Yep, Dawg beat me to it. Piro in one direction, loose altitude, piro in the other, gain.
There is a realy nice, realistic FREE sim over at
www.helifreak.com in the TREX450 stickie section.
It's very basic, only has a TREX450 and no sound for now. But the flights characteristics are very realistic...and you can program in expo, etc.
Skarn