New “impossible turn” video - Acclaim S

[dkkim73]

1 hour ago, PT20J said:

To minimize the altitude loss in the turn you need to load the wing to just above stall. But, since you will want best glide speed coming out of the turn, I’ve found a good compromise is to fly the turn at best glide speed. 

Doing some of this recently really made me want an AoA indicator. 

[M20F]

3 minutes ago, dkkim73 said:

There's a blonde astrophysicist somewhere around here who wants to debrief you on this. 

You had me at blonde and debrief.  

[mike_elliott]

7 hours ago, Jeff Uphoff said:

Wait...you have a Mooney Redbird now, or you were working with one of the ones at Kerrville?

I'd love to do some training in one--things I won't do in my Ovation, such as a spin or impossible-turn practice. I didn't even realize there were Mooney Redbirds floating around. (I've only ever used Diamond ones. Meh.)

--Up.

This was Mooneys in Kerrville. I tried to buy the new one they had not unboxed yet but was not able to come to terms with Albert. It’s been a few years ago —up

[Jeff Uphoff]

3 hours ago, dkkim73 said:

There's a blonde astrophysicist somewhere around here who wants to debrief you on this. 

She's not blonde, but there has been a very famous woman astrophysicist around here flying her M20E.

(This shot is us plus another friend in back on our way to Oshkosh in my Ovation this year.)

--Up.

[toto]

4 hours ago, dkkim73 said:

There's a blonde astrophysicist somewhere around here who wants to debrief you on this. 

She is a civilian contractor, so you do not salute her - but you’d better listen to her, because the Pentagon listens to her about your proficiency. 

[mike_elliott]

I wonder if Don maxwell ended up with the wood spar also that was sitting on the floor of the delivery hangar

@Dmax??

 

 

[hazek]

15 hours ago, exM20K said:

Good point, and for sure > 1G in this maneuver, since that would roughly double the descent rate to 1600-2000 FPM. I would guess that number is holding altitude, so 2G load factor?

You cannot hold altitude when engine is dead. If you try that you will stall.

13 hours ago, PT20J said:

To minimize the altitude loss in the turn you need to load the wing to just above stall.

You cannot load the wing just above stall, by definition you have then stalled.

 

[Ibra]

3 hours ago, hazek said:

You cannot load the wing just above stall, by definition you have then stalled.

Of course, the quickest way to lose altitude is dynamique stall (spins also consume lot of altitude per turn) 

However, to fly a turn with minimum altitude loss you need 45deg bank and few kts above 45 deg stall speed, the typical "best turn speed" is something like 1.2×VS + 10kts (same for min sink speeds at 45 deg), doing 45deg turn at best glide Vbg with unloaded wings (1G) to result in huge altitude loss in turn.

All of this stuff is theoritical, the only case where one is interested in this is gliding ("stalling inside tight thermal to climb" ). If one is interested in more theoritical stuff, a wingover flown at 0G is the quickest was to fly 180 with minimal loss of altitude  

I have done 180 chandelles with power and 180 wingovers without power: in Mooney, with +/-200ft, you are on opposite heading quicker than 45deg loaded turn (in glider -150ft, I am on opposite heading after wingover), unless stuff after an EFATO as no one is brave enough to do it...

All this theoritical aerobatics stuff go into the bin at low altitudes as the human factors kicks in when one loses visual reference of the horizon (the scary ground fills the whole view outside), I was flying with a Polish national champion who did aerobatics by the numbers, he finished with loop at 500ft and wingover at 300ft straight to land on final with zero energy left 

On my side, I tend to keep wings level once under 400ft agl and the speed near Vbg or Vref. I may do +/-20deg bank angle to pick left and right within +/-30deg (sort of rate1 turn as some IFR pilots call it) 

 

 

 

Edited yesterday at 08:51 AM by Ibra

[hazek]

22 minutes ago, Ibra said:

All this theoritical aerobatics stuff go into the bin under 600ft agl as the human factors kicks in when one loses visual reference of the horizon (the scary ground fills the whole view outside)

Exactly. And no one has really taken on board my main point. Which is that even if you execute the turn back perfectly you still are left with only the one good option, low and slow. Never put yourself in a position without an out. Straight ahead if you set up for a field and you're high, maybe there's another field beyond it that you can take, but you can take more time to set up in the first place making hitting that field so much more likely.

My main point is, unless you are Bob Hoover, if you make the turn back it's a gamble, not a predictable outcome. It's a gamble that may end in death - as it so often does. I just wish people, who plan to turn back, would admit to themselves this reality and see if maybe there are lower risk options.

These demonstrations with idle engine instill a false sense of security because every single one of them has an out that wouldn't be there otherwise - the engine. All the while the same time could be spent on learning to judge your glide better, how to aim at fields and making sure you hit them, we have plenty of deaths from people over/undershooting perfectly good fields too. If only we admitted, finally, collectively, that this maneuver is ALWAYS a gamble and there are safer options.

But alas, let's debate the bank angle for this gamble and kill some more people.

[Ibra]

2 hours ago, hazek said:

These demonstrations with idle engine instill a false sense of security because every single one of them has an out that wouldn't be there otherwise - the engine

I agree there is that gamblea element and it gives a flase sense of security.

Aside from myriades of variables like wind, length and layout, most of these "impossible turn videos" talk about ONE SINGLE variable: the critical altitude from which you you bank 45deg (or 60deg) and pull to turn near stall or like there is no tomorrow...

What is missing is SECOND variable which is the altitude by which you tend to level wings on 1G with speed near Vref? 

I assume second altitude is about 300ft-400ft agl in Mooney? and reasonable altitude loss for 270 deg turn is 600ft? while reasonable altitude loss for 360 deg turn is 800ft, so there you go 1100ft-1200ft agl for 360 return and 900ft agl for 180 return (even if one can fly tighter turns in 20s, they ars still showing -1000fpm for these), these are the usual "patten altitudes" where one can make it back from engine failures, anything bellow is "highly optimised": as someone said, in emergency, you either raise to the occasion or descend to the lowest level of competance 

Without some sort of "stop loss" for altitude, the whole manœuvre is pure gamble (or it's "all-in") 

When one fly forced landing from an altitude higher than pattern, they tend to have some key position ("called low key") to reasses if they need to stretch or tighten their base leg (or put flaps), when one fly forced landing straight, they tend to have an aiming point in the field ahead, when one flies "impossible turn", it's more like do it or die hard trying...

Edited yesterday at 11:20 AM by Ibra

[Hank]

22 minutes ago, Ibra said:

when one flies "impossible turn", it's more like do it or die hard trying...

More like "die trying hard."

Some fields have no good options other than a turn back. At home, I have a good option straight out on 36, land on the nice divided 4-lane highway; but on 18, it's forest then lake, so I'll get to practice a water landing and get out of the plane before she sinks . . . or try turning around, there's a great cleared area before the runway. 

[hazek]

Thinking about it. Whoever gave this turn the "impossible turn" name did every pilot such a huge disservice. The name is total misnomer. It's not impossible, more like it's very risky and very likely too risky! If it were called the "super duper risky liable to kill you often turn" people would likely have a much better attitude towards it. It would be clear it's sometimes possible in the right conditions but just that the risks with it are way higher and that it is in fact a far better idea to look for lower risks options if at all available.

[Ibra]

2 hours ago, Hank said:

At home, I have a good option straight out on 36, land on the nice divided 4-lane highway

I think home airfields, one can have few places to "put it" or "cut the loss", also, one would have sampled all low level pattern and all runways under different winds. However, the two absolute height limits will apply everywhere: one height to "turn back" and one height to "level wing" before crash...

Not long time ago, a Mooney M20F tried return from under 300ft agl,

https://asn.flightsafety.org/wikibase/520704

With partial power, the decision of  making "land ahead" or "turn back" is even more complex but one has to adjust the "two decision altitudes" 

 

 

 

 

 

Edited yesterday at 01:58 PM by Ibra

[Paul Thomas]

There is an altitude where you can't turn back, one where my level of skill won't allow me to turn back but the airplane could make it, and one where I can turn back and land. Knowing those is useful.

Even if the maneuver turns out poorly, and one ends up into the fence trying to make the airport, that may be a better outcome than crashing elsewhere. At least, you decrease the odds of putting others are risk and search and rescue should be able to get to you more easily.

My take is use the information at which to turn back to brief what you'll do prior to takeoff. That's the point of this exercise and I see very few people briefing takeoffs. You want to know where turning back is an option but the reality is that most of the time we have better options, I tend to favor crosswind runways.

[Fly Boomer]

6 minutes ago, Paul Thomas said:

There is an altitude where you can't turn back, one where my level of skill won't allow me to turn back but the airplane could make it, and one where I can turn back and land. Knowing those is useful.

I agree, but I have this mantra that subordinates those calculations, and plays on repeat with the volume turned up to 11:  "DON'T STALL".

[PT20J]

9 hours ago, hazek said:

You cannot hold altitude when engine is dead. If you try that you will stall.

You cannot load the wing just above stall, by definition you have then stalled.

 

True, I should have said just below stall. 

[exM20K]

12 hours ago, hazek said:

You cannot hold altitude when engine is dead. If you try that you will stall

That wasn’t what I said. I was referencing the POH angle-of-bank / stall speeds. Being patronizing and pedantic together: Nice job.

[hazek]

18 minutes ago, exM20K said:

That wasn’t what I said.

Apologies. On second reading I admit I don't understand what you were saying. Can you please clarify your point?

[hazek]

Dead attempting the turn back: https://asn.flightsafety.org/wikibase/543251

According to the article at least, they had engine problems after takeoff and attempted to foolishly turn back. I checked on google maps if there were options to land straight ahead. I marked the crash site with an X:

 

But maybe they didn't bank steep enough? Or maybe they should have practices this maneuver more?

 

p.s.: I will now post stories of deaths due to a turn back in this thread

[hazek]

Likely another one: https://asn.flightsafety.org/wikibase/542908

[hazek]

I found these two examples looking only a week back. Are you beginning to see my point?

[takair]

Perhaps mentioned previously….One way to (sometimes) mitigate risk is to plan a downwind departure and in some cases continue to climb over the airport.  Turning toward the downwind earlier than “normal” starts to set one up for an airport landing earlier.  I fully recognize this is not always practical and only find myself using it when I’m feeling paranoid at an airport with limited options and favorable traffic.  I will also use it after performing significant engine work (paranoid).  I know there is still a window on initial climb out where we are still at risk, but the technique does get you to glide range sooner than simply flying away from the airport.  This is not unlike how some instructors teach always remaining in glide range of the runway when doing pattern work.  Flying a tight pattern is not 100% bulletproof, but can contribute to better odds during an engine out.  Just watch your AOA in the turns.  Play the game, “where would I land now” to see the best departure/ pattern from airports you frequent. Your mileage may vary depending on trees, terrain, airspace, traffic, etc, but it sometimes reveals some options you may not notice in a true emergency.  Anyway, my 2 cents, and always hoping for some extra luck at the moment we need it.