Another crash :(

[Skyrys62]

This one today. Close to my hometown and where I fly.
http://wkrn.com/2017/05/12/small-plane-crashes-in-kentucky/

 

[Jim Logajan]

Lose your engine on climb out and you have to push the yoke/stick/side stick right now and aggressively to reduce your pitch angle to best glide. -Skip

Only if you are climbing at less than best glide speed. Otherwise you don't need to push or pull on the elevator control. The plane will naturally (and rather quickly, actually) pitch down so as to maintain trimmed speed. I bet you $50 that if you take an airplane up to the altitude where you practice stalls and put it into a Vx or a Vy climb and the airplane's balance is within its Cg limits and you cut the engine and keep your hands off the elevator control and you video the airspeed indicator, it will barely budge (a few knots at most) from the trimmed climb speed. Left alone it may wallow through a few phugoids, but stall? Not likely.

I feel like I am the only bloody pilot on the planet who has actually experimented with engine loss on climb. I went through several permutations and climb speeds, including one where I had the trim all the way back and flaps down slowly climbing in a C-152 with the stall alarm squealing away. Cut engine - even then it didn't stall. Just pitched dramatically down. Scary - instinct is to pull back.

Mentally prepare yourself to PUSH on climb out under a thousand feet (or 2) should the fan stop.

No. Mentally prepare for the plane to pitch itself down rather abruptly so as to maintain its airspeed. Avoid the instinct to keep the nose up, though (the natural pitch down can be off putting.) I suppose if one needs some psychological trigger to avoid pulling, then an ingrained push may be preferable. Maybe. But it is aerodynamically redundant at best. Same $50 bet as I made to Skip Miller: make a video of the airspeed indicator of your favorite airplane in a climb, cut the engine while keeping hands off the elevator control, then if the video shows the airplane slowing so much it stalls you make an easy $50.

Capitalized for emphasis. Pitch for airspeed.

The airplane already will pitch for the trimmed airspeed. The airplane immediately begins decelerating and the nose begins dropping. In the airplanes I fly (C-152 and C-172) the Vx and Vy speeds aren't far enough from best glide as to make much difference at low altitudes, so mucking with the elevator control is secondary to aileron control and turning to someplace friendly.

If the engine stops on climbout you need to get the nose down quickly to keep from stalling.

Same $50 bet as I made to iflyvfr and Skip Miller.

I think he means 'push' the nose down, should the engine fail. It can take quite a push to keep it flying, and avoid the stall. One has to take what's mostly right in front, low altitude after departure.

Same $50 bet as I made to iflyvfr, Skip Miller, and Salty. The last quoted sentence is not unreasonable, though if some thought is given before each takeoff on friendly places to set down past the departure end, one may up the survival odds.

I don't know that anyone quoted will actually take my bets since none were expecting to be contradicted. I don't know that I would even win any or all of them if they were accepted and acted on, but obviously I have done enough experiments to feel pretty damn confident that an GA airplane withinCg limits will not enter a stall if the engine quits during a climb (probably regardless of configuration.)

Actually I would really like others to try the experiment regardless of any "bet" made to entice others to try it: enter a trimmed climb so hands-off elevator (or light as possible touch on ailerons if needed - rudders as needed of course), cut engine, watch (ideally video record) airspeed and artificial/real horizon to see how much they vary. My experiments have been in only two airplane models. Maybe I'll be out as much as $200 - or maybe this post will start getting some safety education for everyone. Maybe I'll finally bust a myth or be shown wrong.

 

[Jim Logajan]

Put me in the PUSH camp.

On average, it will take a pilot about 3 seconds to recognize what's going on and to react. By this point the airspeed may be very close to a stall, and a good PUSH is what it's going to take to get the nose down to avoid a stall and maybe get somewhere close to best glide so you can aim for something soft.

Only if a pilot attempts to maintain the pitch at the same angle relative to the horizon would an airplane slow to a stall on engine out. But if the pilot is holding a constant pressure, or no pressure (trimmed,) then the air speed will not change much. That is because by regulatory requirement trim (and implicitly constant back pressure) must act as an airplane's speed cruise control.

In fact, no airplane designed to Part 23 standards for trim and longitudinal stability will exhibit the behavior that you claim.

So I extend to you the same $50 bet I presented above: that if you put your E-LSA (presumably built to ASTM standards which have similar longitudinal stability requirements to those in Part 23) into a climb and trim to Vx or Vy climb speed, or hold constant stick force to accomplish same, then your Sky Arrow 600 will not stall within either 3 or even 300 seconds after you cut engine power.

If you decide to publicly accept the bet and I win, don't send me the $50 - just make a donation to Angel Flight West in that amount. But it is safer to not publicly accept the bet and quietly confirm it for yourself, then if it doesn't work out like you thought you aren't out a penny. Keep in mind none of the other posters I offered the bet to has yet publicly accepted. Maybe they don't want to take my money? Maybe weather hasn't been favorable to go up yet and video record the alleged stalls before accepting my bet so as to make it a sure-thing?

 

[Jim Logajan]

Wow. Did not think my post could possibly provoke such a response.

Sorry. The reason I responded at all was your claim, like many others have, that loss of power on climb will cause a stall. This is a myth. The only way to bust a myth is to make people actually try it.

I only know that pilots surprised by an engine failure, for whatever reason and with whatever manipulation of controls, can and do see a rapid degradation in airspeed unless an aggressive "push" is involved. If that "push" is more like a massive decrease in back pressure, so be it - pitch has to be aggressively decreased no matter how you say it. Trim state comes into play as well.

Actually the cause of such stalls is the instinct to pull back on the elevator when the nose starts to drop.

I'm not alone. "A big push" is mentioned in this video:

Shucks no - you are not alone at all - you and many others have already made the claim. Note that the fellow who made that video had to resort to displaying a simulated airspeed indicator rather than a real one. We'll have decent flying weather here later in the week - I'll try to make the video that shows what really happens since no one else seems inclined to even dare try it, nevermind make a video recording.

Not interested in bets or getting into a back-and-forth to prove who's right. My visualization and explanation of what to do if the engine fails after takeoff has held me and my students in good stead for many years. If you prefer a different way to express it, that's fine as well.

Actual engine out demonstrations seem to be done only at cruise speeds in level flight (and sometimes descent), and then only to train for a requirement in the PTS. In such a scenario students are taught to slow the airplane - which involves a PULL since best glide speed is less than cruise. You (and others) are telling them to do the exact opposite if it happens in a climb, but how often do instructors physically demonstrate what happens on engine power loss during climb with, and without, touching elevator control? Looks to me like near zero.

As to the bet and "who is right": All I want to do is stop a myth that points people in the wrong direction as to solutions. I don't know how else to do that. What would you do if somebody posted "If you lose engine power in cruise flight, your airplane will stall unless you PUSH forward on the yoke."? And then you saw a whole bunch of alleged pilots and instructors post agreement?

 

[Jim Logajan]

I'm not sure I understand your bet. In the Cub, I climb out at about 60 with full power. I fly base and final at about 60 at idle. It seems like you're saying no trim adjustment should be needed. But that's not accurate. Eight or nine turns of trim are needed between takeoff and final. Langewiesche asserts that in an ideal airplane, the same stick position will give the same speed regardless of power setting. But the same trim doesn't give the same stick position regardless of power.

Not sure I understand (never flown a Cub.) Are you saying the trim setting for 60 on climb is different from the trim setting for 60 on final? Is it a J3 or Super Cub? That is, are flaps being used on final but not on climb?

 

[Jim Logajan]

You can't make a blanket statement like that; all aircraft are different. For many conventional airplanes, yes. But fly a homebuilt with a high thrust line like a Kolb (or even a certificated aircraft like a Lake amphibian) and you better push forward right now if the engine quits, or even if you reduce the throttle. Very light or high drag aircraft (ultralights or near ultralights, and many biplanes) will slow down below stall speed before the aircraft's stability brings the nose down, and high thrustline aircraft need significant trim adjustments with power changes.

Other reasons to get the nose down fast are to maintain speed for maneuvering and/or flaring if at very low altitude, and to see better over the nose.

I don't dispute anything you wrote - you are correct. Also, I did not intend to make a blanket statement applicable to all airplanes. Earlier in the thread I wrote the following with the intent to narrow my assertion:

In fact, no airplane designed to Part 23 standards for trim and longitudinal stability will exhibit the behavior that you claim.

 

[Jim Logajan]

What is your data set of planes flown that you think won't stall on loss of power?

I've only experimented with a C-152 and C-172. That's all that is available for rent at my FBO.

 

[Jim Logajan]

Sorry, I did not see that LoganJan had responded to my controversial post. But I'm not afraid to take a bet and give it a try, not at all. When I get the opportunity, I will most certainly take your bet for the good of the order and my own edification.

Great! If it doesn't slow to a stall, make a $50 donation to Angel Flight West. If it does, let me know where I should send my $50. I've reserved some time for Friday afternoon in the local C-152 to see if I can get some videos of the attitude indicator, airspeed, and throttle. (Last time I did the experiment I found that the engine did not like throttle being cut fast.)

 

[Jim Logajan]

Yes, very different. J3, no flaps.

I had time to ponder your experience during work today - all I can think that is different between climb and landing is that the engine is at full throttle on climb and much reduced throttle on landing, so the different trim settings might be due to different amounts of propwash over the tail in each scenario. The J3 Cub was designed quite a while back, so the longitudinal requirements back then (to the extent they existed at all) differed from current Part 23 standards.