engine out, reducing drag

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Dave Palacios

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Now I am confused ! seams there might be two opposing ideas about which is best when you want to get the best out of your glide. Just when i thought after hearing a seminar by a well known "presenter" on a webinar (last name something like shrubs) that you want the prop to be stopped, which sounded to me to make sense, not driving the engine with the prop. somewhere in the past i heard you want to have the prop windmilling. lately i thought it was agreed by all "you want the prop stopped". listening to an old podcast this morning Patty Wagstaff was being interviewed about an engine out experience she had, it was mentioned that a windmilling prop is less drag than a stopped prop. Which is it ? what are the thoughts here on the forum. I would hope never to have to put to the test, but if i ever needed to know i wouldn't want to hesitate or take the time to toss a quarter.
 
I think if the prop is stopped it will give less drag than if it is windmilling, but the problem is, how do you get it to stop? You would need to increase pitch and get very slow, and that is not as easy to control as establishing best glide speed with it turning.
 
My Mooney M20F POH says gear up w windmilling prop I have a 10:1 glide ratio. If prop is stopped I have a 12:1 glide ratio. They had to test that to put it in the poh.

10:1 ain’t too shabby, I think in a bird not know for benign stalls I’ll take my 10:1 before trying some maneuver to come close to stall- which I was unable to ever practice.

But I’d say I’m in the camp w my Mooney poh- a stopped prop is less drag
 
Ol' Patty must have been drunk-carting (again) when she said that, cuz that's just not correct. The negative angle of attack induced by the relative airflow direction of a wind-driven airfoil (as opposed to the engine-driven case), will pretty intuitively show you what direction the lifting force of those moving blades is pointing at. A stopped prop merely has the parasite drag inherent to its cross sectional wetted area and any additional joint/interference add-ons. Way smaller drag profile than a moving windmill.
 
hindsight2020 said:
Ol' Patty must have been drunk-carting (again) when she said that, cuz that's just not correct. The negative angle of attack induced by the relative airflow direction of a wind-driven airfoil (as opposed to the engine-driven case), will pretty intuitively show you what direction the lifting force of those moving blades is pointing at. A stopped prop merely has the parasite drag inherent to its cross sectional wetted area and any additional joint/interference add-ons. Way smaller drag profile than a moving windmill.
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Uh Uh Uh , ok, i guess what you are saying you are in the "STOP THE PROP" camp got it !
 
Gilbert Buettner said:
I think if the prop is stopped it will give less drag than if it is windmilling, but the problem is, how do you get it to stop? You would need to increase pitch and get very slow, and that is not as easy to control as establishing best glide speed with it turning.
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Makes sense to me too ! As for how to stop it i have heard pitching up might do it, but seems that you would also be trading AS and then losing altitude trying to get it back. I have heard (from somewhere) that some times it stops on its own, may be with a seized engine. i wouldn't want to put it to the test though.
 
Huckster79 said:
My Mooney M20F POH says gear up w windmilling prop I have a 10:1 glide ratio. If prop is stopped I have a 12:1 glide ratio. They had to test that to put it in the poh.

10:1 ain’t too shabby, I think in a bird not know for benign stalls I’ll take my 10:1 before trying some maneuver to come close to stall- which I was unable to ever practice.

But I’d say I’m in the camp w my Mooney poh- a stopped prop is less drag
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Thank you, me too
 
Dave Palacios said:
you are in the "STOP THE PROP" camp
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You can count me in the "FLY THE PLANE" camp. In an engine out situation, you should be more concerned with what the wing is doing rather than what the prop is doing. That is, unless you have a way to feather it.
 
asicer said:
You can count me in the "FLY THE PLANE" camp. In an engine out situation, you should be more concerned with what the wing is doing rather than what the prop is doing. That is, unless you have a way to feather it.
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But of course!, But If enough altitude (time) i think doing what you can to extend the glide (and might be needed0. a lot would depend on when and where you lost the engine. Flying the plane is obvious i would think.
 
Then add in the “best glide” for distance vs. “minimum sink” for longest time aloft question. Scott Perdue covered it well in this video: https://www.flywire.online/post/what-is-your-best-glide-and-min-sink

Because it’s really difficult to tell in flight if your engine has actually died completely, I’m in the fly the plane and don’t dick around with marginal gains camp trying to stop the prop. Even a bit of thrust from a dying engine is useful and as Seth Lake demonstrates, determining whether or not your engine has actually died completely is more difficult than you think:
 
I tried this recently and agree. It was not as obvious that the engine was not running as you might think. Similar noise, similar vibration. Not exactly the same but with noise cancelling headset on not all that different at least in a small Lycoming.
 
rhkennerly said:
Then add in the “best glide” for distance vs. “minimum sink” for longest time aloft question. Scott Perdue covered it well in this video: https://www.flywire.online/post/what-is-your-best-glide-and-min-sink

Because it’s really difficult to tell in flight if your engine has actually died completely, I’m in the fly the plane and don’t dick around with marginal gains camp trying to stop the prop. Even a bit of thrust from a dying engine is useful and as Seth Lake demonstrates, determining whether or not your engine has actually died completely is more difficult than you think:
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I like Scott Purdue"s Fly wire. As for it being difficult to tell if the engine quit (completely or not) and while i am sure in some cases (maybe most) it can be difficult. From my experience, twice a complete shut down and twice partially. it wasn't difficult at all to tell immediately! what was happening. By the way at least one of the complete shut downs the prop was a dead stop on its own, the first complete shut down i wasn't paying attention to what the prop was doing. In all four cases all went well, made it to an airport and normal landings. I hope these four times covers me for "those who have and those that will". A friend's son was flying his dad's Bo, when it blew the head off one of the barrels, he said it went with a bang, i think he knew the engine was gone.
 
I’ve had my engine quit and I didn’t know it. Absolutely a thing.

I’ve also shut down an engine intentionally and tried to stop the prop. Almost to the point of stall and no joy, still windmilled. Would not recommend wasting time attempting it. Fly best glide and work the problem.
 
rhkennerly said:
Then add in the “best glide” for distance vs. “minimum sink” for longest time aloft question. Scott Perdue covered it well in this video: https://www.flywire.online/post/what-is-your-best-glide-and-min-sink

Because it’s really difficult to tell in flight if your engine has actually died completely, I’m in the fly the plane and don’t dick around with marginal gains camp trying to stop the prop. Even a bit of thrust from a dying engine is useful and as Seth Lake demonstrates, determining whether or not your engine has actually died completely is more difficult than you think:
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I have never seen a more stupid video in my life.
 
Kritchlow said:
I have never seen a more stupid video in my life.
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Other than a few cringy ways he said things at the beginning, the video accurately represents my experiences and conveys useful, accurate information.
 
Personally, I can’t imagine interrupting the immediate tasks of turning toward better terrain while achieving best glide and, if there is time, trying the restart procedure, to play Stop the Prop.

“Nice engine out landing.”
“Thanks. I stopped the prop!”
“BTW, I see your other tank is full.”
 
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Dave Palacios said:
I like Scott Purdue"s Fly wire. As for it being difficult to tell if the engine quit (completely or not) and while i am sure in some cases (maybe most) it can be difficult. From my experience, twice a complete shut down and twice partially. it wasn't difficult at all to tell immediately! what was happening. By the way at least one of the complete shut downs the prop was a dead stop on its own, the first complete shut down i wasn't paying attention to what the prop was doing. In all four cases all went well, made it to an airport and normal landings. I hope these four times covers me for "those who have and those that will". A friend's son was flying his dad's Bo, when it blew the head off one of the barrels, he said it went with a bang, i think he knew the engine was gone.
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Oh I agree, catastrophic failures where the piston comes through the cowling are easy to detect. But a lot are more subtle, a reduction in rpm but maybe not quite dead.
 
If only we had the twin’s “dead foot, dead engine” test for singles. And all the scenarios are, of course, situational. An engine packing it in at 500 ft is a different situation than one going on vacation at 5,000 ft. It just seems there are better uses of your time, altitude, & airspeed than thinking you can go a bit further by wasting time stopping the prop.
 
Kritchlow said:
I have never seen a more stupid video in my life.
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Maybe you could expand on your thinking. I have killed the engine at altitude &, like in the video, find all the key indicators, noise, engine instruments (at least at first), prop blur, to be quite similar to cruise flight.
 
Dave Palacios said:
I like Scott Purdue"s Fly wire. As for it being difficult to tell if the engine quit (completely or not) and while i am sure in some cases (maybe most) it can be difficult. From my experience, twice a complete shut down and twice partially. it wasn't difficult at all to tell immediately! what was happening. By the way at least one of the complete shut downs the prop was a dead stop on its own, the first complete shut down i wasn't paying attention to what the prop was doing. In all four cases all went well, made it to an airport and normal landings. I hope these four times covers me for "those who have and those that will". A friend's son was flying his dad's Bo, when it blew the head off one of the barrels, he said it went with a bang, i think he knew the engine was gone.
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I liked the Perdue video on minimum sink rate airspeed, because I had never come across the concept. If there is nowhere to land, like over mountains, then postponing landing buys you a bit more time to troubleshoot, communicate, & prepare yourself. If there are lots of places to land, but none of them airports (or no one spot much better than another), then stretching your distance over ground is pointless & minimum sink buys you time aloft to restart, plan, & consider.
 
Dave Palacios said:
But of course!, But If enough altitude (time) i think doing what you can to extend the glide (and might be needed0. a lot would depend on when and where you lost the engine. Flying the plane is obvious i would think.
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The trick is unless you practice it, How do you know. I have found some props just won't stop and you will lose a bunch altitude flying along just above stall trying to get it to stop. So unless you have practiced it, (not something I recommend as something you should practice) I would tell you to not even try to stop the prop. Just fly the airplane and handle the emergency like you were trained to do so.

Brian
CFIIG/ASEL
 
Speaking of catastrophic engine failure at altitude: Mike Patey’s SE turban on Turbulence packed it in at 22,000 ft. Real IFR decent to a dead stick. What a pilot! I want to be him when I grow up:
 
rhkennerly said:
Oh I agree, catastrophic failures where the piston comes through the cowling are easy to detect.
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In many of those situations, the prop already made the stop-vs-windmill decision for you.
rhkennerly said:
But a lot are more subtle, a reduction in rpm but maybe not quite dead.
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And if there were a chance for the engine to dramatically roar back to life at the last moment, stopping the prop would preclude that.
 
asicer said:
In many of those situations, the prop already made the stop-vs-windmill decision for you.

And if there were a chance for the engine to dramatically roar back to life at the last moment, stopping the prop would preclude that.
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If it didn't stop on its own and if did, and the engine roared back to life the prop probably would too. I think most here got the wrong idea of the question "windmilling or stopped". if you had partial power i don't know who would attempt to stop the prop, especially if you didn't have time (altitude /final etc). If you had an obvious complete shutdown and were at altitude and needed all the glide distance you can get, and the prop is windmilling, it might be a good idea to try and stop the prop. I don't think it would be good to try too hard, due to lose of speed then altitude, trying to get it to stop . I doubt that there are too many situations that are the same, Its probably not a black and white question.
 
Dave Palacios said:
If you had an obvious complete shutdown and were at altitude and needed all the glide distance you can get, and the prop is windmilling, it might be a good idea to try and stop the prop.
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Correct me if I'm wrong but here's the scenario:

The engine failed and it's obviously a complete shutdown. You pitch for best airspeed, select a landing site and trim. You manipulate the fuel selector, enrichen the mixture, activate the boost pump and cycle the mags. Then you advise ATC and/or squawk 7700. Passengers, if any, are briefed. While all this is going on, you notice that the prop is windmilling. The fork in the decision tree is at this point.
1. The landing site is not moving up the windshield. Would I make an attempt to stop the prop? No.​
2. The landing site is moving up the windshield. Would I make an attempt to stop the prop? Still no. I'd start making plans for another site.​
 
Huckster79 said:
My Mooney M20F POH says gear up w windmilling prop I have a 10:1 glide ratio. If prop is stopped I have a 12:1 glide ratio. They had to test that to put it in the poh.

10:1 ain’t too shabby, I think in a bird not know for benign stalls I’ll take my 10:1 before trying some maneuver to come close to stall- which I was unable to ever practice. Welded down.

But I’d say I’m in the camp w my Mooney poh- a stopped prop is less drag
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Dude, a Piper Archer III is >11.2:1 with the gear welded down and the prop windmilling. (Chart 5-33)
 
rhkennerly said:
Because it’s really difficult to tell in flight if your engine has actually died completely, I’m in the fly the plane and don’t dick around with marginal gains camp trying to stop the prop. Even a bit of thrust from a dying engine is useful and as Seth Lake demonstrates, determining whether or not your engine has actually died completely is more difficult than you think:
Click to expand...
I think that if you pulled the throttle to idle without producing a change in RPM, that would be a good indication that the engine isn't producing any power. That's one of the methods I was taught to use in order to verify which engine has died in a twin.
 
Dave Palacios said:
Now I am confused ! seams there might be two opposing ideas about which is best when you want to get the best out of your glide. Just when i thought after hearing a seminar by a well known "presenter" on a webinar (last name something like shrubs) that you want the prop to be stopped, which sounded to me to make sense, not driving the engine with the prop. somewhere in the past i heard you want to have the prop windmilling. lately i thought it was agreed by all "you want the prop stopped". listening to an old podcast this morning Patty Wagstaff was being interviewed about an engine out experience she had, it was mentioned that a windmilling prop is less drag than a stopped prop. Which is it ? what are the thoughts here on the forum. I would hope never to have to put to the test, but if i ever needed to know i wouldn't want to hesitate or take the time to toss a quarter.
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If you have a controllable pitch propeller, one thing you can do to reduce drag is pull the prop control all the way out. You can't fully feather the prop on a single, but it's a step in the right direction,
 
Palmpilot said:
If you have a controllable pitch propeller, one thing you can do to reduce drag is pull the prop control all the way out. You can't fully feather the prop on a single, but it's a step in the right direction,
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You certainly can pull the prop to low RPM, but many constant speed propeller systems lose the ability move to a higher pitch @ low power settings.
 
Clip4 said:
You certainly can pull the prop to low RPM, but many constant speed propeller systems lose the ability move to a higher pitch @ low power settings.
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Right. In most piston singles, the default prop position is the low pitch/fine pitch/high rpm one. Oil pressure brings it to low rpm. So, if there’s a big blotch of oil on the windscreen chances are you can pull the prop back all you want with no effect.

OTOH, since thinking about whether to pull the prop back will likely take 6-10 times longer than just pulling it back, might as well do it as SOP.
 
One little thing that hasn’t been mentioned yet can make a big deal - flying coordinated will also ensure you get your maximum glide performance, just like a good hard slip can help if you find yourself a little high on a short field in a real emergency. Knowing how to slip can also help if you have oil on your front windscreen and need to line up on short final.
 

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Definitely worth practicing engine out landings from cruise altitudes all the way to the runway. might need to pick a rural airport to make that happen, because coming in from 5 miles away simulated engine failure it is hard to fit into the pattern of a busy airport. But it’s a teachable and also a perishable skill. Which explains sometimes why student pilots losing an engine solo do better than 20 year pilots. Most importantly, realize that if you do lose your engine and you land almost anywhere under control, you will survive, there are 2 to 3 forced landings every day, the vast majority of them never get reported. The NTSB will never put them in the database if there’s no significant injury or damage, which is the usual case. I tried to study this for the better part of a year with the hope of actually coming up with some real data. By searching nationwide news reports, the AIN, and tips from friends and family I amassed quite a database. My plans were to stratify, according to landing site, airplane type, stall speed, cause of the forced landing and all of that. All of that was thwarted by the fact that I realized unless there was serious injury or damage the NTSB never published a report. So I had a lot of basically useless data.

But my take away of that was it around 96% of forced landings were survivable, most with no or little injury. The ones that were fatal, were almost always stall spins, the pilot obviously trying not to hit the ground. One of the most deadly FAA hazardous attitudes which people spend the least time on, is the hazardous attitude of resignation. It goes something like, oh God I lost my engine, I’m going to die, nothing I can do now…. CRASH. That is because we’ve been taught by other pilots, instructors, the media that engine outs are highly fatal. When in fact, they are highly survivable. We can do it to our fellow pilots in an insidious way. One of our friends lands engine out, is not injured, and we say oh man, you were lucky. When in fact, if you look at the data if he/she were seriously injured, they would be unlucky, as the expected result is he/she is not going to be seriously hurt, if they just don’t stall.

So, just don’t stall, fly the plane all the way until it stops, aim for the softest spot you can find. Statistically, you will be fine.
 
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Palmpilot said:
I think that if you pulled the throttle to idle without producing a change in RPM, that would be a good indication that the engine isn't producing any power. That's one of the methods I was taught to use in order to verify which engine has died in a twin.
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It could also be an indication that the engine is running, but your throttle control isn’t working for some reason.

In the twin, you’re not verifying that an engine has failed, you’re verifying that you aren’t shutting down the wrong engine.
 
Our type club's instructors teach deadstick to a landing during our annual recurrency, and talk about prop control a lot.
If you maintain control of the prop, it is much more useful to you than a stopped prop.
With a spinning prop you can pull it out and increase your range dramatically.
Also, say you are on approach with way too much energy, jam it back in and it's a great brake.
 
Engine out, windmilling fixed pitch prop, which is better - closed throttle or wide open throttle?
 
Clip4 said:
Dude, a Piper Archer III is >11.2:1 with the gear welded down and the prop windmilling. (Chart 5-33)
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That is a very high glide ratio for a fixed gear piston single, especially an all-metal design from 50 years ago. I think whoever made the chart was on something. A Diamond Star has a 8.8 glide ratio with the propeller windmilling and a 10.3 ratio with the propeller stopped. A Cirrus is 9:1 with prop windmilling. The Mooney numbers sounded more than reasonable.
 
Silvaire said:
Engine out, windmilling fixed pitch prop, which is better - closed throttle or wide open throttle?
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I can't see any advantage to having the throttle wide open, but if the engine is out it may not make any difference. Trying a restart? I'd probably open it as far as I do on a ground start.

No need to add any excess fuel in that engine compartment.
 
dmspilot said:
That is a very high glide ratio for a fixed gear piston single, especially an all-metal design from 50 years ago. I think whoever made the chart was on something. A Diamond Star has a 8.8 glide ratio with the propeller windmilling and a 10.3 ratio with the propeller stopped. A Cirrus is 9:1 with prop windmilling. The Mooney numbers sounded more than reasonable.
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That sounds reasonable to me too. curious, do you have a link or some thing, that i can use for future reference?
 
dmspilot said:
That is a very high glide ratio for a fixed gear piston single, especially an all-metal design from 50 years ago. I think whoever made the chart was on something. A Diamond Star has a 8.8 glide ratio with the propeller windmilling and a 10.3 ratio with the propeller stopped. A Cirrus is 9:1 with prop windmilling. The Mooney numbers sounded more than reasonable.
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Are you accusing Ward Evans of being on drugs.
 
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