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Cozy MKIV - Seventh Flight Test

Date: August 9, 2002

I piggybacked flight 7 onto flight 4, since they're both pretty short, and 7 isn't dependent upon 5 and 6.

The seventh flight consisted of airspeed calibration.  I flew around Mt. Wachusett (I'm sure you're starting to notice a pattern here) for half an hour at 4500 ft. I started out at 170 mph indicated, and flew in a "U" pattern - first at 90 degrees ground track, per the Garmin GPS, next at 180 degrees ground track, and last at 270 degrees ground track.  Using the GPS ground speed numbers and these three directions (along with the directions from an article in Kitplanes, February 1995 by David Fox), I could calculate the true airspeed.

Using the OAT (57 degrees F) and pressure altitude (4100 ft.), along with the directions in Kitplanes from March, 2001 written by Ed Kolano, I can calculate the calibrated airspeed from the GPS true airspeed.  By comparing these two numbers (and assuming that the GPS is the more accurate) I can derive the error in the airspeed indicator.

I did this for indicated airspeeds 170 mph, 150 mph, 130 mph, 110 mph, 90 mph and 70 mph.

I then landed, trying once again for the shortest possible landing, and then taxied back for one more loop around the pattern before it got dark (no flying at night!!!).

You can read the Flight Test Protocol and test results for Flight 7.

End Date: August 9, 2002


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Copyright 2002, All Rights Reserved, Marc J. Zeitlin