GB2211155A

GB2211155A - Take-off trolleys for flight vehicles

Info

Publication number: GB2211155A
Application number: GB8724301A
Authority: GB
Inventors: Gerald David Walley; Robert Brown
Original assignee: British Aerospace PLC
Current assignee: BAE Systems PLC
Priority date: 1987-10-16
Filing date: 1987-10-16
Publication date: 1989-06-28
Anticipated expiration: 2007-10-16
Also published as: GB2211155B; GB8724301D0

Abstract

A wheeled trolley for carrying flight vehicles particularly space vehicles of the type which take-off in a generally horizontal direction comprising two parallel spaced elongate rocket propelled modular wheeled units joined in use by cross members and separable after use for transportation and storage. The units each carry erectable support means, such as A-frames, upon which the flight vehicles may be supported. The support means is adjustable to support the vehicle in a generally nose-down attitude during low-speed ground manoeuvring, in a position providing optimum air-flow incidence to the vehicle's wings during a take-off run, and, in a high angle of incidence position when a predetermined air speed is attained. The trolley has release means to release the vehicle for free flight at a higher predetermined air speed, and a braking system to slow the trolley down for recovery after the vehicle launch. <IMAGE>

Description

TAKE ; IIIOLteYS FOR nIQir The present invention relates to wheeled trolleys for carrying flight vehicles (for example space vehicles) of the type which take-off in a generally horizontal direction.

At take-off, with a full payload and a full load of fuel, flight vehicles (especially space vehicles) are very heavy. They thus require a substantial undercarriage which, even though it may be retracted into the vehicle to reduce drag during flight, adds to the dead weight of the vehicle and thus requires the burning of fuel beyond that strictly necessary to propel the vehicle and payload on its mission. Moreover, since on landing after a mission the flight vehicle is quite light, having used its fuel and having disposed of its payload (if a satellite launcher, -for exaqp-le) only a relatively lightweight undercarriage is required.

This problem is exacerbated in the case of a flight vehicle which is designed to enter Earth orbit from a horizontal take-off since every unit of structural weight demands many units of fuel to reach orbit.

The present invention has for an objective the provision of a take-off trolley which will not only support a flight vehicle statically for pre-flight checks but will support the flight vehicle during take-off until self-sustaining flight speeds are reached. By this arrangement the flight vehicle can be provided with a relatively lightweight undercarriage suitable for supporting the vehicle during landing when its fuel has been used and for static and low speed manoeuvring. Thus the vehicle needs not to permanently carry a relatively heavy undercarriage throughout its mission with a consequential saving of fuel burned.

Such a trolley, however, is required to perform certain tasks beyond that merely providing wheeled support.

An aircraft with nose wheel undercarriage will initially accelerate along a runway in a level or slightly nose down attitude with the nose wheel and the main wheels on the ground. This attitude is maintained to ensure low drag and hence high acceleration. Near the end of the take-off run, at a predetermined speed, the aircraft is rotated into a noseup attitude in which the nose wheel is lifted fram the ground thus developing sufficiently high lift to became airborne.

It is thus a further object of this invention to provide a take-off trolley which can n alter the attitude of the carried flight vehicle to effect a desired take-off performance. Moreover, it is an objective to arrange that the trolley remains in a constant attitude in which all its wheels remain on the ground irrespective of the attitude of the flight vehicle. By this arrangement the trolley can be readily controlled at all times.

If acceleration boosting capability is desirable without adding to the weight or complexity of the flight vehicle then it is possible that this can be added to the trolley. It is thus yet a further objective of the invention to provide a take-off trolley with thrust developing devices.

Trolleys performing the take-off support functions already described may be dimensionally large. This means that they may not be readily transportable either under their own power, e.g. on normal roads, or in transport aircraft. Thus a still further objective of the invention is to provide a take-off trolley which can be broken down into readily transportable components.

An embodiment of a take-off trolley according to the invention will now be described by way of example and with reference t6 the following drawings in which: Figure 1 is a side view of a take-off trolley with a flight vehicle mounted thereon, Figure 2 is a plan view of Figure 1; Figures 3A and 3B are sectional views taken along axes A-A and B-B respectively of Figure 1; Figures 4A and 4B are side views similar to that of Figure 1, but with the flight vehicle mounted in differing attitudes thereon; and, Figure 5 is a transverse cross section through a transport aircraft fuselage showing a portion of a trolley stowed therein.

Referring initially to the Figures 1 to 3B, a flight vehicle which is designed for entering Earth orbit (and thereby to inject satellite payloads into space) after a generally horizontal take-off, includes an elongate tubular body 1, rear mounted wings 2, a fore plane 3, thrust nozzles 4, a centrally mounted ventral air intake 5, and a relatively lightweight retractable undercarriage shown generally at 6. The flight vehicle is releasably carried by a trolley which is itself assembled fram a pair of similar wheeled units 7. These wheeled units each comprise an elongate body of a length much greater than its width and of low cross-sectional area.Towards the front end are carried two sets of six wheels, one set lying behind the other, and towards the rear end are carried three sets of four wheels, successive sets lying behind one another. The various sets of wheels on each wheeled unit 7 are arranged not only to support a loaded flight vehicle when the wheeled units are assembled to form a trolley but also to ensure that each wheeled unit 7 is drivable by itself when the trolley is separated into its components. To this end, at least some of the wheels are powered for low speed manoeuvring. At least some of the wheels are steerable.

The two wheeled units 7 which together form the trolley are attached rigidly to one another in side-by-side relationship by means of cross members 8. No trolley side loads are transmitted through the carried flight vehicle. Retractable stabiliser pads 9 are carried at intervals along the sides of each wheeled unit. These, naturally, are for static use only.

To carry the flight vehicle, each wheeled unit 7 has a support A-frame 10 near its front end and a support A-frame ll near its rear end. The A-frames on one wheeled unit 7, although of similar construction to the corresponding A-frames on the other wheeled unit 7, are of opposite hand to engage opposite sides of the carried flight vehicle at points 12 and 13 respectively, as clearly shown in Figures 3A and 3B. Each A-frame 10 is pivotally mounted at its base about a transverse axis to its wheeled unit 7. At its apex it carries a telescopic element 15 which connects to one of said attachment points 12 on the flight vehicle. Each A-frame is rotated about its transverse axis by means of a hydraulic jack 14 from a position in which it extends obliquely rearwards to a near vertical position.

Each A-frame 11 is in two parts articulated to one another about a transverse axis lying between the base and the apex of the A-frame.

The base of the A-frame is pivoted to a wheeled unit 7 again about a transverse axis whilst the apex is adapted by means of an attachment 13 to connect to the flight vehicle. Each A-frame ll is rotated about its transverse axis by means of a hydraulic jack 17 coupled to the wheeled unit at 19. When viewed from the side, each A-frame 10 and 11 is also of A-shape, the axes about which they are rotated by the jack 14 and 17 respectively being at rearward base regions of the A-shape.

The forward base regions of the A-shapes are adapted to contact and be coupled to supports provided upon the wheeled unit when the A-frames are in a raised position. This arrangement provides more rigid support for the flight vehicle when in the acceleration and flight positions where inertial and drag loads are high.

To at least reduce shock loads due to trolley movement being transmitted to the flight vehicle, the forward A-frames 10 are provided with shock absorbers near their apices, and the rearward A-frames 11 are provided with shock absorbers 18 extending between the two parts of the A-frame. Alternatively, the rearward A-frames ll can be of single piece rigid form and the shock absorber 17 replaced with a shock absorbing arrangement similar to that of the forward A-frames.

The attachments 12 and 13 respectively locate at strengthened regions 16 and 20 on the flight vehicle.

Each wheeled unit 7 is provided with rocket motors 21 for boosting take-off performance by accelerating the trolley and its carried flight vehicle more rapidly than would be possible by the motors of the flight vehicle. Each wheeled unit thus contains booster motors (and their fuel) and manoeuvring motors for low speed transportation.

In a preferred method of both assembling the trolley from its separate wheeled units and mounting the flight vehicle thereon, the separate wheeled units 7 are manoeuvred into parallel positions on each side of the flight vehicle while it is standing upon its lightweight retractable undercarriage 6. The flight vehicle is in its empty and unladen state.

When the units 7 are accurately aligned (using specially developed devices), the front and rear A-frames are raised to engage and lock onto the flight vehicle at its reinforced regions. The stabilisation pads 9 are then lowered to the ground to effect stabilisation of the semi-assembled trolley and vehicle. At this stage the cross beams 8 are fitted between the two wheeled units 7 and decking panels fitted, thus making a structurally complete single trolley. The stabilisation pads are then retracted. The flight vehicle is then raised slightly on the A-frames so that its undercarriage 6 is clear of the ground and can then be readily retracted.

The flight vehicle is now generally readied for flight by the loading of fuel and cargo, and the whole is then driven under the self-power of the trolley to a take-off point.

Conveniently, the flight vehicle is carried on the trolley in the generally horizontal (or slightly nose down) position shown in Figures 1 and 3B, during low speed manoeuvring. However, at the take-off point, or, less effectively, at a predetermined time after initial take-off roll, the flight vehicle is raised bodily to the position shown at A in Figure 4A. This is an optimum incidence for low drag and for giving adequate ground and trolley clearance for the engine intakes 5.

The take-off run is effected using the combined thrust of the flight vehicle engines and the boosters on the trolley to optimise acceleration. Naturally, the manoeuvre motors on the trolley are disconnected.

At a predetermined air speed, the flight vehicle is rotated with reference to the trolley by raising the forward support until a predetermined incidence angle is reached. The flight vehicle is then released and leaves the trolley since it is now at a speed and angle of incidence to develop the requisite lift. All the trolley wheels remain in contact with ground at all times, unlike the nose wheel of a conventional aircraft which is raised during rotation of the aircraft to take-off incidence.

The trolley is then slowed by cutting the booster rockets and by using its retro-rockets and any other braking system fitted.

Conveniently, the trolley may be driven to a storage area under the power of its manoeuvring motors. At all times the trolley may be steered by remote control - a laser guidance system being used during the take-off run to ensure that a straight course is maintained.

If the launch has to be aborted, the flight vehicle remains locked on trolley, and the front and rear A-frames are lowered to bring the flight vehicle back to its position of low or negative incidence illustrated in Figure 1 and 4B.

After use, the trolley can be disassembled into its component parts, namely the wheeled units 7, the cross members 8, and the decking members. The latter items can be conveniently carried upon the units 7, which as before referenced, are capable of being driven individually. Figure 5 shows a wheeled unit 7 carried in the freight hold of an aircraft.

As an alternative to the assembly and loading procedure above described, the trolley could be first assembled and ramps provided to allow the flight vehicle to be drawn up onto it.

Each of the wheels on the wheeled units 7 has independent suspension actively controlled by microprocessors to compensate for irregularities in the runway surface. It is also adaptive in the sense that the damping system coopsates for the vast change in weight as the flight vehicle develops its own lift and as it finally lifts off. Naturally, a very stiff suspension system is necessary in the fully laden condition whilst a relatively less stiff system is necessary in the unloaded condition to maintain suitable handling.

By the suspension arrangement described, the main shock loadings from the runway surface are absorbed by the suspension system of the wheels, but any residual loadings are absorbed by the shock absorbers associated with the fore-and-aft A-frames and are not materially passed to the flight vehicle.

Claims

1. A wheeled take-off trolley for a flight vehicle including support means upon which the flight vehicle is supported, said support means being adjustable during a take-off run such that the attitude of the flight vehicle can be changed from a low drag position to a high lift position in which the flight vehicle develops take-off lift without altering the attitude of the trolley.

2. A wheeled take-off trolley according to Claim 1 wherein the trolley comprises two parallel spaced elongate wheeled units joined by cross members, said wheeled units being separable for transportation and storage.

3. A wheeled take-off trolley according to Claim 2 wherein each wheeled unit is self powered for manoeuvring purposes.

4. A wheeled take-off trolley according to any one of the preceding claims having jet thrusters for boosting acceleration.

5. A wheeled take-off trolley according to any one of the previous claims having an adaptive wheel suspension to accommodate the difference in loading prior and subsequent to flight vehicle launch.

Amendments to the claims have been filed as follows 1 A wheeled take-off trolley for a flight vehicle including two parallel spaced elongate wheeled units joined by cross members and carrying support means upon which the flight vehicle is supported, said support means being adjustable during a take-off run such that the attitude of the flight vehicle can be changed from a low drag position to a high lift position in which the flight vehicle develops take-off lift without altering the attitude of the trolley and said wheeled units being separable for transportation and storage.

2 A wheeled take-off trolley according to Claim 1 wherein each wheeled unit is self powered for manoeuvring purposes.

3 A wheeled take-off trolley according to any one of the preceding claims having jet thrusters for boosting acceleration.

4 A wheeled take-off trolley according to any one of the previous claims having an adaptive wheel suspension to accommodate the difference in loading prior and subsequent to flight vehicle launch.

5 A wheeled take-off trolley according to any one of the previous claims and means for releasing the flight vehicle at a predetermined self-sustaining flight speed.

6 A wheeled take-off trolley according to any one of the previous claims and wherein the wheeled units are provided with retro-rockets or other braking systems.

7 A wheeled take-off trolley according to any one of the previous claims and wherein the wheeled units are provided with retractable stabiliser pads carried at intervals along their sides for supporting the flight vehicle during static assembly or refuelling operations.

8 A wheeled take-off trolley according to any one of the previous claims and wherein each wheeled unit is provided with a first plurality of sets of wheels at a forward position on the unit and a greater plurality of sets of wheels at a rearward position on the unit.

9 A wheeled take-off trolley as claimed in Claim 8 and wherein at least some of each set of wheels are powered and steerable for low-speed manoeuvring purposes.

10 A wheeled take-off trolley according to any one of the previous claims and wherein the support means comprise forward and rearwardly disposed A-frames, pivotally connected at their bases to their wheeled unit and having telescopic means at their apex for connection to attachment points on the flight vehicle.

11 A wheeled take-off trolley according to any one of the previous claims and wherein the said support means is adjustable to support the flight vehicle in a generally nose-down position during low-speed manoeuvring, in a position providing optimum incidence during initial stages of take-off and, in a high angle of incidence position whenever a predetermined air speed is attained during take-off.

12 A wheeled take-off trolley substantially as herein before described and with reference to Figures 1 to 5 of the accompanying drawings.