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Undershoot with best glide speed

  • Eddchu99
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Eddchu99 created the topic: Undershoot with best glide speed

Hi all,

There was a question asking when there is an engine failure and you are already at the best glide speed for a forced landing, however, it seems like you will undershoot on a windless day, what should you do?

A. Raise the nose
B. Increase the speed
C. Remain at the best glide speed

Thank you very much guys.
#1

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  • John.Heddles
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  • ATPL/consulting aero engineer
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John.Heddles replied the topic: Undershoot with best glide speed

With my eyes rolled up .. (c) is the option they are after.

However .. "none of the above" is the better answer .. none of the options is likely to work to your advantage.

The preferred option (missing) is "find another, closer, paddock to aim for .." In the end analysis, the pilot's plan apparently was somewhat flawed .. the aim is to stay high until you are in the final pattern.

Caveat .. if you are flying a constant speed or adjustable prop .. pull full coarse .. makes a very big difference to the drag and descent angle. Back in my parachute flying days, we routinely used pitch for drag control throughout the descent to allow for a reasonably constant modest power setting for cooling control.

Engineering specialist in aircraft performance and weight control.
#2

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  • Eddchu99
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Eddchu99 replied the topic: Undershoot with best glide speed

Thanks a lot John, may I ask what if there is headwind or tail wind? Will the answer be different?

Thanks again,
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  • John.Heddles
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John.Heddles replied the topic: Undershoot with best glide speed

Indeed.

(a) headwind will see a better glide distance with an increased speed.
(b) tailwind will see a slight improvement in glide distance with a reduced speed.

How much speed change ? Aircraft drag polar dependent.

Engineering specialist in aircraft performance and weight control.
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