MidlifeFlyer
Well-Known Member
[ QUOTE ]
56 KIAS and 10 flaps gives the better climbing performance so why not go from 30 to 10 instead considering that the difference in stalling speed between 20 and 10 flaps may be 2 knots?
[/ QUOTE ]It's not necessarily a stall speed issue.
Assuming we're talking about a Cessna, that 30º tends to produce more drag than lift, so the procedure calls for getting rid of the "worst" part to improve the airplane's initial ability to climb at all. At higher altitudes, a C172 with full flaps can't maintain altitude, let alone reverse the downward momentum as required for a go-around.
But at each additional flap retraction the reduction of drag also takes a bigger hit on lift.
You can see this for yourself at a safe altitude. If you've done a short field takeoff with 10º flaps, you have probably noticed that sinking feeling if you retract the flaps below Vy. And, in recovering from full flap slow flight you can see the effect if, instead of reducing flaps to 20º initially, you bring them directly to 10º.
56 KIAS and 10 flaps gives the better climbing performance so why not go from 30 to 10 instead considering that the difference in stalling speed between 20 and 10 flaps may be 2 knots?
[/ QUOTE ]It's not necessarily a stall speed issue.
Assuming we're talking about a Cessna, that 30º tends to produce more drag than lift, so the procedure calls for getting rid of the "worst" part to improve the airplane's initial ability to climb at all. At higher altitudes, a C172 with full flaps can't maintain altitude, let alone reverse the downward momentum as required for a go-around.
But at each additional flap retraction the reduction of drag also takes a bigger hit on lift.
You can see this for yourself at a safe altitude. If you've done a short field takeoff with 10º flaps, you have probably noticed that sinking feeling if you retract the flaps below Vy. And, in recovering from full flap slow flight you can see the effect if, instead of reducing flaps to 20º initially, you bring them directly to 10º.
