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Old 12-31-2022, 04:57 AM   #1 (permalink)
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Can you Pulse and Glide an airplane?

Can you P&G an airplane, especially one in a pusher config with folding props?
I donít really see why not but maybe there is something I am missing.

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Old 12-31-2022, 10:29 AM   #2 (permalink)
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Yes you can, but you take the risk of not being able to regain a climb back to altitude after that glide. Sometimes those folding props don't unfold, some require a restart of the engine. Rule of thumb when I was current used to be expect any reduction of power to be terminal and the motor could fail at any time.

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Old 12-31-2022, 06:45 PM   #3 (permalink)
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If it's a sailplane specifically designed for that type of use, yes. Sailplanes have L/D ratios from 20 to 50, so can glide for a long time.

If it's a conventional airplane with maximum L/D about 10, then there is no benefit to P&G. On these airplanes the engine is designed to run at its best efficiency point in normal cruise. The efficiency is lower at climb power than at cruise power. Also, the FAA expects the VFR pilot to maintain a constant altitude, and requires the IFR pilot to maintain constant altitude.

My commercial pilot license was current until I decided to quit flying earlier this year. And the C172 is sold, so no more temptation to fly just one more time.
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Old 01-01-2023, 11:47 PM   #4 (permalink)
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Only every time I fly.

I mean, the engines aren't killed, but nobody is exceeding mach as they approach a destination.
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Old 01-05-2023, 06:22 AM   #5 (permalink)
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Not familiar with planes but if propeller pitch is adjustable, seems like you could successfully idle the engine (and prop) without adding much drag.

That said, it seems like most planes cruise at pretty high efficiency.
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Old 01-05-2023, 08:47 AM   #6 (permalink)
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That's what gliders do.
Based on this I'm going to say yes.
https://youtu.be/pIhKIWRMdwk
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Old 01-05-2023, 09:51 AM   #7 (permalink)
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It is possible to glide after a reduction in power, but there is a risk that the aircraft may not be able to regain altitude. There have been instances when folding propellers do not unfold properly or require a restart of the engine. As a general rule, it is advisable to assume that any reduction in power may be terminal and that the engine could fail at any moment.
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Old 01-07-2023, 01:43 AM   #8 (permalink)
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Do aeroplane engines become less efficient once they've cooled down? Warm up variables would have to be calculated/overall distance

Try it and see? (take a parachute)

..edit I just read the oil pan thing (ignore)
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Old 01-07-2023, 02:09 AM   #9 (permalink)
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I don't see much in the way of TSFC (thrust specific fuel consumption) maps. Here's a chart suggesting running engines near the top end is more efficient. I'm not sure what kind of engines these are though.

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Last edited by redpoint5; 01-07-2023 at 02:19 AM..
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Old 01-07-2023, 02:55 AM   #10 (permalink)
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Does Dynamic Soaring count as pulse and glide?
Quote:
https://illumin.usc.edu › dynamic-soaring
Dynamic Soaring - USC Viterbi School of Engineering
Dynamic soaring is a specialized form of gliding flight that has not yet been thoroughly researched. Observations of the albatross seabird show that it is possible to harness abundant energy by flying specific patterns through a boundary layer between two layers of air with differing wind velocities.
https://interestingengineering.com › innovation › dynamic-soaring-spacecraft-interstellar
'Dynamic soaring' could help spacecraft zoom across interstellar space ...
7 Dec 2022"In dynamic soaring as practiced terrestrially, a lift-generating vehicle executes a maneuver that exploits the difference in wind speeds between two different regions of the air, for example,...
Evolved by seabirds over eons, cribbed by Southern Californian hang gliders; it's now being evaluated for interstellar sailing on the stellar winds.

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