WIND-TUNNEL INVESTIGATION OF AN EXTERNAL-FLOW JET-AUGMENTED SLOTTED FLAP SUITABLE FOR APPLICATION TO AIRPLANES WITH POD-MOUNTED JET ENGINES

摘要

A wind-tunnel investigation has been carried out to determine the characteristics of an external-flow jet-augmented slotted flap which appears suitable for application to airplanes with pod-mounted jet engines. The investigation included tests of an unswept wing and of a model of a swept-wing jet transport or bomber. Compressed air jets exhausting from nozzles attached to the lower surface of the wings were used to simulate the jets from pod-mounted jet engines.nThe external-flow jet-augmented flap produced values of circulation lift large enough to warrant serious consideration of its use for increasing the maximum lift coefficients of airplanes with pod-mounted jet engines. The results indicated that static longitudinal stability and. trim up to a lift coefficient of at least 6 could be achieved with a jet transport or bomber airplane equipped with a jet-augmented flap and having a horizontal-tail area equal to 25 percent of the wing area. In order to achieve this result, it was necessary to locate the horizontal tail in a position well above the chord plane of the wing and to incor¬porate both variable tail incidence and an elevator. The results Indi¬cated that an external-flow jet-augmented flap applied to existing Jet transport and bomber airplanes with pod-mounted engines would produce lift coefficients of about 5 for take-off (thrust-weight ratio of 0.25) and lift coefficients of about 5 for landing (thrust-weight ratio of 0.40). These lift coefficients would provide substantial reductions in take-off and landing speeds and distances.