Engine failure turn back.

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964SS

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I flew sailplanes some 35 years ago (Blaník L13). On a winch launch, things happen extremely quickly. When cable snaps, we had three specific procedures. If altitude is 0 - 50m, land straight ahead. If it snaps at 50 - 100m, make a teardrop turn and land back on the runway, downwind. If the altitude is above 100m, fly a tight pattern and land normally.

(sorry for responding to this after the discussion has veered elsewhere; I just saw it)
Winching is a whole other animal. A blast!
However, compared to aero tow, you are really put in a deep whole when the cable breaks. Steep pitch angle bleeds speed immediately. Decisions need to be made immediately. Actually should be made pre launch. At the minimum, immediate stick forward for flying speed, then turn back if altitude and displacement allows. If not, land straight ahead and pick the softest thing to hit. 😉
 

atypicalguy

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The references to "stall velocity" in the article may indicate a problem. Despite the widespread/common use of the term "stall speed," it is a misnomer. Aerodynamically, there is no such thing as a speed at which a wing stalls. There is only a "critical AoA."
If we don't demand 1 g level flight, then the published stall speed is not relevant.
The analysis in the paper appears to be based on maintaining an airspeed above "stall velocity." I'd like to understand how that works a little better.
My understanding from reading the various articles is that they want you to fly the turn with the stall horn just barely sounding, ideally on the inside wing.
 

atypicalguy

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We can put the math to any given scenario. The pilot has to evaluate what strait ahead will result in vs a partial, to complete turn back.
I have done it twice. Once in a Smith Mini Plane in daylight with nothing but Oak trees ahead. It was an instant choice to dump the nose and turn. It worked out fine.
The other time was at night in a Stinson108-3. Once again it was an instant choice to rapidly unload the wing and do a steep turn. I was able to use a closed runway with about a 250 degree turn. I could have rolled out and at least landed on the airport vs the boondocks if I could not make a runway or taxiway. Made it with a good margin, and turned final at about 30' and 70 mph. Depth perception at night is a major factor. It stinks! I made it that time too. I might not again, and I know it.
No textbook can tell a pilot to always do anything, only a pilot can make those choices, and they must do that quickly.
Yes I think all the people who have studied it emphasize the need for pilots to train in the maneuver to be able to execute optimally under pressure.
 

PredragVasic

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Winching is a whole other animal. A blast!
Abso-bleeping-lutely!! The winch launch is essentially like a carrier catapult launch -- you're airborne in five seconds, and climbing at 45º angle two seconds after that! ROC was usually around 1,000 m/min (some 3,000 fpm). The guy holding the wing doesn't even need to run -- the wing gets enough lift almost as soon as you start moving...
However, compared to aero tow, you are really put in a deep whole when the cable breaks. Steep pitch angle bleeds speed immediately. Decisions need to be made immediately. Actually should be made pre launch.
We were diligently trained on this. All of my glider flying was on winch (except of one single aero tow). By the time I accumulated my first hour of dual, I already had over 15 launches and 15 landings... And at least one of those launches was a simulated cable snap. My instructor had simulated those on me, on average, once every ten flights. After my first solo, I had an actual cable snap, perhaps on my fifth solo flight (I pulled a bit too hard on the rotation). I snapped at around 70m altitude AGL, so I did a teardrop turn and landed downwind. My response (nose-down) was immediate, it was drilled into my mind so strongly. It has been well over 30 years, but I feel I'd still instinctively push the nose down if I felt sudden loss of power on climb out, regardless of whether there was a propeller spinning in front of me or not (plane or glider).
 

Vigilant1

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ETA: Below is not a reply to PredragVasic. We cross-posted.
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At risk of stating the obvious: When a glider towrope breaks, it is immediately clear that unpowered flight has begun and will continue until landing. There's no "Reattach Towrope in Flight" checklist. OTOH, an engine failure on takeoff/climbout can be initially intermittent/ambiguous and we have procedures for attempting to regain power. Attempting a restart can be a powerful distraction that has resulted in bad outcomes.
Wherever we choose to put it down, remaining focussed on flying the plane is crucial.
Again, Captain Obvious here.
 

PredragVasic

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At risk of stating the obvious: When a glider towrope breaks, it is immediately clear that unpowered flight has begun and will continue until landing. There's no "Reattach Towrope in Flight" checklist. OTOH, an engine failure on takeoff/climbout can be initially intermittent/ambiguous and we have procedures for attempting to regain power. Attempting a restart can be a powerful distraction that has resulted in bad outcomes.
Very true. I think that former (and current) glider pilots (particularly those with heavy winch launch experience) tend to respond more coherently in engine-out emergencies on powered aircraft. We have it ingrained to immediately assume best gliding distance airspeed and turn the aircraft in the direction of the landing strip. When such a thing happens on climb-out, the similarity with the winch cable snap experience makes the correct response intuitive and instinctive.
 

atypicalguy

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I
Yes, I did see that. The formula is fine for adjusting Vs to non-zero bank angles. But, even at zero degree bank angle the wing still doesn't necessarily stall at Vs if we push the stick forward so that we are not at 1G. The same applies in a bank.
Still, I am not recommending unloading to zero G (and accelerating toward terrra firma at 32 fps^2) as the best technique for making the "impossible turn" with minimal altitude loss.

The paper is an interesting think piece. The simplifying assumptions (instant decision, instant roll to desired bank angle, etc) help keep the length of the paper reasonable, but clearly anyone considering this as a blueprint for action will need to do a lot of work in developing their own technique and "window."
I linked the EAA webinar in another thread I think. Whether you can even make it back to the airfield depends upon many things, like the climb slope of your airplane with whatever power it is making and load, the amount of headwind and crosswind, the glide slope of your plane in the prevailing wind and load condition, the skill of the pilot, the bank angle, and the length of the runway vs the length of the takeoff roll. It is a lot easier on a 7000 ft runway, as my cousin found out in his Mooney. But the Mooney also glides very well. Anyway I think everyone needs to actually go out, map the fore flight data in their plane with them flying it, then translate it back to their airport in 3D to see if their plane will eve make it back to a landable part of the Earth on turn back. One of the planes they tried never made it back to the airfield because its engine was old and the climb slope was too shallow compared to the glide slope, so the altitude didn't matter at all. I think this is probably more common than most people believe, but you won't know unless you try it in whatever plane you fly. I have not tried it yet but I am still a student and I definitely plan to try power off landings as a part of my training, and the turn back if the instructor is up for it.
 

PredragVasic

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Anyway I think everyone needs to actually go out, map the fore flight data in their plane with them flying it, then translate it back to their airport in 3D to see if their plane will eve make it back to a landable part of the Earth on turn back.
Or you could get Xavion, a mobile app by Austin Meyer (the guy who wrote X-Plane flight simulation). Xavion seems to be quite a powerful little tool. If you configure it properly with your aircraft data (weights, V speeds, ROC, glide ratio, etc), the app will draw you, in real time, a circle around your aircraft that will clearly show exactly how far is reachable landing area. It can also suggest the most appropriate landing strip and show you the way there using "highway in the sky" frames on a synthetic vision image. Based on the reported winds aloft and the available GPS data, it will calculate your true airspeed (as well as groundspeed). You can also get barometric altitude, as well as GPS altitude (assuming your phone has the required internal sensors).
 

BJC

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I am still a student and I definitely plan to try power off landings as a part of my training, and the turn back if the instructor is up for it.
Many CFI’s will not teach or endorse a return to airport turn. Once you get your pilot certificate, you will be free to learn spins and then begin to practice the turn back at altitude.


BJC
 

tallank

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My understanding from reading the various articles is that they want you to fly the turn with the stall horn just barely sounding, ideally on the inside wing.
NO! You are flying way on the backside of the curve. You will not go very far doing that and you have a very high chance of spinning in. You have to dump the nose immediately with an engine failure. Spinning in from engine failures happens a lot. Get away from VX. Best glide speed +.
 

Vigilant1

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NO! You are flying way on the backside of the curve. You will not go very far doing that and you have a very high chance of spinning in. You have to dump the nose immediately with an engine failure. Spinning in from engine failures happens a lot. Get away from VX. Best glide speed +.
In this turn, we need to get the nose around, and do it efficiently. Max performing the wing is the way to do that. Now, whether a stall horn is an adequate tool for knowing if we are at/near the critical AoA and whether it is prudent for a particular pilot to be flying this close to the wing's critical AoA under these conditions--these are worthwhile questions.
 

BJC

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NO! You are flying way on the backside of the curve. You will not go very far doing that
Flying the greatest distance is not the objective: positioning the aircraft for a return to the runway is the objective, and what we are discussing.
and you have a very high chance of spinning in.
Why? Spinning is the result of stalling in uncoordinated flight.
Spinning in from engine failures happens a lot.
I wasn't aware of that statistic. Can you provide a citation?

According to the FAA, most stall-spin fatalities occur from the turn to crosswind on takeoff.


BJC
 

Tiger Tim

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I flew sailplanes some 35 years ago (Blaník L13). On a winch launch, things happen extremely quickly. When cable snaps, we had three specific procedures...
When I used to fly winch launched Schweizer 2-33s (yeah, short flights) a 180 was never an option on a cable break. If we had enough runway ahead we’d land straight ahead, if not we’d do a 360 degree turn to burn altitude and land ahead. In our case there was never a place for cable break where a 180 would work. The few who tried always ended up high and overshot the runway into the trees at the end.

It’s neat to know that for your Blaniks that a 180 was an option. More than anything it probably illustrates that there’s no singular right answer for this thread.
 

PredragVasic

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It’s neat to know that for your Blaniks that a 180 was an option. More than anything it probably illustrates that there’s no singular right answer for this thread.
Exactly.

In my case, glider training was done by people who were paid by the government (military), which also provided the hardware. So, the training rules and procedures were fairly rigid and uniform throughout the country. Until the mid-1980s, joining an aero club was free, as was glider training. As the military was tightening the budgets (amid the political turmoils of the late 1980s in the Balkans), the clubs started charging for glider training, but it was still fairly cheap. We got a lot of winch launches/landings (about 15 per hour), which rapidly built stick&rudder skills.

Back on the subject, the 180º turn was for a fairly narrow set of cases, but it was available. Blaník does have spoilers, which significantly increase rate of descent, and which you would usually deploy on your final approach, so once you're lined up with the runway after that 180º turn, the speed brakes would quickly get you down well before running out of runway (even with a strong tailwind). Another minor benefit of such a landing is that the glider is then neatly positioned for the next launch (once the winch team completes the splicing of the cable, that is, which usually took 45 minutes...).
 

atypicalguy

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Or you could get Xavion, a mobile app by Austin Meyer (the guy who wrote X-Plane flight simulation). Xavion seems to be quite a powerful little tool. If you configure it properly with your aircraft data (weights, V speeds, ROC, glide ratio, etc), the app will draw you, in real time, a circle around your aircraft that will clearly show exactly how far is reachable landing area. It can also suggest the most appropriate landing strip and show you the way there using "highway in the sky" frames on a synthetic vision image. Based on the reported winds aloft and the available GPS data, it will calculate your true airspeed (as well as groundspeed). You can also get barometric altitude, as well as GPS altitude (assuming your phone has the required internal sensors).
It sounds like a good start. I do not see how it can provide detailed landing information unless it incorporates topographic maps with local detailed elevations as well as the power lines etc. But it sounds like a useful tool. Knowing what the options are instantly after a failure would be a huge advantage.
 

atypicalguy

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Many CFI’s will not teach or endorse a return to airport turn. Once you get your pilot certificate, you will be free to learn spins and then begin to practice the turn back at altitude.


BJC
I would be happy with power off landings from downwind at this point
 
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Hephaestus

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I wasn't aware of that statistic. Can you provide a citation?

According to the FAA, most stall-spin fatalities occur from the turn to crosswind on takeoff.
11 (11%) 21 U-FIT LOTOT Loss of Thrust On Takeoff, stall then spin.
12 (22%) 42 U-FIT Loss of speed Aw. Flight below DMMS not on takeoff results in stall, spin.

Yes - maneuvering at too low a speed is double the rate of incident than Loss of thrust on takeoff. But the fatality rate is higher for the LOTOT.
 
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