Propeller windmilling, the truth

I suspect you are ignoring far greater risks than those you mention. Do you fly at night, over water, over trees, over mountains or hills, do you switch fuel tanks in flight, are you ever outside glide range of a runway? If you're honest, you'll say yes to at least one of those, and probably more that I didn't list, that are just as great a risk or more, than shutting down an engine in flight, over a runway at 3000 feet AGL.
That's not my point. Those other risks are a necessary part of many flights; there's no point piling unnecessary risks on top of them. I have a >1 in 6 risk of dying from cancer some day, but I still don't play Russian roulette.
 
Since it is quite hard to stop a prop by slowing close to stall it shouldn't take much of a dive to start it spinning.
 
Since it is quite hard to stop a prop by slowing close to stall it shouldn't take much of a dive to start it spinning.

In what aircraft, and for what purpose? You can get a C-65 J-3 prop to stop by accident, if the engine sputters enough, wooden prop. With an aluminum prop, there's enough momentum to usually keep it spinning fast enough to catch and run again. One of the advantages of an aluminum prop on that aircraft. With either prop, it's not demonstrably possible to dive them to restart.

This thread can't be about actual flying. It's like an argument of who's superhero flies faster. Trying to stop the prop by climbing to near stall, because you ran your aircraft out of gas and think that may give you another mile of glide range, is goofy. Practicing the same is, in my view, a Darwin award in the making.
 
That's not my point. Those other risks are a necessary part of many flights; there's no point piling unnecessary risks on top of them. I have a >1 in 6 risk of dying from cancer some day, but I still don't play Russian roulette.
No point in flying gliders then. No point in flying pistons then because turbines are more reliable. No point in flying at night. No point in flying over water. No point in flying IFR.
 
So? There is no practical difference in the scenario I described.
Actually, there is. First, a motor glider is designed and intended to fly and land with no power. Second, it is flight tested in that configuration. And finally, in order to fly a motor glider, you have to have a glider certificate. Which means training in and quite a few landings in a plane with no power.

You can argue this point all you want but it won't change the fundamental fact that intentionally shutting down the engine in a standard category single engine aircraft is simply a bad idea. Can you mitigate the risks of doing so? You can try and be somewhat successful. When the engine doesn't restart and you're forced to land and someone NORDO pulls out onto the runway without looking while you're on short final, what are you going to do? Land on the grass? Hope it's in good shape for that.

There is no comparison to creating an engine out scenario to bird strikes, vacuum pump failures in IFR, and every other situation you come up with. The first one intentionally created. Everything else is incidental, and for the most part, out of our control.

If it's no big deal, why aren't we required to demonstrate an actual engine out landing on our checkride?

But you'll never be convinced. Your mind is made up and you know better than everyone else. So go ahead, shut your engine down and have fun.
 
Actually, there is. First, a motor glider is designed and intended to fly and land with no power. Second, it is flight tested in that configuration. And finally, in order to fly a motor glider, you have to have a glider certificate. Which means training in and quite a few landings in a plane with no power.

You can argue this point all you want but it won't change the fundamental fact that intentionally shutting down the engine in a standard category single engine aircraft is simply a bad idea. Can you mitigate the risks of doing so? You can try and be somewhat successful. When the engine doesn't restart and you're forced to land and someone NORDO pulls out onto the runway without looking while you're on short final, what are you going to do? Land on the grass? Hope it's in good shape for that.

There is no comparison to creating an engine out scenario to bird strikes, vacuum pump failures in IFR, and every other situation you come up with. The first one intentionally created. Everything else is incidental, and for the most part, out of our control.

If it's no big deal, why aren't we required to demonstrate an actual engine out landing on our checkride?

But you'll never be convinced. Your mind is made up and you know better than everyone else. So go ahead, shut your engine down and have fun.
You intentionally put yourself into all those scenarios. I have a glider rating. I was 3000 AGL above a runway. An SEL is also designed to continue to glide with no power. I simply see no difference between my going gliding and shutting off my engine 3000 feet above a runway. In fact, the later is considerable safer. Odds are very high the engine will start right back up, and I was never out of glide distance from the runway. In the glider, the engine will never start up, and if you get real unlucky you can get enough sink to be well out of glide range of the runway.
 
The last couple posts have actually been discussing the real issue I see with the suggestion for real engine out practice.

the pilot. With proper trading and skill it’s a nothing burger. Without it then it’s like nascar.

anecdotal evidence from this website suggests there are some really bad instructors out in the world. I am not comfortable encouraging the in flight shutdown here.
 
Just to clarify, Ive done it once for the learning experience. It’s not something I do regularly. Though I still don’t see what the big deal is.
 
You can get a C-65 J-3 prop to stop by accident, if the engine sputters enough, wooden prop. With an aluminum prop, there's enough momentum to usually keep it spinning fast enough to catch and run again. One of the advantages of an aluminum prop on that aircraft. With either prop, it's not demonstrably possible to dive them to restart.

In the T-Craft I used to own, (A-65, wood prop), I would routinely do prop stopped glides. You had to hold it just above stall speed to get it to stop, and dive almost to redline to get it turning again. It always restarted, but sometimes (over a long runway when there was no traffic) I would glide all the way down.

I don't have numbers, but the plane definitely glided better with the prop stopped. Once I even caught a thermal and gained 1000' before losing the lift. And the plane handled differently with the prop stopped, it was particularly noticeable in the flare.

Should all or even most pilots try it? Absolutely not. Piloting skill is only a (small) part of it, it's more of an attitude thing. For the average point-A-to-point-B flyer it's unnecessary and probably a bad idea... but for many pilots of antique or experimental airplanes there's great pleasure in exploring (and mastering!) the airplane's entire flight envelope. It's about risk vs. reward, everybody draws the line in a different place.
 
No point in flying gliders then. No point in flying pistons then because turbines are more reliable. No point in flying at night. No point in flying over water. No point in flying IFR.
Soaring is the point of flying a glider. Turbines are unaffordable for most of us, so pistons are the only way we can fly a powered plane. Flying at night is sometimes necessary to get home ahead of bad weather. Flying IFR makes the airplane more useful for transportation.

Every one of those is a risk, but it's a necessary risk for participating in the activity. Unless you're a professional stunt pilot working on a film shoot (or similar), flying under a bridge, buzzing a house boat, or shutting down your engine in flight are gratuitous, extra risks, and there's no point adding those on top of the ones you already have to take.
 
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Soaring is the point of flying a glider. Turbines are unaffordable for most of us, so pistons are the only way we can fly a powered plane. Flying at night is sometimes necessary to get home ahead of bad weather. Flying IFR makes the airplane more useful for transportation.

Every one of those is a risk, but it's a necessary risk for participating in the activity. Unless you're a professional stunt pilot working on a film shoot (or similar), flying under a bridge, buzzing a house boat, or shutting down your engine in flight are gratuitous, extra risks, and there's no point adding those on top of the ones you already have to take.
So it’s not gratuitous to fly a glider, but it is to shut down the engine. Okey dokey then.
 
I fly a single, but that doesn't mean that if I had a twin I'd fly it cross-country on one engine just for the heck of it. Every activity involves necessary risks, but a good pilot doesn't add extra, unnecessary risks on top of them.
Well, I know exactly what will happen if my engine quits. You don’t. I gained that knowledge by actually doing it under controlled circumstances that were pretty darn safe, and I took every possible precaution when doing it. In my opinion, I’m safer than you because I did it, not the other way around. I think it’s “scary” to think about, but actually doing it once is not any more risky than flying a glider is.
 
Well, I know exactly what will happen if my engine quits. You don’t. I gained that knowledge by actually doing it under controlled circumstances that were pretty darn safe, and I took every possible precaution when doing it. In my opinion, I’m safer than you because I did it, not the other way around. I think it’s “scary” to think about, but actually doing it once is not any more risky than flying a glider is.
So back to your original claim, do you really still believe that a pilot who isn't willing to shut down their engine in flight shouldn't fly at all?

NACA research shows that the drag difference among a windmilling prop driving an idling engine, a windmilling prop driving a stopped engine, and a stopped prop is negligible. So I have a pretty good idea what will happen if my engine stops — my glide path will be marginally steeper that if I were descending with the engine idling, and it won't be as noisy.

Regardless, I have no intention of trying to glide to the extreme limits of my range, because more pilots die trying to stretch the glide than die putting a piston single down in a short/rough spot under control. I'll just land in the nearest clear area, and let the insurance company worry about the rest.
 
So back to your original claim, do you really still believe that a pilot who isn't willing to shut down their engine in flight shouldn't fly at all?

NACA research shows that the drag difference among a windmilling prop driving an idling engine, a windmilling prop driving a stopped engine, and a stopped prop is negligible. So I have a pretty good idea what will happen if my engine stops — my glide path will be marginally steeper that if I were descending with the engine idling, and it won't be as noisy.

Regardless, I have no intention of trying to glide to the extreme limits of my range, because more pilots die trying to stretch the glide than die putting a piston single down in a short/rough spot under control. I'll just land in the nearest clear area, and let the insurance company worry about the rest.
Where the hell did I claim that? You’re making stuff up now.
 
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That's not what I said at all. Your statement makes it sound like I am saying you shouldn't fly. What I'm saying is that if you feel that shutting off a perfectly healthy engine at 3000 AGL is so dangerous that it should never be done, then you should feel that flying at all is too dangerous because there are dozens of things far more risky that you do every time you fly.
 
I guess I'm not the only one who is computer-addicted around here! ;)
 
In what aircraft, and for what purpose? You can get a C-65 J-3 prop to stop by accident, if the engine sputters enough, wooden prop. With an aluminum prop, there's enough momentum to usually keep it spinning fast enough to catch and run again. One of the advantages of an aluminum prop on that aircraft. With either prop, it's not demonstrably possible to dive them to restart..

Tom is on the money with this one. In the 65 hp Cub with the wooden prop, flying in temperatures below 0 F becomes an adventure.
Slow the engine down to land and you have a very high probability you are going to end up flying a glider. On the Cub I fly, 1,500 rpm is the magic number. At 1,4,99 rpm it stops turning.
 
We had a saying in the military. “Why practice bleeding”.
 
You intentionally put yourself into all those scenarios. I have a glider rating. I was 3000 AGL above a runway. An SEL is also designed to continue to glide with no power. I simply see no difference between my going gliding and shutting off my engine 3000 feet above a runway. In fact, the later is considerable safer. Odds are very high the engine will start right back up, and I was never out of glide distance from the runway. In the glider, the engine will never start up, and if you get real unlucky you can get enough sink to be well out of glide range of the runway.
You did it, it worked, good on you. However, had anything gone wrong and the FAA got involved, they'd charge you with careless or reckless flying. I did almost the same thing, except I pulled the throttle. I know I could have gotten the engine back immediately, you don't.
 
You did it, it worked, good on you. However, had anything gone wrong and the FAA got involved, they'd charge you with careless or reckless flying. I did almost the same thing, except I pulled the throttle. I know I could have gotten the engine back immediately, you don't.
.

1. ********. I was not and they would not consider that reckless. I was 3000 foot over a runway which was 3 times longer than needed to land.

2. pulling the throttle back is not the same thing. Do it and you’ll see. That’s one of the reasons I wanted to see it for myself.

3.all I did was remove fuel from the fuel / spark / air formula. I’m seeing very little that could go wrong when adding the fuel back. Odds of the engine not starting are ridiculous low.

I have now experienced what it’s like when things go slient. You haven’t. Which is safer?
 
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3.all I did was remove fuel from the fuel / spark / air formula. I’m seeing very little that could go wrong when adding the fuel back. Odds of the engine not starting are ridiculous low.
Especially, since such a restart is a certification requirement.
 
Especially, since such a restart is a certification requirement.
I’d almost go so far to say, there no difference whatsoever. If the props still turning, anything that could prevent it from restarting would likely kill it with throttle pulled out.
 
Actually, it can be argued that with the throttle idling, you're more like to get carb ice which needs the vaporization of the fuel to induce the appropriate temperature.
 
In addition to all of this about engine drag (which is true and relevant), the interaction of the windmilling prop with the air also creates more turbulent air than if it were to be stopped. That turbulent air interacts with the rest of the airplane differently as well.
 
Word of caution - be careful about creative but ill-advised "practice" or "training" ideas which aren't established industry flight training norms.

One should imagine how an accident report would read before commencing with the activity. "Pilot intentionally shut down engine and/or stopped the propeller" is guaranteed to be an unfavorable look for the involved party, regardless of how good the idea seemed at the time.
 
"pilot intentionally tied their plane that has no engine to another plane and released it and had to perform a forced landing"

*gasp*
 
Yes, a free-spinning propeller would still provide some drag even if it weren't turning an engine, but the drag would be considerably less.

The information everyone wants is in NACA report 464 "NEGATIVE THRUST AND TORQUE CHARACTERISTICS OF AN ADJUSTABLE-PITCH METAL PROPELLER" (from way back in the 1930s) which examined this question in detail. Here is the resulting drag at 75 mph for the different configurations tested (the table contains other wind speeds as well):

Propeller stopped:
17° pitch: 53.0 lb drag
80° pitch (feathered): 3.3 lb drag

Propeller spinning (17° pitch):
Free spinning: 33.7 lb drag
Turning a stopped engine: 68.6 lb drag
Engine at idle (power for 350 rpm): 60 lb drag

One important point here is that the stopped, unfeathered propeller is producing almost as much drag as the one that's still windmilling and driving the engine, so it's really not worth pulling the plane almost into a stall to stop the prop for extra gliding range.
THANK YOU for this reference! For nearly two decades I've been told that the clutched, free-wheeling prop on a gyrocopter produces far more drag - thus significantly reducing engine-out glide distance - than one that is not clutched and fixed in position in the event of an engine-out, dead stick landing. I own and fly both, and experienced fuel-related engine outs in both. I could not tell the difference, they all have the same 4:1 glide ratio, regardless.

Then yesterday a customer wrote to tell me a windmilling prop produces TEN TIMES more drag than a fixed prop. This paper is exactly what I was looking for to answer people parroting urban legends told to them by folks who have no references, education, nor real-life experience on the matter.
 
One thing to bear in mind is that that 1930s NACA report was simulating a Wright J-5 engine that only turned 2000 rpm at full power, idled at 350, and turned a 9 foot diameter prop (the actual test model was scaled smaller, 4/9 scale). The prop size gives it more leverage than a modern propeller, and the low compression ratio (5.1:1!) means less energy would be required for it to backdrive the engine.

But yeah, it's nowhere near 10X.
 
One thing to bear in mind is that that 1930s NACA report was simulating a Wright J-5 engine that only turned 2000 rpm at full power, idled at 350, and turned a 9 foot diameter prop (the actual test model was scaled smaller, 4/9 scale). The prop size gives it more leverage than a modern propeller, and the low compression ratio (5.1:1!) means less energy would be required for it to backdrive the engine.

But yeah, it's nowhere near 10X.
The salient point of interest to me in the NACA report is found in the conclusion section at the end:

" 4. The drag of a free-wheeling propeller is slightly less than that of a locked propeller in the normal range of blade angle settings."
 
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