On Fri, 09 Jan 2004 16:50:14 GMT, "Tony Cox" wrote:

"Dave S" wrote in message
. net...

Gary... I was looking for actual formalas.. not wild ass guesses or
rough approximations.. Computer spreadsheets use mathematical equations.

Check your reactions. You were given the EXACT mathematical relationship,
and a very close approximation to make in-flight calculations easier. I'm
sure you didn't mean to sound ungrateful, but that is the way it came
across!



There are a few issues before you go off treating any equation
you get here as gospel.

1) Va probably isn't what you think it is. See my other posts.

2) In the case that Va = Vs*sqrt(load-factor) (23.335
equality), don't *ever* be tempted to scale it up if you are
over gross (Alaska, for example). Wings falling off may not
be the limiting factor.

3) If you are under gross (and Va is 23.335 equality), the
scaled Va is probably too conservative. If the 23.335 equality
does not apply, then the adjusted Va may not be conservative
enough.Without further specific analysis, you'll never be sure.

This is something that may be used by others besides myself.

This sounds foolhardy. You might want to ask yourself why
manufacturers don't publish Va vs. weight. And if you go
off telling people they can happily fly at Va without the wings
falling off, you're setting yourself up to be sued.