The proposed simple glider designs were developed in the experimental design circle of the SUT of Kostroma. All of them are made mainly of foam plastic, but differ from each other in dimensions, proportions, weight, wing manufacturing technology, and flight characteristics. Models are recommended for making by young modellers at home, in club classes and technology lessons.
A small, lightweight glider with a wingspan of 200 mm and a weight of 4 g (Fig. 1) belongs to the category of the simplest entertainment models and can be made in a few hours. It is launched in a gym by hand or in calm weather on a sports ground using a catapult. The model with a wingspan of 230 mm and a mass of 7 g (Fig. 2) is somewhat heavier and stronger, and its flight duration is longer (about 15 seconds). The glider is designed to be launched by hand and using a catapult (even in light winds) on a football or other field.
A more complex model (Fig. 3) with a wingspan of 400 mm and a mass of 26 g is a throwing glider. Both beginners and experienced modelers are passionate about building throwing gliders. Competitions are held for this class of models. The main task is to achieve maximum flight duration. Gaining height is ensured only by hand throwing. When designing such a glider, one has to solve a whole range of problems. It is necessary to achieve the optimal ratio of the mass of the model, the shape and area of the load-bearing surfaces so that the glider can be thrown to the maximum height. After takeoff, the model should clearly enter the stable long-term gliding mode. For this purpose, in the proposed design the fuselage nose is made quite short, and the tail boom is made long, but light and strong. With such an aerodynamic design, the almost weightless and compact tail unit is located outside the zone of turbulence from the wing and works efficiently. Even in the absence of upward flows, students in grades 5 and 6, with a correctly executed throw, managed to achieve a microfloat flight duration of up to 30 seconds. To run such a model, a field of at least 200x200 meters in size is required, preferably outside the city.
Preparatory work consists of completing drawings of parts in life size, making templates for the wing, stabilizer, fin and fuselage nose, selection of materials. Requires ceiling foam tiles 3.5 mm thick with dimensions 500×500 mm (sold in building and finishing materials stores), dense types of foam, wood (spruce, pine, linden), PVA glue and paints.
1 - centering weight (lead); 2 - nose of the fuselage; 3 - fuselage (pine); 4 - wing; 5 - stabilizer; 6 - keel; material of parts 2, 4, 5, 6 - foam plastic
1 - centering weight (lead); 2 - nose of the fuselage; 3 - fuselage (pine); 4 - keel; 5 - wing; 6 - spar (match); 7 - stabilizer
1 - centering weight (lead); 2 - nose of the fuselage; 3 - fuselage (pine); 4 - keel; 5 - wing; 6 - reinforcement for the finger (plywood s1.5); 7 - spar (pine); 8 - stabilizer
It is recommended to start creating models with the manufacture of the wing, fin and stabilizer. After marking the contour according to the templates, these parts can be cut out with a scalpel. Then you should start profiling them. In order to simplify the design, the wing has a flat-convex profile along its entire span. A significant portion of the material from the line maximum thickness It is better to remove it with a sharp knife. The surface finishing is carried out using sandpaper of various grains, glued to plywood plates measuring approximately 50x200 mm, with constant monitoring using templates. To give the wing of the model (Fig. 1.2) a small transverse V-shape, before gluing it into the slot of the fuselage along the axis of symmetry, an incision must be made on the upper surface. In the second of the proposed designs, the central part of the wing is reinforced with a short matchstick spar. In the model of a throwing glider (Fig. 3), a slot should be made on the lower surface of the wing and a spar should be glued into it. Further from the wing, where the spar ends, you need to saw off the “ears” and re-glue them under required angle. Pre-joint surfaces are beveled with sandpaper so that the gaps are minimal.
As is known from the practice of launching throwing gliders, a good throw is obtained when the fuselage is grasped with the thumb and middle finger, and the last bend of the index finger rests on the rear edge of the root part of the right console. Therefore, it is advisable to strengthen its lower surface with a 1.5 mm plywood or cardboard overlay under forefinger. The leading edge of the wing can be covered with thin colored paper on liquid PVA. The keel and stabilizer of the models have a “flat board” profile with rounded edges. The notch should highlight the “rudder” and “elevator”.
The nose of the fuselage of the models is made of dense foam, and the fuselage rail is made of light wood. A slot was made in the bow exactly along the wing profile and a cavity was drilled for a lead weight. The exact location of the groove on the lower surface of the fuselage for engaging the rubber cord of the catapult is selected experimentally.
The parts are connected using PVA glue. The wing is carefully inserted into the fuselage slot and fixed with glue. The area where the wing and fuselage meet should be reinforced with strips of drawing paper. Next, the keel and stabilizer are glued.
The finishing of the models includes painting the fuselage slats and paper-covered sections of the wing with nitro enamel.
Debugging of airframes begins with the elimination of distortions, and then proceeds to balancing. The center of gravity of models launched using a catapult (Fig. 1,2) should be at a distance equal to approximately 33% of the wing width, measured from the junction of its leading edge with the fuselage. The throwing glider has a centering of approximately 45°. Adjustment is carried out by increasing the mass of the centering weight or reducing it by drilling it.
During test runs of models, due to minimal deflection of the elevator and rudder, they achieve smooth transition after gaining altitude, hover in a left turn. Recommendations for launching and debugging simplest and throwing gliders were previously given in the magazine.
A. TIKHONOV, Kostroma
How to make a glider with your own hands. This model is an improved version glider models"Hummingbird" "Sinichka" has smooth curves of the wing, stabilizer and keel (Fig. 81). This shape improves the flight qualities of the glider. In addition, all connections of parts are made using glue, without the use of metal corners. Thanks to this, the Tit is lighter than the Hummingbird, which also improves its flight qualities. And finally, the wing of this model is raised above the fuselage rail and secured with wire struts. This device increases stability glider in flight.
We'll start working on the model by drawing working drawings. You already know how to do this. The fuselage of the model consists of a 700 mm long rail with a section in the nose section of 40X6, and in the tail section of 7X5 mm. For the weight you need a board 8-10 mm thick and 60 mm wide made of pine or linden. We cut out the weight with a knife and process its ends with a file and sandpaper. The ledge at the top of the weight will accommodate the front end of the rack. Now let's start making the wing.
Both of its edges should be 680 long and 4X4 mm in diameter. We will make two end roundings for the wing from aluminum wire with a diameter of 2 mm or from pine slats with a length of 250 mm and a cross section of 4X4 mm. Before bending, soak the slats in hot water within 15-20 minutes. The form for making smooth curves can be glass or cans or bottles of the required diameter.
In our glider, the molds for the wing should have a diameter of 110 mm, and for the stabilizer and fin - 85 mm. Having steamed the slats, we wrap each of them tightly around the jar and tie the ends together with an elastic band or thread. Bend this way required quantity slats, leave them to dry (Fig. 82, a). Roundings can be done in another way. Let's draw a rounding on a separate sheet of paper and place this drawing on the board. Drive nails along the contour of the curve. Having tied the steamed strip to one of the nails, we begin to carefully bend it.
We tie the ends of the slats together with an elastic band or thread and leave until completely dry. We connect the ends of the curves with the edges “on the mustache”. To do this, we cut off the connecting ends at a distance of 30 mm from each of them, as shown in Fig. (82, b) and carefully adjust them to each other so that there is no gap between them. We coat the joint with glue, carefully wrap it with thread and coat it with glue on top again. It should be borne in mind that the longer the miter joint, the stronger it is. We bend the ribs for the wing on a machine. We will accurately mark their installation locations according to the drawing.
After each operation (installation of curves, ribs), we will put the wing on the drawing to make sure the assembly is correct. Then we will look at the wing from the end and check whether any rib protrudes above the other “hump”. After the glue at the junction of the ribs and the edges has dried, it is necessary to give the wing a transverse angle V. Before bending, soak the middle of the wing edges under a tap with a stream of hot water and heat the bend over the fire of an alcohol lamp, candle or over a soldering iron. We will move the heated part over the flame so that the rail does not break due to overheating.
We will bend the rail until the heating area remains hot, and we will release it only after it has cooled down. Let's check the transverse angle V by placing the end of the wing against the drawing. Having bent one edge, bend the other in the same way. Let's check whether the transverse V angle is the same on both edges - it should be 8° on each side. The wing mount consists of two Y-posts(struts), bent from steel wire with a diameter of 0.75-1.0 mm and a pine plank 140 mm long and 6X3 mm in cross section. The dimensions and shape of the struts are shown in Fig. (83.
)The struts are attached to the edges of the wing with threads and glue. As can be seen from the picture, the front strut is higher than the rear one. As a result, the wing installation angle is formed. It should be about -4-2°. The plank is attached to the rail with an elastic band. We will make the stabilizer from two slats 400 mm long, and the keel from one such slat. Let's steam the slats and bend them, using a jar with a diameter of 85-90 mm as a mold. In order to mount the stabilizer on the fuselage rail, we plan a strip 110 mm long and 3 mm high.
We will tie the front and rear edges of the stabilizer in the center with threads to this bar. Let's sharpen the ends of the keel's rounding, make holes in the strip next to the edges of the stabilizer and insert the pointed ends of the keel into them (Fig. 84). Now you can start covering the glider frame with tissue paper. We will cover the wing and stabilizer only on top, and the fin on both sides. We'll start assembling the airframe with the tail: we'll place the stabilizer on the rear end of the fuselage rail and wrap an elastic band around the front and rear ends of the connecting strip along with the rail.
To launch the glider model on a rail, we will make two hooks from steel wire and tie them with threads to the fuselage rail between the leading edge of the wing and the center of gravity of the glider. The first launches of the model will be carried out from the front hook. After making sure that the launch is successful, you can launch the glider from the second hook. It should be borne in mind that in windy weather it is better to launch the model from the front hook, and in calm weather - from the rear.
rice-81, a-general view, b-drawing, c-weight template
Fig-82, a-obtaining roundings, b-miter connection
Fig-83 wing mount
GLIDER OR MOTOR GLIDER? Motorless gliding flight has long fascinated humans. It would seem that nothing could be simpler - he attached wings to his back, jumped down from the mountain and... flew. Alas, numerous attempts to take to the air, described in historical chronicles, led to success only at the end of the 19th century. The first glider pilot was the German engineer Otto Lilienthal, who created a balance glider - a very dangerous aircraft for flight. In the end, Lilienthal's glider killed its creator and brought a lot of trouble to gliding enthusiasts.
A serious drawback of the balance glider was the control method in which the pilot had to move the center of gravity of his body. At the same time, the device could turn from obedient in seconds into completely unstable, which led to accidents.
A significant change to the gliding aircraft was made by the brothers Wilbur and Orville Wright, who created an aerodynamic control system consisting of elevators, a rudder and a device for warping (gauching) the ends of the wing, which was soon replaced by more efficient ailerons.
The rapid development of gliding began in the 1920s, when thousands of amateurs came to aviation. It was then that amateur designers in many countries developed hundreds of varieties of non-motorized aircraft.
In the 1930s - 1950s, glider designs were constantly improved. The use of cantilever wings of high aspect ratio, without braces or struts, and streamlined fuselages, as well as landing gear that retracts inside the fuselage, has become typical. However, wood and canvas were still used in the manufacture of gliders.
(wing area - 12.24 m2; empty weight - 120 kg; take-off weight - 200 kg; flight balance - 25%; Maximum speed - 170 km/h; stall speed - 40 km/h; descent speed -0.8 m /s; maximum aerodynamic quality-20):
1– folding (sideways to the right) part of the lantern; 2- air pressure receiver for speed indicator; 3 – starting hook; 4 – landing ski; 5 – strut (pipe made of 30KhGSA 45X1.5); 6 - brake flap; 7 - box-shaped wing spar (shelves - pine, walls - birch plywood); 8 – wing profile DFS-Р9-14, 13.8%; 9 – box-shaped plywood beam; 10 – speed indicator; 11 – altimeter; 12 – slip indicator; 13 – variometer; 14 – rubber ski shock absorber; 15 – PNL parachute; 16 – wheel d300x125
ANB-M – single-seat glider: wing area – 10.5 m2; empty weight – 70 kg; take-off weight – 145 kg.
NSA-Ya – two-seater spark glider
A – fiberglass “Pelican”: wing area -10.67 m2; empty weight – 85 kg; take-off weight – 185 kg; stall speed – 50 km/h.
B-glider “Foma” by V. Markov (Irkutsk): empty weight – 85 kg
A-KAI-502: wingspan - 11 m; wing area - 13.2 m2; wing profile -РША- 15%; empty weight -110 kg; take-off weight - 260 kg; stall speed – 52 km/h; optimal gliding speed – 70 km/h; maximum aerodynamic quality – 14; minimum rate of descent -1.3 m/s.
B – glider “Youth”: wingspan – 10 m; wing area - 13m2; wing profile – RIA – 14%; empty weight – 95 kg; take-off weight – 245 kg; stall speed – 50 km/h; optimal gliding speed - 70 km/h; maximum aerodynamic quality – 13; minimum rate of descent -1.3 m/s.
B – single-seat glider UT-3: wingspan – 9.5 m; wing area - 11.9 m2; wing profile - RSA-15%; empty weight - 102 kg; take-off weight - 177 kg; stall speed - 50 km/h; optimal gliding speed – 65 km/h; maximum aerodynamic quality – 12; minimum descent speed - 1m/s
A real revolution in gliding occurred in the late 1960s, when composite materials appeared, consisting of fiberglass and a binder (epoxy or polyester resin). Moreover, the success of plastic gliders was ensured not so much by new materials, but by new technologies for manufacturing aircraft elements from them.
Interestingly, gliders made of composite materials turned out to be heavier than wooden and metal ones. However, high accuracy of reproduction of theoretical contours of aerodynamic surfaces and excellent external finishing provided new technology, made it possible to significantly increase the aerodynamic quality of gliders. By the way, when moving from metal to composites, the aerodynamic quality increased by 20 - 30 percent. At the same time, the weight of the airframe structure increased, which led to an increase in flight speed, but the high aerodynamic quality made it possible to significantly reduce the vertical rate of descent. This is what allowed “composite” glider pilots to win competitions against those who competed on wooden or metal gliders. As a result, modern glider athletes fly exclusively on composite gliders and airplanes.
The technology for manufacturing composite structures is now widely used in the creation of light aircraft, including amateur aircraft and motor gliders, so it makes sense to talk about it in more detail.
The main elements of a modern glider wing are a box-shaped or I-section spar, which absorbs bending and shear force, as well as the upper and lower load-bearing skin panels, which absorb loads from torsion of the wing.
The construction of the wing begins with the production of matrices for molding the skin panels. First, a wooden blank is made, which exactly reproduces the outer contours of the panel. At the same time, the impeccability of the theoretical contours and the cleanliness of the blank surface will determine the accuracy and smoothness of the surfaces of future panels.
After applying a separating layer to the blank, panels of coarse fiberglass impregnated with an epoxy binder are laid out. At the same time, a load-bearing frame welded from thin-walled steel pipes or profiles of corner section. After the resin has cured, the resulting crust-matrix is removed from the blank and installed on a suitable support.
The matrices for the top and bottom panels, stabilizer, left and right sides of the fuselage, which are usually made integral with the fin, are made in a similar way. The panels have a three-layer sandwich-type construction - their internal and outer surface made of fiberglass, the internal filler is polystyrene foam. Its thickness, depending on the size of the panel, ranges from 3 to 10 mm. Internal and external cladding laid out from several layers of fiberglass with a thickness of 0.05 to 0.25 mm. The total thickness of the fiberglass “crusts” is determined when calculating the strength of the structure.
When making a wing, all layers of fiberglass that make up the outer skin are first molded into the matrix. The fiberglass fabric is first impregnated with an epoxy binder; most often, amateurs use K-153 resin. Then foam filler, cut into strips from 40 to 60 mm, is quickly laid out on the fiberglass, after which the foam is covered inner layer fiberglass impregnated with binder. To avoid wrinkles, the fiberglass coverings are manually aligned and smoothed.
Next, the resulting “semi-finished product” must be covered with an airtight film with a fitting embedded in it and glued with sealant (or even just plasticine) to the edges of the matrix. Further through the fitting from under the film vacuum pump the air is pumped out - while the entire set of panels is tightly compressed and pressed against the matrix. In this form, the set is kept until the final polymerization of the binder.
Glider "Kakadu" (wing area - 8.2 m2; wing profile - PShA - 15%, empty weight - 80 kg; take-off weight - 155 kg):
1 – rear wing spar (consists of a wall with foam core, covered on both sides with fiberglass, and fiberglass shelves); 2 – PS-4 foam filler; 3 - fiberglass shelf of the spar (2 pcs.); 4 - fiberglass aileron mounting unit; 5 – fiberglass tubular aileron spar (wall thickness 0.5 mm); 6 – three-layer panels forming the aileron skin (filler – PS-4 foam plastic 5 mm thick, fiberglass skin thickness outside 0.4 mm, inside – 0.3 mm); 7 - fuselage beam; 8 - fuselage beam shelf (3 mm thick fiberglass); 9 - fiberglass casing 1 mm thick; 10 – PS-4 foam block; 11 – fiberglass sheathing of the wing tip with a thickness of 0.5 to 1.5 mm, forming a torsional contour; 12 - typical wing rib; 13 - fiberglass rib shelf 1 mm thick; 14 – fiberglass rib wall 0.3 mm thick; 15 – front wing spar (design similar to the rear)
A – training glider A-10B “Berkut”:
wing area -10 m2; empty weight – 107.5 kg; take-off weight – 190 kg; maximum speed 190 km/h; stall speed – 45 km/h; maximum aerodynamic quality – 22; range of operational overloads – from +5 to -2.5; design overload – 10.
B - A-10A motor glider with a Vikhr-30-Aero air-cooled engine with a power of 21 hp. In flight, the power plant can be retracted into a compartment located in the middle part of the fuselage.
The length of the motor glider is 5.6 m; wingspan - 9.3 m; wing area – 9.2 m2; take-off weight – 220 kg; maximum speed – 180 km/h; stall speed – 55 km/h; maximum aerodynamic quality – 19; propeller diameter – 0.98 m; propeller pitch – 0.4 m, propeller speed – 5000 rpm
engine - “Hummingbird-350” homemade, two-cylinder, opposed, 15 hp; motor glider length - 5.25 m; wing span -9 m, wing area - 12.6 m2; wing profile – R-P – 14%; hovering aileron profile – R-SH - 16%; empty weight – 135 kg; take-off weight – 221 kg; maximum speed -100 km/h; cruising speed – 65 km/h; stall speed – 40 km/h; maximum lift-to-drag ratio -10
A similar technology is used in the manufacture of spar flanges, with the only difference being that they are laid out from unidirectional glass or carbon fiber. Final assembly wings, empennage and fuselage are usually produced in matrices.
If necessary, spars, frames and ribs are inserted and glued into the finished molded three-layer panel, after which everything is covered and sealed with a top panel.
Since there are large gaps between the parts of the internal set and the cladding panels, it is recommended to use epoxy adhesive with a filler, for example, glass microspheres, when gluing. The gluing contour of the panels from the outside (if possible, from the inside) is glued with fiberglass tape.
The gluing and assembly technology is described here only in general outline, but, as experience shows, amateur aircraft designers quickly comprehend its intricacies, especially if there is an opportunity to see how those who have already mastered this technique do it.
Unfortunately, high price modern composite gliders led to a decline in the mass popularity of gliding sports. Concerned about this, the International Air Sports Federation (FAI) introduced a number of simplified classes of gliders - standard, club and the like, the wingspan of which should not exceed 15 meters. True, there remain difficulties with launching such gliders - this requires towing aircraft or rather complex and expensive motorized winches. As a result, fewer and fewer gliders are brought to the gatherings of amateur aircraft designers every year. In addition, a significant part of the gliders are variations of the BRO-11 designed by B.I. Oshkinis.
Of course, it is best to build your first aircraft in the image and likeness of a reliable, well-flying prototype. It is this “copying” with a minimum amount of trial and error that provides that invaluable experience that cannot be acquired from textbooks, instructions and descriptions.
However, original, more modern aircraft, such as the ANB-M glider, created by P. Almurzin from the city of Samara, periodically appear at SLA rallies.
Peter dreamed of “wings” since childhood. But poor eyesight prevented him from enrolling in a flight school and engaging in aviation sports. But every cloud has a silver lining - Peter entered the Aviation Institute, graduated from it and was sent to an aircraft factory. It was there that he managed to organize a youth aviation design bureau, which was later transformed into the “Polyot” club. And Apmurzin’s most reliable assistants were the students of the Aviation Institute, who dreamed of flying just as passionately as Peter.
The first independently developed design of the club was a glider, made taking into account the technological features of modern aviation production - durable, simple and reliable, on which all members of the club could learn to fly.
The first glider was named NSA - after the initial letters of the last names of its designers: Apmurzin, Nikitin, Bogatov. The wing and empennage of the device were unconventional for gliders of this class metal structure using thin-walled duralumin pipes as spars large diameter. Only the fuselage on the original version of the airframe was made of composite materials. However, in the next version the cabin was designed to be metal, which made it possible to reduce its weight by 25–30 kg.
The creators of the airframe turned out to be not only competent designers, but also good technologists familiar with modern aircraft production. Thus, in the manufacture of thin sheet parts from duralumin, they used a simple technological operation well established in aircraft production - rubber stamping. The equipment necessary for this was made by the young engineers themselves.
The airframes were assembled in basement, where the club was located. The flight characteristics of the new devices turned out to be close to the calculated ones. Soon all club members learned to fly on homemade gliders, making dozens of independent flights from a motorized winch. And at SLA rallies, gliders invariably received the highest praise from specialists, who recognized the NSA-M as the best initial training glider among production and amateur designs. And the “Polyot” club was presented with a new, more suitable room for work and it was reorganized into the “Sports Aviation Design Bureau” at the aircraft plant with a staff of five people.
Meanwhile, work on modernizing the NSA airframe continued - its design was improved, static strength tests were carried out, and preparations were made for mass production of the device.
Everyone enjoys flying on gliders and launching them using a winch, but such flights have one very significant drawback - their short duration. Therefore, in the development of each team of amateur aviators, the transition from a glider to an airplane is quite natural.
Using the well-proven design of the NSA airframe and its production technology, young aircraft designers Almurzin, Nikitin, Safronov and Tsarkov designed and built a single-seat training aircraft "Crystal" ( detailed description the design of this machine - in the previous “lessons” of our school - in “M-K” No. 7 for 2013).
It should be noted that initial training gliders have always attracted both individual amateurs and design teams. Thus, one of the most beautiful training gliders ever demonstrated at SLA rallies was the Kakadu, created by amateur aviators from the city of Otradnoye, Leningrad Region.
This glider is made from three types materials - foam plastic, fiberglass and epoxy binder, and the design of the wing and tail is a kind of small design masterpiece.
The wing ribs are made of foam plastic and covered with thin fiberglass. The tip of the wing, which receives the torque, is a fiberglass shell glued onto a foam core block. The fuselage beam is cut out of foam plastic and covered with fiberglass, and the bending moment is absorbed by fiberglass shelves glued to the upper and lower surfaces of the beam. The quality of work is excellent, the external finishing is the envy of many home-made workers. The only “but” is that the glider refused to fly - 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 have undergone initial flight training on gliders can recommend a more complex aircraft, for example, the A-10B Berkut glider, created by students of the Samara Aviation Institute under the leadership of V. Miroshnik. It’s interesting that the glider’s parameters do not correspond to any sports class and its dimensions are smaller than standard ones. At the same time, the A-10B has very clean aerodynamic shapes, a simple braced wing is covered with fabric, and the device itself is made of the most common plastics. The sufficiently high aerodynamic quality of the glider makes it possible to make even long soaring flights on it. A simple piloting technique allows even a beginner to cope with such a device. It seems that it is precisely such inexpensive and “flying” gliders that are lacking in domestic gliding.
A unique development of the ideas contained in the A-10B was the “Dream” glider, created in a Moscow amateur club under the leadership of V. Fedorov. By design, manufacturing technology and appearance“Dream” is a typical modern sports glider, and in terms of specific wing load and some other parameters it is a typical initial training glider. The “Dream” flies quite well; at SLA rallies this glider was sent flying in tow from the “Vilga” aircraft.
It should be noted that flights of gliders launched from a shock absorber, winch or from a small mountain are extremely limited in time and do not bring the pilot proper satisfaction. Another thing is a motor glider! A device with a motor has much wider possibilities. Moreover, motor gliders, even with low-power engines, sometimes outperform some amateur-built light aircraft in terms of flight performance.
The point, apparently, is that airplanes, as a rule, have a wing span significantly smaller than that of a motor glider, and when the span is reduced, the loss in lift is greater than the gain in mass. As a result, some planes are unable to get off the ground. While training motor gliders with rougher aerodynamic shapes and low-power engines fly great. The only difference between these aircraft and airplanes is their larger wingspan. I think this is why training motor gliders are especially popular among amateurs.
engine power – 36 hp; wing area – 11m2; empty weight – 170 kg; take-off weight – 260 kg; flight centering – 28%; maximum speed – 150 km/h; stall speed – 48 km/h; rate of climb – 2.4 m/s; maximum aerodynamic quality – 15
motor glider length -5 m; wingspan -8 m; wing area – 10.6 m2; empty weight – 139 kg; take-off weight – 215 kg; maximum speed -130 km/h; landing speed – 40 km/h; propeller rotation speed – 5000 rpm);
1 – variometer; 2 – slip indicator; 3 – speed indicator; 4 – altimeter; 5 – pedals; 6 – air pressure receiver; 7 – tubular motor mount; 8 – engine; 9 – cable braces; 10 – rudder control cables; 11 – elevator control rods; 12 – all-moving horizontal tail; 13 – tubular tail struts; 14 – sections of the wing and tail covered with lavsan film; 15 - tail spring; 16 – fiberglass pilot gondola; 17 – aileron control rods; 18 – main landing gear spring; 19 – engine control wiring; 20 – fiberglass spring of the nose landing gear; 21 - wing spar; 22 – aileron linkage units; 23 – aileron (upper skin – fiberglass, lower – lavsan film); 24 – muffler; 25 – fuel tank; 26 – tubular wing strut
wing area – 16.3 m2; wing profile – modified GAW-1 – 15%; take-off weight – 390 kg; empty weight – 200 kg; maximum speed -130 km/h; rate of climb – 2.3 m/s; design overload – from + 10.2 to -5.1; maximum aerodynamic quality -25; propeller thrust – 70 kgf at 5000 rpm
wing area – 18.9 m2; take-off weight – 817 kg; stall speed – 70 km/h; maximum speed of horizontal flight - 150 km/h
wingspan - 12.725 m; front wing span – 4.68 m; motor glider length -5.86 m; front wing area – 1.73 m2; main wing area – 7.79 m2; empty weight – 172 kg; take-off weight – 281 kg; maximum aerodynamic quality – 32; maximum speed – 213 km/h; stall speed – 60 km/h; flight range – 241 km; operating overload range from +7 to -3
Great success in creating the simplest such devices was achieved by students of the Kharkov Aviation Institute, who, under the leadership of A. Barannikov, built the Korshun-M motor glider, and later, under the leadership of N. Lavrova, a more advanced “Enthusiast” was created, which had good aerodynamic shapes and a closed cockpit and a carefully hooded engine.
It should be noted that both of these motor gliders are a further development of the once popular training glider BRO-11 designed by B. Oshkinis. The devices of the Kharkov students have a simple design with no claims to originality, but they are very durable, reliable and easy to control for novice pilots.
At one of the SLA rallies, Ch. Kishonas from Kaunas demonstrated one of the best motor gliders - “Garnis”, made entirely of fiberglass. The covering of the wings and tail surfaces is a transparent lavsan film. Power unit– boat motor “Vikhr-M” with a power of 25 hp, converted for air cooling. The motor can be easily removed from the device.
The motor glider is equipped with several options for easily removable landing gear - a three-wheeled aircraft type, a single-wheeled glider and a float type.
Motor gliders and gliders of the “Kite” and “Garnis” types are built in our country by many amateurs in dozens of copies. I would like to draw the readers’ attention to just one feature of such devices, built in the image and likeness of the BRO-11. As is known, the prototype (as well as its numerous copies) is equipped with hovering ailerons, kinematically connected to the elevator. During the landing approach, the pilot takes control of the control stick, while the ailerons synchronously deflect downward, which causes an increase in lift and a decrease in speed. But, if the pilot accidentally moved the stick towards himself, and then, correcting the situation, moved the stick away from him, the last movement of the stick causes not only deflection of the elevator, but also the return of the ailerons to their original position, which is equivalent to retracting the flaps. At the same time, the lifting force decreases sharply - and the glider “fails,” which is very dangerous when flying at low altitude, before landing.
Experiments conducted by glider pilots flying the BRO-11 showed that without aileron freezing, the takeoff and landing characteristics of the glider practically do not deteriorate, but it is much easier to fly such a glider, which significantly reduces the accident rate. At the same time, for the wing of a low-speed motor glider, the convex-concave profile of the Gottingen F-17 may turn out to be more advantageous - it was once used on the Phoenix-02 motor glider, created by an engineer from TsAGI S. Popov.
The popularity of motor gliders is due, first of all, to the possibility of their launch without special towing devices, as well as due to the emergence of simple, lightweight and fairly powerful motors. At SLA rallies, many original, spectacular flying vehicles of this class, created by amateur designers, were demonstrated. The beautiful A-10A motor glider was built by V. Miroshnik on the basis of the A-10B already familiar to readers. Its power unit is the Whirlwind-25 engine, converted to air cooling; it is located above the fuselage, behind the cockpit. The engine, as a rule, was used only for takeoff and climb. After turning it off, a special mechanism folded the truss with the engine installed on it and put it into the fuselage, which significantly reduced the aerodynamic drag of the aircraft. If necessary, the engine could be pulled out of the niche using the same mechanism and started.
Another aircraft built by students from the Samara Aviation Institute is the Aeroprakt-18 two-seat motor glider. It is compact, lightweight, made entirely of plastic and equipped with a 30-horsepower air-cooled Vikhr-30-aero engine - this model’s engine cannot be retracted in flight, which has made the design simpler and lighter.
Nevertheless, amateur designers continued to develop original versions of mechanisms for retracting engines in flight, and one of these most interesting devices was created by a group of Moscow amateur aviators under the leadership of A. Fedorov for the single-seat twin-engine motor glider Istra. Light motors were completely integrated into the contours of the wing, without protruding beyond its theoretical contours, but propellers rotated in the cracks behind the rear wing spar. When the engines were stopped, the propellers were fixed in a horizontal position and covered with a sliding wing tail.
Another development of Moscow amateur glider pilots is the two-seater motor glider “Baikal”, also equipped with two engines. True, they are not located on the wing, but on a V-shaped pylon above the fuselage. During flight, the engines are retracted into the fuselage - just like on the Istra.
A special feature of A. Fedorov’s motor gliders is their composite design, made in accordance with the canons of modern technologies.
It is generally accepted that the aerodynamic design of modern gliders and motor gliders has completely stabilized. And in fact, everything modern devices of this type differ little from each other, and their geometric proportions are almost the same. Nevertheless, the design idea is looking for new solutions, new schemes and proportions. This was confirmed by the aircraft of Swiss designers and Burt Rutan’s Solitar motor glider. These original motor gliders, made according to the “duck” design, once again demonstrated the advantages of the supporting horizontal tail.
If you are interested in gliding, then you don’t have to buy ready-made models of aircraft; you can make your own glider. This article brings to your attention a lightweight model of a glider with rounded contours.
The selected airframe model, due to its outline, has improved flight performance, and all its connections are made with glue without the use of metal fasteners. The glider wing is raised above the fuselage and secured using wire struts, this feature increases the stability of the model during flight.
The construction of the airframe begins with the construction of drawings of parts (1). The fuselage is a 700 mm long rail with a cross section of 7X5 mm at the tail and 10X6 mm at the nose. For the weight you will need a board made of linden or pine with a width of 60 mm and a thickness of 10 mm - cut the weight out of it using a knife and process the edges of the part with a file or sandpaper. The top shoulder of the weight will then secure the forward end of the fuselage. The glider wing should be 680 mm long and 4x4 mm in section. Two roundings for the edges are made from aluminum wire with a diameter of 2 mm or, alternatively, from wooden slats with a section of 4x4 and a length of 250 mm. Before bending, wooden slats must be soaked in hot water for 15-20 minutes. Glass jars or bottles of the required diameter can be used as a form for bending the slats. IN in this case the wing shapes have a diameter of 110 mm, and the fin and stabilizer are 85 mm each. The steamed slats are folded around the mold, their ends are secured, and left to dry (2).
Another way to achieve a bend is to transfer the outline of the arc onto the board and fasten nails along it. Then the steamed lath is tied to one of the nails and they begin to bend it, the ends of the laths are tied together and left to dry (3).
The edges of the rounded slats are connected to the edges “on the miter” - the ends are cut off at a distance of 30 cm, as shown in the diagram, and adjusted to each other without gaps (4). Then the joint is coated with glue, wrapped with thread and another layer of glue is applied.
The ribs (stiffeners) for the wing are bent on a machine, having previously marked their installation locations according to the drawing. After installing the roundings of the ribs, the wing is applied to the drawing to check the assembly; it is also necessary to make sure that all the ribs are level by examining the wing from the end. After the glue has dried at the junctions of the ribs with the edges, it is necessary to give the wing a bend. To do this, the middle of the edges of the glider wing is wetted hot water and heat the bend over the flame of a candle or soldering iron, moving the rail to prevent overheating. The bending angle is checked by placing the end of the wing against the drawing. Then the procedure is repeated for the second edge and the bending angle is also checked, it should be 8 degrees on each side.
The wing fastening consists of 2 V-shaped edges (struts) made of steel wire and pine strip with a length of 140 mm and a cross-section of 6x3 mm. The edge dimensions are shown in the diagram below. These struts are attached to the wings using thread and glue. The front brace must be higher than the rear brace to form the installation angle (5).
For the stabilizer of the airframe you will need 2 slats 400 mm long, and for the keel one such rail. These slats are also steamed and bent to a diameter of 85-90 mm. To attach the stabilizer to the fuselage, use a strip 110 mm long and 3 mm high; the front and rear edges of the stabilizer are tied to it with threads. The ends of the keel arc are sharpened and inserted into the sockets of the strips next to the edges of the stabilizer (6).
After this, they begin to cover the airframe with tissue paper and assemble it. It starts with the plumage, i.e. The stabilizer is applied to the rear end of the fuselage and we secure the front and rear parts of the connecting strip together with the fuselage rail with an elastic band. To launch the glider with our own hands, we will make 2 hooks from steel wire and fasten them with threads to the fuselage between the leading edge of the wing and the center of gravity of the glider.
All the knowledge gained after reading this article can be used in making a kite.
I had a drawing of this model for several years. Knowing that it flies well, for some reason I could not decide to build it. The drawing was published in one of the Czech magazines in the early 80s. Unfortunately, I was unable to find out either the name of the magazine or the year of publication. The only information that is present on the drawing is the name of the model (Sagitta 2m F3B), the date - either of construction or production of the drawing - 10.1983 and, apparently, the first and last name of the author - Lee Renaud. All. No more data.
When the question arose of building a glider more or less equally suitable for flying in both thermals and dynamics, I remembered a drawing that was lying idle. One careful examination of the design was enough to understand that this model is very close to the desired compromise. Thus, the problem of choosing a model was solved.
Even if I have a ready-to-use drawing of a model at my disposal, I still redraw it with my own hand, with a pencil on graph paper. This helps to thoroughly understand the structure of the model and simplifies the assembly process - you can immediately develop the sequence of manufacturing parts and their subsequent installation. So construction started from the drawing board. Minor changes were made to the design of the airframe, which made it possible to fearlessly tighten the model both on the rail and on the winch.
Intensive use of the glider in the summer of 2003 showed that it is distinguished by predictability, stability and, at the same time, agility - even without ailerons. The glider behaves quite satisfactorily both in thermals, allowing it to gain altitude even in weak currents, and in dynamic conditions. I note that the model turned out to be too light, and sometimes additional loading of the airframe is required - from 50 to 200 grams. For flights in strong dynamic currents, the glider has to be loaded more - by 300...350 grams.
The model can be recommended for beginners only if the training is carried out together with an instructor. The fact is that the model has a relatively weak tail boom and bow. This does not cause any problems if you at least know how to land a glider, but the model may not withstand a strong impact with the nose on the ground.
Characteristics
The main characteristics of the airframe are:
Materials required for manufacturing:
- Balsa 6x100x1000 mm, 2 sheets
- Balsa 3 x100x1000 mm, 2 sheets
- Balsa 2 x100x1000 mm, 1 sheet
- Balsa 1.5 x100x1000 mm, 4 sheets
- Duralumin plate 300x15x2 mm
- Small pieces of plywood 2 mm thick - approximately 150x250 mm.
- Thick and liquid cyacrine - 25 ml each. Thirty minute epoxy resin.
- Film for covering the model - 2 rolls.
- Small pieces of 8 and 15 mm balsa - approximately 100x100 mm.
- Pieces of textolite 1 and 2 mm thick - 50x50 mm is quite enough.
The production of the glider takes less than two weeks.
The design of the model is very simple and technologically advanced. The most complex and critical components - the attachment of the consoles to the fuselage and the rocking of the all-moving stabilizer - will require maximum care and attention when building the model. Carefully study the airframe design and assembly technology before starting its construction - then you will not waste time on alterations.
The description of the model is intended for modelers who already have basic skills in building radio-controlled models. Therefore, constant reminders “check for distortions”, “carefully do [this]” are excluded from the text. Accuracy and constant control are things that go without saying.
Manufacturing
Please note that unless otherwise noted in the text, all balsa pieces have grain along the longer side of the piece.
Fuselage and tail
Let's start building the glider with the fuselage. It has a square cross-section; made of balsa 3 mm thick.
Take a look at the drawing. The fuselage is formed by four balsa plates 3 mm thick - these are two walls 1, as well as the upper 2 and lower 3 covers. All frames 4-8, except frame 7, are made of 3 mm thick balsa.
Cutting everything out necessary details, let's tinker with making frame 7 from three- or four-millimeter plywood. After this, installing the frames on the drawing covered transparent film, glue the walls to them. Having removed the resulting box from the drawing, we will glue the bottom cover of the fuselage, and then we will lay down the bowdens 9 for controlling the elevator and rudder (and, if desired, a tube for laying the antenna).
Let's work on the forward part of the fuselage. We will make the bow boss 10 from scraps of thick balsa, the removable canopy will be made from balsa 3 (walls 11) and 6 (top part 12) millimeters thick. We are not installing the control equipment yet. The only thing you need to do is try it on in place. If necessary, you can remove frame 6, which is more of a technological element than a power element.
We move on to the middle part of the fuselage, to which the wing is attached. We have to make a plywood box 13, which ties together the wing spar, the fuselage itself and the towing hook. The details of the box are shown in a separate sketch. It consists of two walls 13.1 and a bottom, represented by plywood from parts 13.2 and 13.3. We stock up on two-millimeter plywood, a pair of jigsaw files, and get started.
Having assembled the box "dry", we adjust it to the inside of the fuselage, and then glue it in. We will make cuts for the connecting guide of the consoles later, locally. Other holes in the box are also made locally.
After installing the box, you can glue the top fuselage cover 2.
One of the most difficult stages of fuselage assembly begins - manufacturing, fitting and installation of the fin and stabilizer rocker.
As we can see from the drawing, the keel (it is very small, since the rest is the rudder) is formed by a frame of the front 14, rear 16 and top 15 edges, made of two-millimeter balsa and glued between the sides of the fuselage.
The stabilizer rocker 17 is mounted in the frame, and then the side lining is glued to the frame - the keel walls 18 are made of 3 mm thick balsa.
The removable halves of the stabilizer are mounted on a power pin 19 made of steel wire with a diameter of 3 mm, and are driven by a short pin 20 (steel wire 2 mm), glued into the front part of the rocker. The rocking chair is made of textolite 2 mm thick, or plywood of the same thickness. Thin washers are installed between the rocker and the walls of the keel, mounted on a power pin.
It looks simple - we cut out all the parts and put them together. Be extremely careful!!! Once the frame that forms the keel is assembled and the lining is glued to one side, you will begin to install the elevator rocker, connect the bowden to it and get ready to glue the keel wall to the other side.
This is where the main ambush awaits you: if even a drop of thiacrine gets on the rocking chair, which is installed between the walls of the keel without large gaps, all is lost. The rocking chair will dry tightly to the wall, and the keel assembly will have to be repeated again. You should be especially careful when gluing the power three-millimeter steel pin - cyacrine can very easily get inside the keel along it. Use thick glue.
After assembling the keel, do not forget to glue the textolite pads 21, which secure the power pin from distortion.
Finally, we will install fork 22 and sand the fuselage.
Assembly of the rudder and stabilizer is so simple that it does not pose any difficulties. I will only note that the holes for the power pin in the halves of the stabilizer after drilling are impregnated with liquid cyacrine and then drilled again.
Please note that the front parts of the handlebars are made of whole pieces balsa (8 mm thick on the rudder and 6 mm thick on the stabilizer). This significantly simplifies the process of assembling the model, but does not add unnecessary weight, because, as already mentioned, the airframe is already too light.
Having assembled and profiled the rudders, we’ll “roughly” hang them in place and check the ease of movement. Everything is fine? Then we’ll remove them, put them away and move on to the wing.
Wing
The wing design is so standard that it should not raise any questions at all. This is a stacked balsa frame with a forehead 8 sewn up with balsa 1.5...2 mm thick, ribs 1-7 made of two-millimeter balsa with flanges made of balsa 1.5...2 mm thick, and a wide rear edge 11 (balsa 6x25). Spars 9 are pine slats with a section of 6x3 mm, between them a wall of balsa 10 with a thickness of 1.5...2 mm is mounted.
It should be noted that the spar, in general, will be flimsy for such a scope - in case the airframe has to be tightened with a winch. Its strength is quite sufficient for manual tightening.
To avoid “firewood”, I had to glue strips of carbon fabric onto outer side each of the spar flanges. After this improvement, the glider allowed itself to be pulled on a modern winch for F3B class gliders. The consoles, of course, bend, but they hold the load. At least for now...
Wing assembly begins with the manufacture of ribs. The center section ribs are processed in a “package” or “bundle”. This is done like this: let's make two rib templates from plywood 2...3 mm thick, cut out the rib blanks and assemble this package together using M2 threaded pins, placing the templates along the edges of the package. After processing, this solution will provide the same profile along the entire span of the center section. In the drawing, the center section ribs are numbered "1", and the ear ribs are numbered from "2" to "7".
We will do things differently with the ribs of the “ears”. By printing them on laser printer with maximum contrast, we will attach the printout to a sheet of balsa from which we will cut the ribs. After this, with a fully heated iron, we iron the printout, and the images of the ribs will be transferred to the balsa. Just remember that the paper needs to be placed with the image on the balsa, and it is better to first sand the balsa itself with fine sandpaper. Now we can start cutting out the printed parts. At the same time, prepare the details of the lining of the forehead 8 and the center section 12, cut strips of balsa for the flanges of the ribs 14, prepare the blanks of the leading edges 13 and the walls of the spar 10, profile the rear edges 11. Please note that the walls of the spar 10 have a different direction of the wood fibers from other parts - along the short sides. Upon completion of preparation, we can begin assembling the wing without being distracted by the manufacture of the required parts.
First we make the center section parts. We attach the lower flange of the spar to the drawing, install the ribs on it and install the upper flange of the spar. Then we glue the walls of the spar made of three-millimeter balsa 15, located in the root part of the wing. After this, we wrap the resulting box with threads. Let's coat the threads with glue.
We will carry out a similar operation on the other side of the console - where the “ear” will be attached. Only the walls in this case will be made of two-millimeter balsa. Having glued the balsa walls of the spar, we wrap the resulting box. In the future, it will include a guide for attaching the “ear”
Please note that the root rib adjacent to the center section is not installed perpendicular to the spar and edges, but at a slight angle.
The next step is gluing the back edge. Needless to say, this operation, as well as the next one, is also carried out on a slipway.
Assembling the front part of the wing. The order is as follows: the bottom lining, then the top, then the spar wall made of 1.5 or 2 mm thick balsa. Having removed the resulting console from the slipway, we glue the leading edge 13. Notice how the torsional strength of the wing sharply increases after the “closure” of the forehead.
The final stage of assembling the center section is gluing the flanges of the ribs and the balsa lining of the root part of the wing (three central ribs).
The ear assembly is completely similar to the center section assembly and therefore is not described. The only thing worth noting is that the rib adjacent to the center section is not installed vertically relative to the plane of the wing, but at an angle of 6 degrees - so that there is no gap between the “ear” and the center section. We again wrap the root part of the “ear” spar with threads and glue.
Now let's take a long narrow knife and a file in our hands. We have to make holes for the center section guides 15 and the “ear” 16 in the boxes formed by the spar and its walls - two in the center section and one in the “ear”. Having cut through the balsa end ribs, we use a file to level the inner surface of the boxes. We don’t glue the “ear” with the center section yet. We assemble the second console in a completely similar way and proceed to the manufacture of guides.
The center-section guide carries the entire load applied by the handrail to the model when tightened. Therefore, it is based on a strip of duralumin 2…3 mm thick. It is processed so that it fits into the box designed for it without effort or play. After this, a similar-shaped plywood overlay is glued to it with thirty-minute resin, one or two - it depends on the thickness of the duralumin and plywood used. The finished guide is processed so that both consoles fit onto it with little effort.
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The guides intended for attaching the “ears” to the center section parts of the wing are made from three pieces of two-millimeter plywood glued together to obtain a total thickness of 6 mm. Once you have made the guides for the "ears", the "ears" can be glued to the center section parts. It is best to use epoxy resin for this.
All that remains is to glue in the “tongues” 17 and the console fixing pins 18. Two-millimeter plywood is used for the “tongues”, and beech, birch or thin-walled aluminum or steel tube is used for the pins.
That's all, actually. All that remains is to cut out windows for the guide and “tongues” in the center section of the fuselage and drill holes for the wing fixation pins. Keep in mind that here it is necessary to control both the absence of mutual distortions between the wing and stabilizer, and the identity of the installation angles of the left and right consoles. Therefore, take your time and take your measurements carefully. Think: maybe there is a technology that is convenient for you, allowing you to avoid possible flaws when cutting out windows?
Final operations
Now you need to make the cover of the center section of the fuselage compartment 23. It is made of balsa or plywood. The method of attaching it is arbitrary; it is only important that it is removable and firmly fixed in its place. After the lid is made, drill a hole with a diameter of 3 mm in it and the connecting tongues. A pin with a diameter of 3 mm, then inserted into these holes, will not allow the consoles to move apart under load.
To increase the strength of the fuselage at the point where the wing guide is attached, we will have to make another one structural element 24, formed by four struts inside the fuselage, made of three-millimeter plywood. Having inserted guide 15 into the holes prepared for it, we will glue these spacers close to it. We got a kind of “channel” for the guide. It will prevent it from moving too freely in the holes and at the same time add rigidity to the fuselage. Glue the fifth piece of “three rubles” approximately 100 mm closer to the tail. It turned out that the balsa fuselage in the center section was reinforced with a closed box made of plywood. This scheme has fully justified itself in practice.
Now is the time to glue and process the ends of the “ears” 19. After this, you can start balancing the model and check whether one of the consoles is overweight.
Covering the airframe is not too difficult. If this is your first time, read the instructions for using the film. It usually describes in detail how to use this particular film.
Installation of radio control equipment should not cause any special difficulties - just look at the photographs.
Don't forget that the stabilizer on the model is all-moving. Its deviations in each direction should be 5...6 degrees. And even at such costs, it may turn out to be too effective, and the model may be “twitchy”.
The rudder deflection angles should be 15...20 degrees. It is advisable to seal the gap between the rudder and the keel with tape. This will slightly improve the steering efficiency.
Towing hook 25 is made of duralumin angle. Its installation location is indicated in the drawing.
We will cut weights from lead plates about 3 mm thick - they should be shaped like the center section of the fuselage. The total weight of the “sinker” should be at least 150 grams, and better – 200…300. Based on the number of plates in the fuselage, you can adjust the model to different weather conditions.
Don't forget to center the model. The location of the CG on the spar will be optimal for the first (and not only) flights.
The airframe described here was manufactured without ailerons. If you feel like you can’t live without them, install them. If it doesn’t seem like it, don’t fool yourself, the model is controlled quite normally by the rudder.
However, the drawing shows the approximate size of the ailerons. You can think about the fastening of the aileron steering gears yourself. Of course, from the point of view of aerodynamics and aesthetics, it is best to use mini cars.
Flying
Tests
If you assembled the model without distortions, then there will be no special problems with testing. Choosing a day with a steady, gentle wind, go to a field with thick grass. Having assembled the model and checked the operation of all rudders, take a running start and release the glider into the wind at a slight descent angle or horizontally. The model must fly straight and respond to even small deflections of the rudder and elevator. A properly configured glider flies at least 50 meters after a light hand throw.
Start on the rope
When preparing to launch from the rope, don’t forget about the block. The glider is quite fast, and in light winds problems may arise with the lack of speed of the drawer, even when tightening with a block.
The diameter of the handrail can be 1.0…1.5 mm, length - 150 meters. It is preferable to place a parachute at its end rather than a flag - in this case, the wind will pull the line back to the start, reducing the distance you or your assistant runs in search of the end of the line.
After checking the functioning of the equipment, attach the model to the rail. After giving your assistant the command to start moving, hold the glider for as long as you can. Meanwhile, the assistant must continue running, stretching the rope. Release the glider. At the initial moment of takeoff, the elevator must be in neutral. When the glider gains 20..30 meters of altitude, you can slowly begin to take the handle "on yourself". Don't take too much, otherwise the glider will leave the rail prematurely. When the model reaches its maximum altitude, vigorously push the rudders down, putting the model into a dive, and then towards yourself. This is the so-called "dynamo start". With some practice, you will understand that it allows you to gain a few more tens of meters in height.
Flight and landing
Keep in mind that when the rudder is sharply applied in any direction, the glider is prone to some directional swing. This phenomenon is harmful because it slightly slows down the model. Try to move the rudder stick in small, smooth movements.
If the weather is practically calm, the glider may not be loaded. If you have problems flying against the wind or entering thermals, add 100-150 grams to the model. The ballast mass can then be selected more accurately.
Planting, as a rule, does not cause any trouble. If you have built a glider without ailerons, try not to make large rolls low above the ground, because the model will respond late to rudder deflection.
Interestingly, additional loading has virtually no effect on the model’s ability to soar. The loaded glider holds up well even in relatively weak updrafts. The longest flight time in thermals achieved during the operation of the model was 22 minutes 30 seconds.
And the same additional load is simply necessary for flying in dynamic flows. For example, for a normal dynamo flight in Koktebel, the glider had to be loaded to the maximum - 350 grams. Only after this did he gain the ability to move normally against the wind and develop amazing speeds in a dynamic flow.
Conclusion
Over the past season, the model has shown itself to be a good glider for amateurs. However, this does not mean that it is completely without shortcomings. Among them:
- profile too thick. It would be interesting to try using an E387 or something similar on this airframe.
- lack of developed wing mechanization. Strictly speaking, initially the airframe contained both ailerons and spoilers, but in order to simplify the design and develop precision landing skills, it was decided to abandon them.
However, the rest of the airframe is designed “excellently.”
An electric glider based on the described model is currently under construction. The differences are in the reduced wing chord, modified profile, presence of ailerons and flaps, fiberglass fuselage, and much more. Only the general geometry of the prototype has been preserved, and even then not everywhere. However, the future model is the topic of a separate article...