Mitch, I figured you were having a problem when you posted the question.
First thing, I'd remove the ring and go test fly it. Don't forget to allow for altitude. A plane flying 100 mph at x altitude will only show 80 on the airspeed indicator. I don't have my whiz-wheel handy. The next step is to check out the static system. It should be connected to the second output of that fancy pitot/static tube assembly, not vented to the cockpit, fuselage or wing. If that doesn't solve the problem, be aware that a LOT of old airspeed indicators slowly fail giving a faster-than-you-are-really-going indication. I had to replace my ASI. Some people get theirs rebuilt. When I bought my Coupe, it flew a reliable 115-118 mph according to the ASI and 70 mph was the minimum flying speed with the yoke full back. I was puzzled why I had a headwind both directions on every flight compared to my 115 mph flight plan. Careful testing showed the ASI problem. For now, when you go up on each flight during your testing, do a minimum flying speed test and note the ASI airspeed. Add 15 mph or 30% (or a touch more) to that for your approach speed. That'll get you down safely till you get it fixed. (I do that in all aircraft I fly these days - I've learned not to trust old airspeed indicators and installations.) Poke around my website and you'll see a page with expected airspeeds of Coupes depending on the engine and prop. Keep posting questions. We're happy to discuss and solve. Ed Ed Burkhead http://edburkhead.com/Ercoupe/index.htm East Peoria, Illinois ed -at- edbur???khead.??com (remove the ? marks and change -at- to @)
