CN1074373C - aircraft with jet flap propulsion system - Google Patents

Abstract

In the aircraft (1) of the invention, the engine drives a blower and uses compressed air to generate jet flap thrust to increase the lift of the wing (18) and the canard (22). The thickness of the airfoil is greatest just forward of the surface control device (12). The airfoil has a larger trailing edge angle and a larger leading edge radius. The hinge (17) of the surface control device is located near the centre line (19) of the wing and air can blow the surface control device through the air holes (10) in the wing.

Description

aircraft with jet flap propulsion system

Background of the invention

The present invention relates to an aircraft with a jet-flap propulsion system, i.e. an aircraft with a normal main wing; or a further development of this aircraft, i.e. a front wing in addition to the main wing, a so-called Airplane with canards.

Aircraft with jet flap propulsion systems have been known for many years, for example from US Patent No. 2,912,189 or US Patent No. 2,961,192. Also, for many years, a jet-flap propelled aircraft with one front wing has also been known, for example from US Patent No. 3,362,659. Airplanes are even known that employ jet flap propulsion systems for both the front and main wings, see, for example, US Patent No. 3,056,566.

In the past, several aircraft have been manufactured with special and elongated flap and slot configurations in order to reduce stall speed and required runways. These aircraft are called STOL (Short Moment Takeoff and Landing) aircraft. In most cases, the operating costs of such aircraft are approximately 30% higher than conventional aircraft. This is due to additional maintenance costs and higher fuel consumption per unit of distance flown. The increased wing area (lower wing loading) results in increased drag and reduced cruise speed.

Many early aircraft designers using the blown-flap theory have focused their efforts on increasing the lift coefficient of the wing, either to reduce landing speed or to gain increased control. Blowing the flaps provides extra thrust, but this creates problems when the plane slows down for landing. In most prior patents using blown flaps, only a small fraction of the engine power is utilized to avoid the problem of extra thrust. If the full power of the engine is used on the blown flaps, it must be possible to use a nozzle plate deflection greater than 90° in order to achieve landing resistance. In order to be able to take advantage of the Coanda effect to deflect the air, the external pressure must balance the centrifugal force of the nozzle plate. This is only possible if the range of motion of the control flaps is large compared to the slot height. In addition, the nozzle pressure must be low.

Summary of the invention

The aircraft of the present invention adopts the principle of jet flaps to reduce the wing area of the aircraft, thereby reducing the total resistance of the aircraft and reducing fuel consumption as a result.

According to one aspect of the present invention, there is provided an aircraft having at least one engine and at least one blower, also having an air intake for the blower and at least one wing with at least one surface control device, which also has having air duct means leading from the blower to the wing for generating jet flap propulsion in combination with surface control means; characterized by: a) the profile of the wing being thicker towards the rear end than normal wing profile; b) the surface control means, by means of a hinge, articulated just behind the wing at its maximum thickness, has a trailing edge angle greater than that of a typical wing profile and has a larger leading edge radius; c ) the hinge of the surface control is located near the centerline of the wing; and (d) the air holes in the wing for blowing the surface control are also equipped with means to direct the blown air onto the top surface of the surface control .

According to another aspect of the present invention, there is provided an aircraft having at least one engine and at least one blower, also having an air intake for the blower and at least one wing and a front wing; the wing and front Each of the wings has at least one surface control device that acts as an elevator on the front wing and ailerons and flaps on the main wing; , an air duct device for generating jet flap propulsion combined with a surface control device; characterized by: a) the profile of the wing and front wing is thicker toward the rear end than the general wing profile; b) the Surface control means, by means of hinges, articulated just behind the wing and front wing at the point of greatest thickness, with a larger trailing edge angle than normal wing sections and with a larger leading edge radius; c ) the hinge of the surface control device is located near the centerline of the wing and front wing; and d) the air holes in the wing for blowing the surface control device are also equipped with holes to direct the blown air to the surface control device device on the top surface.

The airplane of the present invention uses normal landing speeds, but the reduced wing area makes cruising more economical.

For the cruise performance of an aircraft, the lift/drag * Mach number must be maximized. Most of the drag is created by the wings. Wing drag can be reduced if the aspect ratio (span/chord length) is increased and boundary layer control is also employed. Due to improvements in materials, the aspect ratio is gradually increasing, but there are also disadvantages. Wing tip drag (induced drag): $C_{\mathrm{DI}}=\frac{{\mathrm{<figure-callout\; id="2"\; label="KC\; L"\; filenames="C9519796700101.png,C9519796700102.png"\; state="\{\{state\}\}">KC</figure-callout>}}_L^{}}{\mathrm{\&pi;A}}$ In the formula, K-constant depending on tip-to-root ratio and aspect ratio; C _L -lift coefficient; A-aspect ratio; π=3.1416 When C _DI is equal to 3 ^* C _DO , where C _DO = airfoil drag , to obtain the minimum power. for optimal cruising $C_L=\sqrt{\frac{\mathrm{\&pi;A}}{K}{3C}_{\mathrm{do}}}$

It can be seen from this that any improvement that requires higher strength and lighter materials requires a larger _CL value. Currently flying aircraft, the _CL value of the cruise used by it is smaller than the optimal value of _CL . Typical _CL values for cruising on current aircraft are 0.2 to 0.5. Optimal values are generally around 0.8-1.4, so there is a considerable difference here. Provided an optimal _CL value can be used, a smaller airfoil with lower total drag can be used. In the past, blown flaps were used to increase landing drag and takeoff lift. Past efforts have mainly focused on obtaining the maximum _CL value, with less attention paid to the power used. In the present invention, blowing flaps, boundary layer control and propulsion are all combined, so that the resistance is lower, the cruising performance is better, and it is also possible to expand the speed range. A typical airfoil section is thickened towards its aft end and uses a shorter chord control surface with a trailing edge angle of up to two or three times the trailing edge angle of typical airfoils. The control surface has a large leading edge radius. In this way, a rather large duct can be formed between the wing (or canard) spars to reduce the pressure loss in the duct. Compressed air is blown in through slots in the upper surfaces of the flaps, ailerons, and elevators. In this way, the boundary layer is energized and laminar flow is available on the airfoil profile surface. The short control surface chord length ensures low surface frictional resistance on the control surface and enables large control surface strokes with only a simple articulation structure. Using this large leading edge radius for the control surfaces allows reverse thrust to be obtained by reversing the airflow by virtue of the Coanda effect. Aircraft can also be pressurized and ventilated with compressed air.

Brief description of the drawings

The present invention will be more fully understood from the detailed description given below and the accompanying drawings, which are given by way of illustration only and are not restrictive of the invention. in:

Figure 1 shows an aircraft with a front wing and jet flap propulsion system according to the present invention;

Figure 2 shows the main section of the fuselage of the aircraft shown in Figure 1;

Fig. 3 A represents the section of the elevator part of the wing or the front wing along the X-X direction in Fig. 1, and it also shows a typical airfoil with a dotted line, for comparison;

Fig. 3 B represents the section of the flap portion of wing or front wing along the X-X direction in Fig. 1;

Fig. 3 C represents the section along the X-X direction in Fig. 1 of the aileron part of wing or front wing;

Fig. 4 schematically shows an air duct arrangement with means for controlling the air flow in the duct;

Figure 5A shows a theoretical form of the section shown in Figure 5C to illustrate possible airflow conditions;

Figure 5B shows an alternative theoretical form of the section shown in Figure 5C to illustrate possible air flow conditions; and

Figure 5C shows in more detail the cross-section and airflow slot structure of a surface control device according to the present invention.

Detailed Description of the Preferred Embodiment

A large amount of air is blown through the slots in front of the control surfaces of the wings 18 and the canards 22 to form propulsion to the aircraft 1 . Figure 1 shows the basic layout. When power is applied, the center of lift moves rearwards, thus utilizing the canards 22 to maintain longitudinal stability. When power is applied, to compensate for the rearward movement of the center of lift, more airflow is applied to the canard than to the airfoil because the canard lifts more. Figure 2 shows a section through the fuselage. There is an air intake 2 on each side of the fuselage, while a duct leads through the pressure bulkhead 3 to one or more blowers 5 . The blower can be any type of blower, such as a centrifugal, axial or bypass fan, or a breather for a compressor of a turbine engine, driven by the engine 6 . The engine may be a piston engine of any power plant, any electric or future form engine. The compressed air passes through the duct 9 through the pressure bulkhead 4 in the fuselage to the spanwise duct 7 in the wing and the spanwise duct 8 in the canard. The airflow through the ducts 7, 8 or 9 can be adjusted with the control panel 14 shown in FIG. Figures 3A-3C show a section through a wing or canard. The airflow passes through slots 11 , through holes 10 in the rear wing (or canard) spar web and, by virtue of the Coanda effect, along the upper surface of the control surface 12 . The same is true for the airflow when the control surface is in the fully downward (reversed) position. The profile of the wing 18 or canard 22 is shown in Figure 3A, with a typical airfoil 23 shown in dashed lines for comparison. Surface control devices 12 (eg, elevators, flaps or ailerons). Behind the maximum thickness of the wing 18 or canard 22, it is hinged with a hinge 17. The hinge 17 of the surface control device is located near the centerline 19 of the wing 18 or canard 22 . The airflow slots or air holes 10 in the wing 18 or canard 22 for blowing surface control means 12 are equipped with upper vanes (or extensions) 15 and lower vanes (or sealing surfaces) 16 for directing the blown air Guided onto the top surface 20 of the device 12 . The means 12 may be elevators, flaps or ailerons. A small slit 13 at the front end of the control surface allows free movement of the surface. For cruising, the position of this slit is optimal (see Figures 5A, 5B and 5C), so, according to the ejector principle, there should be no or only a small amount of airflow (as shown in Figure 5C). Arrow 27 indicates the main air flow and arrow 28 indicates the air flow through the slot 13 according to the ejector principle ( FIG. 5A ) and caused by excess pressure in the duct ( FIG. 5B ). Smaller air flow (FIG. 5C) ensures laminar flow on the underside of the wing (canard), thereby reducing drag. The pressure loss on the bottom surface of the wing is partly compensated by the increased airflow over the control surfaces, and with increased thrust, more air is deflected downward on the upper surface, increasing lift. Air will flow upwards through the slots 13 to increase the effectiveness of the control surfaces while also causing an overall power loss. Figure 3 shows the travel 26 of the control surface. The flaps (Fig. 3B) can be moved upwards slightly to create reflected airflow over the wing for high speed flight. When the position is completely downward, the airflow passing through the slit 11 moves along the upper surface of the flap to obtain reverse thrust. This reverse thrust can be used as a brake on flight speed, or to reduce the glide distance on the ground when landing. The control surfaces on the canards (Fig. 3A) travel over 180°. Use this travel as elevator control. The downward 90° position maximizes lift, but further downward movement does not have much effect on lift, but reverse thrust is obtained. This reverse thrust, combined with the reverse movement of the flaps, reduces the flight speed. Fig. 3C shows the stroke of the aileron, wherein 24 represents the stroke when the flap is up, and 25 represents the stroke when the flap is down. In order to maintain the longitudinal stability of the aircraft under extreme movements of these control surfaces, control panels 14 placed in ducts 9 shown in FIG. Balance the airflow between the wings and canards. A separate control lever (or a control wheel) is connected to the control panel. When this control lever is moved forward, airflow is restricted to the canards. With the control lever in the center position, both the air ducts to the canards and to the wings are fully open. When the control lever is moved towards the tail, the airflow will be restricted to the wing. Alternatively, the control board is connected to the longitudinal trim device of the elevator so that when the trim device makes its final movement forward, the airflow is restricted to the canards, and when the trim device makes its final movement towards the tail, Airflow is restricted over the wings. Full forward movement of the control rod moves the control surface of the canards to a fully upward position, closing the slot 11 . After landing, you can take advantage of this, combined with the canards fully down, to get the maximum reverse thrust for the landing taxi, and to ensure that the nose wheels of the aircraft are in contact with the ground. The ailerons and flaps are lowered together, and their downward motion is about half the travel of the flaps. When the flaps are fully down and full control of the ailerons is exercised, the maximum downward travel of the aileron upper surface is approximately 90°. When the aileron is fully up, the opening of the slot 11 is slightly reduced, reducing the air flow on the upwardly moving aileron, thereby reducing the thrust on that side of the aircraft. This will reduce the effect of adverse yaw, so little or no differential aileron movement is required.

Keep the engine in the pressure zone away from the blower, and the blower can act as a supercharger for the engine to increase the power of the engine. The heat from the cooling air coming out of the engine also prevents ice from forming inside the ducts and increases the thrust of the propulsion. The pressurized air from the blower is also used to pressurize and ventilate the aircraft cabin and to heat the cabin by propelling the airflow through the exhaust pipe of the piston engine.

On smaller aircraft, a mirror 21 (FIG. 1) may be mounted on the bottom surface of the elevator near the inside end of the nacelle. These mirrors help the pilot reverse the plane on the ground on the tarmac, and when the control stick is pushed all the way forward, the tail of the plane can be seen on both sides.

Having thus described the invention, it will be obvious that various changes may be made therein. Such changes are not to be regarded as a departure from the spirit and scope of the invention, and those skilled in the art understand that all such changes are included within the scope of the following claims.

Claims (9)

1. An aircraft (1) having at least one engine (6) and at least one blower (5), also having an air intake (2) for the blower and at least one with at least one surface control device (12 ) of the wing (18), it also has an air duct device (9,10) leading to the wing from the blower for combining with the surface control device (12) to generate jet flap propulsion; it is characterized by: a) the profile of the wing (18), which is thicker towards the rear end than normal wing profile; b) the surface control means (12), by means of a hinge (17), is articulated just behind the wing (18) at its greatest thickness, with a trailing edge angle greater than that of a typical wing profile, and Has a larger leading edge radius; c) the hinge (17) of the surface control device is located close to the centerline (19) of the wing (18); and (d) The air holes (10) in the wing (18) for blowing the surface control device (12) are also equipped with means to direct the blown air onto the top surface (20) of the surface control device (12) ( 15,16). 2. An aircraft having at least one engine (6) and at least one blower (5), also having an air intake (2) for the blower and at least one wing (18) and a front wing (22 ); each of the wing and the front wing has at least one surface control device (12) which acts as an elevator on the front wing and an aileron and flap on the main wing; the aircraft There are also air duct means (9,10) leading from the blower to the wing for generating jet flap propulsion in combination with surface control means; characterized by: a) the wing (18) and front wing (22) profiles are thicker towards the rear than normal wing profiles; b) The surface control device (12) is hinged just behind the maximum thickness of the wing (18) and front wing (22) by means of a hinge (17), the trailing edge of which is at an angle greater than that of a normal wing section. The edge angle is large and has a large leading edge radius; c) the hinge (17) of the surface control device is located near the centerline (19) of the wing (18) and front wing (22); and d) The air holes (10) in the wing (18) for blowing the surface control device (12) are also equipped with means to direct the blown air onto the top surface (20) of this surface control device (12) (15,16). 3. Aircraft according to claim 1 or 2, characterized in that the means (15, 16) comprise an extension (15) of the top surface of the wing (18) and are located between the surface control means (12) and the wing ( 18) between a sealing surface (16). 4. Aircraft according to claim 1 or 2, characterized in that the air duct means (7, 8, 9) comprise means (14) for controlling the air flow in the duct. 5. Aircraft according to claim 1 or 2, characterized in that the surface control device (12) is arranged to be pivotable by means of a hinge (17) greater than 180 degrees. 6. Aircraft according to claim 4, characterized in that the control device (14) is connected to at least one control device operated by the pilot. 7. 6. An aircraft as claimed in claim 6, wherein the control means distributes the airflow from the blower to the front wing, to the wing or both. 8. 6. Aircraft according to claim 6, characterized in that the control device or control instrument is connected to other regulating systems or instruments of the aircraft. 9. 8. Aircraft according to claim 8, characterized in that the control device or control instrument is connected to the elevator longitudinal trim system.

Images