GB2375090A

GB2375090A - Rotor tilting system, eg for helicopters

Info

Publication number: GB2375090A
Application number: GB0101165A
Authority: GB
Inventors: David Henry Foote
Original assignee: Individual
Current assignee: Individual
Priority date: 2001-01-17
Filing date: 2001-01-17
Publication date: 2002-11-06
Also published as: GB0101165D0

Abstract

Rotor shaft 15 is mounted to a triangular supporting structure 1 which is supported at its three corners on flexible joints, eg ball joints 8, 11, two of which (8) can be moved upwardly and downwardly by hydraulic rams 9 to tilt the supporting structure 1 and hence the rotor shaft 15 according to control inputs. A third hydraulic ram 10 may act on the third joint 11. Screwjacks may be used instead of hydraulic rams. Two rotor shafts may be mounted on the supporting structure 1 which may house the rotor shaft bearings. The invention is suitable for large model helicopters and remotely piloted, drone or ultralight human-carrying helicopters. It can also be used to tilt gyrocopter or helicopter rotor discs with jet reaction engines at the rotor tips.

Description

Rotor Tilting System

-------------------- This invention is intended to be particularly suitable for large radio controlled model helicopters, remotely piloted helicopters and drone helicopters. but it may have applications in full size human carrying helicopters, particularly ultralight helicopters.

Forwards, backwards and sideways flight of a helicopter is achieved and controlled by tilting the rotor disc or discs in the direction in which flight is desired.

This invention provides a means of doing this without a conventional cyclic pitch control or gimbals.

A specific embodiment of the invention will now be described with reference to the accompanying diagram figure 1. A triangular frame 1 made, for example, of welded steel tube of rectangular cross section is fitted at two of its corners with the sockets 2 of ball and socket joints, as shown. At the third and remaining corner is welded a steel sleeve 3 in which a steel bar 4 slides. On the end of the sliding bar, a socket 5 for another ball and socket joint is welded. The bar can rotate freely within the sleeve and move freely in and out of the sleeve. The bar is slightly longer than the sleeve it runs in so that the sleeve and bar combination is rigid enough when slightly extended to resist any bending loads placed on it. The socket 5 of the ball and socket joint is rigidly fixed to the end of the bar 4. The pin 6 is also rigidly fixed to the bar and it slides. between the pin guides 7 to prevent excessive rotation of the bar in the sleeve.

Hydraulic rams 9 have their cylinders 17 rigidly fixed to the helicopter body structure in the vertical position directly below the sockets 2 and 5 of the ball and socket joints, as shown in figure 1, so that the only movement possible is that generated by the rams themselves. The balls 8 of the ball and socket joints are fitted rigidly to the ends of the hydraulic rams and fit in the sockets as shown. A third ram 10 is fitted similarly to the socket of the other ball and socket joint with a ball 11 fixed rigidly to the end of the ram.

In this case, however, the cylinder 18 end of the ram is attached to the helicopter body structure with another ball and socket joint 12. A pin 13 fixed rigidly to the cylinder of the ram, and that runs in a guide 14 fixed rigidly to the helicopter body structure, prevents the cylinder of the ram from rotating excessivly. The extra amount of freedom of movement given to the ram 10 prevents it from jamming in its cylinder when the triangular frame

moves.

Power unit, for example piston engine, transmission and bearings for rotor drive shaft are mounted rigidly to the triangular frame with the rotor drive shaft 15 or shafts extending out of the top of the frame to the rotor hub or hubs. A single rotor hub may be fitted in the case of a single rotor helicopter or two in the case of counter - rotating coaxial or intermeshing rotors. Power unit (s), transmission (s) and helicopter body not shown for reasons of clarity. A casing 16 welded to the frame 1 could be used to house and support the rotor shaft bearings.

The invention represents a potentially strong and precise system for tilting the rotor disc or discs. Eg. rams 9 could operate as a pair to control roll, when one extended the other would retract by the same amount.

Ram 10 could control pitch. The diagram is intended as a schematic only, component sizes are not to scale. Methods of lubrication to joints and components are not shown for reasons of clarity, as are not hydraulic lines etc.

It may be possible to use other controlled, extendable devices other than hydraulic rams such as screwjacks and some other sort of joint instead of the ball and socket joints. Alternative sliding mechanisms to the bar and sleeve could also be possible.

The invention could also be used to tilt the rotor discs of gyrocopters or helicopters with jet reaction engines mounted on the rotor tips.

Figure 2 shows an alternative version of the invention In this version only two rams are used, attached to balls 11 and 8. Ball 19 is simply rigidly fixed to the helicopter fuselage structure, although its socket is free to tilt and swivel in the normal way about it, the socket being rigidly fixed to the frame 1. Mountings of hydraulic rams connected to 11 and 8 are the same as in figure 1.

Rotor hubs fitted could be of the articulated or of the teetering type. Under some circumstances, with twin counter-rotating rotors, rigid rotors could be used, taking into account structural limitations and so on. A collective pitch could be fitted or not, depending upon size of the helicopter, need for autorotation and so on.

Claims

Claims

------ 1. Rotor shaft or shafts mounted to a supporting structure which is supported at three corners on ball joints or other flexible joints, atleast two of these joints being capable of up or down movement to control the tilt of the structure and therefore the rotor shaft (s) according to control inputs.