This paper presents an alternate method for comparing the inter-relationship between thrust required and aerodynamics for various powered high lift systems. Instead of comparing dimensionless lift, blowing and thrust coefficients and their maximum values, their performance is compared in terms of the minimum amount of installed vectored thrust required for equilibrium level flight. Some high lift systems are superior than others over a limited range of flight speeds or blowing rates. To average out those differences the available excess thrust for forward acceleration is integrated to provide both transition time and total impulse needed for a horizontal acceleration from minimum lift off speed to a reference velocity, where the dynamic pressure equals the wing loading. The results are easily interpreted as they appear in terms of thrust to weight ratio and dimensionless flight speed. The transition time is assumed to be too short to permit changing the engine thrust level and thrust loss due to power take-off. However the blowing momentum and thrust vector angle should be adjusted, as required to maintain level flight. The engine thrust level reported, includes the thrust loss associated with power take-off needed to blow over the wing. Problems associated with the aerodynamic coefficients going to infinity in hover, are examined. Even though various high lift systems have widely different lift augmentation ratios, their transition flight performance turns out to be similar.
Thrust savings limitations with blown high lift wings
Grenzen der Schubeinsparung bei umstroemten Tragfluegeln mit hohem Auftrieb
AIAA-Papers ; Sep ; 1-8
1987
8 Seiten, 12 Bilder, 7 Quellen
Conference paper
English
Thrust savings limitations with blown high lift wings
AIAA | 1987
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