stall practice: what can go wrong?

[cooperplace]

Following on from a recent accident, I'm posting this new thread to avoid direct speculation on the cause of the accident. As a low-hours pilot, I regularly do stall practice in a jab, and it's always been a benign event. Apart from W&B issues, and assuming pre-stall checks have been done, what could go wrong with this procedure, in a jab or any other aircraft in this category?

 

 

[SSCBD]

Instead of answering this question or by the forum of which you may get some out of left field answers or confusion. You have also stated you are low hours so it may be best to go see a CFI in GA and get some stall spin training. That will raise the blood pressure at first, then ask your question face to face with the CFI.

 

 

[cooperplace]

Instead of answering this question or by the forum of which you may get some out of left field answers or confusion. You have also stated you are low hours so it may be best to go see a CFI in GA and get some stall spin training. That will raise the blood pressure at first, then ask your question face to face with the CFI.

not a bad idea.

 

 

[dsam]

Question for an experienced aerobatic pilot:

 

In a fully developed flat-spin (not a nose-down spin) wouldn't a sharp, strong burst of power (i.e. prop-blast) with full down elevator, counter-rotation full rudder, and neutral aileron, bring about significant nose-down pitch for recovery; much like the tail parachute does in certification testing?

 

I've done lots of spin practice in my early gliding years, and happily there were no flat-spins to deal with, and recovery was uneventful. Just as well, as there was no tail parachute, nor motor!

 

Flying radio controlled model aircraft (powered), I've used throttle to assist flat-spin recovery for downward pitch, although the direction of the flat-spin plus engine torque made one direction's recovery quicker than the other.

 

I'm aware that aero engines often stop during extended spins, but I'm assuming the pilot has power still available (although probably not as much power to weight as my model aircraft did).

 

Anyone with experience in this?

 

 

[facthunter]

Models can power themselves out of most things, due high power to weight ratio. Your logic is reasonable but all planes are different. Generally spin recovery is close throttle first. Some consider you can rock the plane with bursts of power in some instances. We get into pure speculation rapidly. Good test pilots would have the possibilities covered plus a spin chute and real one as well. (There is a message there somewhere). Nev

 

 

[djpacro]

In a fully developed flat-spin (not a nose-down spin) wouldn't a sharp, strong burst of power (i.e. prop-blast) with full down elevator, counter-rotation full rudder, and neutral aileron, bring about significant nose-down pitch for recovery ....

Just passing through so a very short, incomplete response.When I do a flat upright spin in something like a Pitts - outspin aileron to flatten it, a lot of power to further flatten it then move the stick forward to accelerate it and flatter still.

 

Power effects include gyroscopic forces as well as direct thrust and slipstream so the effects are different between left and right spins.

 

Perhaps I will find a link for some reading on the subject.

 

 

[dsam]

Models can power themselves out of most things, due high power to weight ratio. Your logic is reasonable but all planes are different. Generally spin recovery is close throttle first. Some consider you can rock the plane with bursts of power in some instances. We get into pure speculation rapidly. Good test pilots would have the possibilities covered plus a spin chute and real one as well. (There is a message there somewhere). Nev

With brakes on and applying power, I can pull the stick back and touch the tail skid onto the grass at run-up. I'd be guessing I have sufficient prop-airflow to make a useful difference in a flat-spin. Here's hoping I never have to put this to the test!

 

 

[facthunter]

You summed it up in the "I'd be guessing". There will be a difference but perhaps not what you want. Nev

 

 

[dsam]

Thanks for the responses on this. No doubt there are a lot of factors at play... gyroscopic forces, engine torque, adverse yaw (if/when ailerons are used), C of G, Centre of rotational mass etc. etc. - to say nothing of human factors (disorientation, inexperience, etc.). Best left to the experts... certainly not territory I want to explore without a genuine aerobatic aircraft & aerobatic rated pilot (and perhaps a parachute)

 

 

[dsam]

For what it's worth, here's a link to someone in the UK spin testing a Eurofox for certification. Looks like it has predictable spin characteristics, not going "flat", although the number of rotations is limited. Good to see this, just for my own peace of mind.

 

 

 

[facthunter]

All looks pretty predictable and fairly benign. A rather nice aircraft in my humble opinion. Nev

 

 

[SSCBD]

Also did not see and cross control entry, but hard to see with the cam position of the stick. I hate to say it but agree with facthunter above.

 

 

[dsam]

It certainly feels safe and predictable in all my normal operations. The only consideration for first timers in a Eurofox is to be confident with rudder to coordinate circuit turns nicely.

 

The full length hanging flaperons give excellent roll response, but demonstrate some (easily corrected) adverse yaw when "flaps" are fully extended for landings. Beneficially, full flap sideslips are permitted, allowing excellent handling on steep sideslipping approaches & short field work.

 

When used for glider towing, the flaperons and sideslips help get it down quickly for the next glider - much loved by the gliding tug pilots.

 

 

[facthunter]

Flapperons have to be appropriately managed, as you state. I'm not an unqualified fan. Some are lazy with rudder and need to adjust. Being used to the DHC-1, I am a cross control tending spin entry person which doesn't suit all aircraft. It becomes obvious when you do it, and centring the stick aileron wise fixes it quickly. Nev

 

 

[djpacro]

Also did not see and cross control entry, but hard to see ....

Yep, so does not show behaviour after mishandling the controls which is a more enlightening test.

[djpacro]

In a fully developed flat-spin (not a nose-down spin) wouldn't a sharp, strong burst of power (i.e. prop-blast) with full down elevator, counter-rotation full rudder, and neutral aileron, bring about significant nose-down pitch for recovery ...?

 

Perhaps I will find a link for some reading on the subject.

The APS Emergency Maneuver Training Pilot Training Manual is free online here:http://www.apstraining.com/wp-content/uploads/Rev3_APS-Training-Manual-PPRRC-200711.pdf

- Page 26 for common reflexive actions in initial stall/spin training - so, if a spin is encountered with nil training then expect one or more of these to occur which will make life much worse eg

 

• Involuntary swearing and sweating • Continuing to hold the elevator control aft because of a dramatic, nose-down flight attitude • Inadvertently applying opposite aileron as a wing dips at the stall break, or as the airplane starts to roll into an incipient spin • Wildly shoving the elevator control forward

- Page 78 for incipient spin recoveries

- Page 80 for fully developed spin recoveries - remember PARE!

 

- Page 83 for aggravated and inverted spin modes "In general, will increased power help or hinder spin recovery?" gets to your question and the answer follows on page 84 - remember PARE!

 

- Page 86 for inadvertent spin entries - remember PARE which is:

 

NASA Standard Spin Recovery: P.A.R.E. Recovery“Power” – Reduce power to idle.

“Ailerons” – Neutralize the ailerons (select flaps up). Do not allow ailerons to be deflected in either direction. “Rudder” – Determine direction of the spin and then push full rudder opposite the rotation of the spin and hold until rotation stops.

 

“Elevator” – Immediately following the completion of pushing full opposite rudder to full control deflection, then:

 

UPRIGHT SPIN: Push elevator forward through neutral INVERTED SPIN: Pull elevator aft through neutral Some aircraft may required full elevator deflection to effectively reduce angle of attack sufficiently to recover. Hold these inputs until rotation stops, then immediately:

 

“Rudder” – Neutralize the rudder (very important, holding opposite rudder deflected during recovery increases the risk of entering a spin in the opposite direction).

 

“Elevator” – Since the nose is now pointing straight down (whether recovering from a developed upright or inverted spin), airspeed will build rapidly. Smoothly but aggressively pull to the prebriefed G-load to effectively bring the nose back to the horizon.

The usual disclaimer wrt types requiring something different and, of course, the Beggs-Mueller or FART techniques if you are sure that it applies to the type in all spin modes.

 

 

[dsam]

Thanks djpacro! Very informative and comprehensive. Much appreciated

 

 

[djpacro]

Adding a separate note about hotshot aerobatic pilots who generally only fly hotshot airplanes - they would know about this, from Alan Cassidy's excellent book "Better Aerobatics":

 

In every one of these types, recovery from a flat spin is quicker and more positive with power on. These aircraft have very powerful rudder and elevator controls whose effectiveness is greatly improved by the increased slipstream that is apparent with full power applied. In each case, this increase in rudder and elevator authority is far greater than the difference in gyroscopic forces with power on and off.

He goes on to explain why you don't see this in other books and then states (but still talking about specific types):

 

When you recover from an intentional spin, the correct control inputs will always work. They will almost certainly work better with power on. The wrong inputs will not recover from a spin. The wrong inputs with power on will make the lack of recovery even more certain.....

The control movements for recovery from an upright flat spin to the left ...

 

First you must apply full right rudder. Then you move the stick back, left and forward. There must be three distinct stick movements and they should be made without rushing so that all three actions have time to work .

 

You must not go directly from the start position to the finish position without visiting the other two stations on the way.

 

If you make this recovery with power on, in one of the aircraft I have listed ... the spin will stop in less than one rotation ... If you do the same with the throttle closed, the receovery will take longer: perhaps two or three turns depending on just how flat and fast it was rotating.

The above is fine if you are a hotshot aerobatic pilot in a hotshot aerobatic airplane. If not, simply remember PARE!

 

 

[facthunter]

I was typing this before I read DJP's post above, so take that into account. It's not a response to it.

 

Do them in a certified plane with an appropriate instructor. That's not just "any" instructor.

 

I think the situation which we have been in since the early 60's is a bit hard to justify. Ie NO actual spin recovery training. I did it thoroughly and then taught it on SOME types. (Not ALL types) This doesn't mean one runs around willy nilly doing spins and I've never got near an unintentional one. I was asked to do one on a BFR a few years ago which was signed out at CPL standard. Happy to do it as I was current and so was the testing instructor.

 

I would be a significantly worse and less safe pilot without that training . I'm sure of that. A lot are interested in this , and I can only repeat myself and urge you to do the training yourself but do it RIGHT. You must understand what is happening and why. Doing it by rote isn't the way. Your benign little plane will be anything but if a load shifts or the wing gets icing on it. Spins are not entirely predictable. Nev

 

 

[dsam]

I agree with all these cautionary comments, facthunter & djpacro.

 

The last thing we need is some self-important "wannabee hotshot" getting themselves into an unrecoverable situation without a properly supervised aerobatic training program, and using an entirely inappropriate aircraft for aerobatic operation.

 

For me, this info is just "hypothetical" background knowledge that helps make me a better pilot during normal operations. As facthunter's signature tag says... "Never stop learning".... Very true indeed!

 

 

[Russ]

Ok.....in me trusty 160, raise nose, wait wait wait, airspeed drops away away, and there I am, just sort of mushy mushy....and that's it. So.....when does the next reaction kick in.....wing drop / spin etc etc.

 

Recovery......level wings...lower nose, ease on power. ( works for me ) this

 

" spinning " thing was never included in my training ( in a jab )

 

So.....is " spinning " in a jab a non event ??

 

 

[facthunter]

When a plane stalls or spins in the real world it won't be like the "prepared and set up" one you do as described. Nev

 

 

[facthunter]

That's why I consider it inadequate training. It just lets you tick the exercise off. Don't kid yourself it means much. Nev

 

 

[dsam]

I suppose the heading of this forum thread is "stall practice", so in most cases with your instructor at an appropriate altitude, stall practice & "incipient spin recognition" is as far as current training allows in RA-Aus. So usually in this very controlled (perhaps overly contrived) circumstance, the outcomes are no surprise, and rather predictably recovered at safe altitude.

 

Sadly, it is the stall-spin scenario you aren't expecting that often brings the tragic results.

 

The classic example is low and too slow in the circuit, with non-coordinated turn whilst steeply banking to final leg. Even fairly well-mannered aircraft can bite you if you let this scenario play out to its often fatal conclusion. Sufficient airspeed, and well-coordinated turns are the key to avoiding problems here.

 

Another example is airframe icing, less problematic here, but much more common in Canada where I did my initial training. Flight characteristics can be changed drastically when ice builds up, and if you don't get to where the ice goes away immediately, anything could happen - and surprisingly soon!

 

 

[Russ]

Ok.....topic is headed in part " what can go wrong "

 

Slow turn onto base ( let's say 45kts ) ...just under stall specs....turning tightish, when and what are the demons about to kick in....

 

Just asking.....