anelon
Well-Known Member
- Joined
- Aug 29, 2005
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My airspeed indicator is notoriously inaccurate. On takeoff, I rarely see much more than 40-45 mph and it is reluctant to get over much more than 60 for awhile even at cruise power settings and level flight. After some time, I'll see 70-80 as yesterday when I took a short (distance-wise) 3 hour trip (with fuel stop, to look at a Cub - imagine that).
Last week I built a manometer after the one in the EAA magazine article last month (http://www.sportaviationonline.org/sportaviation/201109#pg98) and checked the pitot/airspeed with pretty good result ... even with a slow leak somewhere, either in the system or the lashup, the airspeed values were within 4 mph (my ASI reads low by that much). My friend Richard's Wag Sport Trainer reads the other way (ASI high) with a faster leak rate by about 10 mph. We're planning some in-flight comparisons.
I haven't yet disconnected the ASI from the pitot tubing. I thought I might do a reverse blow-out to see if there might be some moisture in the system.
Question: What could cause this inaccuracy?
Last week I built a manometer after the one in the EAA magazine article last month (http://www.sportaviationonline.org/sportaviation/201109#pg98) and checked the pitot/airspeed with pretty good result ... even with a slow leak somewhere, either in the system or the lashup, the airspeed values were within 4 mph (my ASI reads low by that much). My friend Richard's Wag Sport Trainer reads the other way (ASI high) with a faster leak rate by about 10 mph. We're planning some in-flight comparisons.
I haven't yet disconnected the ASI from the pitot tubing. I thought I might do a reverse blow-out to see if there might be some moisture in the system.
Question: What could cause this inaccuracy?
