Plane & Pilot
Tuesday, October 23, 2012

Say When


When you should retract gear, reduce power, stop climb, initiate descent and more


7] When should you extend and retract speed brakes?
Speed brakes can be a wonderful aerodynamic benefit for airplanes with low drag profiles, but some pilots misunderstand their limitations, or more accurately, the lack of them. You can deploy them right up to redline with no adverse effects, and they introduce major drag increase. Extend them near yellow line, and the airplane will react as if it just flew into a wall of Jell-O.

What some pilots don't appreciate is that the bottom limit is pretty much unlimited, as well. Speed brakes can also help dissipate speed around the pattern and may be deployed all the way to the ground, if necessary.

Yes, the standard directive is to retract them prior to landing, but that's more a cosmetic than an operational limitation, with little or no adverse effect if you leave them extended.

Years ago, I was being checked out in a new Beech B36TC Bonanza prior to an editorial trip from Orlando to Oshkosh and on to California. We'd done some air work, and I'd extended the speed brakes for descent prior to our first landing. The check pilot was a courteous, enthusiastic CFI who didn't say much but obviously monitored everything I was doing.

I entered the pattern with speed brakes extended, flew base and final, landed and pulled off the runway for a taxi back, and my check pilot commented, "You really should have retracted the speed brakes for landing. It's dangerous to land with them extended." I asked what would happen if we attempted a takeoff with the speed brakes deployed. He simply shook his head and said that wasn't a good idea. Finally, he consented after moving his seat forward and resting one hand on the yoke.

Of course, there was no difference at all in the takeoff or landing. At speeds below 80 knots, speed brakes made no discernible difference in the Bonanza's handling or stall characteristics. I even reduced the approach speed to a short-field number, 75 knots, and the Bonanza responded with its typical gentle manners.

Later, back at the FBO, the instructor said he never would have thought to try that, but he agreed it made sense that the airplane would manifest virtually no reaction to speed brakes at low airspeeds. He was right.



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