On Sun, 04 Jul 2004 20:26:44 -0700, Jim Harper wrote:

Van's says a 200 horsepower RV8A will cruise at 210mph at 75% power at
8000 feet. Book says it will climb at 2500 fpm at 1500 pounds.

Mine cruises at 182mph and climbs at 1800 fpm.

Please detail how you determined the cruise speed and climb rate. If you
used the IAS and converted to TAS there are a lot of ways that errors can
be introduced. For example, I've seen reports of ASIs with over 10 mph of
instrument error, and I've communicated with builders who found that flush
static ports causing the airspeed to read over 10 mph too low. A local
RV-8 builder had that problem recently. And some of the methods that
people quote for using GPS to get TAS aren't mathematically sound,
although the error here would only be a few mph, unless you've done
something really creative.

Lots of info on how to figure out TAS from GPS data, how to calibrate ASIs
and how to measure static source position error at my web site:

http://go.phpwebhosting.com/~khorton...ex.php?&PID=48
http://go.phpwebhosting.com/~khorton...ex.php?&PID=49

If you used the VSI to determine climb rate, be aware that VSIs can have
very large errors. You really need to use an altimeter and a stop watch.
And you need to understand that the rate of climb that Van quotes is
almost certain an extrapolation down to sea level at standard temperature.
You are almost certainly at a higher altitude when you do your testing,
and the temperature may very well be warmer than standard, so your rate of
climb would be a bit less than 2500 even if everything else is sorted out.

--
Kevin Horton RV-8 (finishing kit)
Ottawa, Canada
http://go.phpwebhosting.com/~khorton/rv8/
e-mail: khorton02(_at_)rogers(_dot_)com