Now that I read it one more. I see the pattern. I misunderstood first that the meter might at fault.
The Airspeed meter reads 0 when no prop creates a pressure differential around the plane. With the prop on idle, it already reads 5 MPH. In-flight it's 20 MPH more. I suggest a vacuum leak to the static port as John suggested. I saw a crack at the static line , directly where the line enters the instrument. That was enough to give a similar false indication. Hartmut ----- Original Message ----- From: John Cooper To: 'John Craparo' ; 'TECH-FORUM' Sent: Tuesday, August 05, 2008 4:38 PM Subject: RE: [ercoupe-tech] Overhauled Engine and 0-200 Crank... By the way, my overhauled (last year) air speed indicator displays 5 mph after starting (not rolling) since installed. In addition, in the air, the indicator is about 20 mph high. John: If the indicator jumps after you crank up the engine, there has to be some sort of interaction with the prop slip stream and (most likely) the static system. If it were the pitot system it would probably read low in flight as it's hard to get more pressure than ram air pressure in flight. John Cooper Skyport Services 4996 Delaware Tnpk Rensselaerville, NY 12147 518 797-3064 www.skyportservices.net ------------------------------------------------------------------------------
