Turn back to the airport - the Impossible Turn

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Re: Turn back to the airport - the Impossible Turn

Postby Speed » Tue Feb 13, 2018 4:55 pm

Interesting discussion. Lot's of emotion (understandable, due to the loss of life involved).
As we can all agree, flying is a thinking man's game. As pilots, we recognize that we are subject to the laws of physics, which are then constrained by our own human limitations. As a glider pilot, I know a successful 180 turn back is possible, given the right conditions (physics, pilot). As we test and evaluate our aircraft and ourselves, we can certainly establish our own operational parameters plus hopefully work towards an ever-increasing envelope of capability and precision. This shouldn't be guess work. And, situationally, each pilot will find a different set of answers for themselves as the physics change and their own capabilities change. I believe there is a place for keeping "turning back to the runway" in our aviator's toolbox. Clearly, we shouldn't be employing tools we don't know how to use yet, nor or the other hand, should it be the only tool in our box. But, especially as "experimental aviators" we must keep our mind in the game at all times. Pre-calculation, testing, and practice are they way we create the safest flying environment, that then gives us the optimal freedom to enjoy it. Unplanned, untrained situational responses should be left to when it is the only option available, and then we should still lean hard on our well-developed understanding of the physics and our own capabilities. Will I turn back to the runway if my engine quits? Well, that depends!
Plans built Sonex #50 (2002); now with Corvair-100hp and Aux Wing tanks (2009); 4th owner (2015).
N77ZZ @ KHWY ... "Speed" (my old Air Force callsign)
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Re: Turn back to the airport - the Impossible Turn

Postby EdW » Fri Mar 02, 2018 3:17 am

Like I said on another forum, ain't no way in Hell I'm going to try to get the insurance companys airplane back to the airport behind me.
FLY THE AIRPLANE UNTIL THE LAST OF THE DUST SETTLES!!!

Ed
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Re: Turn back to the airport - the Impossible Turn

Postby rick9mjn » Fri Mar 02, 2018 11:53 am

I am very much in a agreement, with what “speed” said on Feb. 13 , and what “EdW” said on March 2. . The only thing I can add is this;
. When I was taking Glider lessons, when I was in the glider ( with the instructor setting behind me), ready for the tow plane to start the tow. After I had went through the pre-flight Take off check list.
I would grab the control stick ,with my “trigger finger” pointing straight ahead, And I would keep it pointed straight ahead . Until I reached 200 ft in the tow. That way I was set up (in my mind) for what to do if their was a rope break. Also being ready to push the stick forward ,when the instructor pulled the rope release at 220 ft. This is just cheep/maybe good idea to think about......
good day...../rick
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Re: Turn back to the airport - the Impossible Turn

Postby vigilant104 » Fri Mar 02, 2018 4:11 pm

Question to the masses: Has anyone seen an article on this issue that is specific to the Sonex? I know we should all do our own testing (and actual practice, at altitude), but it would be helpful to have a baseline of information. Yes, every plane is different, but they aren't >massively< different. If we start with some baseline assumptions (climb speed, wind component, turn/lineup technique, delay time to recognize the problem and take action, etc. Weight shouldn't have a significant impact on glide distance, just glide speed ) it would seem possible to come up with a mark on the wall for when a "turn back" is in the realm of the possible. Then, a big dollop of "add X feet for mom and the kids" and we'd have something to start with.

If we have good, acccurate Sonex perforamce data, that would be a start. I suppose we could come up with a standard technique (e.g. climbout airpseed, opposite 30 deg bank for X seconds, then bank into the wind for X seconds to achieve reciprocal heading from climbout, etc) and have a few folks check things out (at altitude) to see what the numbers look like. Maybe this is covered in the Sonex Transition Training syllabus?

Elsewhere, Mike made a general call for input germane to SBPF, maybe this is something worthwhile (if it hasn't been done already). I'm not the most qualified person to do it, but I'd be happy to put something together over time, if there is interest, if this is new ground, and if folks would be willing to chime in with input. The intent would be twofold:
1) Help folks make it back to the runway when it is entirely practical and safe
2) (Much more important) Minimize delay, indecision, and panic in the case of power failure on takeoff. Hopefully, if we have in our heads a distance/AGL altitude that corresponds with "I can safely make it back now" based on some data and practice, the decisionmaking before that point will be more timely, and less stressful (and therefore more accurate). Immediately eliminating the "turn back" option can save valuable time and allow us to concentrate on finding the "least bad" alternative available.
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Re: Turn back to the airport - the Impossible Turn

Postby daleandee » Fri Mar 02, 2018 6:18 pm

vigilant104 wrote:Elsewhere, Mike made a general call for input germane to SBPF, maybe this is something worthwhile (if it hasn't been done already). I'm not the most qualified person to do it, but I'd be happy to put something together over time, if there is interest, if this is new ground, and if folks would be willing to chime in with input. The intent would be twofold:
1) Help folks make it back to the runway when it is entirely practical and safe
2) (Much more important) Minimize delay, indecision, and panic in the case of power failure on takeoff.


A very worthwhile undertaking to say the least! I've had an engine out on take-off in a Challenger 11 LW with a student in the front seat. Engine quit ~100' up. It didn't cross my mind to turn back as I had a good instructor that drilled into my head about not turning back. Still I do think that there are times when it could be considered. Currently on take-off I'm determined to land ahead within about a 30-45º area left to right centered in front of the airplane.

But consider that the crosswind leg after takeoff is done at 5-600' AGL (most airports want 300' below TPA) and the 90º turn is complete. At that point could a turn back be made? We're talking 270º of turns and a downwind landing in a position that may bring you high over the runway depending on how long your departure leg was before the turn (and assuming no obstacles).

There is so much written about this and opinions abound. But if you (with input from the group) can put together some Sonex specific numbers ... I think that would be an awesome piece of information to have. Obviously every pilot will have to set their own minimums and practice this for themselves at altitude but I would give everyone the wise words of my (and many other) instructors ... when the engine stumbles, coughs, sags, or quits, "GET THAT STICK FORWARD!" Once you have flying speed you can take a breath and aim for that spot you planned to use before take-off if something like this were to happen. You did have a plan didn't you?

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Re: Turn back to the airport - the Impossible Turn

Postby lutorm » Fri Mar 02, 2018 9:44 pm

vigilant104 wrote:If we have good, acccurate Sonex perforamce data, that would be a start. I suppose we could come up with a standard technique (e.g. climbout airpseed, opposite 30 deg bank for X seconds, then bank into the wind for X seconds to achieve reciprocal heading from climbout, etc) and have a few folks check things out (at altitude) to see what the numbers look like.


One thing that I read once that stands out to me was "many small airplanes have a poorer climb ratio than they have glide ratio", at least at some weight. In that case, it doesn't matter how high you are: if the engine stops after a climb straight out you aren't making it back.

I'm curious if anyone knows where an 80hp Aerovee-powered Sonex falls in this spectrum. At what weight does the climb ratio equal the glide ratio?
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