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Old 02-21-2004 | 01:25 PM
  #59  
Tall Paul
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Joined: Jun 2002
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From: Palmdale, CA
Default RE: A bone of contention =

We had a special nose made for the Tristar to put pressure probes and vanes out ahead of the aircraft to tests in turbulence and gusts..
ISTR 4 pressure probes pointing off-axis about 45 degrees around the very front, and alpha and beta vanes to measure any off-axis flow.
Testing this led to reports of Tristars flying down ski-slopes in Idaho!
The airspeed system on the F-117 was developed from that. The diamond shape has a total pressure pickup at the very front, with flush pickups on each facet of the probe for alpha and beta which the control system uses.
I don't recall where the static port is on the -117.
We used 16-bit Kollsmann pressure transducers for total and static pressure on the Tristar. These were accurate to less than a foot at 35,000 feet, and less than a knot at .9 Mach.
They were so good the aero guys always questioned the results!
We went as far as flying two Tristars together to get comparison data... which always agreed! (and probably made the world's largest radar blip! )
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