GB1586042A

GB1586042A - Aerodynamic propelling-gear with engaging rotors

Info

Publication number: GB1586042A
Application number: GB72378A
Authority: GB
Original assignee: Office National dEtudes et de Recherches Aerospatiales ONERA
Current assignee: Office National dEtudes et de Recherches Aerospatiales ONERA
Priority date: 1977-06-24
Filing date: 1978-01-09
Publication date: 1981-03-18
Also published as: FR2395187B2; IT1091434B; FR2395187A2

Description

(54) AERODYNAMIC PROPELLING-GEAR WITH ENGAGING ROTORS (71) We, OFFICE NATIONAL D'ETUDES Er DE RECHERCHES AEROSPATIALES (also known by the abbreviation O.N.E.R.A.) a French Body Corporate, of 29-39, Avenue de la Division Leclerc, 92320 Chatillon, France, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement::- This invention comprises improvements in or modifications of the invention of Patent Application No. 42856/77 (Serial No. 1567989) wherein there is claimed apparatus for aerodynamic propulsion comprising two rotors or propellors with engaging blades which rotate about othogonal and substantially concurrent axes and have aerodynamic effects which are adjustable independently of each other by alteration of the pitch of the blades, the rotors comprising means for varying the incidence of their blades in a cyclic manner.

According to the present invention, in apparatus as claimed in Patent Application No.

42856/77, a rotor has variable geometry blades.

According to a preferred feature the geometry of the blades in twist is varied as the pitch is varied.

In the description which follows, which is given by way of example, reference is made to the attached drawings in which: Figure 1 is a front-view of a blade; Figure 2 is a cross-sectional view along the line 9-9 in Figure 1; Figure 3 is a cross-sectional view along the line 10-lOin Figure 1; Figure 4 is an analogous view to Figure 2 but for another condition; Figure 5 is an analogous view to Figure 3, but for this other condition; Figure 6 is a front face view of a blade for another embodiment; Figure 7 is a corresponding sectional view; Figure 8 is an end-view of the blade shown in Figure 7; Figure 9 is an analogous view to Figure 7, but for another condition; Figure 10 is an analogous view to Figure 8, but for this other condition; Figure 11 is a view of a blade, partially cut away, for another embodiment;; Figure 12 is a cross-sectional view along the line 19-19 in Figure 11, but on a larger scale.

A blade 201 (Fig. 1) comprises a blade body 202 and a tubular blade root 203 by which the blade is assembled for rotation on a hub 204, which hub is joined to the shaft 205 of a rotor, around an axis 206, by means of a bearing 207.

Joined to the hub 204 is a toothed sector 208 (Figure 3) with which a toothed wheel 209 is engaged, which wheel forms the end of a shaft 210 assembled for rotation around an axis 211, which is parallel to the axis 206, by means of bearings 212 and 213 which are attached to the root 203.

The shaft 210 is part of a flap 214 which is fitted to the body 202 of the blade along a rectilinear side 215 which is parallel to the axis 206. The flap 214 runs along about half of the length of the blade and its side 216 forms part of the trailing edge 217 of the blade, which edge is extended by the rectilinear part 218 belonging to the body 202.

On the shaft 210, near the end carrying the toothed wheel 209, a helical toothed wheel 221 is fixed, which engages with a tangent screw 222 situated at the end of the shaft 223 of a motor 224.

In the condition shown in Figures 2 and 3, where the pitch of the blade is zero, the mean line 225 of the flap 214 lies along the continuation of the mean line 226 of the body 202 of the blade. When the motor 224 drives its shaft 223, the shaft 210 is driven and the toothed wheel 209, which rests on the sector 208, causes the blade assembly 201 to rotate around the axis 206, whereby the body 202 of the blade then takes up a position in which its mean line 226 makes an angle a with its initial direction indicated schematically by 227, whilst the mean line 225 of the flap 214, which flap is furthermore rotating around the axis 211, makes an angle P with the said direction 227 (Figures 4 and 5).

The root zone of the blade comprising the flap 214 thus has a greater twist than the pitch of the end 228 of the blade.

Reference is now made to Figures 6 to 10.

A blade 311 comprises a blade root 312 by which the blade is assembled for rotation around an axis 313 onto a hub 314joined to the shaft 315 which rotates around the axis of rotation 316 of the rotor; it also comprises a blade body 317. One end 318 of the blade is assembled for rotation onto the body 317.

In the rest position (Figures 6 to 8), the body 317 and the end 318 form a blade of usual configuration, with a leading edge 319 comprising the edge 321 of the body 317 of the blade and the edge 322 of the end 318 of the blade, and a trailing edge 323 comprising the edge 324 of the body 317 of the blade and the edge 325 of the end 318 of the blade, the edges 321 and 322 being a continuation of each other, as is the case for the edges 324 and 325.

The end 318 of the blade and the body 317 of the blade are joined along a section 326 which is inclined relative to the mean line 327 of the blade, so that the end 329 of the said side, at its intersection with the leading edge 319, is further from the axis of rotation 316 of the rotor than is the end 331 at its intersection with the trailing edge 323.

The assembly of the end 318 of the blade for rotation relative to the body 317 of the blade can be achieved by means of elastic blades 332, 333, or by bearings.

In the condition shown in Figures 6 to 8, the pitch of the blade 311 is zero and its mean plane 334 is perpendicular to the axis of rotation 316 of the rotor.

In the condition, no aerodynamic lifting force is exerted on the end 318 of the blades, with the result that, during the rotation of the rotor which comprises the blade 311, the end 318 of the blade remains in the continuation of the body 317 of the blade as shown in Figures 7 and 8.

The condition shown in Figures 9 and 10 corresponds to an adjustment of the pitch of the blade 311, whereby an angle of incidence a has been given to the body 317 of the blade, which is joined to the root 312 of the blade, the angle being relative to the plane 334 which is perpendicular to the axis 316. In this condition, during the rotation of the rotor which comprises the blade 311, the end 318 of the blade is subjected, at its centre of pressure 336 (Figure 9), on the one hand to the aerodynamic lifting force p, and on the other hand to the effect of the centrifugal force c which is exerted on the end. These forces have a resultant r and the end 318 of the blade rotates, around its side 326 of assembly for rotation on the body 317 of the blade, such that its mean line 337 is directed along the resultant r.

In this position, the actual pitch at the end 318 of the blade is smaller than the pitch of the body 317 of the blade, which is favourable for the efficiency of the blade assembly and also of the rotor which comprises the blade.

In a similar embodiment, means are provided for controlling the rotation or pivoting of the end 318 of the blade relative to the body 317 of the blade around the assembly side 326.

Reference is now made to Figures 11 and 12 which pertain to another embodiment. The root 351 of the blade is assembled for rotation around an axis 352, for changing the pitch of the blade, on a hub 353 situated on the shaft 354 of the rotor which rotates around an axis 355. The blade 356 comprises a blade body 357 which is joined to the root 351 of the blade and which houses the extrados parts 358 and intrados parts 359 on either side of the leading edge 361.

The blade structure comprises a box 362 between the parts 358 and 359, and two brackets 363 and 364 are attached to the said box near the root 351, which brackets house two bearings 365 and 366 which are used for the assembly for rotation of a flat lever 368 around an axis 367. At its other end, the lever carries two rollers 369 and 371 which are assem bled for rotation around an axis 372 parallel to the axis 367. The rollers 369 and 371, which have a rubber coating 373, are suitable for cooperating with an intrados part 374 made of an elastically deformable material, for example of light sheet metal, which part is fixed by its inner edge 375 to the extreme edge 376 of the rigid intrados part 359.A deformable triangular prismatic block 378, for example made of rubber, is glued onto the extreme margin 377 of the intrados sheet 374, and the margin 381 of a flexible sheet 382, which is also metallic, is attached to the opposite face of the block; the inner edge 383 of the flexible sheet is joined to the edge 380 of the extrados part 358 and the sheet forms the outer extrados part.

The mixed line 384 is the mean line of the blade when the latter is at zero incidence. - The mixed line 385 is the mean line when the body of the blade has an incidence a. The position of the part of the blade which is adjacent to the trailing edge 398 is then, near the root of the blade, as shown by the continuous line in Figure 19. The intrados sheet 374 is deformed under the action of the rollers 369 and 371, which involves a deformation of the extrados sheet 382 by virtue of the interposition of the block 378 to which both the sheet 374 and the sheet 382 adhere.

This deformation of the intrados sheet and the extrados sheet diminishes with increasing distance from the rollers 369 and 371 controlling the deformation, with the result that the deformation of the intrados sheet and the extrados sheet at the end 391 of the blade can be zero or essentially zero, as shown by the mixed line in Figure 12.

The blade thus exhibits the desired twist.

Control of the twist can be achieved by means of a small shaft 392 supported by bearings 393 and 394 which are joined to the root 351 of the blade and are driven from a transmission 395.

In the condition shown by a continuous line in Figure 12, the twist away from the mean plane 396 of the body of the blade is equal to an angle -P for the part of the blade which is near the root of the blade. The line 397 indicates schematically a twist in the opposite direction, which is equal to +P and which is controlled for a normal pitch of the blade which is the reverse of that which has been shown in the figure.

WHAT WE CLAIM IS: 1. Apparatus as claimed in any claim of Claims 1 to 4 and 6, Patent Application No.

42856/77, (Serial No. 1567989) wherein a rotor or propeller has variable geometry blades.

2. Apparatus according to Claim 1, wherein the variable geometry of the said blades is obtained by the provision of flaps on the blades adjacent their root ends.

3. Apparatus according to Claim 2, wherein the flaps extend along the trailing edges of the blades for about half their length from the root ends.

4. Apparatus according to Claim 2 or Claim 3, wherein each said blade is coupled to its flap such that, as the pitch of the blade is varied in operation, the flap is adjusted angularly on the blade.

5. Apparatus according to Claim 1, wherein the variable geometry of the blade is obtained by the provision at the radially outer end of each said blade of a portion angularly displaceable relatively to the inner portion of the blade.

6. Apparatus according to Claim 5, wherein the outer portion is mounted for rotation on the inner portion about an axis oblique to the mean line of the blade.

7. Apparatus according to Claim 5 or Claim 6, wherein the outer and inner portions of the blade are interconnected by elastic members.

8. Apparatus according to Claim 5 or Claim 6, wherein the outer and inner portions of the blade are connected by bearings.

9. Apparatus according to Claim 1, wherein the variable geometry of the blades is obtained by each such blade comprising an intrados part and an extrados part which are at a distance from the leading edge and are elastically defor mable.

10. Apparatus according to Claim 9, where in the marginal intrados and extrados parts - which are adjacent to the trailing edge are connected to each other by means of an elastic block.

11. Apparatus according to Claim 9 or Claim 10, wherein control of the deformation is effected near the root of the blade, with the result that the part of the blade near the root is considerably deformed, whilst the deformation of the blade becomes progressively smaller with increasing distance from the root.

12. Apparatus according to Claim 11, wherein the deformation is controlled from inside the blade.

13. Apparatus according to Claim 11 or Claim 12, wherein the deformation is controlled by means of the intrados for one direction of deformation and by the extrados for the opposite direction.

14. Apparatus as claimed in any of Claims 5 to 13, wherein the blade is arranged so that its geometry is varied as its pitch is changed.

15. Apparatus as claimed in Claim 1, having variable geometry blades substantially as hereinbefore described with reference to and'as shown in Figures 1 to 5 of the drawings.

16. Apparatus as claimed in Claim 1, having variable geometry blades substantially as hereinbefore described with reference to and as shown in Figures 6 to 10 of the drawings.

17. Apparatus as claimed in Claim 1, having variable geometry blades substantially as hereinbefore described with reference to and as shown in Figures 11 and 12 of the drawings.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. The blade thus exhibits the desired twist. Control of the twist can be achieved by means of a small shaft 392 supported by bearings 393 and 394 which are joined to the root 351 of the blade and are driven from a transmission 395. In the condition shown by a continuous line in Figure 12, the twist away from the mean plane 396 of the body of the blade is equal to an angle -P for the part of the blade which is near the root of the blade. The line 397 indicates schematically a twist in the opposite direction, which is equal to +P and which is controlled for a normal pitch of the blade which is the reverse of that which has been shown in the figure. WHAT WE CLAIM IS:

1. Apparatus as claimed in any claim of Claims 1 to 4 and 6, Patent Application No.