Backcountry Pilot • Airspeed and Altitude

Airspeed and Altitude

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Airspeed and Altitude

Wolfgang Langewiesche, in "Stick and Rudder," explained energy management as "airspeed is altitude and altitude is airspeed." Unable to have altitude quickly safely on takeoff, we prefer to develop airspeed in low ground effect first.. Landing, however, requires getting rid of both airspeed and altitude.

Other than the common sense of spending more time in updrafts by slowing airspeed thus gaining altitude and less time in downdrafts by increasing airspeed thus decreasing altitude short term but increasing altitude long term, there is a dangerous potential loss of control problem with attempting to maintain altitude in unstable air.

In a strong downdraft, do we want to arrive at the bottom near stall airspeed or at cruise or faster airspeed? High altitude orientation might cause us to fight for altitude by staying pitched up all the way down. Now we are both low and slow and in a poor energy management situation. Low altitude orientation, on the other hand, would prefer airspeed for energy safety down low.

Attempting to maintain altitude in unstable air is time inefficient, altitude inefficient, and unsafe.
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Re: Airspeed and Altitude

Exposure to unstable air will increase exposure, but also experience. Experience will teach us that using aileron too much will aggravate the situation, that rudder is the best wing leveler, that keeping a distant point between our legs with rudder will automatically keep the wing level, and that pitching up in updrafts and pitching down in downdrafts is surprisingly effective altitude and airspeed energy management.

In small airplanes, in the mountains summer afternoons, throttle is fully forward with mixture lean. There is no extra energy to manage there.
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Re: Airspeed and Altitude

Nobody asked about keeping wings level in unstable air in a crab. Same as target between legs: rudder only. Now, however, we are directing our butt to the target and not directing the longitudinal axis extended.

Give both a try. It makes life easier, or at least more interesting.

Run two similar airplanes side by side, one maintaining altitude and using coordinated turns to stay level, one pitching up in updrafts and down in downdrafts and using rudder only to direct course to level the wing. See which one gets there quicker because of total energy management.
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Re: Airspeed and Altitude

crab or slip in xwind, or, just to dump altitude while maintaining energy is a skill well worth developing. I really loved the spoilers on gliders, unreal energy management at the tip of your fingers. However, the same management is at the tip of your toes and a crossed aileron. It is a wonderful tool.

The amount of descent one can archive is remarkable with a recovery that is just about instantaneous.

Thoughts Jim??
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Re: Airspeed and Altitude

I very much agree with flaps, forward slip, flaps and rudder to the stop forward slip, slats, spoilers, or just flying wires and other things hanging out to get rid of altitude without gaining airspeed when we want to get rid of both as in landing or forced landing. 75% of engine failure landings touch down in the last half of the landing zone because we teach/allow way too much airspeed on short final and because we don't teach maximum use of flaps and crossed controls.

Really slow flight, hover taxi, or the just above stall airspeed in low ground effect requires good rudder usage. Poor or none rudder usage training leads to too much airspeed on short final and even touchdown.

Pilots live in a flat world nowdays. They truly believe a cross control maneuver, either slip or skid will lead to stall/spin. They don't understand how much can be safely accomplished with rudder only so long as the nose is down. Flat earth has put them in a limited pitch and limited bank bind with few tools to go to in an emergency or just to fly artistically using full energy management.
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Re: Airspeed and Altitude

Thanks Again , Jim .
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Re: Airspeed and Altitude

Soaringhiggy pointed out three very good tools for altitude management to remain on a continuous descent all the way to the numbers without gaining airspeed: flaps, slip, and spoiler. The slip, either side to maintain longitudinal alignment or forward in no wind, does fine with flapless airplanes if we shoot for an aiming point short of the desired touchdown point. Flaps do fine if we use the draggiest portion (full flaps) so we can use power to pull more air without gaining airspeed. Spoilers are great and we have something that will accomplish the same, elevator to pitch up and power to pull the extra drag without gaining airspeed.

We have plenty of tools to direct our course to the numbers (not float an uncontrolled amount down the runway) laterally with rudder and in a stabilized descent with power and in a stabilized deceleration on short final with elevator to pitch up and reduce airspeed to stall airspeed in low ground effect.
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