A situation we all hope to never have: engine quits at a low distance AGL.

What bank angle will produce the least altitude loss for a 180 degree turn? Is this common for all aircraft?

Readings have shown the elevator/wing to be more efficient at turning the aircraft than the rudder alone.

It would seem better not to try to hold altitude on the turn, but one still must avoid stalling the wing. Airspeed is also a factor in gliding efficiency.

What is the best way to turn 180 degrees with least loss of altitude?

Some good references provided. Curious about rudder technique in a steeper bank. At 45 degrees, rudder is pitching nose down some, but should be there to "follow" the wing around the turn (lowest drag). Some elevator, some rudder to swing the tail through the yaw plane, giving up some altitude, so as not to load the wing as much (like an emergency descent)?

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    $\begingroup$ Why do we think this doesn't vary hugely between different aircraft? $\endgroup$ – DJClayworth Aug 29 '19 at 18:56
  • $\begingroup$ It's a lot steeper than most people think. Somewhere around 45 deg or more. When I'm thermalling in a glider at minimum sink, I'll bank to around 45-50 deg to get the smallest turn radius without the sink rate going up significantly. On your airplane, you have to figure it out by experimentation. $\endgroup$ – John K Aug 29 '19 at 19:30
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    $\begingroup$ Even if this does vary hugely between different aircraft, I think this is still a good question that admits a good answer—that answer would just have to point out that it varies between different aircraft, and how and why. Conversely, maybe it really doesn't vary much between different aircraft. $\endgroup$ – Terran Swett Aug 29 '19 at 19:52
  • $\begingroup$ Turn radius being independent of weight suggests similarity, although the fuse design could be extremely variable. $\endgroup$ – Robert DiGiovanni Aug 29 '19 at 20:01
  • $\begingroup$ You should consider the plane AND the wind AND the IAS when deciding on an angle for an emergency 180. Some planes may stall at 45 degrees, for example, depending on the speed. You may want a steeper turn if you need to travel some distance after a turn into a headwind. As a side note, if you need to be aligned with a runway after the turn, consider the crosswind direction when deciding which way to turn. Another side note: Only practice this at altitude or on a simulator. People die regularly practicing emergency 180s at low altitudes. This question is not a duplicate and should be open. $\endgroup$ – xpda Aug 31 '19 at 19:55

Asked and answered, since a any plane without a functioning engine is basicly a glider: What is the optimal bank angle to accomplish a given turn in a glide?

Assuming the question refers to an engine failure after takeoff, there is a lot more to the stunt than just turning with the least amount of altitude loss. In any case, before attempting "the impossible turn" you must be above the safe altitude for the maneuver. If you have not yet reached safe altitude, you make an emergency landing in the front sector. The safe altitude varies heavily with different plane makes and models, but for example a C 172 needs about 500ft and rather aggressive (yet skilfull) handling according to tests made for AOPA Pilot 2002 july article.

To make an efficient 45 degree turn while maintaining a steady speed is not exctly a walk in the park if you have just lost an engine. Attempts to return to the runway after an engine failure during initial climb have a strong tendency to end in tragedy.

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    $\begingroup$ Welcome to Stack Exchange! I'd like to point out that this question is quite specific as to what's considered the "best" bank angle ("least altitude loss for a 180 degree turn"), while the other question is more vague about it ("the greatest turn rate with the smallest loss in altitude"—without specifying how to handle the trade-off between the two contrary objectives). $\endgroup$ – Terran Swett Aug 29 '19 at 20:18
  • $\begingroup$ This is true. I made the bold assumption that the reason to make a 180 after engine loss is to get back to the runway, Why else would you waste precious energy in a life threatening situation? To achieve this goal, you should use the best compromise between rate of turn and loss of energy. Less than 45 deg. bank angle, you drift further away, more than 45, you waste energy having to pull harder and trading altitude for speed not to stall as the load factor increases rapidly, and so does your stall speed. Plus it gets increasingly hard to make fully coordinated turns at higher bank angles. $\endgroup$ – Jpe61 Aug 30 '19 at 9:04
  • $\begingroup$ The simplest answer to the question "What bank angle creates the least energy loss in an emergency engine out 180 degree turn?" would be "more than zero, less than one degrees". This way there would be virtually no energy lost due to the heading change, but it would take ages to make the turn :) $\endgroup$ – Jpe61 Aug 30 '19 at 9:08
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    $\begingroup$ @Jpe61 The question is not asking about the altitude lost "due to the turn" but "during the turn". If your turn took an hour, then lots of altitude would be lost during that hour - much more than for a quicker turn with a higher bank angle. $\endgroup$ – DJClayworth Aug 30 '19 at 15:33
  • $\begingroup$ The headline asks one thing, the body kinda the same but still different. Hence the smiley at the end of my previous comment. $\endgroup$ – Jpe61 Aug 30 '19 at 17:34

We went to an FAA seminar on the emergency turn back to the airport, and 45 degrees was given as the best bank angle after testing by an experienced pilot. Also, taking off and climbing while turning to 45 degrees away from the runway, so that if one had to turn back, the 180 would get you better lined up with the end of the runway, vs taking off, doing a 180, then a further 45, and then 45 the other way to be lined up on the runway. (Sitting here waving my hands in the air picturing this.)

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    $\begingroup$ What's interesting is that in soaring training, we do simulated rope breaks at afew hundred feet. Students are shocked to discover that not only that there is no problem making it around from as low as 300 ft, the real challenge is ** not overrunning the freaking landing zone ** running downwind if there is any significant wind taking off. $\endgroup$ – John K Aug 30 '19 at 3:05

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