New “impossible turn” video - Acclaim S

[Mooney in Oz]

6 hours ago, Immelman said:

there is one thing I'm not certain of: the startle factor and time required to overcome that

To get you into the mindset, for every takeoff it helps if you train yourself to expect an engine failure just before applying full power. Most important to know your minimum altitude before attempting the return.

If fields are available ahead then that would be my first choice.

[Paul Thomas]

One key takeaway for me is a Vy climb an altitude that makes the turn a possibility; I've been transitioning to a cruise climb prior to that.

I'm very impressed by her flying skills and she makes great video. It's really nice to have see/get data from a Mooney. King used a J model to demonstrate the power off 180.

[Scooter]

I used to practice this in a PC 12. 800 feet was the altitude needed to successfully complete. Practiced in the sim multiple times prior to field. Actually worked well with room to spare. However, as stated above many variables to take into consideration.

[Ibra]

On 9/3/2025 at 2:55 AM, Paul Thomas said:

One key takeaway for me is a Vy climb an altitude that makes the turn a possibility; I've been transitioning to a cruise climb prior to that.

I agree, one need to stay on full power at VY, to optimise their profile, there is some value in VY climb as it's near best glide and does not require lot of attitude changes between max power and idle power, also, if one measure risk in time, then Vy is the speed to fly up to some (power off) pattern altitude. 

There are some who claim that VX climb to altitude is better, however:

* EFATO at VX attitude is likely to lead to loss of control (stall warner rings quickly)

* Pitch attitude at VX is nowhere good to see what landing options are? 

* Consuctive and unnecessary climbs at VX do not sound good for long-term engine health (high CHT) and cause a lot of stress on the engine during the initial climb, so it is likely to lead to an EFATO one day.

One day I heard someone suggesting they do climbs at VX instead of VY as it allows to "stay over airport vicinity at pull chute altitude" (BRS/CAPS), at some point one can only say "each to their own" 

 

 

Edited Friday at 07:28 PM by Ibra

[exM20K]

On 9/2/2025 at 8:41 PM, Scooter said:

I used to practice this in a PC 12. 800 feet was the altitude needed to successfully complete. Practiced in the sim multiple times prior to field. Actually worked well with room to spare. However, as stated above many variables to take into consideration.

There was a Redbird Acclaim sim in Kerrville. @mike_elliott did you ever try an impossible turn in that?

-dan

[Ibra]

On 9/3/2025 at 3:41 AM, Scooter said:

I used to practice this in a PC 12. 800 feet was the altitude needed to successfully complete.

In UK, it was a requirement to be able to operate public transport in PC12: you have to plan routes and keep glide into airfields from cruise altitude, and you have to be able to return from takeoff with dead engine once reaching standard pattern altitude (they forget to ask for demo of ILS on 1:20 glide with idle engine from FAF and some headwind )

In PC12, your wing is way "too optimised" for this task, you are climbing 1:6 and gliding 1:16 with 2000ft short field capability 

In M20J, I am on 1:9 climb and gliding 1:11, I need some extra  runway to make it back !

In C172, I am on 1:10 climb and 1:9 glide, these maths do not add up even with 0ft loss after the turn, I am not making it back to the point where I lifted the wheels, one need some wind (or long runway) to make it work but not too much for tailwind landing 

On short runways, these 180 or 360 turns tend to work in something that climbs 1:1 (power), glides 1:30 (clean) and lands 1:5 (flaps), I have done plenty in gliders after winch cable breaks, the lowest was 360 turn from 300ft agl (I should have landed ahead, however, I had enough adrenaline for the whole day !). I tend to be skeptical, how these 180 or 360 turns after EFATO work with aircraft that have shallow climb, steep glide and can't handle short runways, I am also skeptical about the human factor or the required reaction time.

Edited Friday at 08:24 PM by Ibra

[PBones]

On 9/1/2025 at 6:21 PM, exM20K said:

Yeah, but…. Idle throttle and coarse prop have residual thrust rather than the drag of a windmilling prop pushing a dead engine.

plan for 800-1000 FPM descent rate dead stick and best glide. 
2x standard rate turn is approx 30* bank at Vbg (90 KIAS). Stall clean is 67, so some good margin there.

However,

you need approx 240* of turn to reverse course and align with the final.

that is 2/3 of a minute at 2x standard rate turn. And the sink rate is going to go well beyond your wings-level 800FPM perfectly flown deadstick descent. If you have diverted 30% of the lift vector into the turn, you’re now coming down at 1200-1330 FPM. Add the startle factor, and it just won’t work.

This exercise, as demonstrated, reminds me of all the wannabe hedge fund stud traders I crossed paths with years ago who could paper trade their way to a 4.0 sharpe ratio and immense riches.  Seldom did it work out in real time and with real money.

 

I’ll stick with small deviations from the upwind heading, a landing wings-level with as little energy as possible, and a good takeoff briefing so I’m not making things up under stress.

-dan

 

 

I was thinking the same thing, an idling engine is better than no engine for sure. It is probably a good idea to google map any airport you are taking off from to see where a good emergency landing area might be from the upwind take off runway.

[LANCECASPER]

16 hours ago, exM20K said:

There was a Redbird Acclaim sim in Kerrville. @mike_elliott did you ever try an impossible turn in that?

-dan

Maxwells bought that and have it in Longview now.

[Will.iam]

20 hours ago, Ibra said:

I agree, one need to stay on full power at VY, to optimise their profile, there is some value in VY climb as it's near best glide and does not require lot of attitude changes between max power and idle power, also, if one measure risk in time, then Vy is the speed to fly up to some (power off) pattern altitude. 

There are some who claim that VX climb to altitude is better, however:

* EFATO at VX attitude is likely to lead to loss of control (stall warner rings quickly)

* Pitch attitude at VX is nowhere good to see what landing options are? 

* Consuctive and unnecessary climbs at VX do not sound good for long-term engine health (high CHT) and cause a lot of stress on the engine during the initial climb, so it is likely to lead to an EFATO one day.

One day I heard someone suggesting they do climbs at VX instead of VY as it allows to "stay over airport vicinity at pull chute altitude" (BRS/CAPS), at some point one can only say "each to their own" 

 

 

I try not to think about the 35 to 45 seconds of vulnerability climbing to 800ft and I'm usually light weight. At max weight, unless I did a turn, I don't think I could make it back as I'm too far away. 

[Ibra]

1 hour ago, Will.iam said:

At max weight, unless I did a turn, I don't think I could make it back as I'm too far away. 

Indeed, when climb gradient is shallower than glide ratio things becomes tricky for return even with zero altitude loss on turn, obviously, this depends on plenty of parameters remaining runway, wind, weight...so, there is lot of variability.

If one is "really keen" on return, they should start turning after liftoff while the engine is running.

One can do 360 low level pattern at 300ft agl with engine running in Mooney, if engine quits higher, they can tighten the pattern, if the engine quits lower, they can squeeze ahead on remaining runway, taxiways or cross runways...

Edited Saturday at 05:39 PM by Ibra

[Hank]

As far as climb angle being less than engine out glide angle putting you too far from the runway to make it back, this was part of why Bob Kromer recommends steep initial climbs. I climb at Vx to clear obstacles, then at Vy. I need something decent to measure distance with good resolution to see how far away I am at 1000 agl.

But remember, the runway is always longer than your ground run, and you only need to return to the far end of it, not to your liftoff point. My C is in the air around 1000', and my home base is a luxurious 5000' long; my C will glide 2 sm per 1000', so if I'm climbing at 75 knots groundspeed and 800 fpm, that's 1-1/4 minutes and 1.56 miles away, so I only need to go 1.56 miles = 8250 - 4000= 4250 feet. At 2 sm per 1000 feet, that's 10,560' of glide, so I have a bit of altitude to lose in the turn and still be safe. Practice three mistakes high with a CFI before trying anything near the ground! (That's the rule with RC airplanes, and I like it.)

Use your own numbers for groundspeed and initial climb rate, I ballparked mine quite generically above--I've seen groundspeeds from mid-50 to mid-90s, and climb rates from 700-1500 fpm. It would be interesting to build a table of say three groundspeeds and three climb rates and see what the distances look like in each combination, then you'll have an idea of what is required. 

When I visit my inlaws, I'm usually on an 8200' runway, so turning back will be much easier. Note that runway width generally increases with length, too.

Fly like your life depends on it, because it does!

[PT20J]

I think David Rogers and one of his students did an analysis of this maybe 30 years ago. As I recall, the combination that gives maximum radius of operation is a climb at Vx to maximize altitude without getting too far from the runway, a 45 deg bank turn into the wind at just above stall speed to minimize turn radius, and then best glide speed to the runway. Wind and terrain are the biggest variables. Keep in mind that Vx is the speed where thrust/drag is a maximum and will result in a very high deck angle for higher powered, low drag airplanes and isn't that far above stall, so if the engine packs it in and you are at Vx, you will need to aggressively pitch down.

[exM20K]

15 minutes ago, PT20J said:

I think David Rogers and one of his students did an analysis of this maybe 30 years ago. As I recall, the combination that gives maximum radius of operation is a climb at Vx to maximize altitude without getting too far from the runway, a 45 deg bank turn into the wind at just above stall speed to minimize turn radius, and then best glide speed to the runway. Wind and terrain are the biggest variables. Keep in mind that Vx is the speed where thrust/drag is a maximum and will result in a very high deck angle for higher powered, low drag airplanes and isn't that far above stall, so if the engine packs it in and you are at Vx, you will need to aggressively pitch down.

I remember the same article. And I think your recollection is correct. So in my plane, 45° bank and clean at max take off weight, the stall speed is just under 80 KIAS, which doesn’t leave much margin below best glide speed of 90. One would be conducting this entire maneuver with the stall warning blaring in my plane.

-dan

[Hank]

23 minutes ago, PT20J said:

Keep in mind that Vx is the speed where thrust/drag is a maximum and will result in a very high deck angle for higher powered, low drag airplanes and isn't that far above stall, so if the engine packs it in and you are at Vx, you will need to aggressively pitch down.

For my C, Vs1 = 67 mph, Vx = 80 mph and Best Glide = 105 mph. My initial climb is usually 85 mph before lowering the nose to 100 - Altitude in thousands. At WOT, the deck angle at 80 mph would be very steep!

[MikeOH]

2 hours ago, PT20J said:

I think David Rogers and one of his students did an analysis of this maybe 30 years ago. As I recall, the combination that gives maximum radius of operation is a climb at Vx to maximize altitude without getting too far from the runway, a 45 deg bank turn into the wind at just above stall speed to minimize turn radius, and then best glide speed to the runway. Wind and terrain are the biggest variables. Keep in mind that Vx is the speed where thrust/drag is a maximum and will result in a very high deck angle for higher powered, low drag airplanes and isn't that far above stall, so if the engine packs it in and you are at Vx, you will need to aggressively pitch down.

My recollection, as well.  Here it is (as with most of Prof. Rogers' work, there is some math involved!):

 

turnback.pdf

[mike_elliott]

On 9/5/2025 at 3:34 PM, exM20K said:

There was a Redbird Acclaim sim in Kerrville. @mike_elliott did you ever try an impossible turn in that?

-dan

Better than that, I put new Ultra owners into a spin to get out of. As a point of transition training, I do the impossible turn at altitude, 270 deg, 45 deg back, 3 sec “oh $h!t” factor before turning  

800’ seems doable by most. Use 1k for real life. Announce “leaving kill zone “ after passing thru 1k AGL, transition to cruise climb, run cruise climb checklist, enjoy your trip

 

[MikeOH]

47 minutes ago, mike_elliott said:

Announce “leaving kill zone “

I don't recommend saying that out loud with passengers.  Just sayin'

[Jackk]

Depends on A LOT

 

Teaching black and white is DUMB

 

I had a full engine failure, if I followed the rote monkey advice and landed ahead I would have been in a ICU and my plane destroyed, instead I was fine and the paint wasn’t scratched 

 

It depends 

 

Get good training, know you and your planes limits, explore and expand on them if possible, stay dynamic and ahead of the plane 

[hazek]

9 hours ago, exM20K said:

So in my plane, 45° bank and clean at max take off weight, the stall speed is just under 80 KIAS

At which load is that? At 1g load you can bank to 90° and your stall speed is still only the one you have on your IAS indicator. The trick is not to load the wing in the turn, you have to let the plane drop when you bank to 45° for the turn back.

However as I’ve argued this will leave you low with usually the one option left that you’re at best gambling you will make. A position that leads to the death of so many.

[mike_elliott]

23 hours ago, LANCECASPER said:

Maxwells bought that and have it in Longview now.

They actually had 2, initially they had 5. Three were sold off as soon as Jerry Chen left, another was never unboxed. I tried to purchase that one for Mooney Pros, install it at a Clearwater flight school, but couldn’t get Albert Li to recognize the economic sense of not storing it any longer. I eventually lost interest in this pursuit. I’ll ask don what he sank into the one he has, as my 32k didn’t move the boxes this way

[Jeff Uphoff]

12 hours ago, mike_elliott said:

Better than that, I put new Ultra owners into a spin to get out of. As a point of transition training, I do the impossible turn at altitude, 270 deg, 45 deg back, 3 sec “oh $h!t” factor before turning  

800’ seems doable by most. Use 1k for real life. Announce “leaving kill zone “ after passing thru 1k AGL, transition to cruise climb, run cruise climb checklist, enjoy your trip

 

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.

[exM20K]

5 hours ago, hazek said:

At which load is that? At 1g load you can bank to 90° and your stall speed is still only the one you have on your IAS indicator. The trick is not to load the wing in the turn, you have to let the plane drop when you bank to 45° for the turn back.

However as I’ve argued this will leave you low with usually the one option left that you’re at best gambling you will make. A position that leads to the death of so many.

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?

-dan

[M20F]

I made the impossible turn once with Penny Benjamin, my RIO got a great Polaroid of it. 

[PT20J]

7 hours ago, hazek said:

At which load is that? At 1g load you can bank to 90° and your stall speed is still only the one you have on your IAS indicator. The trick is not to load the wing in the turn, you have to let the plane drop when you bank to 45° for the turn back.

However as I’ve argued this will leave you low with usually the one option left that you’re at best gambling you will make. A position that leads to the death of so many.

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. 

[dkkim73]

1 hour ago, M20F said:

I made the impossible turn once with Penny Benjamin, my RIO got a great Polaroid of it. 

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