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Old 25th Apr 2009, 06:38
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India Four Two
 
Join Date: Jun 2002
Location: Saigon SGN/VVTS
Posts: 6,625
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Gertrude asked
What are the options for aborting a tug launch when the glider pilot sees something he doesn't like?
Here are some considerations from the tow pilot's point of view. It happened to me on my first flight of the day at the Canadian Nationals a few years ago. I noticed during my RPM and airspeed check before lift off, that the ASI needle was bouncing around zero. Since I had an open-class glider behind me with water ballast, I made a quick decision to continue the flight, rather than have the glider run into me on the runway as I stopped. I continued the climb, using attitude for speed control and by the time I reached release height, the needle had come up to the correct speed.

We had had a big rainstorm the previous evening and water must have entered the pitot tube, which on a Bellanca Scout, angles slightly upward on the ground. During the flight, the dynamic pressure must have slowly displaced the water into a water trap in the system.

Ironically, each previous day, I had made a quick circuit before towing. For some reason on this day, I didn't!

Here's a picture of the pitot/static system, with a different reason for ASI failure. Unlucky bee!

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