GB2187421A - Foreplanes for flight vehicles - Google Patents

Abstract

A forebody of a flight vehicle, particularly a re-useable single-stage-to-orbit (SSTO) vehicle, includes three preferably congruent foreplanes (18-20) mounted, preferably at equally spaced angular intervals on the forebody, one (18) of which is vertical and is pivotted to act as a yaw control surface and the other two (19,20) are pivotted to act as pitch control surfaces, and interconnecting drives for the three foreplanes arranged so that when the yaw controlling foreplane (18) is turned the other two foreplanes (19,20) move differentially and nullify any torsional loads imparted on the forebody by directional control movements. <IMAGE>

Description

SPECIFICATION Foreplanesforflightvehicles This invention relates to the location and operation offoreplanes on a flight vehicle. By the terms 'foreplane' is meant any lift producing plane, fin or winglet mounted forwardly of the centre of gravity of the vehicle.

A re-usable Single-Stage-to-Orbit (SSTO) vehicle may carry very large quantities of propulsive fuel and oxidant which are preferably contained within a long, slender body in orderto minimise supersonic drag. Balance considerations enforce a rearward centre ofgravity location and, as a corollary, this renderstheforward portion of the body (the forebody) a highly destabilising influence on the control and inherent stability characteristics of the vehicle. Additionally, since there is a rearward centre of gravity location there is insufficient momentarm toovercomethede-stabilisation effect of the forebody by fins carried aft of the centre of gravity.

Thus a 'canard' configuration of control by foreplanes carried by the forebody is both desirable and feasible. But although bending loads due to the foreplanes on the forebody can be (and indeed, must be) structurally accepted, it is desirable that torsional loads should be avoided, bearing in mindthatall structural loads on the forebody caused by aerodynamic loads whether induced by control actions or by atmospheric gusts should be minimised.

According to one aspect of the present invention, a flight vehicle includes a forebody region, three foreplanes mounted on and extending generally radially from the forebody region one of said three foreplanes having pivot means to effect vehicle control in yaw and the othertwo having pivot means to effect vehicle control in pitch, the threeforeplanes having interconnecting means whereby when said oneforeplaneis pivoted, the othertwo are each pivoted differentially through halfthe pivot angle of said one foreplane in addition to any control movements for pitch control whereby anytorsional loads imparted upon the forebody by the directional control movements are substantially nullified.

Preferablythethreeforeplanesarecongruentand are mounted at equally spaced angular intervals on said forebody region.

By this arrangement if can be shown that such differential movements of said othertwoforeplanes add to the yaw control force exerted by said one foreplane by about 50%.

One embodiment of a flight vehicle according to the present invention is described byway of example with reference to the accompanying drawings in which Figure lisa general view of a single stage to orbit space vehicle, Figure2 is a frontview of the vehicle, Figure 3 is an enlarged view of a forebody region of Figure 1 showing foreplane disposition, and, Figure 4is a similarviewto that of Figure 3 butwith theforeplanes moved angularly to effect left yaw control on the vehicle.

In the drawings a re-usable single-stage-to-orbit vehicle has a long slender body 10 which contains large quantities of fuel 11 and oxidant 12, a payload region 13, and rear mounted propulsion engines 14.

A main wing 15 is mounted towards the rear ofthe fuselage. The effect ofthis layout is a rearwardly positioned centre of gravity shown generally at 16, and a forebody region 17 extending well forward of thecentrn-of-grnvity 16,which, as previously described is highly destabilising and requires the vehicle to be provided with suitable stabilisation and control means. Such means comprises three foreplanes 18, and 19,20 carried by the forebody so thatstabilisation and control can be effected.

The three foreplanes are mounted at 1 20" intervals to one another and extend generally radially ofthe forebody. Conveniently,theyare mounted upon spigots 21 for pivotal movement under the control of actuators 22.

Thatforeplane referenced 18 extendsvertically with reference to the vehicle, that is to say when the vehicle is in a straight and level flight attitude. It is thus the primary directional control surface and steers the vehicle in yaw.

The two foreplanes referenced 19 and 20 extend laterally downwards with reference to the vehicle.

They thus form longitudinal control surfaces and control the vehicle in pitch. Further pitch control may be effected by surfaces to the rear of the main wing 15.

Bythisarrangementofcongruentforeplanes, since normal,that is to say lateral, gust loadings are proportional to the sine of the incident flow angle on each surface, it can be shown thatthetorsional loading on the forebody induced by a gust from any direction is zero.

The torsional loading due to directional control may be nullified by operating the "pitch" pair of foreplanes 19,20 differentially through half the angle of the "yaw" foreplane 18. Moreover the lateral component of the loads on the differentially operated foreplanes 19 and 20 (proportional to 2 x sin 30 = 1 x angulartravel) augments the effectiveness of the foreplane 18 by some 50%.

Figure 4 illustrates theforeplanes set to provide a left yaw control effect. That actuator 22 associated with the foreplane 18 is set to cause the foreplane 18 to pivot as illustrated from the null position shown in 'broken' outline at 18' through an angle Xto the position shown in 'hard' outline at 18".

Simultaneously the foreplanes 19 and 20 are caused to pivot as illustrated by their associated actuators 22 from the null position shown in 'broken' outline at 19' and 20', respectively to the position shown in 'hard' outline at 19" and 20", respectively. That foreplane referenced 19 is moved through an angle of X/2 in the negative sense whilst that referenced 20 is moved through an angle of X/2 in the positive sense. For right yaw, the positive and negative signs ofthe angles are reversed.

Means to effect the interconnected movement of the foreplanes are not shown, but can be mechanically or preferably, electrically signalled.

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

Claims (5)

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Foreplanesforflightvehicles This invention relates to the location and operation offoreplanes on a flight vehicle. By the terms 'foreplane' is meant any lift producing plane, fin or winglet mounted forwardly of the centre of gravity of the vehicle. A re-usable Single-Stage-to-Orbit (SSTO) vehicle may carry very large quantities of propulsive fuel and oxidant which are preferably contained within a long, slender body in orderto minimise supersonic drag. Balance considerations enforce a rearward centre ofgravity location and, as a corollary, this renderstheforward portion of the body (the forebody) a highly destabilising influence on the control and inherent stability characteristics of the vehicle. Additionally, since there is a rearward centre of gravity location there is insufficient momentarm toovercomethede-stabilisation effect of the forebody by fins carried aft of the centre of gravity. Thus a 'canard' configuration of control by foreplanes carried by the forebody is both desirable and feasible. But although bending loads due to the foreplanes on the forebody can be (and indeed, must be) structurally accepted, it is desirable that torsional loads should be avoided, bearing in mindthatall structural loads on the forebody caused by aerodynamic loads whether induced by control actions or by atmospheric gusts should be minimised. According to one aspect of the present invention, a flight vehicle includes a forebody region, three foreplanes mounted on and extending generally radially from the forebody region one of said three foreplanes having pivot means to effect vehicle control in yaw and the othertwo having pivot means to effect vehicle control in pitch, the threeforeplanes having interconnecting means whereby when said oneforeplaneis pivoted, the othertwo are each pivoted differentially through halfthe pivot angle of said one foreplane in addition to any control movements for pitch control whereby anytorsional loads imparted upon the forebody by the directional control movements are substantially nullified. Preferablythethreeforeplanesarecongruentand are mounted at equally spaced angular intervals on said forebody region. By this arrangement if can be shown that such differential movements of said othertwoforeplanes add to the yaw control force exerted by said one foreplane by about 50%. One embodiment of a flight vehicle according to the present invention is described byway of example with reference to the accompanying drawings in which Figure lisa general view of a single stage to orbit space vehicle, Figure2 is a frontview of the vehicle, Figure 3 is an enlarged view of a forebody region of Figure 1 showing foreplane disposition, and, Figure 4is a similarviewto that of Figure 3 butwith theforeplanes moved angularly to effect left yaw control on the vehicle. In the drawings a re-usable single-stage-to-orbit vehicle has a long slender body 10 which contains large quantities of fuel 11 and oxidant 12, a payload region 13, and rear mounted propulsion engines 14. A main wing 15 is mounted towards the rear ofthe fuselage. The effect ofthis layout is a rearwardly positioned centre of gravity shown generally at 16, and a forebody region 17 extending well forward of thecentrn-of-grnvity 16,which, as previously described is highly destabilising and requires the vehicle to be provided with suitable stabilisation and control means. Such means comprises three foreplanes 18, and 19,20 carried by the forebody so thatstabilisation and control can be effected. The three foreplanes are mounted at 1 20" intervals to one another and extend generally radially ofthe forebody. Conveniently,theyare mounted upon spigots 21 for pivotal movement under the control of actuators 22. Thatforeplane referenced 18 extendsvertically with reference to the vehicle, that is to say when the vehicle is in a straight and level flight attitude. It is thus the primary directional control surface and steers the vehicle in yaw. The two foreplanes referenced 19 and 20 extend laterally downwards with reference to the vehicle. They thus form longitudinal control surfaces and control the vehicle in pitch. Further pitch control may be effected by surfaces to the rear of the main wing 15. Bythisarrangementofcongruentforeplanes, since normal,that is to say lateral, gust loadings are proportional to the sine of the incident flow angle on each surface, it can be shown thatthetorsional loading on the forebody induced by a gust from any direction is zero. The torsional loading due to directional control may be nullified by operating the "pitch" pair of foreplanes 19,20 differentially through half the angle of the "yaw" foreplane 18. Moreover the lateral component of the loads on the differentially operated foreplanes 19 and 20 (proportional to 2 x sin 30 = 1 x angulartravel) augments the effectiveness of the foreplane 18 by some 50%. Figure 4 illustrates theforeplanes set to provide a left yaw control effect. That actuator 22 associated with the foreplane 18 is set to cause the foreplane 18 to pivot as illustrated from the null position shown in 'broken' outline at 18' through an angle Xto the position shown in 'hard' outline at 18". Simultaneously the foreplanes 19 and 20 are caused to pivot as illustrated by their associated actuators 22 from the null position shown in 'broken' outline at 19' and 20', respectively to the position shown in 'hard' outline at 19" and 20", respectively. That foreplane referenced 19 is moved through an angle of X/2 in the negative sense whilst that referenced 20 is moved through an angle of X/2 in the positive sense. For right yaw, the positive and negative signs ofthe angles are reversed. Means to effect the interconnected movement of the foreplanes are not shown, but can be mechanically or preferably, electrically signalled. CLAIMS

1. Aflightvehicle including a forebody region, threeforeplanes mounted on and extending generally radiallyfrom the forebody region at equally spaced angular intervals, one of said foreplanes having pivot means to effect vehicle control in yaw and the othertwo foreplanes having pivot means to effectvehiclecontrol in pitch, the threeforeplanes having interconnecting means wherebywhen said one foreplane is pivoted, the other two are each pivoted differentially th rough half the pivotangleofsaid oneforeplane in additionto any control movements for pitch control whereby anytorsional loads imparted upon the forebody by the directional control movements are substantially nullified.

2. Aflightvehicle as claimed in Claim 1 and wherein the three foreplanes are congruent and are mounted at equally spaced angular intervals on said forebody region.

3. Aflightvehicle as claimed in Claim 1 or Claim 2 and wherein said interconnecting means are signalled mechanically.

4. Aflightvehicle as claimed in claims 1, 2or3 and wherein said interconnecting means are signalled electrically.

5. Aflightvehicle substantially as hereinbefore described with reference to Figures 1 to 4 of the accompanying drawings.