Aerodynamic canard design pros and cons. Aircraft according to the “duck” design. Why the front horizontal tail

Canard (aerodynamic design)

Rutan Model 61 Long-EZ. An example of an aircraft built using the canard aerodynamic design.

"Duck"- an aerodynamic design in which an aircraft’s longitudinal controls are located in front of the wing. It was named so because one of the first aircraft made according to this design - Santos-Dumont's 14 bis - reminded eyewitnesses of a duck: forward control planes without a tail at the rear.

Advantages

The classic aerodynamic design of an aircraft has a drawback called “balancing losses.” This means that the lifting force of the horizontal tail (HO) on an aircraft with a classic design is directed downward. Consequently, the wing has to create additional lift (essentially, the lift force of the aircraft is added to the weight of the aircraft).

The canard design provides pitch control without loss of lift for balancing, because the lifting force of the PGO coincides in direction with the lifting force of the main wing. Therefore, aircraft built according to this design have better load-carrying characteristics per unit wing area.

However, ducks are practically never used in their pure form due to their inherent serious disadvantages.

Flaws

Airplanes built using the “Duck” aerodynamic design have a serious drawback called “peck tendency.” “Peck” is observed at high angles of attack, close to critical. Due to the slope of the flow behind the front horizontal tail (FH), the angle of attack on the wing is less than that of the FH. As a result, as the angle of attack increases, flow stall begins first at the PGO. This reduces the lifting force on the PGO, which is accompanied by a spontaneous lowering of the aircraft’s nose - “pitch” - which is especially dangerous during takeoff and landing.

Pilots trained to fly airplanes with a classical aerodynamic configuration, when flying a canard, complain about the limited visibility created by the PGO.

Also, the movable horizontal tail located at the front helps to increase the effective dispersion area (RCS) of the aircraft, and therefore is considered undesirable for fifth-generation fighters (examples: the American F-22 Raptor and the Russian PAK FA) and the developed promising long-range bomber (PAK DA), made in compliance with radar stealth technologies.

Tandem biplane - a “duck” with a closely spaced front wing - a design in which the main wing is located in the flow bevel zone from the front horizontal tail (FH). Saab JAS 39 Gripen and MiG 1.44 are balanced according to this scheme.

Also, various variations of the canard design are used for many guided missiles.

Literature

Flight tests of aircraft, Moscow, Mechanical Engineering, 1996 (K. K. Vasilchenko, V. A. Leonov, I. M. Pashkovsky, B. K. Poplavsky)

aerodynamic design- Rice. 1. Aerodynamic designs of the aircraft. aerodynamic design of the aircraft. A. s. characterizes the geometric and design features of the aircraft. A large number of signs are known by which A. s. is characterized, but they are generally accepted... ... Encyclopedia "Aviation"

The invention relates to aircraft with a front horizontal tail. The canard aircraft includes a wing, fuselage, propulsion system, landing gear, vertical tail and a biplane front horizontal tail (FH). The aircraft has a uniform loading of the wing and the airfoil per unit area, with the ratio of the distance between the airfoil planes to the arithmetic mean of the chord values of each of the planes equal to 1.2. The invention is aimed at reducing the size of the aircraft. 1 ill.

The invention relates to aircraft with a front horizontal tail, mainly ultra-light, sport aircraft.

A canard-design aircraft is known, including a wing, fuselage, propulsion system, landing gear, vertical tail and biplane front horizontal tail.

For a canard-type aircraft, the load on the front horizontal tail (FH) per unit area is significantly less than that of the wing. This situation is a consequence of the fact that the ratio of the distance between the PGO plans to the arithmetic mean of the chord values of these plans is only 0.7. Since the bearing area of the PGO is used inefficiently, an increase in the size of the wing area and front horizontal tail is required, which increases the size of the aircraft.

The technical problem solved by the present invention is to reduce the size of the aircraft.

The problem is solved due to the fact that according to the invention, in a canard aircraft, including a wing, fuselage, propulsion system, landing gear, vertical tail and a biplane front horizontal tail (FH), there is a uniform load of the wing and FH per unit area, ensured by the ratio of the distance between the plans of the PGO to the arithmetic mean of the values of the chords of each of the plans, equal to 1.2.

This design of the aircraft makes it possible to reduce its size.

The invention is illustrated by a specific example of its implementation and the accompanying drawing.

In fig. 1 shows a cross-section of a biplane front horizontal tail of a canard-type aircraft along a plane parallel to the base plane of the aircraft made in accordance with the invention.

The “canard aircraft” device includes a wing, fuselage, propulsion system, landing gear, vertical tail and a biplane front horizontal tail, consisting of a lower plane and an upper plane. In this case, the specific load of the PGO is equal to the specific load of the wing and is, for example, 550 newtons per 2.2 square meter. That is, there is a uniform load on the wing and PGO per unit area.

In fig. 1, the value of the chord of the lower plan 1 PGO is indicated by the letter bн, and the value of the chord of the upper plan 2 is indicated by the letter bв. The distance between the top 2 and bottom 1 plans is indicated by the letter h.

The chord bн of the lower plan 1 is equal to the chord bв of the upper plan 2 and is, for example, 300 mm. The distance h between plans 1 and 2 is, for example, 360 mm. In this case, the ratio of the distance h to the arithmetic mean of the plan chords is 1.2.

The value of this ratio ensures uniform loading of the wing and PGO for ultra-light sports aircraft. This follows from the following circumstances.

A decrease in the value of h leads, on the one hand, to a rearward shift of the aircraft's focus, which is positive until the load on the airborne space becomes equal to the load on the wing. On the other hand, a decrease in the value of h is accompanied by an increase in the inductive reactance of the PGO, which is certainly negative. In this regard, it is clearly impossible to determine exactly what distance between the PGO plans should be chosen. At the same time, it must be borne in mind that from the point of view of reducing the total area of the wing and the airfoil and, consequently, the size of the aircraft, the condition of uniform loading of the wing and the airfoil per unit area must be met.

With the same or almost identical loading of the wing and the landing gear, the condition is met that the critical angle of attack of the wing is exceeded by three degrees over the critical angle of attack of the landing gear in their landing configuration. This condition is mandatory to prevent “pitch” - a sharp lowering of the aircraft’s nose due to a stall in the flow at the PGO. In this case, a slight difference in load is possible both in favor of the PGO and the wing.

The value of the above ratio was revealed through analytical studies and verification of their results through flight tests of an aircraft model, on which it was possible to change the distance between the PGO plans.

INFORMATION SOURCES

An aircraft with a canard design, including a wing, fuselage, propulsion system, landing gear, vertical tail and a biplane front horizontal tail (FH), characterized in that it has a uniform loading of the wing and FH per unit area, ensured by the ratio of the distance between the plans of the FH to the arithmetic mean of the chord values of each of the plans, equal to 1.2.

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AIRCRAFT "DUCK" PATTERN

Since the first heavier-than-air aircraft to take off, the Wright brothers' Flyer (1903), was built according to a design that is today known as a "duck," it seems logical to begin the story about aircraft of unconventional designs with aircraft of this class.

MISTAKEN TERM

First of all, the term "duck" is a misnomer. In aviation, a “duck” is generally understood to mean an aircraft whose horizontal tail—the stabilizer and elevators—are located in front of the wing and not behind it. This term can be applied with equal success to airships and gliders. In particular, the first models of Zeppelin rigid airships were equipped with forward horizontal control surfaces in addition to the traditional tail ones.

Typically, the term "canard" refers to the location at the front of the aircraft of the main, rather than auxiliary, aerodynamic control means.

This term first appeared in France; its origin is probably due to the fact that the wing of a flying duck is closer to its tail than to its head, and not at all because this bird controls its flight with the help of a special organ located in front of the wing. Aircraft of this design have become quite widespread.

Many canard aircraft can be thought of as tandem wing aircraft, with the front wing being relatively small. In this case, the front horizontal tail (FH), usually consisting of fixed (stabilizers) and moving (elevators) surfaces, bears a significant part of the aerodynamic load.

In recent years, the term "canard" has come to be used to describe aircraft equipped with auxiliary aerodynamic control surfaces mounted on the nose of, generally speaking, fairly conventional aircraft (as well as some delta-wing aircraft), to provide trim or flow control to the aircraft. flow, and not to exercise basic control or create part of the total lifting force, as is the case on a classic “duck”.

WHY FRONT HORIZONTAL TERMINATION?

Before the Wright brothers actually began building the airplane, they
Firstly, the Wright brothers perfectly understood the functions of the “horizontal rudder” in controlling the position of the aircraft in space and believed that the front empennage would perform such functions more effectively than the tail one. In this they turned out to be right, but, of course, they did not know the shortcomings of such a technical solution.

The second main reason for their choice was the location of the first flights, which were carried out from a sandy site, and therefore there was no possibility of using a wheeled landing gear. Both the previously created gliders and the first Flyer were equipped with a skid landing gear, in which the fuselage of the aircraft was located very close to the ground. At the same time, the Wright brothers understood the need for a high angle of attack during takeoff and landing. A low-slung vehicle like the Flyer would certainly have had its tail surface hooked to the ground if it had been chosen; therefore, the designers abandoned this solution. They installed a vertical fin at the tail of their aircraft. The beams supporting the keel were equipped with hinges and, with the help of cable wiring, could be deflected upward without affecting the controllability of the aircraft, since the keel did not deflect relative to the oncoming flow.

ADVANTAGES

In the modern understanding, the main advantage of the canard aerodynamic design is considered to be increased maneuverability of the aircraft, which attracts creators of military equipment to this design. The higher maneuverability of aircraft of this type has proven to be very useful in improving the characteristics of some of the recently created ultra-light aircraft.

Another advantage of aircraft with a canard design is that it is almost always possible to build such an aircraft with natural anti-spin protection: the stall of the air flow on the PGO occurs earlier than on the wing, which creates most of the lift, so the nose of the aircraft in this case is slightly lowers and the machine returns to normal flight.

FLAWS

A significant disadvantage of the canard design is that aircraft of this design are characterized by longitudinal instability. Instead of damping the aircraft's movements relative to the transverse axis (pitch), as, for example, the fin of an arrow does, the effect of air flow on the front horizontal tail increases the corresponding disturbances.

In his notes, O. Wright noted that the pitch stability of the "duck" is determined by the skill of the pilot. The experience of the first flights showed that in the case when a significant lifting force is created on the front horizontal tail, it has a significant impact on the balancing of the aircraft.

A flow disruption at the PGO causes approximately the same effect on the balancing of the aircraft as, for example, folding a pair of table legs; the other two legs continue to support the opposite end, and the table falls in the direction where there is no support.

Therefore, the anti-spin advantages of canard aircraft quickly faded.

Aircraft of this design almost completely disappeared from aircraft manufacturing practice until, at the beginning of the Second World War, in-depth studies of the “duck” began to be carried out, aimed at finding possible ways to improve the maneuverability characteristics of aircraft.

However, even during this period of aviation development, it was not possible to realize the advantages of this scheme. Only in recent years have several very successful canard aircraft been created, which have demonstrated the advantages of this design in some specific conditions for the use of aviation technology.

However, these aircraft have already used special means to prevent a powerful flow stall from the PGO. This is achieved by increasing the critical angle of attack by blowing the flow onto the PGO, using aerodynamic profiles with different load-bearing properties, or using the PGO as only a balancing surface (in this case, the PGO does not create any noticeable contribution to the lift force), for example, on airplanes with a large area close to a delta wing or “tailless” airplanes with a forward-swept wing.

Some modern rockets are built using the canard design, but the control systems of these rockets usually operate using on-board computers and automatic stability enhancements that generate and implement balancing commands that prevent the build-up of disturbances in the pitch channel.

It should be noted that all canard aircraft, implemented in accordance with the technical level achieved before the 1960s, were a complete disaster. As if anticipating this, the Wright brothers already in 1909 (when they began to use a wheeled landing gear, which made it possible to lift the aircraft from the ground and ensure a set angle of attack at acceleration) abandoned the PGO and installed elevators in the tail of the device near the rudder.

The "duck" design is most widely used in the field of ultra-light aircraft. This class of modern aircraft has made its way back to the type of flight performed by the Wright brothers, which is characterized by a very limited speed range, limited maneuverability and a relatively small payload.
More aircraft of this design were probably designed and built between 1980 and 1983 than in all previous aviation history.

: forward control planes without a rear tail.

Advantages

Also, various variations of the canard design are used for many guided missiles.

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Literature

Flight tests of aircraft, Moscow, Mechanical Engineering, 1996 (K. K. Vasilchenko, V. A. Leonov, I. M. Pashkovsky, B. K. Poplavsky)

Notes

Aircraft components

Elements aircraft glider

Controls

Aerodynamics and wing mechanization

Avionics and instruments

Engine control and fuel system

Chassis and braking systems

Escape systems

Other systems

An excerpt characterizing the Duck (aerodynamic design)

The horses were brought in. Denisov became angry with the Cossack because the girths were weak, and, scolding him, sat down. Petya took hold of the stirrup. The horse, out of habit, wanted to bite his leg, but Petya, not feeling his weight, quickly jumped into the saddle and, looking back at the hussars who were moving behind in the darkness, rode up to Denisov.
- Vasily Fedorovich, will you entrust me with something? Please... for God's sake... - he said. Denisov seemed to have forgotten about Petya’s existence. He looked back at him.
“I ask you about one thing,” he said sternly, “to obey me and not to interfere anywhere.”
During the entire journey, Denisov did not speak a word to Petya and rode in silence. When we arrived at the edge of the forest, the field was noticeably getting lighter. Denisov spoke in a whisper with the esaul, and the Cossacks began to drive past Petya and Denisov. When they had all passed, Denisov started his horse and rode downhill. Sitting on their hindquarters and sliding, the horses descended with their riders into the ravine. Petya rode next to Denisov. The trembling throughout his body intensified. It became lighter and lighter, only the fog hid distant objects. Moving down and looking back, Denisov nodded his head to the Cossack standing next to him.
- Signal! - he said.
The Cossack raised his hand and a shot rang out. And at the same instant, the tramp of galloping horses was heard in front, screams from different sides and more shots.
At the same instant as the first sounds of stomping and screaming were heard, Petya, hitting his horse and releasing the reins, not listening to Denisov, who was shouting at him, galloped forward. It seemed to Petya that it suddenly dawned as brightly as the middle of the day at that moment when the shot was heard. He galloped towards the bridge. Cossacks galloped along the road ahead. On the bridge he encountered a lagging Cossack and rode on. Some people ahead - they must have been French - were running from the right side of the road to the left. One fell into the mud under the feet of Petya's horse.
Cossacks crowded around one hut, doing something. A terrible scream was heard from the middle of the crowd. Petya galloped up to this crowd, and the first thing he saw was the pale face of a Frenchman with a shaking lower jaw, holding onto the shaft of a lance pointed at him.
“Hurray!.. Guys... ours...” Petya shouted and, giving the reins to the overheated horse, galloped forward down the street.
Shots were heard ahead. Cossacks, hussars and ragged Russian prisoners, running from both sides of the road, were all shouting something loudly and awkwardly. A handsome Frenchman, without a hat, with a red, frowning face, in a blue overcoat, fought off the hussars with a bayonet. When Petya galloped up, the Frenchman had already fallen. I was late again, Petya flashed in his head, and he galloped to where frequent shots were heard. Shots rang out in the courtyard of the manor house where he was with Dolokhov last night. The French sat down there behind a fence in a dense garden overgrown with bushes and fired at the Cossacks crowded at the gate. Approaching the gate, Petya, in the powder smoke, saw Dolokhov with a pale, greenish face, shouting something to the people. “Take a detour! Wait for the infantry!” - he shouted, while Petya drove up to him.
“Wait?.. Hurray!..” Petya shouted and, without hesitating a single minute, galloped to the place from where the shots were heard and where the powder smoke was thicker. A volley was heard, empty bullets squealed and hit something. The Cossacks and Dolokhov galloped after Petya through the gates of the house. The French, in the swaying thick smoke, some threw down their weapons and ran out of the bushes to meet the Cossacks, others ran downhill to the pond. Petya galloped on his horse along the manor's yard and, instead of holding the reins, strangely and quickly waved both arms and fell further and further out of the saddle to one side. The horse, running into the fire smoldering in the morning light, rested, and Petya fell heavily onto the wet ground. The Cossacks saw how quickly his arms and legs twitched, despite the fact that his head did not move. The bullet pierced his head.
After talking with the senior French officer, who came out to him from behind the house with a scarf on his sword and announced that they were surrendering, Dolokhov got off his horse and approached Petya, who was lying motionless, with his arms outstretched.
“Ready,” he said, frowning, and went through the gate to meet Denisov, who was coming towards him.
- Killed?! - Denisov cried out, seeing from afar the familiar, undoubtedly lifeless position in which Petya’s body lay.
“Ready,” Dolokhov repeated, as if pronouncing this word gave him pleasure, and quickly went to the prisoners, who were surrounded by dismounted Cossacks. - We won’t take it! – he shouted to Denisov.
Denisov did not answer; he rode up to Petya, got off his horse and with trembling hands turned Petya’s already pale face, stained with blood and dirt, towards him.
“I’m used to something sweet. Excellent raisins, take them all,” he remembered. And the Cossacks looked back in surprise at the sounds similar to the barking of a dog, with which Denisov quickly turned away, walked up to the fence and grabbed it.
Among the Russian prisoners recaptured by Denisov and Dolokhov was Pierre Bezukhov.

There was no new order from the French authorities about the party of prisoners in which Pierre was, during his entire movement from Moscow. This party on October 22 was no longer with the same troops and convoys with which it left Moscow. Half of the convoy with breadcrumbs, which followed them during the first marches, was repulsed by the Cossacks, the other half went ahead; there were no more foot cavalrymen who walked in front; they all disappeared. The artillery, which had been visible ahead during the first marches, was now replaced by a huge convoy of Marshal Junot, escorted by the Westphalians. Behind the prisoners was a convoy of cavalry equipment.
From Vyazma, the French troops, previously marching in three columns, now marched in one heap. Those signs of disorder that Pierre noticed at the first stop from Moscow have now reached the last degree.

The history of this project dates back to the early 80s. At the experimental machine-building plant named after V. M. Myasishchev, design and research work was carried out to develop the concept of a new heavy-duty aviation transport system.

In the early 80s of the last century, similar work was carried out in several aviation design bureaus and, of course, in the scientific center of domestic aviation TsAGI.

The concept of a heavy transport aircraft developed at TsAGI is quite well known in aviation circles; the author of the development was the head of design research, Yu. P. Zhurikhin.

The demonstration model of the TsAGI transport system has been repeatedly demonstrated at international aviation exhibitions.

Design developments of EMZ named after. V. M. Myasishchev were carried out within the framework of the topic, which received the index “52”. They were carried out under the leadership of the chief designer of the EMZ V. A. Fedotov, the theme leader at the initial stage was the deputy chief designer R. A. Izmailov. The leading designer on the topic and essentially the author of the concept was V. F. Spivak.

The concept of Project 52 provided for the creation of a unified transport aircraft with unique transport capabilities. The main objective of the project was to ensure the air launch of a reusable aerospace rapid response aircraft. It would not be economically feasible to create such a unique aircraft with a take-off weight of 800 tons for only one task. Therefore, from the very beginning, the concept of the “52” project provided for the use of this aircraft for unique transport operations, including the transportation of military equipment and military units, industrial cargo beyond large sizes and weight.

The design concept of “52” was based on the “external load” principle. Only this principle makes it possible to place loads that are completely different in shape and size. In this case, the aircraft fuselage practically degenerates as a means of accommodating the load, therefore, by maintaining the minimum required size of the fuselage, it would be possible to significantly reduce the weight of the aircraft structure. That's all, it would seem a very simple idea on the basis of which the entire project is built.

In this article we will not consider the “52” project in detail. We will refer those interested to the multi-volume publication “Illustrated Encyclopedia of Aircraft EMZ named after. V.M. Myasishchev”, where the development of the project is described in sufficient detail.

The author of these lines had to directly participate in these works, and in this article I would like to talk about those projects, or more correctly, ideas that were also considered in the process of developing the concept, but were not developed and were not worked out in sufficient detail.

The very idea of creating a super-heavy transport aircraft did not arise on its own. The Ministry of Aviation Industry (MAP) set the specific task of transporting large cargo in the interests of the national economy of the country.

The USSR, with its vast territories and large industrial centers scattered throughout the country, needed a solution to this problem, because it is obvious that it is more economically profitable to transport ready-made and assembled units.

Nuclear reactors, convectors of metallurgical production, gas tanks and distillation columns of chemical production and many other cargoes, all of them, when transported assembled “by air”, could be put into operation quite quickly, which means less time and correspondingly lower costs.

Any transport operation “on the ground” is a whole event for many transport services. Detailed study of the route, demolition of bridges and overpasses, power lines if they interfere with transportation, and so on... These are the timing, these are the costs, in some cases this is simply an insoluble problem.

Cargoes weighing from 200 to 500 tons, with overall dimensions ranging from 3 to 8 m in diameter and 12 m to 50 m in length were intended for transportation. It is clear that, of course, not all of the proposed cargo could be transported by air, but the project “52” could transport most of the cargo if it were implemented.

So the idea arose not only to reduce the size of the fuselage to the minimum possible, but to abandon it altogether. Why not make the transported cargo itself “work”? This idea was prompted by the fact that many cargoes intended for transportation looked like elongated cylindrical bodies, that is, they looked like a fragment of the fuselage.

Of course, the cargo itself, the material from which it was made and its design had to satisfy the strength conditions when installing it on an airplane. The inclusion of cargo in the aircraft's power circuit promised a significant gain in the aircraft's weight efficiency and, accordingly, increased its transport efficiency.

How can the transported cargo itself be included in the power scheme of a transport aircraft? It’s very simple, you need to make the transported cargo winged! There is such an aerodynamic design of the aircraft called “tandem”. In this scheme, the aircraft's supporting system consists of a pair of wings arranged tandemly behind each other with longitudinal spacing. The transported cargo is located between the wings precisely in the center of gravity of the entire supporting system of the aircraft, everything is very simple, although it is well known what a big problem solving the problem of centering a heavy cargo poses.

The tandem scheme has a slightly larger area of the aircraft's load-bearing system compared to the classical scheme, but this scheme turns out to be the most suitable for cargo transportation tasks.

Both wings generate lift without losing lift to the longitudinal trim inherent in a classic aircraft design. Optimal profiling of both wings and degradation of their installation angles make it possible to minimize the negative impact of wing interference and therefore reduce aerodynamic losses.

One of the variants of the tandem aircraft consisted of two independent sections with a full-fledged wing with mechanization of the leading and trailing edges. The wing of the front section is made according to a low-wing design to reduce the effect of the flow bevel on the rear wing. The power plant engines are installed on vertical pylons on top of the front section wing. The pylon engine suspension is considered to be quite universal, allowing the required number of engines to be varied during the development process.

The location of the engines above the upper surface of the wing made it possible to use the effect of increasing the lifting force of the wing due to the jet blowing over the engines (Coanda effect). Due to the greater load on the front wing, the front wing was made with a slightly smaller area compared to the rear wing.

The front section is equipped with its own chassis - the main one, consisting of two four-wheeled main supports and two two-wheeled underwing supports. The spacing of the main and underwing landing gear along the longitudinal axis of the aircraft ensured the longitudinal stability of the front section at the airfield in the undocked position.

On top of the front section behind the cockpit there is a rear-facing glazed cabin for the load operators, who monitor the condition of the cargo and the load securing systems during the flight.

The rear section of the tandem aircraft is similar to the front. The wing of the rear section is overhead, with a slightly larger span. Vertical tail washers are installed on the rear wing. Due to the small effective shoulder, the vertical tail is made of a large area, with two fins.

The rear section of the tandem aircraft does not have engines; the landing gear is designed similarly to the front section. Due to the high location of the wing on the rear section, the underwing landing gear is attached to the vertical tail washers.

An important feature of the “tandem” scheme is also that when the aircraft takes off from the runway, the aircraft takes off flat-parallel, with virtually no pitch angle; this feature of the “tandem” is ideal for transporting long loads, since the explosion of an aircraft on takeoff with a long externally slung cargo becomes problematic for a classic aircraft.

To secure various loads, transitional ring trusses were provided, adapted to the specific load.

In order to increase the transport efficiency of the tandem aircraft, it was also planned to use a passenger module closed between the front and rear sections of the aircraft.

The open-loop design of the tandem aircraft made it possible to adapt the aircraft to loads of varying lengths, this made the aircraft an efficient transport vehicle. In the case of an empty aircraft, both sections were joined using connecting ring trusses.

The design of a tandem aircraft with a truss fuselage looked less radical.

Fundamentally, the idea of the concept remained the same, but the fuselage was still preserved, albeit in a somewhat exotic form - two fuselage beams in the form of spatial trusses. A special feature of this tandem aircraft design was that the rear wing with its landing gear and cargo fastening units could move along the trusses to the desired position, depending on the size of the cargo being transported and its alignment. In all other respects, the concept repeated the first scheme. The shortcomings of this scheme were clearly visible, but the only positive thing was that the search for further productive ideas lay through these schemes.

The “tandem” scheme has not yet exhausted itself, perhaps it will find a worthy application in the very near future, we’ll see.

Source. V. Pogodin Valery Pogodin. Tandem - a new word in aviation? Wings of the Motherland 5/2004