Plane & Pilot
Tuesday, October 23, 2012

Say When


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



To reach optimum cruise speed quicker, climb 100 feet above your planned cruising altitude, leaving in max climb power, and then push over and descend to cruise altitude. Level the airplane and wait for airspeed to peak before very slowly reducing to cruise power.
That means if the runway length is 4,000 feet or less, it barely matters when you retract the wheels, as you won't be able to stop in less space anyway. If you're flying from a longer runway, you'll have space to reposition the gear to down. For that reason, I retract the gear at about 100 feet, regardless of runway length. (Yes, I'm aware there's nearly always a difference in flap configuration between takeoff and landing, but this is a general rule.)

3] When should you reduce power after takeoff if you're flying behind an engine that uses a METO (maximum except takeoff) power setting?
Some engines are approved for max continuous operation all the way to level-off. Others may have three- or five-minute limitations, usually requiring a reduction in rpm.

Too often, owners of airplanes that have big fuel burns on takeoff are eager to get the power back as soon as the wheels are in the wells to reduce fuel flow and also to staunch the financial bleeding.

Bad idea. Reducing power too soon not only costs performance and minimizes the safety pad of altitude, it may result in higher cylinder temperatures—never a good idea. The engine will run cooler at full power and full rich than at a lower setting.

If you have a three- or five-minute limitation on max power, use it all. On most singles, five minutes at full power will generate at least 3,000 feet of altitude, a good pad in case you need to make some hard decisions. Reducing power too soon could wind up being the ultimate false economy.

4] When should you reduce power to cruise and begin the level-off?
Some pilots believe there's such a thing as a cruise "step," an imaginary aerodynamic condition that allows any airplane to fly faster on the same power at the same weight and altitude. Sorry, no such magical condition exists.

There's a legitimate technique for reaching optimum cruise speed quicker, but it has nothing to do with a step. Climb 100 feet or so above your planned cruising altitude, leaving the power against the stop (or at max climb); then, push over and descend to cruise height. Level the airplane and wait until airspeed peaks before VERY slowly reducing to cruise power.

Leveling a hundred feet high and descending back down to your cruising altitude will deliver slightly bigger numbers on your ASI—but only temporarily. Eventually, the final cruise indication will stabilize at exactly the same speed as if you leveled at the optimum altitude initially. There will be a very small short-term benefit of the dive-down technique, but it won't result in any permanent speed increase.



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