SR-10 light jet trainer - Design

The SR-10 is a single-engine jet aircraft, fitted with a single forward-swept wing, allowing for excellent maneuverability. Built on normal aerodynamic circuit with high-located wing scale 8.4 m with swept on days -10° and edge development wings with rotatable aircraft stabilizer SR-10 has a length of 9.59 m and normal take-off mass of 2400 kg (maximum takeoff and maximum landing weight 2700 kg). Estimated maximum flight speed is 900 km/h (Mach 0.85), absolute ceiling 6000 m, practical flight range-1200 km. According to requirements and financial customer opportunities, information control may be formed from both traditional electromechanical appliances and modern multilateral indicators.

The somewhat unusual aerodynamic design, which gives the aircraft a futuristic look, makes piloting the aircraft easier. The machine even forgives some pilot errors that inevitably arise in the training process. The forward-swept wing is the main difference from the design of the Yak-130. It allows elegantly performing a rule of equal areas, not inflating the diameter of the fuselage, which significantly reduces the drag of the aircraft. In addition, the wing is struggling with overflowing streams - a swept flow wing tends to flow not to the edge of the wing, where the upper and lower flows could, joining, forming eddies that create significant aerodynamic losses (it is with this effect the newfangled winglets on Boeing and Airbus are fighting).

In an aft-swept wing configuration the spanwise flow normally thickens the boundary layer at the tips. The flow on an FSW tends to separate first at the inboard section while good flow conditions can be maintained at the tip because of low induced angles of attack of the outer wing sections and because the air tends to flow toward the root rather than to the tip as it does on a sweptback wing. These flow conditions result in stall characteristics which allow the ailerons to remain effective at high angles of attack, even after most of the wing has stalled. Thus the FSW aircraft is more controllable at higher lift coefficients.

The forward-swept wing solves the problem of the end of twists without winglets and thickening of the end of the wing, while maintaining a clean aerodynamic profile. In addition, this wing in a different aerodynamic focus shifts with increasing angle of attack, rather than the straight wing and normal wing sweep - it has a positive effect on the maneuverability of the aircraft without the use of a large area of wings (compare the relative area of the keel and the elevators at the Yak- 130 and SR-10). Generally swept wings have one excellent feature: it (when properly designed) has virtually no stalling. An aircraft with forward-swept wing retains stability and controllability at all angles of attack.

Forward swept wings of metal are limited in their use due to the static stability phenomenon of divergence at high speed flight conditions. Making the wing out of composite materials offers relief from this phenomenon. However, forward swept wings made from composites are still quite flexible when installed on aircraft. This has led to the observation of a newly discovered dynamic stability phenomenon called rigid body (whole vehicle) structural mode coupling. This occurs as a result of coupling between properly phased wing bending and the aircraft rigid body pitching mode when the frequencies of the two modes are close together. The consequences of rigid body structural mode coupling (also known as rigid body/wing bending flutter) are structural dynamic instability that can be critical with certain aircraft configurations, a degradation in aircraft handling and ride qualities, and increased wing design loads for gusts.

They do have some disadvantages, not the least of which is the aerodynamic design of the inner wing region. The outer wing design is fairly straight forward and it is not difficult to maintain well swept isobars. Over the inner wing, however, there is a tendency for a very strong, unswept shock to form at high subsonic Mach numbers and at high lift coefficients.

As the power plant the AI-25tlsh turbojet engine with a thrust of 1850 kgf was considered, but developed the ability to installation and modern engines - such as type Rd-1700 and Al-55i with a thrust of 1700-1760 kgf. The prototype is equipped with the engine AI-25TL (apparently, used and retreaded). In fact, installation of the AI-25 was a temporary solution, in the final version the Russian engine AL-55 will be installed in the plane of - including the version with thrust vector control. Developed by JSC «A.Lyulka-Saturn" aircraft engine AL-55 is created with maximum use of the experience and the design and technological solutions, accumulated during the creation of the AL-31F, which are equipped with fighters Su-27. The engine was designed for use in training aircraft Yak-130 and MiG-AT. Yes - the Yak-130 motors, although implementation in production in Russia, is scheduled to throw out and replace it with a purely Russian design.

It cannot be said that the situation with the AL-55 was all rosy - the first motor designs had a tendency to spontaneous combustion, which caused difficulties in passing state tests, and delayed the flight tests. But the problem seemed to be successfully overcome. At the same time the engine variant AL-55F was developed with the afterburner combustion chamber, having a thrust of 3000 kg. The engine had a high specific parameters, big resource (up to 2000 h.) And a small mass. These data and altitude-speed characteristics of the engine AL-55 in comparison with similar domestic and foreign engines show a clear preference for the AL-55. Compared to the RD-1700 engine the AL-55 is smaller, with more thrust and lower fuel consumption. The cost of the AL-55 engine in series production will be approximately $ 500-700 thousand.

A prototype unmanned aerial system was designed on the basis of the SR-10. It will include the UAV Argument, which is an unmanned version of the SR-10. Information on this development has already been submitted for discussion by representatives of the Ministry of Defense, but a decision on the future of the UAV is yet to be made.