RU2196075C2 - Delta-plane - Google Patents

Abstract

FIELD: light aircraft manufacture; designing deltaplanes. SUBSTANCE: proposed delta- plane has flexible wing 1 with trapezium 2 articulated at point 3 of suspension of wing 1 on pylon 4 of trolley 5 where two seats 6 and 7 are mounted in tandem, power plant 8 with pusher propeller 9 mounted after trailing edge of wing 1 and rigid wing 10 projecting above its surface; center section of this wing is mounted on lower portion of trolley 5 above plane of rotation of blades of propeller 9; delta-plane is also provided with stabilizer 12 mounted after propeller 9 at negative angle relative to longitudinal axis of trolley 5 which does not exceed angle of attack of beginning of stall on it; it is secured to center section by means of two fins. Flexible wings 1 and propeller axle are mounted in accordance with the following formula: P Hp + Yk Xgk = 0, where P is thrust force of propeller 9; Hp is distance between axis of propeller 9 and point 3 of suspension of wing 1; Yk is normal aerodynamic force of rigid wing 10; Xgk is distance between line of action of normal force of rigid wing 10 and point 3 of suspension of flexible wing 1. EFFECT: improved take-off , landing and aerodynamic characteristics ; enhanced safety of flight. 4 dwg

Description

 The invention relates to light aircraft construction and can be used in the design of hang-gliders.

 Known deltalet containing a wing and a motor vehicle, pivotally connected to each other, a propeller group containing an internal combustion engine, on which is mounted a reduction V-belt gear and an airscrew. The gearbox is a device made of large and small pulleys, with the small pulley mounted directly on the motor shaft, and the large one on a fixed axis mounted on a special bracket mounted on the crankcase. The propeller is mounted directly on the pulley. The wing pivotally connected to the carriage is located in the plane of the rotating screw and therefore is located above it, and the wing control trapezoid is at the level of the pilot’s chest [1].

The disadvantages of this design are
- high drag;
- low aerodynamic quality;
- limited functionality of the pilot when controlling the device.

 The closest in technical essence and the achieved result is a deltalet containing a flexible wing with a steering trapezoid, pivotally mounted at the suspension point on the pylon of a motorized carriage, in the body of which two tandem seats are installed, a power unit with a pushing propeller mounted behind the wing trailing edge and protruding above the surface of the latter [2].

The disadvantages of the known design are
- adverse interference between the input jet of the propeller and the wing of the deltalette, which reduces the bearing properties of the wing;
- complication of flight control due to a change in the sign and magnitude of the effort on the control trapezoid when taking off the deltalet from the ground at take-off, as well as when changing the engine thrust in flight;
- a large load on the flexible wing during flight, which degrades the aeroelastic characteristics of the deltlet;
- the tendency to spontaneous roll of the deltalet due to the lack of aerodynamic compensation of the reactive moment;
- the lack of protection of the propeller from the effects of foreign objects from the surface of the earth at takeoff and landing modes.

 The task of the invention is to improve the take-off and landing characteristics of the deltalet, simplify flight control, increase the bearing properties of the wing, improve the aerodynamic characteristics of the deltalet, increase flight safety.

 This problem is solved in such a way that a deltalet containing a wing with a steering trapezoid, pivotally mounted at the suspension point on the pylon of a motorized carriage, in the body of which two tandem seats are installed, a power unit with a pushing propeller mounted behind the rear edge of the wing and protruding above the surface of the latter additionally contains a rigid wing, the center wing of which is mounted on the bottom of the motorized car under the plane of rotation of the propeller blades, and a stabilizer mounted behind the propeller under by a negative angle to the longitudinal axis of the cart, not exceeding the angle of attack of the onset of airflow disruption on it, and attached with two keels to the center wing, while the flexible wing and the axis of the propeller are set in accordance with the formula P • Hp + Yк • Xgk = 0 where P is the propeller thrust; Нр - distance from the axis of the propeller to the suspension point of the flexible wing; Yk is the normal aerodynamic force of the hard wing; Xgk is the distance from the line of action of the normal force of the rigid wing to the suspension point of the flexible wing.

 Figure 1 presents the proposed deltlet (side view), figure 2 is a top view; figure 3 is a front view; figure 4 is a graphical explanation of the calculation formula.

 The deltalet contains a flexible wing 1 with a steering trapezoid 2, pivotally mounted at point 3 of the suspension suspension of the flexible wing 1 on the pylon 4 of the motorized carriage 5, in the body of which two tandem seats 6 and 7 are installed, a power unit 8 with a propeller 9, a hard wing 10, the center section 11 of which is mounted on the lower part of the carriage 5 under the plane of rotation of the blades of the screw 9, and the stabilizer 12, mounted behind the propeller 9 and attached with two keels 13 and 14 to the center section 11 (Fig.1-3).

 This design of the deltalet provides a reduction in the distance between the flexible wing 1 and the carriage 5 and the displacement of the plane of rotation of the propeller 9 back beyond the trailing edge of the wing 1, which eliminates the possible adverse interference between the wing 1 and the input stream of the propeller 9, which is typical for deltlets with a traditional layout , where the input stream together with the stream ejected by it creates an additional rarefaction under the lower surface of the wing and reduces the lift. The extension of the plane of rotation of the propeller 9 over the trailing edge of the wing 1 weakens the overall effect of the input jet of the propeller 9 on the wing 1, and in take-off and landing modes, when the jet of the propeller 9 is most intense and the angle of installation of the wing 1 increases (its trailing edge drops ), the inlet stream further accelerates the flow both on the lower and upper surfaces of the wing 1, as a result of which the load-bearing properties of the wing in its central sections slightly increase. The reduced distance between the wing 1 and the carriage 6 also leads to the fact that the thrust vector of the engine of the power plant 8 passes near the point 3 of the suspension, as a result of which when changing the thrust of the engine in flight there is no change in the sign and magnitude of the force on the steering trapezoid 2, which greatly simplifies deltlet control. The distance between the wing 1 and the carriage 5 is selected so that the load on the steering trapezoid 2 does not change due to a change in the lifting force on the hard wing 10 caused by a change in the operating mode of the engine of the power plant 8. The moment relative to the attachment point of the wing 1 created by the engine rod P by shoulder HP, should balance the moment from the normal aerodynamic force Yk of the hard wing 10 acting on the shoulder Xgk (figure 4), and is illustrated by the calculation formula. The use of an additional rigid wing 10 unloads in flight the flexible wing 1, which helps to improve the aeroelastic characteristics of the latter. In addition, the wing 10 also improves takeoff and landing characteristics, as it is located in the lower part of the carriage 6 and near the surface of the earth experiences a screen effect (its aerodynamic quality increases). Placing the propeller 9 above the center section 11, when the screw 9 rotates, creates supercirculation on the center section 11 (the inlet stream accelerates the flow and creates additional rarefaction over the surface of the center section 11) and increases the lifting force on the additional rigid wing 10 as a whole. This effect is enhanced by the presence of keels 13 and 14 and is most noticeable on take-off when the engine is operating at maximum speed. In addition, the center section 11 and the keels 13 and 14 protect the propeller from getting foreign objects on it during the takeoff and run of the deltlet.

 At the same time, for deltalets with a well-known traditional take-off layout, the so-called “pumping” effect is characteristic, when when the device is lifted off the ground, the rolling resistance disappears, the moments are unbalanced relative to the suspension point, and under the influence of an unbalanced moment from the engine thrust, the motor vehicle tries to change its position relative to the wing. The pilot feels this in the form of a significantly increased pushing force at the moment of separation from the ground on the control trapezoid and, if this force is not opposed, the trapezoid approaches the chest. This phenomenon creates inconvenience in controlling the device. Compared with the known deltlets in the proposed design, by reducing the distance between the wing and the trolley, the thrust vector arm Hp is reduced relative to point 3 of the wing suspension, and the pumping effect is practically not manifested.

In addition, on modern deltallets with increased engine power in the regimes with maximum thrust, the reactive moment arising on the engine shaft becomes significant. This leads to the fact that there is a spontaneous roll of the cart. In the proposed deltalet, in comparison with the prototype, a stabilizer 12 is installed behind the plane of the propeller 9, which interacts with the swirling output stream of the screw 9 in such a way that an additional positive aerodynamic load is created on one half of it and a negative one on the other. As a result, a roll moment is created on the stabilizer 12, acting in the direction opposite to the reactive moment. In addition, the stabilizer is installed at a negative angle to the longitudinal axis of the truck, not exceeding the angle of attack of the beginning of the stall of the air flow on it, for example at an angle of about 10 ^o , which increases the margin of longitudinal static stability of the deltlet.

Sources of information
1. Auth. St. USSR 1779641, class B 64/31/02, 01/03/1991.

 2. General aviation. Publishing House "Scientific and Technical Center for General Aviation", 1997, 9, p. 8 (prototype).

Claims (1)

A deltlet containing a flexible wing with a steering trapezoid, pivotally mounted at the suspension point on the pylon of a motorized carriage, in the body of which two tandem seats are mounted, a power unit with a pushing propeller mounted behind the rear edge of the wing and protruding above the surface of the latter, characterized in that it additionally contains a rigid wing, the center wing of which is installed in the lower part of the truck under the plane of rotation of the rotor blades, and a stabilizer mounted behind the propeller under the negative angle to the longitudinal axis of the cart, not exceeding the angle of attack of the beginning of the stall of the air flow on it, and attached with two keels to the center section, while the flexible wing and the axis of the propeller are set in accordance with the formula
P Hp + Yk Xgk = 0,
where P is the propeller thrust;
Нр - distance from the axis of the propeller to the suspension point of the flexible wing;
Yk is the normal aerodynamic force of the hard wing;
Xgk is the distance from the line of action of the normal force of the rigid wing to the suspension point of the flexible wing.

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