Interesting Impossible turn paper

"The model shows that optimum conditions for returning to the departure runway result from climbing at Vmax, executing a gliding turn through a 190-220 degree heading change, using a 45 degree bank angle at 5% above the stall velocity in the turn using a teardrop shaped flight path. ​
"​



I'll try it only if I have Nick in the right seat doing the calcs....​

 
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Steve said:
"The model shows that optimum conditions for returning to the departure runway result from climbing at Vmax, executing a gliding turn through a 190-220 degree heading change, using a 45 degree bank angle at 5% above the stall velocity in the turn using a teardrop shaped flight path. ​
"​



I'll try it only if I have Nick in the right seat doing the calcs....​
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Nick like me? I'm game!
 
I think Professor Rogers did a lot of flying as well as a lot of theoretical computations, and has produced a very good piece of work. I recommend, however, that you make your initial attempts at this maneuver while pretending the ground is at an altitude allowing safe recovery from an incipient spin, i.e., if you think 2000 feet is as low as you'd want to enter an incipient spin, make your first attempt using 2000 AGL as the simulated ground.
 
totally agree ron. was just throwing the link out to inspire some discussion. Not trying to get people to go out and try it.
 
tonycondon said:
totally agree ron. was just throwing the link out to inspire some discussion.
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OK...how's this for discussion...

The pilots I know who could be counted on to maintain the level of proficiency and control to perform the "impossible turn" maneuver consistently (including the added stress of, well, a low altitude engine failure), would all just find a place straight ahead, or thereabouts, to put the airplane down. Wouldn't even attempt it.

Hot sticks may be great, but most of them that I know will take "margin" over "spectacular talent".

Fly safe!

David
 
tonycondon said:
totally agree ron. was just throwing the link out to inspire some discussion. Not trying to get people to go out and try it.
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I am trying to do that -- preferably with a sane instructor in the right seat (not like the one involved in that Cirrus wreck trying this back in January who didn't know when to give up). It's another tool you can have in your toolbox for the day when things go really sour and you lack another, better alternative.
 
MauleSkinner said:
most of them that I know will take "margin" over "spectacular talent".
David
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thats why they are the hot sticks.
 
of course ron, i shouldve said i dont mean for people to go out trying it at low alt. right away
 
MauleSkinner said:
The pilots I know who could be counted on to maintain the level of proficiency and control to perform the "impossible turn" maneuver consistently (including the added stress of, well, a low altitude engine failure), would all just find a place straight ahead, or thereabouts, to put the airplane down. Wouldn't even attempt it.
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I don't think it takes all that much more than the basic level of proficiency we should all have, and I'm sure that there are airports/runways when there really isn't anywhere good straight ahead right after takeoff. If you learn it, practice it, and become proficient, you'll be able to use it if you ever happen to need it.
 
i agree ron. seems people still manage to screw it up though. every pre solo glider student has to be able to execute this manuever at least once before soloing. all you have to do is turn.
 
I personally did extensive testing of this method in my Lance a few years ago. The first dozen attempts WILL NOT WORK. It takes practice to get it right. The pull to get that bank angle at that airspeed is much harder than you anticipate. Great skill to have, but it is a skill, like any other, that needs to be practiced.

I got the Lance down to about 560 feet altitude loss, including a 3-second "WTF" delay. But that took a lot of work.
 
tonycondon said:
seems people still manage to screw it up though. every pre solo glider student has to be able to execute this manuever at least once before soloing.
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Because most pilots are afraid of the low-speed regime -- IMO an unintended consequence of the FAA's emphasis on stall/spin avoidance.
 
Ken Ibold said:
I got the Lance down to about 560 feet altitude loss, including a 3-second "WTF" delay. But that took a lot of work.
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Ken, is the 3 second delay real-world? I read the paper a while ago and recall some discussion on actually recognizing there's a problem and then unfreeze enough to begin recovery, but don't recall if they talked about how long that was ... guess I'll scroll back up and re-read it...
 
gkainz said:
Ken, is the 3 second delay real-world? I read the paper a while ago and recall some discussion on actually recognizing there's a problem and then unfreeze enough to begin recovery, but don't recall if they talked about how long that was ... guess I'll scroll back up and re-read it...
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I've seen as long as 8 seconds used in some of these simulations. I don't recall what real-world research has shown.
 
agreed ken. and us glider weirdos are used to moderate banked turns at slow speed.
 
Here is a video of me pulling the mixture and killing the engine from 400 ft in a C-172SP with a turn back to the runway.

http://www.jesseangell.com/video/400ft.wmv

Don't give me some big verbal lesson about doing it; it was purely my choice.
 
you really are a super pilot!
just barely made it though, and right on the centerline! i suppose you planned it that way :)
 
Attended an AOPA sponsored Wings seminar last night. One of the better ones I've been to. Subject was Pilot Decision-Making. The last topic was the "impossible turn" scenario. Presenter advocated every pilot determine the minimum achievable altitude loss in each plane they flew to safely accomplish this manuever with an instructor then make a hard number choice to use for real.

Another tool in the kit...
 
tonycondon said:
you really are a super pilot!
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Finally! Someone beleives me!
tonycondon said:
just barely made it though, and right on the centerline! i suppose you planned it that way :)
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Oh. Of course. I AM THAT GOOD.
 
Ron Levy said:
... and I'm sure that there are airports/runways when there really isn't anywhere good straight ahead right after takeoff.
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So, what would be your plan for an engine failure below the altitude at which you can make "the impossible turn"?
 
maule,
make a turn so that something landable is in front of me, or at least within glide range. if the airport is surrounded by unlandable terrain (city or mountains or something) then id strongly consider not coming back.
 
tonycondon said:
i agree ron. seems people still manage to screw it up though. every pre solo glider student has to be able to execute this manuever at least once before soloing. all you have to do is turn.
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This is NOT the same maneuver, Tony...from a 200' rope break, even a 2-22 has to open spoilers before it's pointed toward the runway again in order to make the touchdown zone. I had one student, with a 300' rope break in a G-103, get us back over the end of the runway too high to land...we had to do a 360 to get down from there.

Fly safe!

David
 
well the only difference is that the glider (yes even a 2-22) glides much better than the airplane. which is why we can turn back so much lower
 
tonycondon said:
well the only difference is that the glider (yes even a 2-22) glides much better than the airplane. which is why we can turn back so much lower
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I see the difference as figuring out the minimum altitude for the turn in an airplane (560 feet has been stated for the Lance, just as an example), and using THAT altitude.

This would be the equivalent of a rope-break-and-return at or below 100 feet in a glider, and I've never heard of anybody teaching it from those altitudes.

If you're going to take that 560 feet in the Lance, and make your hard deck for the turn somewhere around 800-850 feet, I'd consider it the same maneuver. In other words, even the lower altitudes we use in gliders still give us tremendous margin for error and poor technique.

Fly safe!

David
 
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david,
gotcha. i was just referring to the fact that every pre solo glider guy has actually turned back and landed on the runway. the difference between the absolute minimum altitude possible to complete the manuever and a hundred or two feet above that is not much in the mind of the student (oh my god the ground is so close) and they will tense up and make the same mistakes they wouldve made a little lower, i think. Definitely something us power guys need to practice more, safely of course.
 
tonycondon said:
Definitely something us power guys need to practice more, safely of course.
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k. I'll teach you. :D
 
tonycondon said:
gotcha. i was just referring to the fact that every pre solo glider guy has actually turned back and landed on the runway. the difference between the absolute minimum altitude possible to complete the manuever and a hundred or two feet above that is not much in the mind of the student (oh my god the ground is so close) and they will tense up and make the same mistakes they wouldve made a little lower, i think. Definitely something us power guys need to practice more, safely of course.
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Now we're on the same page ;)

I'm a firm believer that simulating something at altitude also differs greatly from the real thing...the "muscle memory" aspects are the same, but having the ground rushing up at you (or close by you) has tremendous effects on a person's ability to allow the muscle memory to do things the same way. I've flown with a LOT of pilots who plan for a 144 foot-per-mile climb gradient in the event of an engine failure who refuse to fly single-engine airplanes loaded up that make the same or slightly better gradients.

The other thing to consider is, can you make that turn with your wife screaming in the intercom, and her fingernails digging into your leg? I know more than one pilot who has the marks from that, too.

Personally, I'll make the turn back to the runway from the same minimum altitude that I will simulate it with students. If there's not enough margin for simulation, there's not enough margin for the real thing. Same as I would with the glider.

Fly safe!

David
 
Jesse, you had me going there!
 
Ken Ibold said:
I personally did extensive testing of this method in my Lance a few years ago. The first dozen attempts WILL NOT WORK. It takes practice to get it right. The pull to get that bank angle at that airspeed is much harder than you anticipate. Great skill to have, but it is a skill, like any other, that needs to be practiced.

I got the Lance down to about 560 feet altitude loss, including a 3-second "WTF" delay. But that took a lot of work.
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I have taught this maneuver in Lances, Arrows, C172, Bonanzas and Mooneys. The first three times the stick does not make it. The first time he's overconfident and flubs a major component. (start at 2000 agl with a good pilot, 3000 with a not so good....) The second time he gets the maneuver passable and requires 1100 vertical feet. The third time he gets it to about 900 feet and is soaking wet.

The last time he maybe does better, maybe not (esp. in the Arrows where the gear drops out). I don't let 'em stall....and they all conclude they need 900-1000 feet.
 
There is no question in my mind that this maneuver (and many others) would be much easier if our planes all had AOA gauges. As it is, we have to guess by feel whether we're pulling enough in the turn, and the margins at that point are very small between not pulling enough to make the turn and pulling into a stall/spin. Since the exact bank angle and aircraft load affect the critical speed (but not critical AOA), there's no set IAS for which to look.
 
Ken Ibold said:
I personally did extensive testing of this method in my Lance a few years ago. The first dozen attempts WILL NOT WORK. It takes practice to get it right. The pull to get that bank angle at that airspeed is much harder than you anticipate. Great skill to have, but it is a skill, like any other, that needs to be practiced.

I got the Lance down to about 560 feet altitude loss, including a 3-second "WTF" delay. But that took a lot of work.
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I got the Porterfield down to 200 ft or less without the WTFD, but with it's low wing loading and slow speeds, 3 seconds doesn't amount to much altitude loss either. OTOH, the best I could do in the Baron was about 1200 ft give or take a few hundred (mostly give). Part of the difference is the turning radius, which in the Porterfield is a small fraction of what the Baron needs.
 
Ron Levy said:
There is no question in my mind that this maneuver (and many others) would be much easier if our planes all had AOA gauges. As it is, we have to guess by feel whether we're pulling enough in the turn, and the margins at that point are very small between not pulling enough to make the turn and pulling into a stall/spin. Since the exact bank angle and aircraft load affect the critical speed (but not critical AOA), there's no set IAS for which to look.
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There is a binary AOA indicator called the stall horn in many planes. And since it's supposed to be set for 5-10 Kt above stall AOA, I'd think you could try holding the pitch to where the horn was intermittant and get pretty close to optimum. The problem I have with this is it's awfully difficult to ignore the well honed reaction of unloading (significantly) when the horn goes off at low altitude.
 
MauleSkinner said:
Now we're on the same page ;)

I'm a firm believer that simulating something at altitude also differs greatly from the real thing...the "muscle memory" aspects are the same, but having the ground rushing up at you (or close by you) has tremendous effects on a person's ability to allow the muscle memory to do things the same way. ...

The other thing to consider is, can you make that turn with your wife screaming in the intercom, and her fingernails digging into your leg? I know more than one pilot who has the marks from that, too.

Personally, I'll make the turn back to the runway from the same minimum altitude that I will simulate it with students. If there's not enough margin for simulation, there's not enough margin for the real thing. Same as I would with the glider.
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Man, you are a lot braver than I am (or am I misunderstanding your point?). While I agree that the sight picture for the "real thing" is a lot scarier than practicing at a safer altitude, I just can't see the benefit in practicing steep turns just above stall speed close to the ground. This sounds a lot like one of Ron's "practicing bleeding" sessions to me.
 
lancefisher said:
Man, you are a lot braver than I am (or am I misunderstanding your point?). While I agree that the sight picture for the "real thing" is a lot scarier than practicing at a safer altitude, I just can't see the benefit in practicing steep turns just above stall speed close to the ground. This sounds a lot like one of Ron's "practicing bleeding" sessions to me.
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You're probably misunderstanding my point...Take your 200 feet for the Porterfield, add the WTFD, and enough additional altitude so that the turn could be made comfortably at something approximating best glide speed, and you have the altitude at which I will teach and/or perform the maneuver in real life.

Fly safe!

David
 
MauleSkinner said:
You're probably misunderstanding my point...Take your 200 feet for the Porterfield, add the WTFD, and enough additional altitude so that the turn could be made comfortably at something approximating best glide speed, and you have the altitude at which I will teach and/or perform the maneuver in real life.
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I think I'd start teaching it at least 1000 feet above that, and work down from there if I'm comfortable with the trainee's performance.
 
MauleSkinner said:
OK...how's this for discussion...

The pilots I know who could be counted on to maintain the level of proficiency and control to perform the "impossible turn" maneuver consistently (including the added stress of, well, a low altitude engine failure), would all just find a place straight ahead, or thereabouts, to put the airplane down. Wouldn't even attempt it.

Hot sticks may be great, but most of them that I know will take "margin" over "spectacular talent".

Fly safe!

David
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We practice this relatively easy and very practical maneuver at safe altitudes on a regular basis for training flight students. It's not difficult for anyone competent in private pilot skills or above.
 
jangell said:
Here is a video of me pulling the mixture and killing the engine from 400 ft in a C-172SP with a turn back to the runway.

http://www.jesseangell.com/video/400ft.wmv

Don't give me some big verbal lesson about doing it; it was purely my choice.
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A zero reaction-time lag for your film shows just how close a from 500ft AGL turn could be with God only knows how many seconds of lag time.

BTW: Do you use stick or cursor controls?
 
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Dave Krall CFII said:
We practice this relatively easy and very practical maneuver at safe altitudes on a regular basis for training flight students. It's not difficult for anyone competent in private pilot skills or above.
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If it's "relatively easy", why is it necessary to initiate it above the minimum altitude?
 
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