GB2214882A

GB2214882A - A canard actuation assembly

Info

Publication number: GB2214882A
Application number: GB8803648A
Authority: GB
Inventors: David William Gurney
Original assignee: British Aerospace PLC
Current assignee: BAE Systems PLC
Priority date: 1988-02-17
Filing date: 1988-02-17
Publication date: 1989-09-13
Also published as: GB8803648D0

Abstract

A canard fin deployment and control assembly, which can work with any size of fin and is capable of imparting greater deployment angles than conventional methods and also allowing unrestricted control angles to be obtained. <IMAGE>

Description

A CANARD ACTUATION ASSEMBLY The invention relates to a canard fin deployment and control assembly particularly, though not exclusively, to large fins which require large deployment angles and large control angles.

It is well known to use canard fins on articles such as projectiles (e.g. Merlin), however, with the current methods of deployment and control there is a limit to the size of fin that can easily be used and also a limit on the possible deployment angles.

One object of this invention is to provide a canard fin deployment and control assembly, which can work with any size of fin and is capable of imparting greater deployment angles than conventional methods, and also allowing unrestricted control angles to be obtained.

According to one aspect of the invention there is provided a canard actuation assembly for use on an article to be controlled in flight, comprising a canard; motor means; movable support means for moving said canard from a stowed to deployed position and for controlling said canard when in said deployed position; and means to couple said motor means and said movable support means.

Preferably said movable support means comprises a crank shaft linked to a yoke, said link being such that when the canard is in the stowed position relative movement of said crank shaft and said yoke is not possible; and when the canard is in the deployed position relative movement of the crank shaft and yoke is possible.

Advantageously said means to couple said motor means and said movable support means comprises a plurality of sets of gears.

Reference will now be made, by way of example, to the accompanying drawings in which: Figure 1 is a partial sectional view, from the front, of a canard fin and its deployment mechanism; and Figure 2 is a sectional view of the same fin and deployment mechanism.

Referring to Figures 1 and 2, a canard fin 1 may be moved from a stowed position A to a deployed position B.

The canard fin 1 is attached pivotably to crank shaft 2, at one end 3. Referring to Figure 1, the other end of the crank shaft 2 is attached to a yoke 4 which is rotatable about shafts 5 and 6. The rotation of yoke 4 is actuated by motor 7 via gear sets 8 and 9, resulting in the movement of the canard fin from its stowed to deployed position.

With the fin 1 in the stowed position A, shaft 2 and yoke 4 are axially locked by means of a square 13. Crank shaft 2 is splined to gear set 9, in order to allow relative axial movement; and the crank shaft 2 is held locked up by either a yoke detent 10 or by riding on a curved track (not shown). This results in gear set 9 being locked up, so that the motor will rotate yoke 4 from the stowed to deployed position. At this point the crank will drop into detent 11 under the influence of spring 12, and crank square 13 will be disengaged from the yoke, and the yoke will be locked up.

Once the yoke has been locked up gear set 9 will be freed and further drive of motor 7 will rotate the crank 2 within yoke 4 to provide control of the canard fin 1.

In this case, the gearing ratios of the gear sets were 4:1 and 4.67:1 for set 8 and 4:1 for set 9. The resulting deployment ratio is 18.67:1 and the resulting control ratio is 75:1. The control ratio has been found to be about the most effective, but not the only, working ratio.

It should be noted that a spiroid set or worm could be used instead of the gear set, if the motor axis was altered; however, compactness of the assembly may suffer.

Claims

1. A canard actuation assembly for use on an article to be controlled in flight, comprising a canard; motor means; movable support means for moving said canard from a stowed to deployed position and for controlling said canard when in said deployed position; and means to couple said motor means and said movable support means.

2. A canard actuation assembly according to Claim 1, wherein said movable support means comprises a crank shaft linked to a yoke, said link being such that when the canard is in the stowed position relative movement of said crank shaft and said yoke is not possible; and when the canard is in the deployed position relative movement of the crank shaft and yoke is possible; this will allow both deployment and subsequent control over very large angles.

3. A canard actuation assembly according to Claim 1 or Claim 2, wherein said means to couple said motor means and said movable support means comprises a plurality of sets of gears.

4. A canard actuation assembly substantially as hereinbefore described with reference to, and as illustrated in, Figures 1 and 2 of the accompanying drawings.