Drawings and descriptions of the "Quickie" aircraft. Aircraft according to the “duck” design Aerodynamic design of the “duck” pros and cons

Based on material from the magazine "Modelist-Constructor" from the times of the USSR

Fragment of the 3rd edition of the directory "Who's Who in Robotics"

In the first decade of the 20th century. They didn’t yet know how the plane should be designed. And often on aircraft of those times the horizontal tail was placed in front of the wing on the forward fuselage. Such aircraft began to be called “ducks”, since their forward fuselage nose part in flight resembled a flying duck with an outstretched neck. This name is assigned to aircraft in which the horizontal tail is located in front of the wing. Aircraft manufacturers returned to the canard design when they began designing supersonic aircraft to eliminate the reduction in overall lift that conventional aircraft experienced from the tail. And a free-flying aircraft model, made according to the “duck” design, can be better adapted to hovering.

Aerobatic aircraft model "UII-GBird" with a 2.5 cm³ engine, having a "duck" design. The horizontal tail with the elevator is attached to its aerobatic wing on two beams. The engine with a pulling propeller is located in the nose of the short fuselage. The nose wheel strut is mounted directly behind the engine. The main landing gear struts are located at the beam attachment points. On the trailing edge of the wing there are two fins, deflected asymmetrically, as shown in the drawing.

The painstaking work to select the position of the center of gravity paid off and led to success in competitions. During testing of the model, another significant advantage of the “duck” scheme was revealed. If the engine suddenly stopped while performing aerobatic maneuvers, having lost control, it went into a dive, and then, without the intervention of the modeller, it came out of it and made a safe landing. This is explained by the fact that when diving without control, the weight moment of the elevator around the axis of its hinged suspension causes the steering wheel to deflect downward with the trailing edge. As a result, a moment arises that causes the “duck” to exit the dive, and then a smooth landing.

A canard cord model built and successfully tested by Japanese aircraft modellers.

When designing any canard model, to ensure stable flight it is very important to correctly select the center of gravity relative to the leading edge of the wing chord. The distance from the tip of the wing chord to the center of gravity of the model, necessary for stable flight, is determined by the formula: X = 70Lgo x Sgo/Scr - 0.1b, where: Sgo - area of ​​​​the horizontal tail in square decimeters, Sc - wing area in square decimeters, Lth is the horizontal tail arm, that is, the distance from the toe of the stabilizer chord to the toe of the wing chord, in decimeters, b is the wing chord in mm.

This formula is given for the case when a pushing screw is used on the model. For example, for a model with Sgo = 10.5 dm²; Lgo = 6.3 dm; Skr= 31.9 dm²; X = 126 mm. If, on a model made according to the “duck” scheme, a pulling screw is used, placed in front of the wing, then X is found using an even simpler formula: X = 70Lgo x Sgo/Scr

In the United States, two experimental models of the F-16XL fighter, created on the basis of the F-16 fighter-bomber, are being tested. If it was previously reported that the power plant of the new fighter remained the same, now, according to the foreign press, it is planned to use a more powerful F-101DFE engine, created on the basis of the F-101 engine of the B-1 strategic bomber. Compared to the base model, the wing area of ​​the new aircraft was significantly increased (it amounted to 60 m2), the length of the fuselage increased by 1.4 m. Thanks to such changes in the design, the fuel capacity increased by 80%.

It is hoped that the F-16XL fighter will be capable of long-term flights at supersonic cruising speed. For takeoff and landing, it will require a runway less than 600 m long.

The aircraft's avionics are planned to include an upgraded AN/APG-66 radar station, an AN/ALQ-165 electronic suppression station, the Lantirn electro-optical system and a new digital computer for the weapon control system. Magazine "Equipment and weapons" from the times of the USSR

How to avoid balancing losses? The answer is simple: the aerodynamic configuration of a statically stable aircraft must exclude balancing with negative lift on the horizontal tail. In principle, this can be achieved using the classical scheme, but the simplest solution is to arrange the aircraft according to the “canard” scheme, which provides pitch control without loss of lift for trim (Fig. 3). However, canards are practically not used in transport aviation, and, by the way, quite rightly so. Let's explain why.

As theory and practice show, canard aircraft have one serious drawback - a small range of flight speeds. The canard design is chosen for an aircraft that must have a higher flight speed compared to an aircraft configured according to the classical design, provided that the power plants of these aircraft are equal. This effect is achieved due to the fact that on the canard it is possible to reduce air friction resistance to the limit by reducing the area of ​​the aircraft's washed surface.

On the other hand, during landing the “duck” does not realize the maximum lift coefficient of its wing. This is explained by the fact that, in comparison with the classical aerodynamic design, with the same interfocal distances of the wing and the main body, the relative area of ​​the main part, as well as with equal absolute values ​​of the margins of longitudinal static stability, the “canard” scheme has a smaller balancing arm of the main part. It is this circumstance that does not allow the canard to compete with the classical aerodynamic design in takeoff and landing modes.

This problem can be solved in one way: increase the maximum lift coefficient of the PGO ( ) to values ​​that ensure canard balancing at landing speeds of classic aircraft. Modern aerodynamics has already given “ducks” high-load profiles with values Su max = 2, which made it possible to create a PGO with . But, despite this, all modern canards have higher landing speeds compared to classic designs.

The disruptive characteristics of the “ducks” also do not stand up to criticism. When landing in conditions of high thermal activity, turbulence or wind shear, the PGO, providing balancing at the maximum permissible Su aircraft, may have . Under these conditions, with a sudden increase in the angle of attack of the aircraft, the PGO will reach supercritical flow, which will lead to a drop in its lift, and the angle of attack of the aircraft will begin to decrease. The resulting deep disruption of the flow from the PGO puts the aircraft into a mode of sharp uncontrolled dive, which in most cases leads to disaster. This behavior of the “ducks” at critical angles of attack does not allow the use of this aerodynamic design in ultra-light and transport aircraft.

I belong to that category of modellers who are interested in designing and building an airplane themselves, and then enjoying flying it. But the main pleasure comes from the result of creative search.

After flying for several seasons on a homemade Diamant with OS MAX 50, it became a little boring. It was clear what the plane could do and what I could do. Of course, I could have honed my 3D aerobatics skills, but my soul was asking for something unusual. I wanted to build an airplane that no one else has, and which would have unique aerobatic capabilities unique to it.

Attempt 1

I watched how radio fighters fly, and the idea came up to build a “flying wing” type fanfly. No sooner said than done. The drawing was drawn, the layout worked out, and now the plane is ready.

• Swing: 1450 mm
• Length: 1000 mm
• Weight: 2000 g
• Engine: OS MAX 50

I drive out onto the field and realize that I haven’t built anything interesting. Yes, it flies, yes, it spins some figures. But nothing interesting, everything is as usual, even a little boring.

Having analyzed the situation, I understand that this was how it should have been... The classic scheme and the “flying wing” scheme have been worked out to the smallest detail, and cannot offer anything new. Creative stagnation has begun...

Being in a crisis, I leaf through old magazines and come across a model of the “Duck” scheme. This is starting to get interesting.

Idea

The weft pattern has one interesting feature. The steering surfaces are located in front of and behind the center of gravity. Accordingly, if you mix the elevator with the ailerons and do it like in line aerobatics, then the turning moment from the elevators will be applied in front and behind the center of gravity. This in turn will allow you to make loops of a very small radius. It was also known from large aviation that this scheme behaves very stably in stall modes. But the pushing propeller located at the rear did not contribute to the performance of 3D aerobatics.

The conclusion suggested itself: the engine should be placed in front, but then problems arose with alignment. Since the main wing is located at the rear (unlike the classical design, where the stabilizer does not bear the weight of the aircraft, in the canard design it creates lift), and the center of gravity is within 10-20% of the MAR, it was not possible to balance this design. Again a dead end... Leafing through further magazines, I find an old issue of "Wings of the Motherland", which talks about aircraft of special designs, and among them is the "Tandem" design. And the most interesting thing is that there are formulas for calculating the position of the center of gravity. I present an excerpt from this article.

Excerpt from an article in the magazine "Wings of the Motherland" for February 1989.

When flying at high angles of attack before stalling, stall should occur first on the front wing. Otherwise, when stalling, the plane will sharply lift its nose and go into a tailspin. This phenomenon is called “pickup” and is considered completely unacceptable. A way to combat “pickup” on canards and tandems was found a long time ago: it is necessary to increase the installation angle of the front wing relative to the rear, and the difference in installation angles should be 2-3 degrees.

A properly designed aircraft automatically lowers its nose, moves to lower angles of attack and picks up speed, thereby realizing the idea of ​​creating a non-stall aircraft. For a “standard duck” (the horizontal tail area is 15-20% of the wing area and the tail shoulder is equal to 2.5-3 MAR), the center of gravity should be located in the range from 10 to 20% of MAR. For a tandem, the centering should be within 15-20% V eq (chord of an equivalent wing), see figure. The equivalent wing chord is defined as follows:

V eq = (S p +S h)/(l p 2 +l h 2) 1/2

In this case, the distance to the nose of the equivalent chord is equal to:

X eq = L/(1+S p /S z *K)-(S p +S z)/(4*(l p 2 +l z 2) 1/2)

Where K is a coefficient that takes into account the difference in wing installation angles, bevels and flow deceleration behind the front wing, equals:

K = (1+0.07*Q)/((0.9+0.2*(H/L))*(1-0.02*(S p /S h)))

In the given formulas:

• S p - area of ​​the front wing.
• S z - area of ​​the rear wing.
• L - tandem aerodynamic arm.
• l p - the span of the front wing.
• l z - the span of the rear wing.
• Q - excess of the installation angle of the front wing over the rear.
• H is the height distance between the axis of the front and rear wings.

Final version

Now the general idea has formed. We put the engine in front, make the wings the same, and move the receiver and battery to the tail of the plane.

The aileron drive on the front and rear wings is separate. A total of 6 steering gears are used.

It was scary to immediately build a plane for the 50th engine. A whole range of questions remained unclear: on which wing to make ailerons, and on which elevator, or both; what angles of attack should the wings have; how far the wings should be spaced apart from each other; and, in general, will it fly?

But the creative itch took over the mind, and all doubts were cast aside. I am building a "Tandem" for the 25th engine. I’ll use it to check how it flies...

Attempt 2

The model is drawn, drawn and built. The following happened.

• Both wingspan: 1000 mm
• Length: 1150 mm
• Wing chord with aileron: 220 mm
• Distance between wings: 200 mm

The front wing was placed 20 mm lower than the engine axis, the rear wing 20 mm higher. The wings were absolutely identical and mutually interchangeable, only ailerons were made on one wing, and elevator on the other.

Flight

The first flight only added confidence in the correct direction of the search. The model was absolutely predictable and adequate in the air, stable at low speeds and did not spontaneously fall into a tailspin. The scheme with the elevator on the front wing showed better results compared to the scheme when the elevator was on the rear wing. This is due to the fact that at low speeds it acted as flaps, increasing the lift on the front wing.

It's decided! I am studying the behavior of this model in the air and starting to build a model for 61 engines. While the big plane is being built, we fly on the small one. During the flights we find another interesting feature of the model. She could stop and stand in the air against the wind. When pulling the stick toward itself at low throttle, it showed a tendency to parachute.

The result is the following:

• Swing: 1400 mm
• Length: 1570 mm
• Chord with aileron: 300 mm
• Distance between wings: 275 mm

The first flight is carried out with ailerons on the rear wing and elevator at the front.

Impression:

Steady, stable at all speeds, very predictable. However, the flight of the large model revealed one peculiarity. The plane reacts very sensitively to the elevator. That is, I brought it into horizontal flight, trimmed it at medium throttle - it flies smoothly and steadily, but as soon as you touch the altitude control, it abruptly, but at a small angle, changes the direction of flight. It’s not that it’s annoying or dangerous, you just need to take into account that the model reacts very sensitively to the elevator.

This is of course unacceptable for a training aircraft, but our FAN is designed for an advanced pilot.

Now I'm trying to mix the elevator and ailerons. That is, when I pull the handle towards myself on the front wing, both ailerons go down, and on the rear wing they go up. But when I roll, the ailerons work in parallel on both wings.

The model's unstable behavior in horizontal flight was most likely due to incorrect wing angles. Unfortunately, it was not possible to change them without significant alteration.

The model is finally set up, I’m trying out what it can do in the air.

1. I'm taking off the gas. I pull the handle towards myself (squeezed expenses). The model slows down almost to a stop, then smoothly nods, accelerates and repeats the same thing. No tendency to spin. That is, if you do not deliberately disrupt the flow from the wing, then the stall occurs very smoothly and is immediately restored with a set of speed.
2. I'm taking off the gas. I pull the handle on myself (full expenses). The model stops in the air and, maintaining a horizontal position, begins to descend like a parachute. Parachute figure. I give the handle from myself - she turns over on her back and continues her descent vertically downwards (it’s just some kind of plague). "Shifter" figure. That is, the model is capable of being controlled by rudders in the mode of 100% flow separation from the load-bearing planes!
3. Expenses to the maximum - I'm twisting the loop. True, this cannot be called a loop. Rather, it is a classic “waterfall” from a 3D complex. The model spins around the lantern, while slowly descending. Moreover, there is no need to work with gas. And it is very easy to change the direction of rotation when shifting the rudders. Shaker figure.
4. I make a “parachute” and deflect the rudder. I get a very slow flat corkscrew - a "dry leaf" figure.
5. Such a figure as the “harier” goes into the category of children’s.
6. A “square loop” turns out to be exactly square, since the turning radii at the corners are almost unreadable.

It would take a very long time to describe the figures. I'll just say one thing. This plane can do more than I can, and is capable of teaching an advanced pilot several more new maneuvers that are inaccessible on conventional aircraft. And I especially want to note the predictability and stability of the aircraft, no matter what you do with it.

Looks like I got what I WANTED!

Attempt 4

Although the second and third aircraft showed excellent flight performance, one more very important question remained: what are the optimal angles of attack for the wings? To solve this problem, it was decided to build a model for the 50th engine, with the ability to change the angle of attack of the wings on the ground. In addition, model No. 3 was destroyed due to hardware failure.

It was also decided to place the front wing above the engine axis, and the rear below (on the previous model it was the other way around, I just wanted to check - I’ll say right away that I didn’t notice any changes in the behavior of the model.) and make a slight bevel along the leading edge, the front wing received an implicit the pronounced positive "V" and the posterior negative "V". This was supposed to give stability at low speeds in forward and reverse aerobatics, respectively.

I will not dwell in detail on the description of the design and manufacturing process. She is no different from the usual Fanfly and is clear from the photographs.

The archive contains a description of a light single-seat aircraft with an original design.
The plane is called "Quickie".

The archive is a scanned manuscript with diagrams in Adobe PDF format.

Although at first glance, this plane seems too unusual and may cause mistrust, nevertheless, read the following text.
This is an excerpt from the book by V.P. Kondratiev “We ​​Build Airplanes Ourselves.” As follows from his words, an aircraft built according to this design promises very good performance.

The advantages of the duck are well known. Briefly, they boil down to the following: in contrast to the normal scheme, in a statically stable “duck” the lifting force of the horizontal balancing tail is added to the lifting force of the wing. Therefore, with the same load-bearing properties, the wing area can, roughly speaking, be reduced by the amount of the tail area, as a result of which the size, weight and aerodynamic drag of the aircraft decrease, and its aerodynamic quality increases (Fig. 97). Even more profitable is the tandem, which in terms of the balancing method is not fundamentally different from the “duck”, but allows you to create an even more compact machine. In fact, in a tandem arrangement, the total load-bearing area is divided into two equal or approximately equal wings, the linear dimensions of which are approximately 1.4 times smaller than a similar wing of a normal aircraft.

The negative properties of the “duck” are associated, first of all, with the influence of the front wing on the rear. The front one slopes down and the air flow flowing around the rear wing slows down, its effectiveness decreases (Fig. 98). The optimal solution to this problem is to space the wings as far apart as possible along the length of the fuselage and in height. To prevent the rear wing from getting caught in the wake vortex of the front wing when flying at high angles of attack, the front wing is raised higher than the rear wing or lowered as low as possible. This was done, in particular, on the Kwiki tandem. Failure to comply with this condition leads to longitudinal instability at high angles of attack.

One more condition should be taken into account. When flying at high angles of attack before stalling, stall should occur first on the front wing. Otherwise, when stalling, the plane will sharply lift its nose and go into a tailspin. This phenomenon is called “pickup” and is considered completely unacceptable. A way to combat “pickup” on a canard was found a long time ago: it is enough to increase the angle of the front wing relative to the rear. The difference in installation angles should be 2-3°, which guarantees that the flow will stall primarily on the front wing. Next, the plane automatically lowers its nose, switches to lower angles of attack and picks up speed - thus, the idea of ​​​​creating a non-stall aircraft is realized, of course, subject to the required alignment.

..
Tandem aircraft and their aerodynamic features:
Shadowing of the rear wing by the front wing when flying at high angles of attack. 1 - small interference in cruising flight at low angles of attack; 2 - strong shading of the rear wing at high angles of an aircraft with an unsuccessful configuration, 3 - good arrangement of wings with low interference at high angles of attack (m - the longitudinal moment coefficient is negative, the slope of the curve is typical for a stable aircraft, α - angle of attack)

The construction of tandems was sporadic until then. until in 1978, the same tireless Rutan demonstrated his defiantly “incomprehensible” Kwiki tandem at a gathering of US amateur designers in the city of Oshkosh. When starting to develop this machine, Rutan set the task of creating an aircraft with high flight characteristics with an engine of the lowest possible power. Of course, the best results could be obtained using a tandem circuit. Indeed, two wings with an area of ​​approximately 2.5 m^2 made it possible to make an aircraft of minimal overall dimensions with the least aerodynamic drag and high aerodynamic quality. At the same time, the engine is 18 liters. With. enough to achieve a speed of 220 km/h, a rate of climb of 3 m/s, a ceiling of 4600 m. The take-off weight of the aircraft, made entirely of plastic, is 230 kg. Like Rutan’s previous creations, “Kwiki” was reproduced by amateurs from different countries in dozens of copies. American aviation experts consider the Kwiki a “minimal” aircraft. It is economical, cheap and easy to build. The production cycle for its manufacture is only 400 man-hours. Amateur designers from many countries can purchase drawings, a set of blanks, and a completely finished apparatus.

Followers of Rutan were also found in our country. At SLA-84, the Kuibyshev amateur club “Aeroprakt”, headed by student Yu. Yakovlev, presented its version of “Kwiki” - A-8

There are already a lot of good amateur clubs in our country. Kuibyshevsky is one of the most famous. “Aviation in practice” is how the club members decipher the name of their “company”, created in 1974 in the red corner of the factory dormitory by a graduate of the Kharkov Aviation Institute Vasily Miroshnik. The fate of Aeroprakt was difficult. The club was repeatedly closed, “dispersed”, changed addresses and leaders. However, failures and difficulties only strengthened the young enthusiasts.

Over more than fifteen years of history, dozens of people have passed through Aeroprakt - schoolchildren, students, young workers, who later became good engineers, designers, and pilots. In the traditions of Aeroprakt there is complete freedom of technical thought and democracy. The club always had several small creative groups that were simultaneously building three or four aircraft. And for the most daring and “crazy” technical ideas there has always been only one judge - practice and personal experience. It was precisely this atmosphere of creative cooperation and competition that became a constant source of enthusiasm, thanks to which Aeroprakt still exists. It was these conditions that made it possible to most fully demonstrate the talent of our best amateur designers, including Vasily Miroshnik, Peter Almurzn, Mikhail Volynets, Igor Vakhrushev, Yuri Yakovlev and many others - regular participants and winners of SLA rallies.

The aircraft created at Aeroprakt are well known. In order to better imagine the scale of Aeroprakt’s activities, it is enough just to recall the names of the aircraft of this club that took part in SLA rallies. Among them are the A-6, A-11M, A-12 aircraft, the A-05 seaplane, the A-7, A-10B gliders and the A-10A motor glider, which have the “company” designation “A” and were built in the “branch” » "Aeroprakta" - SKB Kuibyshev Aviation Institute under the leadership of V. Miroshnik. Almost all of the listed aircraft were winners of the rallies.

The greatest success fell on the tandem A-8 (“Aeroprakt-8”), built by a student at the Kuibyshev Aviation Institute, Yuri Yakovlev.

Externally, the A-8 resembles the Kwiki. But it should be noted that before the tandem of Yu. Yakovlev in our country very little was known about the features of this scheme. What should be the relative position of the wings and their profile, where should the center of gravity of the aircraft be located, how will the machine behave when flying at high angles of attack? All these questions could be answered only by testing the device.

..
Tandem aircraft A-8(Yu. Yakovlev, Aeroprakt). Front wing area - 2.47 m2, rear wing area - 2.44 m^2, take-off weight - 223 kg, empty weight - 143 kg, maximum lift-to-drag ratio - 12, maximum permissible speed - 300 km/h, maximum operational overload - 6, run - 150 m, run - 150 m.
1 - engine, 2 - pedals, 3 - cabin fan air intake, 4 - wing hinge units, 5 - aileron control rods, 6 - aileron, 7 - rudder and tail wheel control rods (cable in a tubular sheath), 8 - control shaft , 9 - PLP-60 parachute, 10 - engine control lever, 11 - gas tank, 12 - elevator control rods, 13 - engine start handle, 14 - rubber engine mount shock absorbers, 15 - elevator, 16 - side control stick, 17 - flashlight lock, 18 - ignition switch, 19 - speed indicator, 20 - altimeter, 21 - attitude indicator, 22 - variometer. 23 - accelerometer, 14 - voltmeter

The A-8 was built very quickly, but did not start flying right away. The first takeoff attempt on the SLA-84 in Koktebel ended in failure: after a short takeoff run, the plane landed. I had to significantly shift the alignment back and change the angles of the wings. Only after these modifications, in the winter of 1985, the aircraft was able to take off, demonstrating all the advantages of the unusual aerodynamic configuration. Compactness, small wetted surface and, as a consequence, low aerodynamic drag inherent in aircraft of such an aerodynamic configuration, made it possible on the A-8, equipped with a 35 hp engine. s, achieve a maximum speed of 220 km/h and a climb rate of 5 m/s. Tests carried out by test pilot V. Makagonov showed that the aircraft is light and easy to fly; control, has good maneuverability and does not go into a tailspin. Its creators and professional pilots successfully flew the tandem. Readers will be interested in the assessment given to the aircraft by V. Makagonov:

— When performing runs on the SLA-84, the A-8 discovered an imbalance in the longitudinal control channel, as a result of which a significant diving moment from the rear wing developed during the takeoff run at a speed lower than the takeoff speed. This moment could not be compensated by the elevator. After the rally, the aerial practitioners solved the problem of a balanced takeoff by reducing the angle of the rear wing to 0°. This turned out to be enough so that during the take-off run, with the control stick fully taken over, the speed at which the tail wheel rises to the take-off position and the take-off speed practically coincide. After liftoff, the aircraft easily balances in the longitudinal channel. There are no tendencies to turn or roll. The maximum rate of climb is 5 m/s obtained at a speed of 90 km/h. In horizontal flight, a maximum speed of 190 km/h was achieved. The aircraft readily increases speed to 220 km/h with a slight decrease and, when entering level flight, maintains it for a long time. Obviously, with a more successful selection of a fixed-pitch propeller, the speed can be higher. Throughout the entire speed range, the aircraft is stable and well controlled, cross-links in the lateral dynamics are clearly visible. With the control stick fully engaged and the engine running at low throttle at a speed of 80 km/h, a stall in the flow on the front wing is observed, the aircraft lowers its nose slightly, followed by the restoration of flow and an increase in pitch. The process is repeated in a self-oscillating mode with a frequency of 2-3 oscillations per second with an amplitude of 5-10°. The breakdown is not sharp, so the dynamics are smooth. There are no tendencies towards heeling and turning during a stall. The dependence of the forces on the handle and pedals on their stroke is linear with maximum values ​​of the forces on the ailerons and rudder, height not exceeding 3 kg and on the rudder not exceeding 7-8 kg. The aircraft uses a side control stick, so the costs of the stick are low. The aircraft demonstrated good maneuverability. At a speed of 160 km/h, the turn is performed with a bank of 60°, and the forced turn at a speed of 210 km/h with a bank of 80°. Wrist control, an ergonomically advantageous seat and a canopy that is excellent from a viewing point of view create fairly comfortable flight conditions.

On the eve of SLA-85, Aeroprakt was once again closed, and all aircraft were in a sealed room. Yuri Yakovlev and his friends had to make a lot of efforts before the A-8 and other club aircraft were delivered to Kyiv. Arriving at the rally a little late, the A-8 immediately attracted the attention of both spectators and specialists, and the magnificent flights of V. Makagonov largely contributed to the fact that the tandem became one of the most popular aircraft at the rally. When summing up the results, the A-8 was recognized as the best experimental aircraft. Its author was awarded prizes from the Central Committee of the Komsomol, the magazine “Technology for Youth” and TsAGI. On the recommendation of the technical commission of the meeting, by decision of the Ministry of Aviation Industry, the A-8 was transferred to TsAGI for purging in a wind tunnel, and then to the Flight Test Institute for more detailed studies in flight. The main prize for Yuri Yakovlev, of course, was an invitation to work at the OKB named after O.K. Antonov.

The A-8 is made entirely of plastic. The front and rear single-spar wings have approximately the same design. The wings are detachable, but have no spanwise connectors. When docking, the wings are inserted into special cutouts in the fuselage. The front wing is equipped with an RAF-32 aerodynamic profile and is installed at an angle of +3°, the rear wing with a Wortman FX-60-126 profile is installed at an angle of 0°.

The wing spars have a wall made of fiberglass and shelves lined with carbon fiber. The wings are covered in three layers (fiberglass - polystyrene foam - fiberglass). When gluing parts and assembling components of the A-8 airframe, various epoxy adhesives were used, mainly K-153.

The semi-monocoque fuselage also has a three-layer plastic construction. It is glued together with the keel. The landing gear consists of two kart wheels measuring 300x100 mm, installed in special fairings at the ends of the front wing, and a fiberglass spring spike with a steerable tail wheel measuring 140x60 mm. The main wheels are equipped with mechanical brakes. The role of the chassis shock absorber is performed by the rather elastic front wing itself. The aircraft control system includes: a flap on the front wing, which acts as an elevator, ailerons on the rear wing, and a rudder. The drive for controlling the ailerons and elevator is located on the side handle with small strokes, while the pilot’s handle in flight rests on a special armrest. Thus, the principle of hand control is practically implemented. The side control stick of the A-8 was highly praised by all the pilots at the rally.

The A-8 uses the RMZ-640 engine from the Buran snowmobile. The motor develops a power of 35 hp. With. at 5000 rpm. The propeller has a diameter of 1.1 m and a pitch of 0.7 m. The maximum static thrust of the propeller is 65 kg. The gas tank is located in the forward part of the fuselage under the pilot's feet. The engine is designed to use A-76 gasoline.

The only question that bothers me the most after reading this is:
What was the further fate of the A-8 aircraft?
Where did the A-8 aircraft disappear from the production range at the current Aeroprakt?

For a “standard duck” with an area of ​​horizontal tail (front wing) within 15...20% of the area of ​​the main wing and an empennage arm equal to 2.5...3 V Cach (the average aerodynamic chord of the wing), the center of gravity should be located at within the range from - 10 to - 20% VSAKH. In a more general case, when the front wing differs in parameters from the tail of a “standard canard” or a “tandem”, in order to determine the required alignment, it is convenient to conventionally bring this arrangement to a more familiar normal aerodynamic design with a conventional equivalent wing (see Fig. .).

The alignment, as in the case of the normal scheme, should lie within 15...25% of the VEKV (chord of the conventional equivalent wing), which is as follows:

In this case, the distance to the toe of the equivalent chord is equal to:

Where K is a coefficient that takes into account the difference in wing installation angles, bevels and flow deceleration behind the front wing, equals:

Please note that empirical formulas and recommendations for determining alignment are quite approximate, since the mutual influence of the wings, bevels and flow deceleration behind the front wing are difficult to calculate; this can be accurately determined only by blowing. For amateur aviators to experimentally check the alignment of an aircraft with an unusual design, we recommend using flying models, including cord models. In aircraft manufacturing practice, this method is sometimes used. And in any case, for an amateur-built aircraft, the alignment determined by the formulas should be clarified when performing high-speed taxis and approaches.

based on materials: SEREZNOV, V. KONDRATIEV "IN THE SKY TUSHINA - SLA" "Modelist-Constructor" 1988, No. 3