WO2001076942A1

WO2001076942A1 - The system of aerodynamic members

Info

Publication number: WO2001076942A1
Application number: PCT/PL2001/000021
Authority: WO
Inventors: Jerzy Czaplejewicz
Original assignee: Jerzy Czaplejewicz
Priority date: 2000-04-11
Filing date: 2001-03-14
Publication date: 2001-10-18
Also published as: PL198000B1; PL339586A1; AU2001241298A1

Abstract

The system consists of at least two elongated and flattened aerodynamic members (1, 2), parallel to each other as well as at least one thin plate (3) placed between the members (1, 2). The members are shaped as elongated planes (1, 2) with aerofoil profile cross-section. The distance (H) between the plate (3) and chord of each plane is constant and ranges between 5 % and 50 % of mean length of this plane's chord.

Description

The system of aerodynamic members.

Technical Field

The subject of the invention is system of aerodynamic members which when placed m a stream of flowing gas are a source of aerodynamic force with direction different to the direction of the flowing gas. In particular the invention relates to a system applicable to flying objects such as aircraft wings or helicopter rotors.

Background Art

With given speed of flowing gas and given profile, the magnitude of aerodynamic force depends mainly on the size of aerodynamic member. Therefore it is the mam objective for any aviation constructions to maximise the lifting surface of aerodynamic members i.e. aircraft wings or helicopter rotors. With unchanged wmgspan increasing the surface of wings by extending the chord reduces the aspect ratio which is aerodynamically inefficient. On the other hand increasing aspect ratio with unchanged chord (which is aerodyna ically favourable) leads to increased wmgspan and costly and complicated construction solutions required to ensure the stiffness with little increase in wing weight. Very wide wings are subject to significant dynamic loads during the flight and make it difficult to manoeuvre on ground.

These shortages can be overcome by multi-planes i.e. two or more parallel planes one above another. However, the need to ensure proper flow of air stream around the profile, which is necessary for aerodynamic lift to come into existence, requires the distance between planes to be a significant multiple of their maximum thickness. Reducing the distance results in fall of total aerodynamic lift of the system and leads to increase of front and induced drag. On the other hand because of the distance at least one plane (with classic double-plane aircraft - usually the upper one) can not be mounted onto fuselage using beams located inside the wing. Therefore the wing is fixed to the fuselage using complex support "outside" construction, which increases the resistance of the whole flying object. Obtaining additional aerodynamic lift of helicopters rotor by using additional rotor blade with each basic blade has not been yet known. A known increasing of aerodynamic lift can be currently obtained by increasing number of rotor blades or using so called tandem rotor systems. This however results in unfavourable interference between rotors, leading to much lower then expected increase in aerodynamic lift. An important shortcoming of a helicopter is noise. It is known from literature (e.g. "The research of the Aviation Institute" issue 2/3/97, Warsaw, ISSN 0509- 6669, page 45 and following) , that main noise source are fast rotating rotors which speed can not be much reduced as it would cause a fall in aerodynamic lift.

Disclosure of Invention

The essence of the invention is a system of at least two elongated and flattened aerodynamic members, parallel to each other, and at least one thin plate placed between the members. The members can be in the form of elongated planes with cross section of aerofoil profile, where mean chord of one plane is greater then mean chord of the other. The plate separating the planes is connected to them by number of thin partitions parallel to each other and perpendicular to the plate. Distance between the plate and the chord of each plane ranges between 5% and 50% of the chord length. The length of the each next plane can be shorter then the previous one and is not more then 60% of the length of the previous plane in particular. The thin plate separating the planes may be fixed with them by supports of a drop like cross-section shape

Industrial Applicability

The system of aerodynamic members according to the invention allows to construct aerodynamic lifting assembles consisting of wings with high aspect ratio. The increase of aspect ratio and total lifting surface results in significant increase of aerodynamic lift with the same wingspan. Wing built according to the invention is stiffer and lighter then conventional wing, therefore carrying capacity of flying object is higher. The invention also allows to built an aircraft that is characterised by lower then conventional moment of inertia on longitudinal axis, which is particularly important for military and aerobatics aircraft.

For helicopters, the invention offers all of the above virtues and in addition it allows eliminating the second rotor which makes it a lot easier to convey drive. Increase of rotor aerodynamic lift allows also reducing its revolving speed. Therefore the load on main fitting is reduced and so is the noise.

Brief Description of Drawings

The invention in several embodiments is schematically presented on the drawings. Figure 1 is a side view of an aircraft with wings constructed according to the invention, when Figure 2 is top view of the aircraft.

Figure 3 presents the measurement of distance between the chord and the plate.

Figure 4 presents an aircraft wing with more then two planes, one over another.

Figure 5 is a cross section of on of embodiment of wing according to the invention with planes of different mean chords, when Figure 6 shows a perspective view of such wing.

Figure 7 and Figure 8 are cross section and perspective view respectively of another embodiment of the wing according to the invention.

Next embodiment of the invention present Figure 9 (cross section) and Figure 10 (perspective view) .

Figures 11 and 12 present the front and top view respectively of the light aircraft with another embodiment of wings according to the invention.

Figure 13 presents the front view of one of embodiment of the helicopter rotor according to the invention.

Figures 14 and 15 are top views of two embodiments of helicopter rotor blades according to the invention.

Figures 16 and 17 present the cross sections of shown in fig. 14 and 15 rotor blades' embodiments respectively.

Examples of Carrying Out the Invention

The system according to the invention can be used to construct light aircraft and helicopter rotor. The aircraft has two trapezium planes 1 and 2 with flat-convex subsonic profile NACA 2409. The planes are parallel and placed one above the other. Metal or synthetic thin plate 3 is placed between planes 1 and 2 and fixed to these planes. Plate 3 is fixed to the upper and lower plane by a number of thin partitions 4. The partitions 4 are perpendicular to the plate 3 and parallel to the longitudinal axis of the aircraft. Distance H between plate 3 and chords of each plane is constant and amounts to 7% of mean length L of plane's chord 5. Depending on used aerofoil profile this distance may vary between 5% and 50% of chord 5 length. Wing built as described above is then fixed to spars mounted to aircraft's fuselage. Applying the invention, with unchanged wingspan for this class of aircraft, results in almost twofold increase of aerodynamic lift compared to traditional solutions, which allows for significant reduction in takeoff distance and landing speed. Wings constructed according to the invention can have use in other types of aircraft, particularly in heavy aircraft, e.g. in passenger or transport planes. The invention is not limited only to double-plane aircraft, it also allows to construct aircraft with additional plane 2a under the lower plane .

For practical reasons it is sometimes required that chord of one of the planes is shorter then the chord of the other plane. In the light of aircraft construction described above it is more beneficial that chords ratio of the lower plane 2' and upper plane 1' is 80:100. The length of the partitions 4 connecting the plate 3 and the planes 1' and 2' is the same as the length of plane 2' chord. This solution improves visibility from cockpit and may be beneficial in respect of aerodynamic characteristics of the aircraft. Other embodiments of wings with different planes mean chord length are also possible. For example, to ease access to cockpit, upper plane 1 ' ' may be narrower then lower plane 2 ' ' . In another variation, where upper plane 1' ' ' is wider then lower plane 2' ' ', fronts of the partitions 4 are chamfered. This way plane 1 ' ' ' is borne on longer distance which allows to use lighter construction, reducing the weight of the wing. The method of fixing plate 3 to planes using partitions 4 as described above is only an example and it may be done in any other way which will ensure stiffness and strength of the construction, at the same time reducing aerodynamic drag.

The next embodiment of the invention is a tourist aircraft with wings in three-planes system. Each of wing is formed by three planes 11, 12, 13 separated by two thin plates 3' and 3' ' . In contradistinction to the described earlier in two-plane system each of the next plane (counting from the longest one) is shorter from the previous one. The length of the followed, second plane is 60% of the length of the previous, first one and then the length of the followed third plane is 60% of the length of the previous, second one. The given difference in length of the following planes are minimum and there is a possibility to construct as per invention the multi-wing system where the length of the followed plane is less then 60% of the length of the previous one. Plates 3' and 3'' are fixed with planes 11, 12, 13 by a supports 14 of a drop like cross section. By support 14 application instead of thin partitions 4, the multi-planes assembly is stiffer what allows to reduce wing spars durability. Additional advantages of the support 14 in a drop like shape is proved better discharging of electrostatic current and supplementary fuel tanks may be fixed inside as well for example.

The invention allows constructing multi-blades rotors for helicopters. Fig. 13 presents four-blades (15, 16, 17 and 18) rotor separated by three plates 19, 20 and 21, where length of the next blade is not longer then 60% of the length of the previous one.

A sample helicopter rotor blade is a substitute for the rotor blade designed for helicopter type IS-2 and described in "Prace Instytutu Lotnictwa" ("The research of the Aviation Institute") issue 2/3/98 (Warsaw, ISSN 0509-6669, page 167 and following). It is composite rotor blade 3.25 m long, profile ILHX4A1-12 with mean chord of 0.2 m. An additional blade 7 with the same profile was placed over original blade 6. Aluminium plate 8 is mounted between the rotors using number of parallel partitions 9, the same type as for the aircraft wing described earlier. Upper blade 7 has identical shape with blade 6, however there is no ferrule zone. Length of upper blade 7 chord is 80% of that of lower blade 6. Distance H between the plate 8 and the chord of each blade is 10% of the length of lower blade 6 mean chord.

In another embodiment of the described above rotor blade equivalent, the two upper blades 1 ' , 1 ' ' and two separating plates 8' , 8' ' are fixed to the lowest blade in the described above manner. Similar to the previous example the average chord length of the middle blade 7 amounts to 80% of the average chord length of the lower blade 6. At the same time the middle blade 1 ' length amounts to 60% of an active lower blade 6 length. The average upper blade 1 ' ' length amounts to 80% of the average middle blade 7' length. The upper blade 1 ' ' length amounts to 60% of the middle blade 7' .

Claims

Patent claims .

1. The system of aerodynamic members which when placed in flowing gas stream become source of aerodynamic force with direction different then the direction of the flowing gas, characterised in that the system includes at least two elongated and flattened aerodynamic members (1, 2) parallel to each other, and at least one thin plate (3) placed between the members (1, 2) .

2. The system as claimed in Claim 1, characterised in that the aerodynamic members (1,2) are shaped as elongated planes with aerofoil profile cross-section.

3. The system as claimed in claim 2, characterised by being consisted of two planes (1,2) where a mean chord length of one of the planes is greater then mean chord length of the other plane.

4. The system as claimed in claim 2 or 3, characterised by thin plate (3) being fixed to planes (1,2) using number of thin partitions (4) substantially parallel to each other and substantially perpendicular to the plate (3) .

5. The system as claimed in Claim 2 or 3 or 4 characterised by the distance between the plate (3) and chord of each plane being constant and ranging between 5% and 50% of mean length of this chord.

6. The system as claimed in Claim 2, characterised by the shorter length of the following plane then the length of the previous plane.

7. The system as claimed in Claim 6 characterised by the length of the following plane being not more then 60% of the previous plane length.

8. The system as claimed in Claim 6, characterised by mean chord length of the aerodynamic cross-section of the following plane being longer then the average chord length of the previous plane.

9. The system as claimed in Claim 7, characterised by mean chord length of the aerodynamic cross-section of the following plane being longer then the average chord length of the previous plane

10. The system as claimed in Claim 6, characterised by mean chord length of the aerodynamic section of the following plane being shorter then the mean chord length of the previous plane.

11. The system as claimed in Claim 7, characterised by mean chord length of the aerodynamic section of the following plane being shorter then the mean chord length of the previous plane.

12. The system as claimed in one of Claims from 6 to 11 characterised by the distance between the thin plate (3) and the section chord of each of plane is advantageously constant and ranging between 5 % and 50% of mean length of this plane.

13. The system as claimed m Claim 2 or 3 or 6 or 7 or 8 or 9 or 10 or 11, characterised by thm plates (3', 3'') being fixed to adjoining planes (11, 12, 13) using supports (14) of the drop like cross-section.

14. The system as claimed m Claim 5, characterised by thm plates (3', 3'') being fixed to adjoining planes (11, 12, 13) using supports (14) of the drop like cross-section.

15. The system as claimed m Claim 12, characterised by thm plates (3', 3'') being fixed to adjoining planes (11, 12, 13) using supports (14) of the drop like cross-section.

16. The system as claimed m one of Claims from 6 to 11, characterised by thm plate (8) being fixed to adjoining planes (6, 7) using number of thm partitions (9) substantially parallel to each other and substantially perpendicular to the plate (8) .

17. The system as claimed m Claim 12, characterised by thm plate (8) being fixed to adjoining planes (6, 7) using number of thm partitions (9) substantially parallel to each other and substantially perpendicular to the plate (8) .