I'm getting real curious about my airspeed calibration, as well as how it might vary with the canopy open and/or closed. I'm mostly interested in cruise and down around 80MPH. (Surprise, surprise)
So here's what I propose to do, as an academic exercise, before deciding
what
to do next, with an assistant to do the paperwork while I fly the plane:
1. Obtain a winds aloft forecast. If there are more than a 10 or so
knots at 3000, do
it another day. If it's variable winds, do it another day. If
neither, note the forecast
wind direction. Plot two headings, one directly into the forecast
wind, one directly
down-wind.
2. Take off and climb to 3000. Turn on the GPS. Canopy open.
3. Establish a heading directly down-wind, and fly for five minutes at
100MPH IAS.
Note the GS on the GPS every 30 seconds.
4. Make a 180, and establish the opposite heading, straight and level
100MPH IAS.
Note the GS on the GPS every 30 seconds.
5. Repeat steps 3 & 4 at 80 MPH IAS
6. Repeat steps 3, 4, & 5 with the canopy shut.
7. Land, take the work-sheets home, and solve for TAS in each
condition, taking
the average of the GS readings in both directions.
8. Figure out what it all means (i.e., it's off by so many knots, the
canopy has
such and such an effect, I probably have a static leak, etc.)
Comments? (Pete Hogan doesn't know it yet, but I'll try an con him into
being in
the right seat for this one. Ooops, I guess he knows now. You see, his
VERY
PRETTY Alon sits right in front of my somewhat less pretty 415D at N85).
Greg
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