That's a pretty good summary, Chris. We designed transonic wind tunnels
with perforated test section walls to allow us to accelerate through
this region, and provided wall suction to prevent choking. The
perforated walls also reduced the reflection of shock waves back onto
the test model. The Germans preferred slots to perforations in their
early designs, and NACA/NASA followed that path. We had the advantage
of having Dr. Bernard Goerthert, who led the German research, as our
facility director. I first met Dr. Goerthert at Wright Field around
1952, and followed him to Tullahoma when I was released from active duty
in 1953. A small scaled model wind tunnel was used to optimize the wall
design.
Jim Nichols
Tullahoma, TN USA
On 12/26/2016 8:19 AM, Chris Trask wrote:
We learned in Undergraduate Pilot Training (UPT) that the shock wave
increases drag in the trans-sonic region, about 0.95 to 1.05 times the speed of
sound, where the shock wave first appears ahead of the leading edge and
gradually moves to behind the trailing edge. You're not exactly supersonic
until the shock wave is behind the trailing edge.
Jim, Does the creation of a sonic boom contribute to an increase in
drag? Or is it a reduction? Or does it drag neutral?
Chris
When the going gets weird, the weird turn pro
- Hunter S. Thompson
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