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Wing drop at stall

Old 26th Aug 2019, 16:37
  #61 (permalink)  
 
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When I flew the spin testing on the MXP740 Savannah with a Jabiru 2.2L engine, the engine generally stopped at about 2 turns. It was never considered appropriate to give it a deliberate spinning clearance anyhow, so that was no big deal - but it did show the wisdom of the teaching that you always do such testing over a runway! (Although, as for your Robin, it also restarted easily enough.)

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Old 26th Aug 2019, 23:57
  #62 (permalink)  
 
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Cessna produced a pamphlet in the late 1970’s that expanded on the spin for all Cessna SEP’s by model. For all models the first 180 deg of rotation was considered the spin entry and a normal stall recovery ( ie start with pushing wheel forward) could be used. Only after 2 full turns is the spin considered fully developed and the POH spin recovery method should be used.

The bottom line line for an initio is if you are teaching spinning where you let the spin wind up so that a full spin recovery should be used you are providing negative training as the pro spin controls must be maintained in order to get the aircraft to be established in a spin. The objective of the exercise should be to instil the automatic and instinctive reactions so that the aircraft never gets near to an actual spin mode.
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Old 27th Aug 2019, 07:54
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Big Pistons Forever

From your quote of the Cessna pamphlet it makes no sense to me for the following reasons; the PA28-140 Service bulletin 753, Dec 1982 gives a height loss of 1,000 ft for one spin, Cessna 152/172 manuals also give 1,000 ft loss for the first rotation, Robin 2160 suggests 1300 ft should be allowed for a full recovery from the first rotation.

The above figures are given for the published POH spin recovery technique. In most of the light aircraft POH the standard spin recovery carried out for type approval is used although sometimes badly written and vague using terms: "briskly", "pause" etc. The original Slingsby manuals did state that the hand control should be moved forward and centralised but following a number of fatalities this was later amended adding "...even if the stick requires moving fully forward to its limit".
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Old 27th Aug 2019, 09:56
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Frog - absolutely nothing you are saying contradicts anything either BPF or I have said. Are you arguing with yourself?

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Old 27th Aug 2019, 16:48
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I'm not seeking to contradict anyone but put simply searching for good reason to change my view in a debate. Rudeness certainly will not resolve the issue Genghis. You may well keep in mind a quote attributed to Socrates: "the last act of a loser in an argument is to resort to the tool of slander." which of course if true helps no one.

BPF can of course speak for himself but without seeing or at least having a verifiable quote from the Cessna pamphlet i'm not convinced that Cessna have written the words referred to from the pamphlet. I'm absolutely certain though that BPF is genuine in how he remembers the pamphlet and is simply wishing to make a valuable contribution as am I..
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Old 28th Aug 2019, 04:15
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The Cessna manual is available at this link

https://mikeklochcfi.files.wordpress...pin-manual.pdf

from page 2

Here, in the entry phase, recovery from or prevention of the spin is as simple as normal stall recovery since, in fact, at this point that's all we are really faced with. Coordinated use of rudder and aileron to oppose any tendency to roll should be applied with emphasis on the rudder due to its generally more powerful influence at this point. This should be accompanied by relaxation of elevator back pressure to reduce the angle of attack below that of the stall. Coordinated use of all controls should then be applied to return to normal level flight.
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Old 28th Aug 2019, 10:57
  #67 (permalink)  
 
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An almost textbook spin entry maybe?
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Old 28th Aug 2019, 21:23
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No expert on spinning other than normal flying instructor stuff in 152, 172, PA28140 and Tomahawk over 40 years..
But my last Tomahawk spin was exciting, normal entry couple of spins and standard recovery technique..
Then the nose pitched down into a very high rotational mode i had never seen before. But the manual printed that this could occur.
So i waited and waited, getting lower and lower. So at what point do you think this is not coming out.
I had read the Slingsby accident report and conclusions and that came back to me, so i went pro spin, pulled hard back and then recovery mode but more forceful.
And it snapped out of the spin.
I never spun the Tomahawk again, that was some years ago.
I have seen the NASA spin video, but they all seem quite gentle.
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Old 28th Aug 2019, 22:47
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BPF

Thank you very much for producing the Cessna Pamphlet which is extremely interesting.

Your said:
"Cessna produced a pamphlet in the late 1970ís that expanded on the spin for all Cessna SEPís by model. For all models the first 180 deg of rotation was considered the spin entry and a normal stall recovery ( ie start with pushing wheel forward) could be used. Only after 2 full turns is the spin considered fully developed and the POH spin recovery method should be used."

The pamphlet did not say anything of the kind. Below is word for word copied and pasted from the pamphlet:

During this incipient phase, spin recoveries in those airplanes approved for intentional spins are usually rapid, and, in some airplanes, may occur merely by relaxing the pro-spin rudder and elevator deflections. However, positive spin recovery control inputs should be used regardless of the phase of the spin during which recovery is initiated. Briefly, these control inputs should be 1) neutral ailerons and power off, 2) full rudder opposite to the direction of rotation, 3) just after the rudder reaches the stop, elevator briskly forward to break the stall, and 4) as rotation stops, neutralize the controls and recover from the resulting dive. Using these procedures, recoveries are typically accomplished in from 1/8 to 1/2 turn during the incipient phase.

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Old 28th Aug 2019, 23:49
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Flying Frog

i miss remembered the exact wording but it would seem clear to me that Cessna is saying that what is in effect a stall recovery will work in the incipient phase (ie up to full 2 rotations). They also state unsurprisingly that a text book spin recovery will also work and is the recommended method after the spin entry phrase (more than 1/2 rotation)

I stand by my contention that spin training, that is deliberately entering a spin in order to effect the recovery using the POH actions, has no place in an initio flight training. All training should be recognition and recovery of the stall, including control of yaw so the airplane never proceeds past the spin entry phase before full control is regained.

Departure from controlled flight that could result in a spin should be demonstrated with realistic scenarios like a full power climbing turn stall ( ie mishandled short field takeoff) or a low power turning descending stall with a boot full of inside rudder ( base to final stall spin)

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Old 29th Aug 2019, 05:10
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Just to add an Australian flavour to the discussion after three flat spin accidents in pilot training with three fatalities in recent years. Refer
https://www.flightsafetyaustralia.co...ation-warning/ following the release of the first accident report. None of the aircraft were approved for intentional spins yet were practicing incipient spins per the PPL training syllabus.

With our new Part 61 licensing regulations, CASA expanded the scope of stall training for PPLs requiring incipient spins in a variety of scenarios yet omitted to define what was actually required in their so-called Manual of Standards.

I note that the people who write AFMs would use this definition of a spin from AC 23-8C: "A spin is a sustained autorotation at angles-of-attack above stall. ....". The manufacturer of the aircraft in that first accident report confirmed that intentional incipient spin entries are not permitted.

We are still waiting for further advice from CASA and I eagerly await the next two accident reports as I anticipate other issues.
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Old 29th Aug 2019, 08:07
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djpil

I agree with you completely and it is a concern that there is not a recognised definition of an incipient spin. Our own debate illustrates the point. BPF, the Cessna pamphlet in no way supports the idea that a stall recovery technique should be used for an incipient spin recovery ".....merely by relaxing the pro-spin rudder and elevator deflections," indeed it warns against it: "...... positive spin recovery control inputs should be used regardless of the phase of the spin during which recovery is initiated". We know that some types are very difficult to spin and just as hard to maintain in a spin such as the C172 and, only by way of explanation the pamphlet acknowledges this but goes no further. It must always be remembered and continuously emphasised to the student, it seems many instructors as well, that a well balanced aeroplane within its "utility" limits may be a very different beast than when it is operated outside these limits closer to it's maximum all up weight and aft centre of gravity.

Last edited by Fl1ingfrog; 29th Aug 2019 at 09:02.
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Old 29th Aug 2019, 09:04
  #73 (permalink)  
 
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Incipient spin training, like every training while maneuvering on the back side of the power curve involves skills, reflexes, techniques, knowledge and awareness that can only be instilled through specialised adavanced training requiring the full investment of the instructor. This in terms of proficiency and achieving consistency thereafter. It takes time, money and dedication .


There are schools and instructors out there, not many of them, which are qualified for the task. Its not enough to be good, one must master the realm of slow flight and spin. It is too dangerous in terms of risks and implications. Master it to the point that it will be difficult to make a mistake. This is the "cost " of better safety.


Slow flight up to the full spin is a flight regime with its own rules and techniques; which are often counterintuitive It takes specialised assistance and hours of personal rehearsal after reaching consistency, as it is a perishable skill, it has to be kept "current" .


The debate will be sterile and never ending, just go out there, learn, practice, the endless debate will be resolved showing the maneuver and its recovery ONCE in full confidence, period.

It will look "easy", which it is not, but became "easy" after hours and hours of correct practice.. Like eveything in aviation and also in life, there are no short cuts to profesionalism. You have to give it the time and your full investment.
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Old 29th Aug 2019, 18:24
  #74 (permalink)  
 
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Originally Posted by BigEndBob View Post
No expert on spinning other than normal flying instructor stuff in 152, 172, PA28140 and Tomahawk over 40 years..
But my last Tomahawk spin was exciting, normal entry couple of spins and standard recovery technique..
Then the nose pitched down into a very high rotational mode i had never seen before. But the manual printed that this could occur.
So i waited and waited, getting lower and lower. So at what point do you think this is not coming out.
I had read the Slingsby accident report and conclusions and that came back to me, so i went pro spin, pulled hard back and then recovery mode but more forceful.
And it snapped out of the spin.
I never spun the Tomahawk again, that was some years ago.
And that, dear readers, demonstrates why I think that people who spin without a parachute or other "get out of gaol card" are extremely foolish and I endeavour never to do so myself.

G
Genghis the Engineer is offline  
Old 30th Aug 2019, 00:05
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What Genghis said

Deliberately entering a spin and not recovering immediately ( ie within 1/2 turn or ideally less) is an aerobatic maneuver and should be taught as an essential part of an introduction to aerobatics in an aerobatic aircraft (or glider) under the guidance of a aerobatic instructor, not in a non aerobatic airplane with an instructor with no aerobatic training or experience

More than 25 years ago the FAA eliminated spinning from the PPL syllabus in favor of enhanced stall recognition and recovery training. Since then the fatal accident rate for stall spin accidents has actually gone down.
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Old 30th Aug 2019, 05:33
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The same happened in the UK, I'm pleased to say. Ab initio spin training was killing instructors.

I had to demonstrate spin recovery for my initial issue Instructor rating. Since then, during a revalidation, I have had demonstrated to me aileron reversal from a turning full-power stall in a C152. The examiner very carefully turned to the left. At about 30 deg AOB and a silly pitch attitude, the right wing gave up lifting and we snapped pretty quickly to the right - 'you have control - recover'. Actually, it entered a spiral dive to the right as balance had been maintained throughout so recovery was pretty easy even though the aircraft had dramatically changed both pitch and roll attitude. I think the examiner had practiced this a lot to get it to go just right. I'm pleased the examiner saw fit to show me things that are outside the strict syllabus with a detailed de-brief of how not to let the student get you there. We have the option to attend a 2-day seminar every other revalidation. I've been to one and won't again. I get far more value from a day with an examiner, even though it takes me outside my comfort zone (and is more expensive).

Where is the value in a seminar, anyone?

TOO
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Old 30th Aug 2019, 19:38
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Well every instructor renewal i have done in the UK involves spinning, if we take the C152 up.
Also done on instructor courses.
Getting harder to find suitable aircraft.
And they are all getting older.
Have been one or two accidents spinning certain types, but can't say it was epidemic to stop doing in benign aircraft. If anything if a few demos scares the student, good, don't stall!
And the seminars have been a waste of time, we might as well just purchase the notes they give us and save us the hassle of losing two days pay.
A better system would be a list of recommended videos to watch and learn.
I think the US has done that, with credits through a AOPA scheme.

TheOddOne, The turn with the flick out seemed a favorite of a certain Mr P S, often done in types not approved for spinning. Few spin accidents aren't actual spins, just wing drops, incipient, to very steep spiral dives, still requiring lots of height to recover.

Last edited by BigEndBob; 30th Aug 2019 at 19:55.
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Old 31st Aug 2019, 09:12
  #78 (permalink)  
 
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My 2d worth from what I learnt at CFS in the early 90s. The definition of a full spin (CFS) is 'when the aerodynamic and inertial forces have reached a state of equilibrium'. I like this, if you sit and think about it, it makes sense. Identification of a spin is (CFS again) 'buffet with un-demanded roll'. But how do you know your incipient spin has progressed to a full spin? with some aircraft, it's obvious. With others, not quite so. About half way through my RAF instructing career, the spinning syllabus changes with recoveries from the incipient stage being practiced before full recoveries. The incipient recovery for most types is centralise the controls, close the throttle, recover from the ensuing unusual attitude. Essentially, the current UPRT recovery. If this doesn't work, you are in a full spin and the correct spin recovery for that aircraft type should be applied.
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