation are quite enough.

The new machine, in addition to improved technical characteristics, has a number of design features and even innovations that increase its reliability in operation and survivability - after all, an amphibian is a waterfowl. And I call it a “bird” because it moves through the air both above the water and above the ground.

Structurally, the new machine consists of four main parts: a fiberglass body, an air spring, a flexible fence (skirt) and a propeller unit.

Leading a story about a new car, you will inevitably have to repeat yourself - after all, the designs are in many ways similar.

Amphibious hull identical to the prototype both in size and design - fiberglass, double, three-dimensional, consists of inner and outer shells. It is also worth noting here that the holes in the inner shell in the new apparatus are now located not at the upper edge of the sides, but approximately in the middle between it and the bottom edge, which ensures faster and more stable creation of an air cushion. The holes themselves are no longer oblong, but round, with a diameter of 90 mm. There are about 40 of them and they are evenly spaced along the sides and in front.

Each shell was glued in its matrix (used from the previous design) from two or three layers of fiberglass (and the bottom - from four layers) on a polyester binder. Of course, these resins are inferior to vinyl ester and epoxy resins in terms of adhesion, filtration rate, shrinkage, as well as release. harmful substances when dried, but have an undeniable advantage in price - 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.

1 - segment (set of 60 pieces); 2 - balloon; 3 - mooring duck (3 pcs.); 4 - wind visor; 5 - handrail (2 pcs.); 6 – mesh protection of the propeller; 7 - outer part of the annular channel; 8 – rudder (2 pcs.); 9 – steering control lever; 10 - a hatch in the tunnel for access to the fuel tank and battery; 11 – pilot's seat; 12 – passenger sofa; 13 - engine casing; 14 - paddle (2 pcs.); 15 - silencer; 16 - filler (polystyrene); 17- inner part ring channel; 18 - lantern navigation light; 19 - propeller; 20 – propeller bushing; 21 - drive toothed belt; 22 - knot for fastening the cylinder to the body; 23 – attachment point of the segment to the body; 24 - engine on a motor mount; 25- inner shell corps; 26 - filler (polystyrene); 27 - outer shell of the body; 28 - dividing panel of the injected air flow

The matrices were made in advance according to the 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 casing shells - about 4 mm). Before baking the elements, all roughness and scratches were carefully removed from the working surface of the matrix, and it was covered three times with wax diluted in turpentine and polished. After that, a thin layer (up to 0.5 mm) of red gelcoat (colored varnish) was applied to the surface with a sprayer (or roller).

After it dried, the process of gluing the shell began using the following technology. First, using a roller, the wax surface of the matrix and one side of the stackomat (with smaller pores) are smeared 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, a small slot can be made in the mat). The subsequent layers of glass mats are laid in the same way to the required thickness (3-4 mm), with the installation, where necessary, of embedded parts (metal and wood). Excessive flaps along the edges were cut off when gluing "wet".

a - outer shell;

b - inner shell;

1 - ski (tree);

2 - sub-slab (wood)

After separately manufacturing the outer and inner shells, they were joined, fastened with clamps and self-tapping screws, and then glued around the perimeter with strips of the same glass mat 40–50 mm wide, smeared with polyester resin, from which the shells were made. After attaching the shells to the edge with petal rivets, a vertical side strip of a 2-mm duralumin strip with a width of at least 35 mm was attached around the perimeter.

Additionally, with pieces of fiberglass impregnated with resin, carefully glue all corners and places where fasteners are screwed in. The outer shell is coated on top with a gel coat - a polyester resin with acrylic additives and wax that add shine and water resistance.

It should be noted that using the same technology (the outer and inner shells were made using it), smaller elements were also glued: the inner and outer shells of the diffuser, the rudders, the engine cover, the wind deflector, the tunnel and the driver's seat. A 12.5-liter gas tank (industrial from Italy) is inserted inside the case, into the console, before fastening the lower and upper parts of the cases.

inner shell shell with air outlets to create an air cushion; above the holes - a row of cable clips for hooking the ends of the scarf of the skirt segment; two wooden skis glued to the bottom

For those who are just starting to work with fiberglass, I recommend starting the manufacture of a boat with these small elements. The total mass of the fiberglass hull, together with skis and an aluminum alloy strip, diffuser and rudders, is from 80 to 95 kg.

The space between the shells serves as an air duct along the perimeter of the apparatus from the stern on both sides to the bow. The upper and lower parts of this space are filled with building foam, which provides an optimal cross-section of the air channels and additional buoyancy (and, accordingly, survivability) of the apparatus. Pieces of foam plastic were glued together with the same polyester binder, and strips of fiberglass, also impregnated with resin, were glued to the shells. Further, the air comes out of the air channels through evenly spaced holes with a diameter of 90 mm in the outer shell, "rests" against the skirt segments and creates an air cushion under the apparatus.

A pair of longitudinal skis made of wooden bars are glued to the bottom of the outer shell of the hull to protect against damage from the outside, and in the aft part of the cockpit (that is, from the inside) there is an under-engine wooden plate.

Balloon. The new hovercraft model has almost twice the displacement (350 - 370 kg) than the previous one. This was achieved by installing an inflatable balloon between the body and segments of the flexible fence (skirt). The balloon is glued out of PVC material Uіpurіap, manufactured in Finland with a density of 750 g/m 2 , according to the shape of the body in plan. The material has been tested on large industrial hovercraft such as Khius, Pegasus, Mars. To increase survivability, the cylinder can consist of several compartments (in this case, three, each with its own filling valve). The compartments, in turn, can be divided in half lengthwise by longitudinal partitions (but this version of their execution is still only in the project). With this design, a broken compartment (or even two) will allow you to continue moving along the route, and even more so to get to the coast for repairs. For economical cutting of the material, the cylinder is divided into four sections: bow, two stern. Each section, in turn, is glued together from two parts (halves) of the shell: the lower and upper ones - their patterns are mirrored. In this version of the cylinder, the compartments and sections do not match.

a - outer shell; b - inner shell;
1 - nasal section; 2 - side section (2 pcs.); 3 - aft section; 4 - partition (3 pcs.); 5 - valves (3 pcs.); 6 - lyktros; 7 - apron

On the top of the cylinder, “lyktros” is glued - a strip of Vinyplan 6545 “Arktik” material folded in half, with a braided nylon cord embedded along the fold, impregnated with “900I” glue. "Liktros" is applied to the side rail, and with the help of plastic bolts the cylinder is attached to an aluminum strip fixed on the body. The same strip (only without the enclosed cord) is glued to the balloon and from the bottom-front (“at half past eight”), the so-called “apron” - to which the upper parts of the segments (tongues) of the flexible fence are tied. Later, a rubber bumper was glued to the front of the cylinder.

Soft elastic guard"Aerojeep" (skirt) consists of separate, but identical elements - segments, cut and sewn from dense light fabric or film material. It is desirable that the fabric is water-repellent, does not harden in the cold and does not let air through.

Again, I used Vinyplan 4126 material, only with a lower density (240 g / m 2), but domestic percale-type fabric is quite suitable.

The segments are slightly smaller than on the "balloonless" model. The pattern of the segment is simple, and you can either sew it yourself, even manually, or weld it with high-frequency currents (FA).

The segments are tied with the tongue of the lid to the lippase of the balloon (two at one end, while the knots are inside under the skirt) around the entire perimeter of the Aeroamphibian. The two lower corners of the segment with the help of nylon construction clamps are suspended freely from a steel cable with a diameter of 2 - 2.5 mm, wrapping lower part inner shell of the body. In total, up to 60 segments are placed in the skirt. A steel cable with a diameter of 2.5 mm is attached to the body by means of clips, which in turn are attracted to the inner shell with petal rivets.

1 - scarf (material "Viniplan 4126"); 2 - tongue (material "Viniplan 4126"); 3 - pad (fabric "Arctic")

Such fastening of the skirt segments does not much exceed the time of replacing a failed element of the flexible fence, compared to the previous design, when each was fastened separately. But as practice has shown, the skirt turns out to be efficient even if up to 10% of the segments fail and their frequent replacement is not required.

1 - outer shell of the body; 2 - inner shell of the body; 3 - overlay (fiberglass) 4 - bar (duralumin, strip 30x2); 5 - self-tapping screw; 6 - cylinder lyktros; 7 - plastic bolt; 8 - balloon; 9 - cylinder apron; 10 - segment; 11 - lacing; 12 - clip; 13-collar (plastic); 14-cable d2.5; 15-string rivet; 16-grommet

The propeller installation consists of an engine, a six-bladed propeller (fan) and a transmission.

Engine- RMZ-500 (similar to Rotax 503) from the Taiga snowmobile. Produced by Russian Mechanics OJSC under license from the Austrian company Rotax. The motor is two-stroke, with a petal inlet valve and forced air cooling. It has established itself as a reliable, powerful enough (about 50 hp) and not heavy (about 37 kg), and most importantly, a relatively inexpensive unit. Fuel - AI-92 gasoline mixed with oil for two-stroke engines (for example, domestic MGD-14M). Average fuel consumption - 9 - 10 l / h. The engine was mounted in the aft part of the apparatus, on a motor mount attached to the bottom of the hull (or rather, to the sub-engine wooden plate). Motorama has become higher. This is done for the convenience of cleaning the aft part of the cockpit from snow and ice, which get there through the sides and accumulate there, and freeze when stopped.

1 - output shaft of the engine; 2 - leading toothed pulley (32 teeth); 3 - toothed belt; 4 - driven toothed pulley; 5 - nut M20 for mounting the axis; 6 - remote bushings (3 pcs.); 7 - bearing (2 pcs.); 8 - axis; 9 - screw bushing; 10 - rear strut support; 11 - front over-engine support; 12 - front strut support-bipedal (not shown in the drawing, see photo); 13 - outer cheek; 14 - inner cheek

Propeller - six-bladed, fixed pitch, 900 mm in diameter. (There was an attempt to install two five-bladed coaxial screws, but it was unsuccessful). The screw sleeve is duralumin, cast. The blades are fiberglass, coated with a gel coat. The axis of the screw hub was lengthened, although the old 6304 bearings remained on it. The axle was mounted on a rack above the engine and fixed here with two spacers: two-beam - in front and three-beam - at the back. In front of the propeller there is a mesh fence grille, and behind - air rudder feathers.

The transmission of torque (rotation) from the engine output shaft to the propeller hub is carried out through a toothed belt with a gear ratio of 1: 2.25 (the drive pulley has 32 teeth, and the driven pulley has 72).

The air flow from the screw is distributed by a partition in the annular channel into two unequal parts (approximately 1:3). A smaller part of it goes under the bottom of the hull to create an air cushion, and a large part goes to the formation of propulsion (traction) for movement. A few words about the features of driving an amphibian, specifically - about the beginning of the movement. When the engine is idling, the machine remains stationary. With an increase in the number of its revolutions, the amphibian first rises above the supporting surface, and then begins to move forward at revolutions from 3200 - 3500 per minute. At this point, it is important, especially when starting off the ground, that the pilot first raise back apparatus: then the aft segments will not catch on anything, and the front segments will slide over bumps and obstacles.

1 - base (steel sheet s6, 2 pcs.); 2 - portal rack (steel sheet s4.2 pcs.); 3 - jumper (steel sheet s10, 2 pcs.)

The control of the "Aerojeep" (changing the direction of movement) is carried out by aerodynamic rudders, pivotally fixed behind the annular channel. The steering is deflected by means of a two-arm lever (motorcycle-type steering wheel) through an Italian Bowden cable going to one of the planes of the aerodynamic steering wheel. The other plane is connected to the first rigid link. On the left handle of the lever is fixed a carburetor throttle control lever or a “trigger” from the Taiga snowmobile.

1 - steering wheel; 2 - Bowden cable; 3 - knot for attaching the braid to the body (2 pcs.); 4 - Bowden braid of the cable; 5 - steering panel; 6 - lever; 7 - thrust (rocking chair is conditionally not shown); 8 - bearing (4 pcs.)

Braking is carried out by "throttle release". In this case, the air cushion disappears and the apparatus rests on the water with its body (or skis on snow or ground) and stops due to friction.

Electrical equipment and appliances. The device is equipped with a rechargeable battery, a tachometer with an hour meter, a voltmeter, an engine head temperature indicator, halogen headlights, a button and a check for turning off the ignition on the steering wheel, etc. The engine is started by an electric starter. Installation of any other devices is possible.

The amphibious boat was named "Rybak-360". It passed sea trials on the Volga: in 2010, at a rally of the Velkhod company in the village of Emmaus near Tver, in Nizhny Novgorod. At the request of the Moscow Sports Committee, he participated in demonstration performances at a celebration dedicated to the Navy Day in Moscow on the Rowing Canal.

Technical data "Aeroamphibian":

Overall dimensions, mm:
length……………………………………………………………………..3950
width…………………………………………………………………..2400
height…………………………………………………………………….1380
Engine power, hp……………………………………………….52
Weight, kg……………………………………………………………………….150
Load capacity, kg………………………………………………….370
Fuel reserve, l……………………………………………………………….12
Fuel consumption, l/h………………………………………………..9 - 10
Overcome obstacles:
rise, hail………………………………………………………………….20
wave, m………………………………………………………………………0.5
Cruise speed, km/h:
by water………………………………………………………………………….50
on the ground………………………………………………………………………54
on ice………………………………………………………………………….60

M. YAGUBOV Honorary Inventor of Moscow

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In Russia, there are entire communities of people who collect and develop amateur hovercraft. This is a very interesting, but, unfortunately, difficult and far from cheap activity.

KVP body manufacturing

It is known that hovercraft experience much less stress than conventional planing boats and boats. The entire load is taken by a flexible fence. Kinetic energy during movement is not transferred to the hull and this circumstance makes it possible to mount any hull without complicated strength calculations. The only limitation for the amateur STOL hull is weight. This must be taken into account when performing theoretical drawings.

Another important aspect is the degree of resistance to the oncoming air flow. After all, aerodynamic characteristics directly affect fuel consumption, which, even for amateur SVPs, is comparable to the consumption of an average SUV. Professional aerodynamic design worth big money, so amateur designers do everything "by eye", simply borrowing lines and shapes from the leaders of the automotive industry or aviation. About copyright in this case, you can not think.

For the manufacture of the hull of the future boat, you can use spruce slats. As a sheathing - plywood 4 mm thick, which is attached with epoxy glue. Pasting plywood with a dense fabric (for example, fiberglass) is impractical due to a significant increase in the weight of the structure. This is the most technologically uncomplicated way.

The most sophisticated members of the community create fiberglass cases from their own computer 3d models or by eye. To begin with, a prototype is created and a material such as foam plastic is removed from which the matrix is removed. Further, the hulls are made in the same way as fiberglass boats and boats.

The unsinkability of the hull can be achieved in many ways. For example, by installing water-tight partitions in the side compartments. Better yet, you can fill these compartments with foam. You can install inflatable balloons under the flexible fence, similar to PVC boats.

SVP power plant

The main question is how much, and he meets the designer all the way through the design of the power system. How many engines, how much the frame and engine should weigh, how many fans, how many blades, how many revolutions, how many degrees to make the angle of attack and in the end how much it will cost. It is this stage that is the most costly, because in artisanal conditions it is impossible to build an engine internal combustion or a fan blade with the desired efficiency and noise level. You have to buy such things, and they are not cheap.

The most difficult stage of the assembly was the installation of a flexible fence of the boat, which holds the air cushion exactly under the hull. It is known that due to constant contact with rough terrain, it is prone to rapid wear. Therefore, canvas fabric was used to create it. The complex configuration of the fence joints required the consumption of such fabric in the amount of 14 meters. Its wear resistance can be increased by impregnation with rubber adhesive with the addition of aluminum powder. This coating is of great practical importance. In case of wear or tear of the flexible fence, it can be easily restored. By analogy with building up a car tread. According to the author of the project, before you start making a fence, you should stock up on maximum patience.

Installation finished fence, as well as the assembly of the hull itself, must be carried out provided that the future boat is keel up. After raskantovy case, you can install the power plant. For this operation, you will need a mine with dimensions of 800 by 800. After the control system is connected to the engine, the most exciting moment in the whole process comes - testing the boat in real conditions.

The quality of the road network in our country leaves much to be desired. The construction of transport infrastructure in some areas is not feasible for economic reasons. With the movement of people and goods in such areas, vehicles operating on other physical principles will do just fine. Do-it-yourself full-size hovercraft cannot be built in artisanal conditions, but large-scale models are quite possible.

Vehicles of this type are capable of moving on any relatively flat surface. It can be an open field, a pond, and even a swamp. It is worth noting that on such surfaces unsuitable for other vehicles, the SVP is able to develop a fairly high speed. The main disadvantage of such transport is the need for large energy costs to create an air cushion and, as a result, high flow fuel.

Physical principles of operation of the SVP

The high permeability of vehicles of this type is ensured by the low specific pressure that it exerts on the surface. This is explained quite simply: the contact area of the vehicle is equal to or even exceeds the area of the vehicle itself. In encyclopedic dictionaries, SVPs are defined as vessels with a dynamically generated reference thrust.
Large and small hovercraft hover above the surface at a height of 100 to 150 mm. In a special device under the housing, excess air pressure is created. The machine breaks away from the support and loses mechanical contact with it, as a result of which the movement resistance becomes minimal. The main energy costs are spent on maintaining the air cushion and accelerating the apparatus in a horizontal plane.

Drafting a project: choosing a working scheme

For the manufacture of an operating model of the SVP, it is necessary to choose an effective hull design for the given conditions. Drawings of hovercraft can be found on specialized resources, where patents are posted with a detailed description of various schemes and methods for their implementation. Practice shows that one of the most successful options for media such as water and hard ground is the chamber method of forming an air cushion.

In our model, a classic two-engine scheme with one pumping power drive and one pusher will be implemented. Small-sized do-it-yourself hovercraft made, in fact, are toys-copies of large devices. However, they clearly demonstrate the advantages of using such vehicles over others.

Ship hull manufacturing

When choosing a material for a ship's hull, the main criteria are ease of processing and low specific gravity. Homemade ships hovercraft are classified as amphibious, which means that in the event of an unauthorized stop, flooding will not occur. The ship's hull is sawn out of plywood (4 mm thick) according to a pre-prepared template. To perform this operation, a jigsaw is used.

A homemade hovercraft has superstructures that are best made from Styrofoam to reduce weight. To give them a greater external resemblance to the original, the parts are glued on the outside with foam plastic and painted. Cabin windows are made of transparent plastic, and the rest of the parts are cut from polymers and bent from wire. Maximum detail is the key to similarity with the prototype.

Air chamber dressing

In the manufacture of the skirt, a dense fabric made of polymeric waterproof fiber is used. Cutting is carried out according to the drawing. If you do not have experience transferring sketches to paper manually, then they can be printed on a large-format printer on thick paper, and then cut out with ordinary scissors. The prepared parts are sewn together, the seams should be double and tight.

Do-it-yourself hovercraft, before turning on the injection engine, rest on the ground with their hull. The skirt is partially rumpled and is located under it. The parts are glued with waterproof glue, the joint is closed by the body of the superstructure. This connection provides high reliability and allows you to make mounting joints invisible. Other external parts are also made of polymeric materials: a propeller diffuser guard and the like.

Power point

As part of the power plant there are two engines: forcing and sustainer. The model uses brushless electric motors and two-bladed propellers. Remote control of them is carried out using a special regulator. The power source for the power plant are two batteries with a total capacity of 3000 mAh. Their charge is enough for half an hour of using the model.

Homemade hovercraft are controlled remotely via radio. All components of the system - radio transmitter, receiver, servos - are factory-made. Installation, connection and testing of them is carried out in accordance with the instructions. After the power is turned on, a test run of the motors is performed with a gradual increase in power until a stable air cushion is formed.

SVP Model Management

Self-made hovercraft, as noted above, have remote control via the VHF channel. In practice it looks like in the following way: The owner is holding a radio transmitter. The engines are started by pressing the appropriate button. Joystick controls the speed and direction of movement. The machine is easy to maneuver and quite accurately maintains the course.

Tests have shown that the SVP confidently moves on a relatively flat surface: on water and on land with equal ease. The toy will become a favorite entertainment for a child aged 7-8 years with a fairly developed fine motor skills of the fingers.

What is a "hovercraft"?

Technical data of the machine

What materials are needed?

How to make a body?

What engine is needed?

DIY hovercraft

Hovercraft is a vehicle capable of moving both on water and on land. Such a vehicle is not at all difficult to do with your own hands.

What is a "hovercraft"?

This is a device where the functions of a car and a boat are combined. As a result of this, a hovercraft (HV) has been obtained, which has unique off-road characteristics, without loss of speed when moving through water due to the fact that the hull of the vessel does not move through the water, but above its surface. This made it possible to move through the water much faster, due to the fact that the friction force of the water masses does not provide any resistance.

Although the hovercraft has a number of advantages, its scope is not so widespread. The fact is that not on any surface this device can move without any problems. It needs soft sandy or soil soil, without the presence of stones and other obstacles. The presence of asphalt and other solid bases can cause damage to the bottom of the vessel, which creates an air cushion when moving. In this regard, "hovercraft" are used where you need to swim more and drive less. On the contrary, it is better to use the services of an amphibious vehicle with wheels. The ideal conditions for their use are impassable swampy places where, apart from a hovercraft (Hovercraft), no other vehicle can pass. Therefore, SVPs have not become so widespread, although rescuers of 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 a transport or how to make it yourself?

Hovercraft is an expensive mode of transport, average price which comes to 700 thousand rubles. Transport type "scooter" is 10 times cheaper. But at the same time, one should take into account the fact that factory-made vehicles are 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 designs assembled in garages.

Factory models have always been focused on a highly professional direction, connected either with fishing, or with hunting, or with special services. As for homemade SVPs, they are extremely rare and there are reasons for this.

These reasons include:

Pretty high cost, as well as expensive maintenance. The main elements of the apparatus wear out quickly, which requires their replacement. And each such repair will result in a pretty penny. Only a rich person will allow himself to buy such an apparatus, 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 to move on water.
The working product creates a lot of noise, so you can only move around with headphones.
When driving against the wind, the speed drops significantly and fuel consumption increases significantly. Therefore, homemade SVPs are more of a demonstration of their professional abilities. The vessel not only needs to be able to manage, but also be able to repair it, without significant costs.

Do-it-yourself 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. Technical education will not hurt either. If the latter condition is absent, then it is better to abandon the construction of the apparatus, otherwise you can crash on it at the 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 factor that this is, in fact, an air vehicle, although it is very low to the surface of the earth. If all 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.