RU2381142C1 - Two-wing system with positive interference - Google Patents

Abstract

FIELD: aircraft engineering.

SUBSTANCE: proposed system comprises front and rear wing, the latter being mounted behind and above the former. Distance between rear wheel profile leading edge and profile rear edge makes 0.5 to 1.5 of rear wing profile aerodynamic chord length in the planes of system lengthwise section for at least half the front wing span. Rear wing profile and elongation are selected to make rear wing increment for angle of attack exceed that of front wing.

EFFECT: higher economy and improved flow over wings, better aircraft lengthwise stability and reduced span and area of aerodynamic control surfaces.

4 dwg

Description

The invention relates to aircraft, in particular to aircraft, and can be used on aircraft to improve the aerodynamic characteristics of the wing.

To date, the main fleet of aircraft are aerodynamic planes "monoplane". The “monoplane” scheme gained predominant distribution, despite the disadvantages: relatively large stabilization losses, significant overall dimensions, and low payload. The only advantage of the “monoplane” scheme is the use of one wing, and in this regard, the absence of problems associated with providing satisfactory conditions for the flow around two or more wings.

Known aircraft tandem scheme, containing two wings located on the fuselage one after another. The disadvantages of the tandem scheme are the large mass separation and the presence of flight modes in which the rear wing is obscured by the front. Due to these shortcomings, the scheme was not developed.

To reduce shading and mass dispersion, one of the tandem wings can be made with a smaller area. Known Canard aircraft, in which the front wing is smaller than the rear. Aircraft are also known in which the rear wing has a smaller area than the front. The disadvantage of these aircraft is the lack of longitudinal stability.

Known experimental aircraft scheme "polyplan", in which the wing is made in the form of a wing lattice, consisting of three or more plans. This scheme is not widespread due to the complexity of the calculations and the lack of a theoretical basis.

Known aircraft having two wings with a variable installation angle, which are located in the nose and tail of the fuselage. Actuators are provided that can provide the required lifting force by changing the angle of the wings, made rotary relative to the hinges. There is an automatic stabilization system using spoilers or steering surfaces, made with the ability to disable it at the time of longitudinal control of the aircraft (RU 2244662, 20.01.2005).

Known aircraft containing a fuselage having upper and lower decks, a front wing located in the nose of the fuselage, with a variable angle of the bearing surfaces, and an automatic longitudinal stabilization system using spoilers or rudders. Additionally introduced the rear wing, which is located on the upper surface of the upper deck of the fuselage, which is offset from the lower deck. The mounting and rotation of the front wing is provided. The wings are made rotary with hinge axes and with the possibility of providing a given angle of attack during longitudinal control of the aircraft and spaced along the length and height of the fuselage to eliminate the aerodynamic effect of the front wing on the rear wing. The front wing is installed in the bow and is located on the upper surface of the lower deck of the fuselage (RU 2286287, 10.27.2006).

The disadvantages of these structures are the parasitic flow of air from under the upper wing to the lower one, as well as the fact that the tail horizontal stabilizer reduces the aerodynamic quality of the structures.

The closest analogue of the claimed invention is an aircraft containing a combination of two wings, one of which is installed in front and the other behind the center of gravity of the aircraft, so that the aerodynamic focus of the isolated combination of wings coincides with the center of gravity of the aircraft (RU 2102287, 01.20.1998).

The objective of the invention is the creation of such a design of a two-wing system with positive interference, which would eliminate the above disadvantages and would be a simple self-stabilizing two-wing system with no parasitic connection between the wings, minimal shadowing of the rear wing and a small mass spacing.

The technical result achieved by the implementation of this invention is to increase efficiency, improve the flow of air around the wings and ensure the longitudinal stability of the aircraft due to the special arrangement of the wings for the formation of an interference system, as well as to reduce the size and area of the aerodynamic bearing surface in comparison with aircraft of known aerodynamic schemes and rational use of horizontal aerodynamic surfaces.

The specified technical result is achieved in a two-wing system with positive interference, comprising a front wing and a rear wing mounted back and up relative to the front wing, while in the planes of the longitudinal section of the system for at least half the span of the front wing the distance between the nose of the rear wing profile and the trailing edge the profile of the front wing is 0.5-1.5 lengths of the aerodynamic chord of the profile of the rear wing, and the profile and extension of the rear wing are selected so that the increment is lifting There was more strength in the angle of attack at the rear wing than at the front.

The area of the rear wing is less than the area of the front wing.

The essence of the claimed invention is illustrated by drawings, where figure 1 shows a view of a two-wing system with positive interference (DKSPI) in plan; figure 2 is a view of a section aa in figure 1 of the longitudinal plane DKSPI.

The positive-interference double wing system comprises a front wing 1 and a rear wing 2 mounted rearward and higher relative to the front wing 1. The front and rear wings 1, 2, due to their special arrangement, form an interference system that improves airflow around the wings and ensures longitudinal stability of the aircraft.

The area of the front wing 1 is larger than the area of the rear wing 2, which is located relative to the front wing 1 in such a way that reduces air flow through the trailing edge of the front wing 1. In addition, the geometric parameters of the rear wing 2 are selected so as to obtain a larger increase in lift angle of attack than the front wing 1.

The essence of the claimed invention is that in the planes of the longitudinal section of the considered wing system, the distance L between the nose 3 of the profile of the rear wing 2 and the trailing edge 4 of the profile of the front wing 1 is 0.5-1.5 lengths of the aerodynamic chord of the profile of the rear wing 2. This condition must be observed for at least half the front wing span 1.

The recommendation on the optional observance of the parameter L over the entire front wing span is related to the fact that the aircraft does not always require an excessive stall margin. For example, the possibility of stalling in a corkscrew is mandatory for sports aerobatic and training aircraft, and providing positive interference throughout the wing will lead not to a corkscrew, but to parachuting.

The invention can be implemented using both rectangular in plan and other wings.

The principle of operation of the DKSPI is that the rear wing reduces the rarefaction of air above the rear edge of the front wing. As a result, the flow of air from under the lower plane of the front wing to its upper plane through the trailing edge is reduced, and thus, the intensity of the boundary layer is reduced. Since the intensity of the boundary layer determines the stall characteristics of the wing, the stall of the air flow on the front wing occurs farther from the toe. Accordingly, turbulence behind the front wing decreases, and the rear wing operates in a laminated air flow.

DKSPI has the ability to self-stabilize in pitch. Stabilization is carried out due to the fact that with an increase in the angle of attack of the wing system, the increment of the bevel angles of the flow behind the front wing decreases, and the angle of attack of the rear wing increases faster. Also, the profile and lengthening of the hind wing are chosen so that the increment of the lifting force along the angle of attack at the hind wing is greater. As a result, stabilization is carried out simultaneously in two components, and its margin is sufficient when centering up to 40-50% of the average aerodynamic chord (MAR) of the front wing.

When designing an aircraft using DKSPI, it is necessary to ensure that the boundary layer on the front wing or most of it is sufficiently weakened, while minimizing the flow of air from under the rear wing to the front. This design principle allows you to compensate for the loss of lift from the flow of air between the wings by the increase in lift in the front wing due to the improvement of its streamlining.

By varying the parameter L and the height of the rear wing relative to the front one, it is possible to increase the critical angle of attack of DKSPI to a value of more than 30 degrees.

The parameter L depends on the elongation of the wings. The greater the elongation, the greater the value of L can be, ceteris paribus.

Through the use of DKSPI the following is achieved:

1. The decrease in the magnitude of the bearing surfaces of the aircraft, since the bearing area is distributed over two wings. In addition, there is no need to compensate the bearing area of the negative lift of the stabilizer.

2. Reducing the length of the aircraft.

3. Reduced weight of the aircraft due to the smaller wingspan.

4. Reducing the mass separation of the aircraft due to the close location of the wings and the small weight of the rear wing.

5. Improving operational angles of attack.

6. The possibility of refusing to mechanize wings by increasing operational angles of attack.

7. The possibility of refusing to use a horizontal stabilizer on an aircraft.

DKSPI can be used to design aircraft and ekranoplanes with improved technical and economic characteristics.

Using DKSPI built an experimental four-seater ekranolet (figure 3). Conducted since June 2007, tests of the ekranolet confirmed the ability of the DKSPI to work at angles of attack of more than 30 degrees and stabilize with pitch.

Claims (1)

A two-wing system with positive interference, characterized in that it contains a front wing and a rear wing mounted behind and above the front wing, while in the planes of the longitudinal section of the system for at least half the span of the front wing, the distance between the nose of the rear wing profile and the rear edge of the profile the front wing is 0.5-1.5 the length of the aerodynamic chord of the rear wing profile, and the profile and lengthening of the rear wing are chosen so that the increment of the lifting force along the angle of attack at wing it was more than that of the front wing.

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