Aeroprakt A-8
Posted: 30 Jun 2018, 13:32
At SLA-84, the Kuibyshev amateur club Aeroprakt, headed by student Yakovlev, presented the A-8.
Externally, A-8 reminds "Quickie" Bert Rutan. But it should be noted that very little has been known about the peculiarities of this scheme before the Y.Yakovlev tandem in our country. What should be the mutual arrangement of the wings and their profile, where is the center of gravity of the aircraft, how will the machine behave when flying at large angles of attack? All these questions could be answered only by testing the apparatus.
A-8 was built very quickly, but it did not start to fly at once. The attempt of the first take-off on the SLA-84 in Koktebel ended in failure: after a short takeoff the aircraft skiped. It was necessary to substantially shift back the centering and change the angles of the installation of the wings. Only after these improvements in the winter of 1985 the plane was able to rise into the air, demonstrating all the advantages of an unusual aerodynamic layout. Compactness, a small wettable surface and, as a result, low aerodynamic drag, inherent in the aircraft of such an aerodynamic scheme, allowed on the A-8 equipped with a 35-liter engine. s, to achieve a maximum speed of 220 km / h and a climb rate of 5 m / s. The tests carried out by test pilot V. Makagonov showed that the aircraft is easy and simple; management, has good maneuverability and does not break into a tailspin. On the tandem, its creators and professional pilots flew successfully. For the readers, the assessment given to the aircraft by V. Makagonov will be of interest:
- When running runs on SLA-84, the A-8 showed an imbalance in the longitudinal control channel, as a result of which a significant dive moment from the rear wing developed at a speed less than the tearing speed. This moment could not be compensated by the elevator. After the flight, the aeropraktovtsy solved the problem of balanced take-off by reducing the angle of the rear wing installation to 0 °. This was enough to ensure that at the take-off with fully taken control handle speed of lifting the tail wheel to take-off position and the speed of separation almost coincide. After detachment, the aircraft is easily balanced in the longitudinal channel. There are no tendencies to turn and bend. The maximum climb rate - 5 m / s is obtained at a speed of 90 km / h. In a horizontal flight, a maximum speed of 190 km / h is reached. The aircraft willingly increases the speed to 220 km / h with a slight decrease and when it leaves the horizontal flight it retains it for a long time. Obviously, with a more successful selection of a propeller of a fixed pitch, the speed can be greater. Over the entire range of speeds, the aircraft is stable and well-controlled, cross-links in lateral dynamics are clearly manifested. With the control knob completely selected and the engine running on a small gas at a speed of 80 km / h, the flow on the front wing is observed, the aircraft lowers the nose slightly, and then the flow is restored and the pitch is increased. The process is repeated in an autooscillatory mode with a frequency of 2-3 oscillations per second with an amplitude of 5-10 °. Disruption is not sharp, so the dynamics are smooth. Trends in heeling and reversal are not observed. The dependence of the forces on the handle and the pedals on their stroke is linear with the maximum values for the forces on the aileron and the rudder, the height is not more than 3 kg and along the rudder direction is not more than 7-8 kg. The aircraft uses a side handle, so the costs of the handle are small. The aircraft showed good maneuverability. At a speed of 160 km / h, the turn is made with a roll of 60 °, and an accelerated turn from a speed of 210 km / h with a roll of 80 °. Hand control, an ergonomically advantageous armchair and a lantern, which is excellent from the point of view of the survey, create rather comfortable flight conditions.
Externally, A-8 reminds "Quickie" Bert Rutan. But it should be noted that very little has been known about the peculiarities of this scheme before the Y.Yakovlev tandem in our country. What should be the mutual arrangement of the wings and their profile, where is the center of gravity of the aircraft, how will the machine behave when flying at large angles of attack? All these questions could be answered only by testing the apparatus.
A-8 was built very quickly, but it did not start to fly at once. The attempt of the first take-off on the SLA-84 in Koktebel ended in failure: after a short takeoff the aircraft skiped. It was necessary to substantially shift back the centering and change the angles of the installation of the wings. Only after these improvements in the winter of 1985 the plane was able to rise into the air, demonstrating all the advantages of an unusual aerodynamic layout. Compactness, a small wettable surface and, as a result, low aerodynamic drag, inherent in the aircraft of such an aerodynamic scheme, allowed on the A-8 equipped with a 35-liter engine. s, to achieve a maximum speed of 220 km / h and a climb rate of 5 m / s. The tests carried out by test pilot V. Makagonov showed that the aircraft is easy and simple; management, has good maneuverability and does not break into a tailspin. On the tandem, its creators and professional pilots flew successfully. For the readers, the assessment given to the aircraft by V. Makagonov will be of interest:
- When running runs on SLA-84, the A-8 showed an imbalance in the longitudinal control channel, as a result of which a significant dive moment from the rear wing developed at a speed less than the tearing speed. This moment could not be compensated by the elevator. After the flight, the aeropraktovtsy solved the problem of balanced take-off by reducing the angle of the rear wing installation to 0 °. This was enough to ensure that at the take-off with fully taken control handle speed of lifting the tail wheel to take-off position and the speed of separation almost coincide. After detachment, the aircraft is easily balanced in the longitudinal channel. There are no tendencies to turn and bend. The maximum climb rate - 5 m / s is obtained at a speed of 90 km / h. In a horizontal flight, a maximum speed of 190 km / h is reached. The aircraft willingly increases the speed to 220 km / h with a slight decrease and when it leaves the horizontal flight it retains it for a long time. Obviously, with a more successful selection of a propeller of a fixed pitch, the speed can be greater. Over the entire range of speeds, the aircraft is stable and well-controlled, cross-links in lateral dynamics are clearly manifested. With the control knob completely selected and the engine running on a small gas at a speed of 80 km / h, the flow on the front wing is observed, the aircraft lowers the nose slightly, and then the flow is restored and the pitch is increased. The process is repeated in an autooscillatory mode with a frequency of 2-3 oscillations per second with an amplitude of 5-10 °. Disruption is not sharp, so the dynamics are smooth. Trends in heeling and reversal are not observed. The dependence of the forces on the handle and the pedals on their stroke is linear with the maximum values for the forces on the aileron and the rudder, the height is not more than 3 kg and along the rudder direction is not more than 7-8 kg. The aircraft uses a side handle, so the costs of the handle are small. The aircraft showed good maneuverability. At a speed of 160 km / h, the turn is made with a roll of 60 °, and an accelerated turn from a speed of 210 km / h with a roll of 80 °. Hand control, an ergonomically advantageous armchair and a lantern, which is excellent from the point of view of the survey, create rather comfortable flight conditions.