Analysis of Spread Multi-Jet VTOL Aircraft in Hover
Year: 2024
Type: dissertation
Abstract: An investigation of VTOL aircraft lift losses in hover has been conducted to evaluate a method for a simplified test technique. Three flat plate models were tested to determine their usefulness in predicting hover characteristics by comparing results between plate and three dimensional models. Attempts to correlate the out of ground effect results for the plate models with the empirical expression for calculating jet-induced loads were successful for the models which used engine simulators producing efflux characteristics similar to the three dimensional model engines. Data for the model using engine simulators with characteristics unlike those of the three-dimensional model simulators could not be correlated in this manner. In ground effect, comparisons of induced lift loads indicated correlation between the plate and three-dimensional models were within 2 percent of thrust in the height range dominated by the fountain effect. However, small outward deflection of lift-engine exhaust was found to cause a decrease in beneficial fountain on the order of 5 to 10 percent -of thrust. The engine arrangement of a midspan pod VTOL lift-fan transport model showed a strong adverse effect on lift loss due to engine deflection. Dashpots proved useful in eliminating data scatter caused by flow-induced model vibration. Data obtained for the plate models could be correlated to three-dimensional results by the application of a geometrical equivalent height correction factor ∆h/De. The correlation of plate and tunnel models indicated that lift losses in ground effect were essentially independent of the efflux characteristics for the engine simulators.
DOI: 10.25777/qe6c-xc06
Author: Albang, Leroy F.
Institution: Old Dominion University
Language: English
Subfield: Computational Mechanics
Field: Engineering
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W775566862