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Inadvertent Spin- wheels up or down?


Raptor05121

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On 12/9/2017 at 2:20 PM, Raptor05121 said:

Hypothetical situation. You're in a spin in your Mooney. Disregarding ability to reach the gear, more pressing issues, altitude, etc etc etc: Would it be aerodynamically advantageous to lower the gear or leave it up?

Back story on the Piper Forums, I've never heard of this:

 

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Why would a person be messing around with the gear lever while correcting an inadvertent spin.  Might as well take a quick check of your pulse-ox during the spin too.

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I couldn't tell... is there a lag on the AI or just so much data whizzing by every second the lag is more behind my eyes than in front... :)

The last video from the tail is interesting...  water vapor is streaming from the wing tips... a sign of low pressure (lift?) knocking water out of solution...

With such a fast stall recovery, it looks as though the Pipistrel wing design keeps the wing tip section with airlerons from stalling, or recovers very quickly..(?)

Four people riding in a stalling airplane takes a lot of planning and preparation and testing to prove the results...long before boarding...

 

best regards,

-a-

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1 hour ago, Hank said:

Interesting vapor trails coming from the wingtios starting in spin #8. What's up with that? Only noticed them on tbe view from the tail.

Descended into some humid air, I think.

Or maybe that's where the exit is for the relief tubes.

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On 12/10/2017 at 3:36 PM, squeaky.stow said:

If you are in a spin, you are stalled. Your priority is to reduce the angle of attack to get the wing flying again. That means full down elevator and some patience. Stopping the autorotation if you can with full opposite rudder and idle power will 

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Full down elevator will not help in some aircraft... the F-15, for example, will not recover from a spin with full forward stick.  Recovery procedures vary by airframe... most say to neutralize the controls, then apply full opposite rudder.  In some aircraft, rudder may not help... and Aileron is required.  It all depends on the jet/plane.  To say “full down elevator and some patience” is a pretty broad statement, that isn’t very accurate.

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8 hours ago, Hank said:

Interesting vapor trails coming from the wingtios starting in spin #8. What's up with that? Only noticed them on tbe view from the tail.

The wingtip trails are the fuel coming out of the wing tank vents due to centrifugal forces and low wind impact velocity on the vents.. When low on fuel the fuel may un port from the tank fuel pick up during a spin. Aerobatic planes have a flop fuel pick up hose that follows the fuel.

José

Edited by Piloto
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On 2017-12-16 at 5:54 PM, M016576 said:

Full down elevator will not help in some aircraft... the F-15, for example, will not recover from a spin with full forward stick.  Recovery procedures vary by airframe... most say to neutralize the controls, then apply full opposite rudder.  In some aircraft, rudder may not help... and Aileron is required.  It all depends on the jet/plane.  To say “full down elevator and some patience” is a pretty broad statement, that isn’t very accurate.

Agreed that fighters can require some very different techniques for spin recovery. This is partly because of the ratio of fuselage mass to wing mass (which is the opposite of GA aircraft design) and the partly because of the effect of fly by wire flight control computers on the pilot's control inputs. There is some good literature available on the topic of fighter aerodynamics, but none of this is really relevant to the question which this thread began with which is the discussion of spin recovery in a GA aircraft like the Mooney. 

The Mooney POH is pretty clear (at least for my K) Don't do them. But if you do end up in one: 1) Full opposite rudder. 2) Control wheel forward (as much as it takes to break the stall. 3) Ailerons neutral. 4) Throttle idle. Deviate from this advice and you are now a test pilot. But not the cool kind.

Other than slight variations on the order of the above steps, I have never seen a GA aircraft (canards excepted) that had any other spin recovery procedure recommended by the manufacturer.

 

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22 hours ago, squeaky.stow said:

Agreed that fighters can require some very different techniques for spin recovery. This is partly because of the ratio of fuselage mass to wing mass (which is the opposite of GA aircraft design) and the partly because of the effect of fly by wire flight control computers on the pilot's control inputs. There is some good literature available on the topic of fighter aerodynamics, but none of this is really relevant to the question which this thread began with which is the discussion of spin recovery in a GA aircraft like the Mooney. 

The Mooney POH is pretty clear (at least for my K) Don't do them. But if you do end up in one: 1) Full opposite rudder. 2) Control wheel forward (as much as it takes to break the stall. 3) Ailerons neutral. 4) Throttle idle. Deviate from this advice and you are now a test pilot. But not the cool kind.

Other than slight variations on the order of the above steps, I have never seen a GA aircraft (canards excepted) that had any other spin recovery procedure recommended by the manufacturer.

 

The F-15C is a mechanical flight control system, not digital fly by wire like the hornet and super hornet.  I’ve flown all 3- the recoveries are similar for departure spin despite the fact the F-15 is mechanical and the F-18 is digital fly by wire.  But you are correct, a fighter is different than a GA piston.

pushing the yoke/control wheel/stick full forward will increase the rotation rate in many aircraft, light GA included.

the mooney says “forward of nuetral” which does not say full forward.  The bonanza A35 does say full forward, though. The baron says ease yoke back pressure , Seneca is similar (although with twins the cg and weight distribution changes things a little).  

Back to the original comment, though: you said “full down elevator and some patience.”  That is not the written procedure in a mooney- and will actually increase your rotation rate, and could delay the spin recovery.  Like you said- test pilot, but not the cool kind.

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Off topic, and just as an aside, the F15 actually has both mechanical and fly by wire.  If the stick gets jammed, you can still fly it by applying pressure to the stick.  If the electrics die, you can still fly by moving the stick.  I've been told that the fly by wire is quicker so that is what usually moves the controls.  Agreed though that fighters often use different control inputs to exit a spin.

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10 hours ago, Bob - S50 said:

Off topic, and just as an aside, the F15 actually has both mechanical and fly by wire.  If the stick gets jammed, you can still fly it by applying pressure to the stick.  If the electrics die, you can still fly by moving the stick.  I've been told that the fly by wire is quicker so that is what usually moves the controls.  Agreed though that fighters often use different control inputs to exit a spin.

That is true- but it’s not really fly by wire... or at least it’s not reall digital fly by wire as it’s applied in the F-18.  The system is called “CAS” or Control Augmentation System.  The CAS is an overlay on the mechanical system which allows for slightly more rudder and stabilator deflection. Its applied through a force sensor in the stick.  The CAS tends to “fall offline” during aggressive maneuvering of the jet.... if that were to occur in an F-18 or F-16, the jet would depart controlled flight- in the eagle, you just lose a little instantaneous turn performance and a little departure resistance.  But you’re correct- my statement above wasn’t wholly accurate- the F-15 does have an augmentation system.

the F-15E has a digital flight control system, similar to the F/A-18.  I’ve never flown the E model eagle, but supposedly it flys very nicely.  I can’t validate that the CAS moves the jet before the mechanical controls - but I do know that the CAS cannot fully deflect the stabs.

Edited by M016576
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2 hours ago, Mcstealth said:

What is PARE?

Isn't it Power (to idle), Ailerons (wings level), Rudder (opposite spin direction), Elevator (to recover from dive when spin stops)? I don't do aerobatics and have no spin training, but that's what I recall. 

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17 hours ago, Mcstealth said:

If I was taught that, I don' remember it. 

I've never been taught spins either, it is all ground-based self education. Judging by the reaction above, I got it right. It's certainly something to NOT practice in your Mooney!

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On 2017-12-21 at 8:17 PM, M016576 said:

That is not the written procedure in a mooney- and will actually increase your rotation rate, and could delay the spin recovery.

Do you have a reference source for this? The part about increasing your rotation rate I mean.

I agree that my "full down and patience" was pretty generic. The actual Mooney POH says "Control Wheel......FORWARD of neutral in a brisk motion. Additional FORWARD elevator control may be required if the rotation does not stop." 

In other words Mooney appears to be saying that more nose down may be required to stop the rotation, not less.

I have never spun a Mooney and don't plan to try, but I have done literally hundreds of spins in aircraft that are certified to do so, and one inadvertent one in an aircraft that was most emphatically NOT certified for spins. (F-5) What I can tell you from that experience is that the longer you remain in a fully developed spin, the more likely it is to flatten out due to rotational inertia, and the more it flattens out, the more forward elevator you will need and the longer it will take to recover, hence my generic comment about full down and patience. Whether or not an GA single is certified for spins depends largely on whether the flight controls can generate enough aerodynamic force to overcome the combined forces of CG location and the gyroscopic inertia functioning in a spin. A tail that is too small, has limited control surface authority, or is blanked aerodynamically by its position (some T-tails) may not be able to do this. 

For those interested in PARE and a great summary of spin aerodynamics, here is a good source with lots of additional references: https://en.m.wikipedia.org/wiki/Spin_(aerodynamics)

M016576, you have me curious about how you ended up flying both the Eagle and Hornet/Super Hornet. Did you go from the USAF to Naval Reserves, or do an exchange or something? I have always been envious of the American Guard and Reserve programs. My F-16 time came courtesy of an exchange tour with the USAF, but you don't often meet someone who has flown both USAF and Navy types.

Oh, and Merry Christmas to everyone on Mooneyspace! As a newbie Mooney owner, this forum has been an incredibly valuable source of information. I would never have known about WeepNoMore or LOP or so many other technical issues without you folks. And Happy New Year.

Regards, Mark

 

 

 

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8 hours ago, squeaky.stow said:

Do you have a reference source for this? The part about increasing your rotation rate I mean.

I agree that my "full down and patience" was pretty generic. The actual Mooney POH says "Control Wheel......FORWARD of neutral in a brisk motion. Additional FORWARD elevator control may be required if the rotation does not stop." 

In other words Mooney appears to be saying that more nose down may be required to stop the rotation, not less.

I have never spun a Mooney and don't plan to try, but I have done literally hundreds of spins in aircraft that are certified to do so, and one inadvertent one in an aircraft that was most emphatically NOT certified for spins. (F-5) What I can tell you from that experience is that the longer you remain in a fully developed spin, the more likely it is to flatten out due to rotational inertia, and the more it flattens out, the more forward elevator you will need and the longer it will take to recover, hence my generic comment about full down and patience. Whether or not an GA single is certified for spins depends largely on whether the flight controls can generate enough aerodynamic force to overcome the combined forces of CG location and the gyroscopic inertia functioning in a spin. A tail that is too small, has limited control surface authority, or is blanked aerodynamically by its position (some T-tails) may not be able to do this. 

For those interested in PARE and a great summary of spin aerodynamics, here is a good source with lots of additional references: https://en.m.wikipedia.org/wiki/Spin_(aerodynamics)

M016576, you have me curious about how you ended up flying both the Eagle and Hornet/Super Hornet. Did you go from the USAF to Naval Reserves, or do an exchange or something? I have always been envious of the American Guard and Reserve programs. My F-16 time came courtesy of an exchange tour with the USAF, but you don't often meet someone who has flown both USAF and Navy types.

Oh, and Merry Christmas to everyone on Mooneyspace! As a newbie Mooney owner, this forum has been an incredibly valuable source of information. I would never have known about WeepNoMore or LOP or so many other technical issues without you folks. And Happy New Year.

Regards, Mark

 

 

 

Mark-  I should be clear on this: I’m not a mooney test pilot, nor have I spun a mooney.  Upon reading my above posts- I come off as more of the “authority” on this subject than I am.  However, like you, I’ve spun multiple aircraft, albeit all in a military setting.  The only prop aircraft I’ve spun is the T-34C.

here are two sources regarding elevator position in relation to spins, and spins in general- the first is very generic, the second is a NASA paper that is far more in depth.  On the NASA paper, read the “elevator effectiveness” section, or just the whole thing- it’s a good read.

19720005341.pdf

https://www.aopa.org/news-and-media/all-news/2010/june/03/spin-myths

the key I’ve found in my experience is to know the jet or plane you’re flying and to follow the written procedure.  Full forward during the incipient phases can tighten up your spin (initially, although if rudder is applied, should in general break the stall, depending on the mode... but yes certainly not the first move), or worse: invert you.

so I guess both of us have made some generalities in this topic- as it’s pretty much inevitable to do- but full forward and patience, is not the written procedure and would not be where I’d choose to start my recovery. Instead I’d go with the recovery procedure outlined in the book.

I started in the US Navy- Flew Super Hornets, then Hornets for 12 years.  I left the Navy and was “hired” by the Air National Guard as a F-15C instructor pilot. I’ve been doing that for just over 6 years now.  The Guard is a pretty interesting operation: a mix between USAF, Navy, Marines and “guard babies.”  Makes for a diverse cultural dynamic.  I’m very lucky to be the “token” navy guy in my unit- it’s been a great ride!

 

Edited by M016576
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