| dc.description |
The slender wings and bodies suitable for supersonic flight
have, in general, relatively poor aerodynamic characteristics
especially at lay speeds. In order to improve their performance
the use of edge blowing has been explored. In this scheme high
velocity air jets in the form of thin sheets are used to fix
separation lines on the wing or body and to favourably influence
the external stream. Thus the equivalent wing, called here the
"Jet Wing” is composed of the wing-body itself plus the extended
curved jet sheets which spring from its edges. A limited use of
edge jets has been proposed in the 'Jet Flap' concept but the
efficiency of this device fails off with decreasing aspect-ratio and
the problem of trimming could be severe as most of the increased
lift is generated near the trailing edge.
At very law aspect-ratios a considerable part of the lift
is contributed by the leading-edge vortices which dominate the
flow field at moderate incidence. It follows therefore that leading
edge blowing is particularly useful for small aspect-ratio wings and
the trimming problem can be avoided by a suitable jet arrangement
which does not disturb the conical nature of the flow. When
sufficiently large auxiliary thrusts are available peripheral jet
sheets can be deflected downwards close to the ground, the air craft
becoming a Ground-Effect-Machine, with substantial reductions in
both take-off and landing speeds and distances. |
|