Engine out practice

Discussion in 'Flight Following' started by Adam Weiss, Feb 9, 2020.

  1. Weekend Warrior

    Weekend Warrior Pre-takeoff checklist

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    How do you know he's not? Bob Hoover was a great pilot, one of the best. But how did he get there? Did he become that good by never pushing himself? I'm not advocating trying Bob Hoover stunts, but if a person takes baby steps to improve themselves, the sky's (literally) the limit.
     
  2. denverpilot

    denverpilot Tied Down

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    He wrote that his early days of test flying military aircraft as they were assembled — and all of the engine failures — were one of the reasons he knew his energy state so well, and that led to the Shrike Commander show.

    Which, he dedicated later to the Space Shuttle... a gliding brick with wings. :)

    Basically he was forced to fly things with engines that often blew up on the first flight. :)
     
  3. Weekend Warrior

    Weekend Warrior Pre-takeoff checklist

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    "Flying the Feathered Edge". I highly recommend it. 711kb-Q64qL._SL1200_.jpg
     
  4. denverpilot

    denverpilot Tied Down

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    Yup. Good flick.
     
  5. Tantalum

    Tantalum Final Approach

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    ..and up until now I was agreeing with most of your posts!! While the Aero Commander is high wing Ted Smith eventually came around and started moving the wings lower, see Aerostar
     
  6. CharlieD3

    CharlieD3 Line Up and Wait

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    Yeah? But Bob flew the Shrike.

    High wing for the win!



    Steam or glass? Conti v Lyco? Cessna/Piper?


    Gosh, I kill me!
     
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  7. Martin Pauly

    Martin Pauly Pre-takeoff checklist

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    Can we agree that "dead stick" means the engine is not making any power?

    If the engine is not making power, the prop may or may not stop. If it does stop, you are lucky, because a stopped prop - feathered or not - creates much less drag than a windmilling one.

    - Martin
     
  8. MBDiagMan

    MBDiagMan En-Route

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    Yes, it was confidence building. That guy pulled the power seemingly all the time and he taught pulling the power abeam the threshold as you describe. When in my little taildragger or my son in laws 172, that is still my landing method. A complex is a different story. I don’t do that in my Mooney or the son in laws Baron. Those planes are a different kettle of fish,
     
  9. denverpilot

    denverpilot Tied Down

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    Sure. Why not?

    NO power. Not even idle.

    But it really means the prop is stopped. :)

    If you want to say windmilling with no power, say windmilling with no power. LOL.

    @steingar was talking about idle power on the post I originally responded to. ;)
     
  10. donjohnston

    donjohnston Line Up and Wait

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    That's what I thought. But the link on post 44 shows otherwise. (unless I misinterpreted it)
     
  11. Martin Pauly

    Martin Pauly Pre-takeoff checklist

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    Don, what exactly do you see in that blog post (link on post #44) that you thinks differs from the above? I just read it, and it looks consistent: a stopped prop has less drag (resulting in lower sink rate, better glide ratio) than a windmilling one.

    - Martin
     
  12. brcase

    brcase Pattern Altitude

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    Only the Altimeter, had two VSI (Variometers) that both worked fine.
     
  13. brcase

    brcase Pattern Altitude

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    I have a disassembled one I keep just this purpose.

    Brian
     
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  14. Tantalum

    Tantalum Final Approach

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    I always liked the little whistling sound they make to show when you're going up or down

    I love Bruno's YouTube channel:
     
  15. donjohnston

    donjohnston Line Up and Wait

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    My bad. I got the "idle" and "mixture cut-off" reversed. :oops:

    The good news is that the difference between a stopped prop and an idling engine with the prop in fine pitch isn't that much. So for training purposes, it's close enough.

    What is very surprising (to me) is the difference between an idling engine with the prop in coarse pitch vs. a stopped engine with the prop windmilling in coarse pitch. I'm guessing that with the engine stopped, the windmilling doesn't generate sufficient oil pressure to get the prop all the way to the coarse pitch stops.
     
  16. MauleSkinner

    MauleSkinner Final Approach

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    My guess is the increased performance from a stopped prop would often be offset by the increased distraction of a stopped prop. ;)
     
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  17. donjohnston

    donjohnston Line Up and Wait

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    Lucky for me that I can't see my prop. :D
     
  18. Dana

    Dana Cleared for Takeoff

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    A windmilling prop in fine pitch (high rpm) has a lot of drag, much more than a stopped prop. Coarse pitch will be less drag than fine, though how much less I can't say.

    But I suspect that the only pilots who have an interest in actually trying such things mostly fly behind fixed pitch props.
     
  19. Huckster79

    Huckster79 Cleared for Takeoff

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    In a typical fixed pitch plane where the prop will naturally windmill does it make sense to purposefully stop it? Is the extra distance gained with it stopped worth the time of working to get it stopped? Idk...
     
  20. dtuuri

    dtuuri En-Route

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    If I was trying to make it back to within swimming distance of shore (for me, I guess floating on my back to shore would be more like it), I'd stop it.
     
  21. Adam Weiss

    Adam Weiss Pre-takeoff checklist

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    I didn't know either...hence the experiments.
    I'm going to keep trying different scenarios to get a better feel of the performance of my plane when the engine is dead.
     
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  22. dtuuri

    dtuuri En-Route

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    I'm tempted to crack a joke about posting a NOTAM first, but with this crowd somebody is sure to take me seriously.
     
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  23. bobmrg

    bobmrg En-Route

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    Figure 12-3 in the Airplane Flying Handbook is a graphic of prop drag at different blade angles. Goes up dramatically at less than 20 degrees or so and is at maximum when windmilling. The proper name is "flat plate drag," because a windmilling prop is like having a circular flat plate the size of the prop disc bolted to the front of the crankshaft.

    Bob
     
  24. Salty

    Salty Final Approach PoA Supporter

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    I don't buy that. You may be exactly right, but I just can't see how physics can explain that. I don't think the prop is creating more drag by moving. I do think that work is being done to turn the crankshaft and compress the air in the engine over and over again, and that work is creating more drag, but I don't see how that has anything to do with it being a flat circular plate. But this topic makes my head hurt, I don't pretend to understand it at all.
     
  25. Tantalum

    Tantalum Final Approach

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    For what it's worth, the sailboats I used to crew on for races would leave the engine in gear during racing as the theory was a stopped propeller created less drag, than even one in neutral but spinning in the water (engine off ofcourse). The fancier boats either had props that folded together, or would feather
     
  26. dtuuri

    dtuuri En-Route

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    I don't claim to know either and would like to hear from an aero engineer. Intuitively it would seem you sort of answered your own question. The dynamic pressure available from the airflow can't, to my way of thinking, exceed that available from the area of the prop arc. The resistance to the prop turning depends on its RPM and the number of compression strokes, but I don't see how it can find more driving force than available from the arc area. So, the flat plate "rule" is an asymptote.
     
  27. Brad W

    Brad W Pre-takeoff checklist

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    yea...I won't claim to know for sure...but i think that flat disk thing is just an "approximation" for some equations. Probably works out empirically compared to some practical testing
     
  28. bobmrg

    bobmrg En-Route

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    With no combustion taking place in the cylinders, the prop is being turned by the relative wind. Because the prop is connected to the crankshaft, the pistons are being forced up and down and the valves are opened and closed by the camshaft. Every time a piston rises against a closed exhaust valve it compresses the air in the cylinder...that is doing "work" and the energy to perform that work has to come from somewhere.

    Bob
     
  29. Salty

    Salty Final Approach PoA Supporter

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    Ok, you restated exactly what I said. That has nothing to do with a flat plate.
     
  30. LongRoadBob

    LongRoadBob Cleared for Takeoff

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    I’m only guessing here but since when the SHTF the pilots mindset might be a deciding factor? Better to be somewhat familiar with how the plane handles, what you have to do than starting from scratch? And the alternative is just to give up. Just because training for it isn’t perfectly the same doesn’t mean there isn’t value in it. I’m a little surprised hearing you say this.
    I’m sure it isn’t easy to dead stick, but all one can do is get familiar as best they can with the process.
    I doubt that folks that have experimented think “ok, I got this now”, it’s just to familiarize with the situation isn’t it? Knowing it isn’t realistic.
     
  31. IK04

    IK04 Pattern Altitude

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    Here is the definition of disk solidity from Chapter 2 of the Helicopter Flying Handbook. It uses the main rotor from a helicopter as the example, but a propeller has the same characteristics:

    "The solidity ratio is the ratio of the total rotor blade area, which is the combined area of all the main rotor blades, to the total rotor disk area. This ratio provides a means to measure the potential for a rotor disk to provide thrust and lift."

    There is also induced drag and profile drag acting on a rotating blade which adds to the total drag of a rotating propeller.

    Helicopter people are accustomed to these terms, so it rarely comes up in airplane discussions (until now!)...
     
  32. Tantalum

    Tantalum Final Approach

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    Maybe my post was less clear than it could have been. I was supporting Adam's decision to do this in a controlled environment. When the real world scenario might unfortunately happen, it's not his first time actually flying and landing a plane without an engine, but he has some experience with how the added performance impact from a totally dead engine, and the pilot's mindset factors into the experience

    We practice engine out, but I've never had a CFI actually kill the engine, and unless we were right next to the airport, they've all called the exercise off around 700 AGL or so.. which is exactly when those life and death decisions start to really happen

    Other things like Mixture, Mags, Fuel, etc., are easy memory items, it's actually flying and landing a totally dead plane that I think there's value in knowing what the experience is like, so that if it ever happens that's not your first time having to do it (on top of all the extra added stress). Like how in scuba school they have you practice taking your regulator out, etc., actually underwater.. just just via memorization
     
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  33. PaulS

    PaulS Final Approach

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    At the end of the day it doesn't matter, engine running, turned off, prop turning, prop stationary. It will never be the same from day to day, it's an approximation affected by things like weather, air temperature, wind direction, turbulence, pilot performance, plane performance. With this in mind, I doubt I would ever attempt this, nothing gained over pulling the power and leaving the engine on, at the end of the day it's an approximation to what you may encounter should the engine go TU.
     
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  34. Tantalum

    Tantalum Final Approach

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    This is why I at least in something with a parachute there's a 99% chance I'm going to pull.. I'd much rather be sitting next to the plane waiting for the Uber thinking "gee, maybe I could have glided and landed on this road" as upposed to wishing last minute I pulled as I hit the trees
     
  35. PaulS

    PaulS Final Approach

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    Same here, but it took a while and some prodding from my CSIP to get to that mentality. If I'm over an airfield when it happens then I'll probably glide it in as a pull is not without risk but if there is any question, it will be pull.
     
  36. IK04

    IK04 Pattern Altitude

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    Flying Cowboys style:

     
  37. Dana

    Dana Cleared for Takeoff

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    I have a piece of paper somewhere saying I'm an aero engineer but I've never actually worked as one. I've never seen an analysis of a windmilling prop that I can recall, but yes, the flat plate is way more than you'd see.

    Back of the envelope calculation, gliding at 60 kts, a 74" diameter flat plate would produce 400# of drag. For a 1200# airplane, that would add 2000 fpm of descent, a 3:1 glide ratio, and we know it's nowhere near that. A stopped prop, assuming 6" blade width, would have about 1/10 the drag of the flat plate. The windmilling prop will be somewhere in between; the energy needed to pump air through the non running engine is not insignificant.

    As for "should I stop the prop?"... you'll lose some altitude mushing slow enough to get it to stop. If you're high enough that the improvement in glide outweighs the hit to get it to stop, you should; at low altitude it's not worth it. But the critical altitude will be different for every airplane.
     
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  38. IK04

    IK04 Pattern Altitude

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    Flat plate drag is the drag of a solid object such as a sling load and is not the same thing as disk solidity.

    A spinning multibladed airfoil has several forms of drag, whether it is connected to an engine or not. It's physics, man...
     
  39. bobmrg

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    It's pretty esoteric, but the "flat plate" presented to the relative wind by the windmilling prop creates turbulence, which heats the air (however minutely).
    From Chapter 12, Airplane Flying Handbook:

    "Propellers
    The propellers of the multiengine airplane may outwardly appear to be identical in operation to the constant-speed propellers of many single-engine airplanes, but this is not the case. The propellers of multiengine airplanes are featherable, to minimize drag in the event of an engine failure. Depending upon single-engine performance, this feature often permits continued flight to a suitable airport following an engine failure. To feather a propeller is to stop engine rotation with the propeller blades streamlined with the airplane's relative wind, thus to minimize drag. [Figure 12-2]
    Feathering is necessary because of the change in parasite drag with propeller blade angle. [Figure 12-3] When the propeller blade angle is in the feathered position, the change in parasite drag is at a minimum and, in the case of a typical multiengine airplane, the added parasite drag from a single feathered propeller is a relatively small contribution to the airplane total drag.
    At the smaller blade angles near the flat pitch position, the drag added by the propeller is very large. At these small blade angles, the propeller windmilling at high rates per minute (rpm) can create such a tremendous amount of drag that the airplane may be uncontrollable. The propeller windmilling at high speed in the low range of blade angles can produce an increase in parasite drag, which may be as great as the parasite drag of the basic airplane."

    Google flat plate drag. Expect to be overwhelmed with technical talk.

    Bob
     
  40. bobmrg

    bobmrg En-Route

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    From Aerodynamics for the Naval Aviator:

    At smaller blade angles near the flat pitch position, the drag added by the propeller is very large. At these small blade angles, the propeller windmilling at high RPM can create such a tremendous amount of drag that the airplane may be uncontrollable. The propeller windmilling at high speed in the low range of blade angles can produce an increase in parasite drag which may be as great as the parasite drag of the basic airplane. An indication of this powerful drag is seen by the helicopter in autorotation. The windmilling rotor is capable of producing autorotation rates of descent which approach that of a parachute canopy with the identical disc area loading. Thus, the propeller, windmilling at high speed and small blade angle can produce an effective drag coefficient of the disc area which compares with that of a parachute canopy. The drag and yawing moment caused by loss of power at high engine-propeller speed is considerable and the transient yawing displacement of the aircraft may produce critical loads for the vertical tail. For this reason, automatic feathering may be a necessity rather than a luxury.