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Flow Environment Study Near the Empennage of a 15-Percent Scale Helicopter Model

Development of advanced rotorcraft configurations has highlighted a need for high-quality experimental data to support the development of flexible and accurate analytical design tools. To provide this type of data, a test program was conducted in the Langley 14- by 22-Foot Subsonic Tunnel to measure the flow near the empennage of a 15-percent scale powered helicopter model with an operating tail fan. Three-component velocity profiles were measured with laser velocimetry (LV) one chord forward of the horizontal tail for four advance ratios to evaluate the effect of the rotor wake impingement on the horizontal tail angle of attack. These velocity data indicate the horizontal tail can experience unsteady angle of attack variations of over 30 degress due to the rotor wake influence. The horizontal tail is most affected by the rotor wake above advance ratios of 0.10. Velocity measurements of the flow on the inlet side of the tail fan were made for a low-speed flight condition using conventional LV techniques. The velocity data show an accelerated flow near the tail fan duct, and vorticity calculations track the passage of main rotor wake vortices through the measurement plane.

Development of advanced rotorcraft configurations has highlighted a need for high-quality experimental data to support the development of flexible and accurate analytical design tools.

The Biggest Snowball Ever!

The biggest snowball ever catches Paul and his friends. Tomorrow is Christmas Day, and there is a chance the children will not be rescued in time.

The biggest snowball ever catches Paul and his friends. Tomorrow is Christmas Day, and there is a chance the children will not be rescued in time.

A Snowball in a Microwave

In my youth I came across the one for me but not knowing my place in this world and the inexperience of youth I let her go. This story is written to her expressing my feelings of our time together and the lessons that she had taught me on life, love and the internal pursuit of happiness.

This story is written to her expressing my feelings of our time together and the lessons that she had taught me on life, love and the internal pursuit of happiness.