SCHOOL OF AIRCRAFT (PART 5) | MODEL CONSTRUCTION

GLIDER OR GLIDER? Unpowered gliding flight has long attracted man. It would seem that what is easier is attached to the back wings, jumped down the mountain and … flew. Alas, many attempts to rise into the air, described in historical Chronicles, has led to success only in the late nineteenth century. The first glider was a German engineer, Otto Lilienthal, glider balance created is very dangerous to fly the aircraft. In the end, the glider of Lilienthal killed its Creator and brought a lot of trouble enthusiasts gliding flight.

A serious shortcoming of the balance of the glider was the control method, in which the pilot had to move the centre of gravity of his body. The apparatus of the obedient could of seconds to become absolutely unstable, that led to accidents.

A significant change in planning aircraft made brothers Wilber and Orville Wright, created a system of aerodynamic control that consists of the elevators, rudder and apparatus for skew (gazirovanye) wing tips, which soon replaced the more effective ailerons.

The rapid development of gliding started in the 1920-ies, when the aircraft has come thousands of fans. That’s when Amateur designers from many countries have developed hundreds of varieties non-motorised aircraft.

In the 1930 – 1950s years of the construction of gliders continuously improved. Characterized by the use of a cantilever without braces and struts of the wings of large aspect ratio, fuselage a streamlined shape, and the chassis, retractable into the fuselage. However, in the manufacture of gliders continued to be applied to wood and canvas.

Glider “the Nightingale” by L. Solovyov (wing area-12,24 m2; empty weight -120 kg; take – off weight- 200 kg; flight alignment – 25%; Maximum speed – 170 km/h; stall speed – 40 km/h; the rate of decline of -0.8 m/s; the maximum aerodynamic quality-20):

1 – folding (right side) of the lamp; 2 — air receiver pressure speed indicator; 3 – start-up hook; 4 – landing ski; 5 – brace (pipe 30KHGSA 45X1,5); 6 — brake plate; 7 — box wing spar (shelves – pine walls and birch plywood); 8 – wing profile DFS-P9-14, 13.8 per cent; 9 – plywood box-beam; 10 – speed indicator; 11 – altimeter; 12 – gauge slide; 13 – variometer; 14 – rubber ski damper; 15 – parachute PNL; 16 – wheel d300x125

Training gliders design P. Alimarina:

ANB-M – single glider: the wing area of 10.5 m2; empty weight – 70 kg; take – off weight- 145 kg.

NSA-I – double glider-spark

Training glider-spark NSA-I

Training gliders:

A – GRP Pelikan: wing area -10,67 m2; empty weight – 85 kg; takeoff weight – 185 kg; the stall speed 50 km/h.

B-glider “Foma” Vladimir Markov (Irkutsk): empty weight – 85 kg

Gliders of initial training:

And KAI-502: a wing span of 11 m; wing area of 13.2 m2, wing profile, RSA – 15%; empty weight -110 kg; takeoff weight-260 kg; the stall speed is 52 km/h; optimum gliding speed is 70 km/h; maximum glide ratio is 14; the minimum rate of descent of 1.3 m/s.

B – glider “Youth”: wingspan – 10 m; wing area — 13m2; wing profile – RIA – 14%; empty weight – 95 kg; takeoff weight – 245 kg; stall speed: 50 km/h; optimum gliding speed is 70 km/h; maximum glide ratio is 13; the minimum rate of descent of 1.3 m/s.

In – person glider UT-3: the wingspan is 9.5 m; wing area is 11.9 m2; wing profile – RSA-15%; empty weight-102 kg; takeoff weight — 177 kg; the stall speed of 50 km/h; optimum gliding speed – 65 km/h; maximum glide ratio is 12; the minimum reduction rate of — 1m/s

The real revolution in gliding occurred in the late 1960-ies, when the composite materials consisting of fiberglass and binder (epoxy or polyester resin). Moreover, the success of plastic gliders was provided not so much new content, how many new technologies of manufacture of the aircraft.

Interestingly, the gliders made of composite materials was heavier than wood and metal. However, the high fidelity of the theoretical contours of the aerodynamic surfaces and beautiful exterior finish, provide new technology will significantly increase the aerodynamic quality of a glider. By the way, the transition from metal to composites aerodynamic efficiency has increased by 20 to 30 percent. The mass of the airframe was increased, which led to an increase in flight speed, but high aerodynamic quality have enabled to significantly reduce the vertical descent rate. This allows glider pilots-“composition” to win the competition from those who were on a wooden or metal gliders. As a result, modern athletes-glider pilots fly solely on composite gliders and airplanes.

The technology of manufacturing of composite structures is now widely used to create light, including Amateur aircraft and gliders, so it makes sense to tell more about it.

The main elements of a modern glider wing are the spar or box beam, perceiving the bending and shear strength, as well as the upper and lower load-bearing cladding panels, the load from the torsion of the wing.

The construction of the wing begins with the manufacture of matrices for molding trim panels. First manufactured wooden blank, which exactly reproduces the contours of the outer panel. The perfection of the theoretical contour and the surface finish of the discs will determine the accuracy and smoothness of the surfaces of future panels.

After applying to the disc of the separation layer laid out the rough fiberglass cloth impregnated with epoxy binder. Simultaneously pasted power frame, welded from thin steel tubes or profiles angle section. After curing of the resin the resulting crust-matrix is removed from pigs and placed on a suitable stand.

Similarly, matrices are made for the top and bottom panels, stabilizer, left and right sides of the fuselage, which are usually made integral with the keel. The panels have a three-layer structure of type “sandwich” – their inner and outer surface is made from fiberglass, the inner filler is Styrofoam. Its thickness depending on panel sizes ranging from 3 to 10 mm. Inner and outer skin is laid several layers of fiberglass with a thickness of 0.05 to 0.25 mm. the Total thickness of the glass cloth “crusts” is defined when calculating the design strength.

In the manufacture of the wing in the first matrix privorovyvat all the layers of fiberglass, the components of the outer skin. Fiberglass pre-impregnated with epoxy binder -most fans use resin K-153. Then the fiberglass quickly spread the foam filler, cut into strips 40 to 60 mm, then the foam covered inner layer of binder impregnated fiberglass. To avoid creases, glass cloth sheathing manually aligning and looks.

Further, the resulting “semi-finished” should be covered with an airtight film with embedded in her nipple and glue it with sealant (or even clay) to the edges of the matrix. Further, through the fitting of film from a vacuum pump the air is evacuated – the entire set of panels tightly squeezed and pressed into the matrix. As such, the set is aged prior to the final polymerization of the binder.

Glider “Kakadu” (wing area of 8.2 m2; wing profile – RSA – 15%, empty weight – 80 kg; takeoff weight – 155 kg):

1 – rear wing spar (consists of walls with foam filler, covered on both sides by fiberglass, and fiberglass shelves); 2 – foam filling SS-4; 3 — shelf fiberglass side rail (2 PCs); 4 — fiberglass node linkage Aileron; 5 – fiberglass tubular spar of the Aileron (wall thickness 0.5 mm); 6 – three-layer panels forming the skin of the ailerons (filler – foam PS-4 with a thickness of 5 mm, the thickness of the fiberglass cover on the outside of 0.4 mm, inside — 0.3 mm); 7 — fuselage beam; 8 — shelf fuselage beams (glass thickness 3 mm); 9 — casing made of fiberglass with a thickness of 1 mm; 10 – the block of foam PS-4; 11 – fiberglass leading edge wing with a thickness of 0.5 to 1.5 mm, forming the torsion circuit; 12 — typical rib of the wing; 13 — shelf fiberglass rib thickness of 1 mm; 14 – fiberglass wall of the rib is 0.3 mm thick; 15 – front wing spar (design is similar to the rear)

The sailplane and glider design V. Miroshnik

Glider and glider designed by V. Miroshnik:

A – a training glider A-10B “eagle”:

wing area -10 m2; empty weight – 107,5 kg; takeoff weight of 190 kg and a maximum speed of 190 km/h stall speed 45 km/h; maximum glide ratio is 22; the range of operating overloads from +5 to -2.5; the estimated overload – 10.

B — glider A-10A engine “Vikhr-30-Aero” air-cooled power 21 HP In-flight powerplant can clean the compartment located in the middle part of the fuselage.

The length of the glider – 5.6 m; the wingspan is 9.3 m; wing area – 9,2 m2; take – off weight- 220 kg; maximum speed – 180 km/h; stall speed 55 km/h; maximum glide ratio is 19; the diameter of the propeller – 0,98 m; the pitch is 0.4 m, frequency of rotation of the rotor is 5000 rpm

Glider “Kite-M” (HAI-29M):

engine – “Kolibri-350” homemade, two-cylinder, opposed, power 15 HP; the length of the glider — 5,25 m; wingspan -9 m, wing area – 12.6 m2 ; wing profile – R-P – 14%; profile hangs Aileron – R-s — h- 16%; empty weight – 135 kg; takeoff weight – 221 kg; the maximum speed is 100 km/h; cruising speed – 65 km/h; stall speed – 40 km/h; maximum glide ratio -10

Similar technology is used in the production of shelves of longerons, the only difference is that their spread from unidirectional glass or carbon fibers. The final Assembly of the wing, tail and fuselage is usually performed in the matrices.

Optionally, in the finished formed three-layer panel put and glued the spars, frames and ribs, and then everything is covered and sealed by the upper panel.

Since the details of internal set and the cladding panels are large gaps, it is recommended when gluing, use of epoxy glue with a filler, e.g., glass microspheres. The outline of the gluing of the panels from the outside (and inside) glued glass cloth tape.

Technology vyklicky and assemblies described here only in General terms, but, as experience shows, the aircraft fans quickly enough to comprehend its intricacies, especially if you have the opportunity to see how it is done by those who have already mastered this technique.

Unfortunately, the high cost of modern composite gliders led to the fall of a mass of gliding. Alarmed by this, the international Federation of air sports (FAI) have introduced a number of simplified classes of gliders, standard, club and the like, the wingspan should not exceed 15 meters. However, difficulties remain with the launching of the gliders – it requires aircraft towing or quite complex and expensive motoliberty. As a result, the gatherings of Amateur aircraft ULTRALIGHT every year brought fewer gliders. To all, a significant part of the variation present gliders BRO-11 construction of B. I. Oscines.

Of course, the construction of its first aircraft is best done in the image and likeness of a reliable, good flying prototype. It is this “copying” with a minimal amount of trial and error gives the invaluable experience that cannot be acquired from textbooks, instructions and descriptions.

However, at conventions SLA periodically and original, more modern aircraft, such as glider NSA-M, created by P. Almuminum from the city of Samara.

Peter dreamed of “wings” from childhood. But poor eyesight prevented him to enter flight school and engage in aviation sports. But there is a silver lining – Peter entered the Aviation Institute, graduated and was assigned to the aviation factory. It was there that he was able to organize youth aviation design, later transformed into the club’s “Flight.” And the most efficient assistants of Aparina were students of the aviation Institute, as much as Peter, who dreamed of flying.

The first self-developed design of the club was a glider, made with the technological features of a modern aircraft production – durable, simple and reliable, on which to learn to fly all members of the club.

The first glider was called the NSA – according to the initial letters of surnames of its designers: Appearsin, Nikitin, Bogatov. The wing and the tail unit was unconventional for a glider of this class the metallic structure with the use of as thin-walled duralumin spars of large diameter pipes. Only the fuselage in the original version of the airframe was made of composite materials. However, in another embodiment, the cockpit has designed a metal, allowing for 25 – 30 kg to reduce its weight.

The creators of the glider was not only literate designers, but also good technology, familiar with modern aircraft production. Thus, in the manufacture of thin sheet metal parts made of aluminum they used a simple, well-proven in aircraft manufacturing technological operation – stamping rubber. The necessary tooling was made by young engineers themselves.

The Assembly of the gliders were produced in the basement that housed the club. The flight characteristics of new vehicles have appeared close to settlement. Soon all the club members learned to fly in a homemade glider, having dozens of independent flights from motoliberty. And at conventions, ULTRALIGHT gliders have consistently received the highest rating of specialists recognize the NSA-M the best glider of initial training among production and Amateur designs. And the club Polet introduced a new, more suitable work premises and it was reorganized into the “Design Bureau of sport aviation” at an aircraft factory with a staff of five people.

Meanwhile, work on the modernization of the airframe, the NSA continued to improve its design, conducted the static test of strength, preparing for serial production of the device.

All good flying gliders with the launch of them with motoliberty, but such flights, there is one very significant drawback – the short-term. Therefore, the development of each group of aviation enthusiasts is quite natural is the transition from the airframe to the aircraft.

Using a well established airframe of the NSA and the technology of its production, the young aircraft designers Alarsin, Nikitin, Safronov and kings designed and built the single training plane “Crystal” (a detailed description of the design of this machine – in the previous “lessons” of our school in the “M-K” № 7, 2013).

It should be noted that the gliders initial training has always attracted both fans of single and design teams. So, one of the most beautiful gliders of the training of those that ever were shown at gatherings of ALS, was recognized as the “Cockatoo”, created by aviation enthusiasts from the city of Otradnoe in Leningrad region.

This glider is made of three kinds of materials – foam, fiberglass and epoxy binder, and the design of the wing and tail is a sort of small design masterpiece.

Rib of the wing is made from foam and are covered with thin fiberglass. Toe wing, perceiving torque, is laminated to the foam block filler fiberglass shell. Fuselage beam carved from foam and covered with fiberglass, and the bending moment perceive fiberglass shelves, glued to top and bottom surfaces of the beam. The quality of work – excellent exterior finish – the envy of many DIY. The only “but” to fly the glider refused – as it turned out, in an effort to reduce the weight of the structure, the creators of the glider unnecessarily reduced the wing.

Enthusiasts who passed flight training in gliders initial training, we can recommend more sophisticated apparatus, for example, glider A-10B “eagle”, created by students of the Samara aviation Institute under the direction of V. Miroshnik. Interestingly, the parameters, the glider does not correspond to any sports class and for its size it is less than the standard. While A-10B very clean aerodynamic shape, a simple strut-braced wing is covered with cloth, and the unit itself is made of the most common plastics. A sufficiently large aerodynamic quality of the airframe is able to perform it even long soaring flights. A simple tecnique and allows the beginner to cope with such apparatus. It seems that it is inexpensive and “flying” gliders do not have enough domestic gliding.

A peculiar development of the ideas embodied in the A-10B was the glider “Dream”, created in the Moscow Amateur club under the direction of Vladimir Fedorov. Design, manufacturing technology and the appearance of the “Dream” is a typical modern sports glider, and the specific load on the wing and some other parameters – a typical glider initial training. Flies the “Dream” is quite good, at conventions ULTRALIGHT this glider was sent flying in tow aircraft “Wilga”.

It should be noted that the flights of the gliders with the launch of their with isolator, winch, or small mountains are extremely limited in time and not bring the pilot to adequately meet. Another thing – glider! At the machine with the motor capabilities are severely wider. And even gliders with small motors sometimes exceed the flight data of some light aircraft Amateur-built.

It is, apparently, that the aircraft, usually the wing span is substantially less than that of the glider, and when you reduce the scale of losses in lift are large than the gain in mass. As a result, some aircraft are not able to get off the ground. While training gliders with a rough aerodynamic shape and low-power motors fly well. The only difference of these aircraft from the aircraft is greater wingspan. I think that is why the training gliders are very popular among fans.

Glider HAI-35M “Enthusiast”:

the power of the engine 36 l,p.; wing area – 11m2; the empty weight of 170 kg; takeoff weight – 260 kg; flight alignment – 28 %; maximum speed – 150 km/h; stall speed of 48 km/h; rate of climb is 2.4 m/s; the maximum aerodynamic quality – 15

Glider “Garnis” B. Oskinis and H Kishonasa (Kaunas)

the length of the glider -5 m; wingspan -8 m; wing area – 10,6 m2; empty weight – 139 kg; takeoff weight – 215 kg; maximum velocity of -130 km/h; landing speed 40 km/h; rotation frequency of the propeller – 5000 Rev/min.);

1 – variometer; 2 – slip indicator; 3 airspeed indicator; 4 – altimeter; 5 – pedal; 6 – receiver air pressure; 7 – tubular motor; 8 – engine; 9 – cable brace; 10 – control cables, rudder; 11 – pull Elevator control; 12 – all-moving horizontal tail; 13 – tube struts stabilizer; 14 – sections of wing and tail, covered with Mylar film; 15 — tail spring; 16 – fiberglass gondola pilot; 17 – thrust control the ailerons; 18 – spring main chassis; 19 – control wiring engine; 20 – spring fiberglass nose landing gear; 21 — wing spar; 22 – hinge Aileron; 23 – Aileron ( upper casing – fiberglass, bottom – Mylar film); a 24 – silencer; 25 – fuel tank 26 – tubular strut wing

Double glider “Aeroprakt-18” (SKB KuAI):

wing area is 16.3 m2; wing profile modified GAW-1 – 15%; take-off weight of 390 kg; empty weight – 200 kg; maximum velocity of -130 km/h; rate of climb – 2, 3 m/s; the calculated overload from + 10,2 up to -5,1; maximum aerodynamic efficiency -25; the thrust of the propeller – 70 kgs at 5000 rpm

Double motoglider “Baikal” with the power plant of the two coupled 40-horsepower motors “Whirlwind-25” air cooling:

wing area – 18,9 m2; take-off weight – 817 kg; the stall speed of 70 km/h; the maximum speed of horizontal flight-150 km/h

Glider “Solitare” designed by Burt Rutan with a 23-horsepower engine КFМ-107E. located on the folding rack in the forward fuselage:

the wingspan is 12,725 m; the span of the front wing – 4,68 m; the length of the glider -5,86 m; area of the front wing – 1.73 m2; the area of the main wing – 7,79 m2; empty weight – 172 kg; takeoff weight of 281 kg; maximum aerodynamic quality – 32; the maximum speed is 213 km/h, stall speed – 60 km/h; the range of 241 km; range of operating overloads from +7 to -3

Great success in the simplest of such devices is made up students of the Kharkiv aviation Institute, built under the leadership of A. Barannikova glider “Kite-M”, and later under the leadership of N. Laurel was created more perfect “Enthusiast”, had a good aerodynamic shape, a closed cockpit and carefully zakuporivaniya engine.

It should be noted that both of these glider are a further development of the popular in his time of training glider BRO-11 design B. Oskinis. Machines of Kharkov students have a simple design with no claim to originality, but they are very durable, reliable and available to management for novice pilots.

At one of the gatherings SLA H Kishonas from Kaunas showed one of the best-gliders – “Garnis” made entirely of fiberglass. The covering of the wings and tail – transparent Mylar film. The power unit is an outboard motor “Whirlwind M” capacity 25 HP, converted by air cooling. The motor is easily removed from the machine.

The motoglider is equipped with several options readily detachable chassis -tricycle-type aircraft, glider and float balancing.

Motor gliders and gliders on the type of “Kite” and “Garnis” are built in our country by many fans in dozens of instances. I want to draw readers ‘ attention only to one feature such devices, constructed in the image and likeness of BRO-11. As you know, prototype (and its many copies) is fitted with drooping ailerons, kinematically associated with the wheel height. When landing, the pilot takes over the control stick, the ailerons simultaneously deflected down, causing an increase in lift and decrease speed. But, if the pilot accidentally touched the handle, and then correcting the situation, gave the handle away from you – the last movement of the handle causes not only the deflection but also the return of the ailerons in the original position, which is equivalent to cleaning the flaps. Thus the lifting force decreases sharply, and the glider “falls”, which is very dangerous when flying at low altitude, before landing.

The experiments carried out by the glider pilots, flying BRO-11, showed that without hovering ailerons takeoff and landing characteristics of the glider practically does not deteriorate, but to fly a glider is much simpler, which significantly reduces the accident rate. Thus for the wing of the glider-the slug might be a better convexo-concave profile of the “göttingen F-17” – at the time it is used on the glider Phoenix-02, by the engineer of TSAGI S. Popov.

The popularity of the gliders is due, primarily, to start without a special towing devices, and also due to the emergence of simple, easy and powerful enough motors. At conventions SLA was shown a lot of original, spectacular flying machines of this class are created by designers and fans. Beautiful glider A-10A was built by V. Miroshnik on the basis of already familiar to readers AND 10B. Power unit he – engine “Vikhr-25 converted for air cooling; it is located above the fuselage, behind the cockpit. The engine typically is used only for takeoff and climb. After turning it off a special mechanism was folding farm with the installed on it with the engine and cleaned it in the fuselage that significantly reduced aerodynamic drag of the aircraft. If necessary, the engine using the same mechanism could be put forward from a niche and start.

Another aircraft built by students of the Samara aviation Institute, double glider “Aeroprakt-18”. It is compact, lightweight, made entirely of plastic and is equipped with a 30 horsepower engine “Vikhr-30-Aero” air-cooled – this model has the engine in flight is not removed, which allowed to simplify and to facilitate construction.

However, Amateur designers continued to develop the original versions of the arrangements of cleaning of the motors in flight, and one of the most interesting devices was created by a group of Moscow aviation enthusiasts under the direction of A. Fedorov for single twin-engine glider “Istra”. Light engines were fully inscribed in the contours of the wing, not speaking for his theoretical outlines, and the propellers revolved in the cracks behind the rear wing spar. When you stop the engine the screws were fixed in a horizontal position and closed by sliding the shank of the wing.

Another development of the Moscow glider pilots of Amateur – double motoglider “Baikal”, is also equipped with two engines. However, they are placed not on the wing, and V-shaped pylon above the fuselage. In flight, the engines are retracted into the fuselage – just like on “Istra”.

The feature of A. Fedorov-gliders – composite construction, made in accordance with the canons of modern technology.

It is considered that the aerodynamic design of modern gliders and motor-gliders is fully stabilized. In fact, all modern devices of this type differ little from each other, and their geometric proportions are almost identical. However, the design ideas looking for new solutions, other schemes and proportions. The evidence of Swiss aircraft designers and glider Bert Rutan “Solitare”. These original gliders, made by the scheme “duck”, once again demonstrated the advantages of a bearing of the horizontal tail.

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