<<<<<<<<<<<<<<<<--->>>>>>>>>>>>>>>>
         <<  Lancair Builders' Mail List  >>
         <<<<<<<<<<<<<<<<--->>>>>>>>>>>>>>>>

Dan:

Agree that for most general aviation flying, forget the aerodynamic heating and compressibility effects.  I got focussed on this topic when Brent Regan and I were preparing to the Denver to OSH race.  In Brent's Lancair IV racing at 320 knots TAS, the aero heating is about 20F and the TAS error is about 20 knots.  I think you would agree that errors of this size are not negligible.  Keep in mind that this forum has Lancair IV builders also.

Even a strictly stock Lancair IV at 290 Knots has a TAS error of more than 15 knots if you use a standard E6B and cockpit readings with accurate instrumentation.  I have grown tired of Lancair IV jockies claiming 310 knot cruise speeds when it ain't so, and so want to save others from possible embarassment and disappointment when they learn the limitations of their instrumentation. I am in complete agreement concerning the accuracy of most general aviation instrumentation: awful.  Brand new tachometers that read 100 RPM low, fuel level gages that work "kind of," and temperature instrumentation that should be marked as "cold - warm - hot" instead of in degrees.  We should expect better. And we should strive for better.

Fred

LML website:   http://www.olsusa.com/Users/Mkaye/maillist.html