"Orval Fairbairn" wrote in message
news

It depends on how fast you are going. At 200 Kt,you may get about 2" or
so of ram air pressure, which translate to about 1 PSI.

I would probably need it most at best glide speed - you know, when there's
that eerie silence up front.

Say 80 mph or so.

Rich (knots are for boats) S.