GB1605235A - Aircraft thrust reversing devices - Google Patents

Description

(54) IMPROVEMENTS RELATING TO AIRCRAFT THRUST REVERSING DEVICES (71) We, BRITISH AEROSPACE PUBLIC LIMITED COMPANY, a British Company organised under British Aerospace (Nominated Company) Order 1980 and British Aerospace (Appointed Day) Order 1980, of 100 Pall Mall, London SW1Y 5NR, 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 relates to thrust reversing means for jet propelled aircraft.Where thrust reversing means protrude into the free airstream when following a translatory path from a stowed non-thrust reversing condition to an extended thrust reversing condition, and where said means require to be operated at air speeds greater than normal touchdown speeds, for example those encountered during flight, damage is liable to be caused by the impingement force of the free airstream.

An object of the present invention is to provide an arrangement whereby such damage is prevented. A further object, of relevance when fuselage, wing or tailplane trailing edge regions lie adjacent the stowed position of the thrust reversing means and impede the translatory path thereof, is to provide an arrangement whereby local regions of this structure are moved to clear the translatory path.

According to the present invention an aircraft includes a jet propulsion efflux outlet, thrust reversing means translatable from a stowed non-thrust reversing position to a thrust reversing position, in which the efflux is forwardly redirected, by way of a translatory path in which said means protrude into the free airstream, and airflow modifying means movable from a low drag position to an extended position in which the free airstream is prevented from impingement with excessive force on the translating thrust reversing means.

Where the airflow modifying means, when in the low drag position, lie within the translatory path of the thrust reversing means they may be moved to the extended position forward of said path.

Two preferred embodiments of the invention are described with reference to the accompanying drawings in which: Figure 1 is a diagrammatic perspective view of part of the rear end of an aircraft in a non-thrust reversing configuration, Figure 2 is a similar view but in a thrust reversing configuration, Figure 3 is a diagrammatic perspective view of part of the rear end of an alternative aircraft in a non-thrust reversing configuration, and Figure 4 is a similar view to that of Figure 3 but in a thrust reversing configuration.

In the Figures 1 and 2 an aircraft has a fuselage 1 and laterally extending tailplane portions 2 and 3. The fuselage 1 terminates in a jet propulsion efflux outlet 4 flanked on each side by faired regions 5 and 6 from which the tailplane portions extend.

The efflux outlet 4 is provided with a target-type thrust reverser of known design.

This includes two deflector buckets 7 and 8 which, in the stowed non-thrust reversing position of Figure 1, lie upstream and to each side of the outlet 4 flush with the surface of the aft fuselage. For thrust reversal these buckets 7 and 8 are translated bodily outwards and rearwards and subsequently inwards and rearwards to the position of Figure 2 in which they abut together aft of the outlet 4 so that the efflux impinges directly thereon and is at least partially reversed in direction.

The translatory path followed by the buckets 7 and 8 subjects them to the free airstream and in relatively high speed conditions such as those encountered during flight which are greater than normal aircraft touchdown speeds they are liable to be damaged by the impingement force. Accordingly, to prevent such damage the trailing edges of the faired regions 5 and 6 are each formed with airflow modifying members in the form of pivoted flaps mounted in pairs 9, 10 and 11, 12 respectively. Those referenced 9 and 11 lie flush with the upper surfaces of the fairings 5 and 6 when in the low drag position of Figure 1 whilst those referenced 10 and 12 lie flush with the lower surfaces.Each flap is pivoted to swing upwards or downwards from the position of Figure 1, where the flaps of each pair lie closely adjacent one another and form trailing edges of the faired regions, to the extended position of Figure 2 where the free airstream is prevented from impinging directly onto the translating reverse thrust buckets 7 and 8 by the opened pairs of flaps. Movement of the flaps is effected by jacks 13 covered by airflow smoothing shrouds. In this embodiment, since in the low drag position of Figure 1, the flaps 9, 10 and 11, 12 lie adjacent the stowed buckets 7 and 8 respectively and obstruct their translatory path, movement of the flaps to their extended position also ensures that the path is cleared.

In Figures 3 and 4, a delta winged aircraft has a fuselage 21 terminating in a jet propulsion efflux outlet 22. The outlet is provided with a similar thrust reversal arrangement to that of Figures 1 and 2. It has two deflector buckets 23 and 24 which are housed and operated as described previously. During translation from the position of Figure 3 to that of Figure 4 the deflector buckets 23 and 24 are protected from the free airstream by airflow modifying members in the form of twin flaps 25 and 26 which in the low drag position of Figure 3 lie flush on opposite sides of the aft fuselage upstream of the buckets 23 and 24. The flaps 25 and 26 are pivoted to swing laterally outward to the extended position of Figure 4. Movement is effected by jacks 27.In this embodiment the disposition of the flaps 25 and 26 is such that they remain clear of the translatory path of the buckets 23 and 24.

WHAT WE CLAIM IS: 1. An aircraft including a jet propulsion efflux outlet, thrust reversing means translatable from a stowed non-thrust reversing position to a thrust reversing position, in which the efflux is forwardly redirected, by way of a translatory path in which said means protrude into the free airstream, and airflow modifying means movable from a low drag position to an extended position in which the free airstream is prevented from impingement with excessive force on the translating thrust reversing means.

2. An aircraft according to Claim 1 wherein the airflow modifying means, when in the low drag position, lie within the translatory path of the thrust reversing means and move to the extended position forward of said path.

3. An aircraft according to Claim 1 or Claim 2 wherein the airflow modifying means comprise pairs of pivoted flap members, the flap members of each pair lying closely adjacent one another to form a trailing edge of the aircraft when in the low drag position and being pivoted apart to reach the extended position.

4. An aircraft according to Claim 1 or Claim 2 wherein the airflow modifying means comprise door-like members which lie flush with the aircraft contour in the low drag position and open to protrude into the free airstream in the extended position.

5. An aircraft substantially as described with reference to Figures 1 and 2 or Figures 3 and 4 of the accompanying drawings.

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

Claims (5)

**WARNING** start of CLMS field may overlap end of DESC **. flaps mounted in pairs 9, 10 and 11, 12 respectively. Those referenced 9 and 11 lie flush with the upper surfaces of the fairings 5 and 6 when in the low drag position of Figure 1 whilst those referenced 10 and 12 lie flush with the lower surfaces. Each flap is pivoted to swing upwards or downwards from the position of Figure 1, where the flaps of each pair lie closely adjacent one another and form trailing edges of the faired regions, to the extended position of Figure 2 where the free airstream is prevented from impinging directly onto the translating reverse thrust buckets 7 and 8 by the opened pairs of flaps. Movement of the flaps is effected by jacks 13 covered by airflow smoothing shrouds.In this embodiment, since in the low drag position of Figure 1, the flaps 9, 10 and 11, 12 lie adjacent the stowed buckets 7 and 8 respectively and obstruct their translatory path, movement of the flaps to their extended position also ensures that the path is cleared. In Figures 3 and 4, a delta winged aircraft has a fuselage 21 terminating in a jet propulsion efflux outlet 22. The outlet is provided with a similar thrust reversal arrangement to that of Figures 1 and 2. It has two deflector buckets 23 and 24 which are housed and operated as described previously. During translation from the position of Figure 3 to that of Figure 4 the deflector buckets 23 and 24 are protected from the free airstream by airflow modifying members in the form of twin flaps 25 and 26 which in the low drag position of Figure 3 lie flush on opposite sides of the aft fuselage upstream of the buckets 23 and 24. The flaps 25 and 26 are pivoted to swing laterally outward to the extended position of Figure 4. Movement is effected by jacks 27.In this embodiment the disposition of the flaps 25 and 26 is such that they remain clear of the translatory path of the buckets 23 and 24. WHAT WE CLAIM IS:

1. An aircraft including a jet propulsion efflux outlet, thrust reversing means translatable from a stowed non-thrust reversing position to a thrust reversing position, in which the efflux is forwardly redirected, by way of a translatory path in which said means protrude into the free airstream, and airflow modifying means movable from a low drag position to an extended position in which the free airstream is prevented from impingement with excessive force on the translating thrust reversing means.

2. An aircraft according to Claim 1 wherein the airflow modifying means, when in the low drag position, lie within the translatory path of the thrust reversing means and move to the extended position forward of said path.

3. An aircraft according to Claim 1 or Claim 2 wherein the airflow modifying means comprise pairs of pivoted flap members, the flap members of each pair lying closely adjacent one another to form a trailing edge of the aircraft when in the low drag position and being pivoted apart to reach the extended position.

4. An aircraft according to Claim 1 or Claim 2 wherein the airflow modifying means comprise door-like members which lie flush with the aircraft contour in the low drag position and open to protrude into the free airstream in the extended position.

5. An aircraft substantially as described with reference to Figures 1 and 2 or Figures 3 and 4 of the accompanying drawings.