Spin practice

[djpacro]

The CASA Day VFR Syllabus is very clear as to how far is meant by an incipient spin in GA training: A5.2 Recover from incipient spin

 

Adjusts aeroplane attitude and power setting following incipient spin entry (stall with wing drop) and resumes normal balanced flight

[David Isaac]

The CASA Day VFR Syllabus is very clear as to how far is meant by an incipient spin in GA training: A5.2 Recover from incipient spin

Am I being too technical in my attempt to understand the limits of that statement? Should I assume zero rotation or just the rotation caused by the wing drop followed by the immediate recovery? What are the limits to the stall testing under the aircraft approval?

 

 

[Guest Maj Millard]

Would a 'spin' be considered more than a half rotation ?? And continuing ....................Maj....

 

 

[M61A1]

On another note Drifters have been spin tested, just probably not an approved testing regime, the first Austflight Drifters were stated as unspinnable, and I "was told ..." rigging was altered to improve performance and they "became" spinnable. Wayne Fisher developed an experimental VH registered aerobatic Drifter VH-VSI (hopefully with a beefed up structure).

A little bit of thread drift, I'm fairly sure that Fisher's Drifter is built considerably lighter those that were approved, and by reducing weight, you reduce a lot of load, especially when you start throw it around.

 

 

[Guest Maj Millard]

A little bit of thread drift, I'm fairly sure that Fisher's Drifter is built considerably lighter those that were approved, and by reducing weight, you reduce a lot of load, especially when you start throw it around.

The standard certified Boonah Drifter had TRIPLE sleeved wing spars FRONT and REAR, plus 3/16 th or 1/4" brace cables all round. All the critical plates were at least a 1/4" thick. I know Wayne was aware of all this inbuilt strength and Probabily incorporated it into his VSI design. Additionally a lighter plane is a stronger plane as it weight that breaks things, when the gs pile on, and I'm sure Wayne knew that also.

Watching him do aeros in that aircraft is mesmerising, and a masterfull performance. I also saw him do low- level stuff at Inglewood one year, and that was most impressive also. A tribute to a great pilot and a great aircraft design !........we miss ya Wayne.................Maj....

 

 

[David Isaac]

Would a 'spin' be considered more than a half rotation ?? And continuing ....................Maj....

Not normally.

Incipient is the starting rotation following the wing drop before the plane enters a fully developed stable spin. Normally the incipient stage will be one to one and half rotations in my personal experience. But DJP has pointed out that with the right technique he can enter a fully developed spin in half a rotation (and I believe him). DJP can better describe than me because he is an Aerobatic instructor of aerobatic instructors. I have only done spins in Cessnas, Citabrias, Decathalons, Cubs and Austers (with only the Citabria and Decathlon being aerobatic types).

 

Spinning is a fascinating subject in its own right and there are dozens of very interesting articles on it. Understanding what is happening to the aircraft aerodynamically is also fascinating. Fin and rudder design and position plus Cof G are critical factors.

 

 

[Guest Maj Millard]

Not normally.Incipient is the starting rotation following the wing drop before the plane enters a fully developed stable spin. Normally the incipient stage will be one to one and half rotations in my personal experience. But DJP has pointed out that with the right technique he can enter a fully developed spin in half a rotation (and I believe him). DJP can better describe than me because he is an Aerobatic instructor of aerobatic instructors. I have only done spins in Cessnas, Citabrias, Decathalons, Cubs and Austers (with only the Citabria and Decathlon being aerobatic types).

Hell David , You make me feel so insignificant ...I've only done spins in a C 172 ( unintentional at altitude off an aggressive stall) and a couple during training in a little poor C 152...................Maj.......

 

 

[naremman]

A discussion on spinning certainly draws a multitude of opinions.

 

For those inclined for some interesting reading put "Airtourer spin" into Google and feast on the information of the three articles from the "Airtourer Newsletter", particularly the two authored by John O'Halloran. One is a general article on spinning, and the other spinning as it relates to the Airtourer and CT4. John purchased his Airtourer in the mid 80's when he was a RAAF Test Pilot assigned to ARDU at Edinburgh. He was then "forced" to a FA18 squadron, and from there moved to Cathay Pacific as their Test Pilot.

 

I had the good fortune to be instructed by an ex Army pilot in the early 1970s and once I had my PPL he moved me onto the Tiger Moth and Chipmunk, and did not stint on the stalling and spinning characteristics of either. I had purchased a Victa Airtourer and gained my aerobatic rating with John Douglas so I was incredibly fortunate to have been instructed and gained access to the top echelon of flying instructors. 40 years ago gaining access to appropriate aircraft and knowledgeable instructors was a lot easier than in todays environment. I think I had to pay $10 an hour for JD and the lovely red 80/87 Avgas was going into the aircraft at around 30 cents a litre!

 

Whilst I am happy to have the spin training, that training and my aerobatic time have the principle benefit of me being more aware of when an aircraft is approaching aerodynamic distress, and do something before I have to use my spin recovery skills.

 

Of the five aircraft that I have flown and spun intentionally the Tiger Moth heads my list as the one I preferred spinning. To me the Tiger spin is the textbook in action. The incipient spin in the Airtourer is classic, and the falling leaf is great, though the altimeter seems to go backwards pretty fast. As John O"Halloran clearly states, all aircraft possess different handling characteristics but the recovery technique is almost usually universal.

 

One book I really enjoyed reading was "A Flying Career" by Ron East. Those of us in WA knew Ron as a great Examiner of Airmen initially with the Department of Civil Aviation, and then the many subsequent name changes and diminution. Ron as an Englishman had joined the RAF at the onset of WW2, and for most of the war was only let loose on aircraft painted yellow. His instructional career continued after the war and he saw the introduction of the Chipmunk to replace his much loved Tiger Moths. With defence cutbacks Ron become a 10 pound Pom and instructed at RVAC before taking on the CFI job at LVAC. His arrival in Aus was at about the time that the Chipmunk was being introduced into the aero club scene and there were a number of spinning related fatalities. From reading Ron's book I formed the understanding the theories and opinions of spinning the Chippie were remarkably varied and sometimes expressed robustly! Probably not much has changed.

 

It might be time to seek DJP's knowledge as I recall some US stats from a few years ago of the high proportion of those involved in spinning incidents actually being rated for spins. The two fatal spin accidents I am aware of in WA were both well credentialed aerobatic pilots, one a respected CFI, flying aerobatic aircraft who had the ground intervene all too suddenly.

 

Personally I am glad that I have had spinning included in my flying experience, albeit well instructed, in the right aircraft and always with at least my 3000 feet insurance policy.

 

 

[David Isaac]

If you practice spinning, have plenty of altitude and I mean more than 3,000' if you are going to experiment.

 

DJP really enlightened me on what can go wrong even in spin certified aircraft.

 

 

[Bandit12]

Do you think it matters what you do spin training in the sense of Powered Vs Gliders ?Yep that's the Place Bandit.

Doing it in gliders would be better than not doing it at all. Doing it in powered would be more similar to what you are used to flying, and with the right aircraft you could also do accelerated spins, really unusual attitudes etc. One of my favourites was being told to recover when the airspeed was zero, and the Pitts was vertical looking at the ground. Instinctive reaction - start pulling back, straight into a stall with such low airspeed. One thing is for sure, no matter what aircraft type you choose to do it in (aside from those ones not certified for it of course), spin training and unusual attitudes recovery is money well spent.

 

 

[Dafydd Llewellyn]

You missed the point I was attempting to make. I am NOT advocating spins in Ultralight aircraft. I asked the question whether or not Normal category and LSA ultralight aircraft were tested to a one turn spin recovery at all (as normal category GA aircraft are) as part of their certification /approval process. The question was in relation to whether or not you could/should legally teach "INCIPIENT" stall /spin recognition and recovery, NOT FULLY DEVELOPED SPINS in RAA training aircraft (it would seem perhaps safe in Jabirus). If it is properly taught by an instructor, exceeding VNE should not even be a risk. Hell if you are a dick head you can exceed VNE in any aircraft, you don't have to be doing stall/spin training.On another note Drifters have been spin tested, just probably not an approved testing regime, the first Austflight Drifters were stated as unspinnable, and I "was told ..." rigging was altered to improve performance and they "became" spinnable. Wayne Fisher developed an experimental VH registered aerobatic Drifter VH-VSI (hopefully with a beefed up structure). Also I believe there was an aerobatic version of the Winton Sapphire (hopefully you would know whether that is true or not). In any case my question was related to testing to at least one turn and recovery as normal category GA aircraft are.

 

Dafydd all I am trying to establish is whether or not we actually should or do teach true incipient stall/spin recognition and recovery as stated in the RAA syllabus, because I don't believe we do teach what the syllabus says.

No, I think you missed my point. I was definitely NOT talking about fully-developed spins. Those normal category aircraft (and some ultralight types, whose manufacturers were sufficiently conscientious to do so, which were tested for one-turn spins, the term means exactly what it says - here's the requirement, as written in FAR Part 23 (most design standards are similar). There was no requirement in the design standard for the Skyfox or the original Jabiru, but we did it anyway.

 

§ 23.221 Spinning.

 

(a) Normal category airplanes. A single-engine, normal category airplane must be able to recover from a one-turn spin or a three-second spin, whichever takes longer, in not more than one additional turn after initiation of the first control action for recovery, or demonstrate compliance with the optional spin resistant requirements of this section.

 

(1) The following apply to one turn or three second spins:

 

(i) For both the flaps-retracted and flaps-extended conditions, the applicable airspeed limit and positive limit maneuvering load factor must not be exceeded;

 

(ii) No control forces or characteristic encountered during the spin or recovery may adversely affect prompt recovery;

 

(iii) It must be impossible to obtain unrecoverable spins with any use of the flight or engine power controls either at the entry into or during the spin; and

 

(iv) For the flaps-extended condition, the flaps may be retracted during the recovery but not before rotation has ceased.

 

This has to be done at the maximum weight and the most aft CG position - one normally tests with the CG at around 1% of the mean aerodynamic chord further aft than the eventual POH aft limit; and it's quite common to weigh the aircraft before and after the sortie, with the pilot aboard, to ensure the test loading was within tolerance. One has to test with ailerons neutral, aileron into the spin, aileron against the spin, power on, power off, and for all flap positions (if the aircraft has flaps).

 

I did the certification spin testing for the CA22 Skyfox and the original Jabiru; and after 360 degrees of rotation, which took about 2 seconds, I had the utmost difficulty in staying within the aircraft speed limits during the recovery. Could not stay in the spin for 3 seconds, the wings would have come off, I suspect. I usually hit about 140 kts IAS in the Jabiru, which is too damn fast in an aircraft without control mass-balance, and about 115 kts IAS in the Skyfox, which is also too damn fast for those wings. So, if one is going to do incipient spin training on such an aircraft, you are going to be within about 2/3 of a second of being a test pilot - and you won't be wearing a parachute, as I was. Therefore, my view is that the safety margin for incipient spin training is too small, in these aircraft.

 

Also, those tests were done with a spin-recovery parachute system installed - there's quite a bit of knowledge involved in making a satisfactory one of those (see photo)

 

 

 

 

[David Isaac]

Thanks Dafydd,

 

So if I interpret your answer correctly, the answer to my question is: there is NO requirement to do the FAR Part 23 Spinning (single rotation) tests (or equivalent) for any Ultralight or LSA aircraft; and

 

If that is the case RAA Aus should NOT have stall/ incipient spin training in our flight training manual and we should definitely NOT be teaching incipient spins as defined in our flight training section of the Ops manual, because NO RAA Aus aircraft could meet the necessary requirements. So am I correct in going back to my original assertion that RAA Aus should just teach stall with wing drop and remove any reference to incipient spin? Perhaps this raises the question of the suitability of RAA Aus aircraft for training purposes?

 

I speculate then that since all 'Normal' category GA aircraft must meet this FAR 23 requirement for a single rotation spin, the application of stall/incipient spin training is not so much an issue.

 

 

[Dafydd Llewellyn]

Thanks Dafydd,So if I interpret your answer correctly, the answer to my question is: there is NO requirement to do the FAR Part 23 Spinning (single rotation) tests (or equivalent) for any Ultralight or LSA aircraft; and

If that is the case RAA Aus should NOT have stall/ incipient spin training in our flight training manual and we should definitely NOT be teaching incipient spins as defined in our flight training section of the Ops manual, because NO RAA Aus aircraft could meet the necessary requirements. So am I correct in going back to my original assertion that RAA Aus should just teach stall with wing drop and remove any reference to incipient spin? Perhaps this raises the question of the suitability of RAA Aus aircraft for training purposes?

 

I speculate then that since all 'Normal' category GA aircraft must meet this FAR 23 requirement for a single rotation spin, the application of stall/incipient spin training is not so much an issue.

In answer to your first question: It depends on the certification basis of the aircraft concerned. The Skyfox and the early Jabiru were certificated against CAO 101.55 and the advance issue of British Civil Airworthiness Requirements (BCAR) Section S - otherwise known as CAP 482- March 1983. Neither of those standards requires one-turn spin testing. However, the current issue of BCAR S (issue 3) does require it. As fas as I can discover, the design standard for the TL2000 Sting does not require it. The ASTM standard for LSA (F2245) does require it. CS-VLA does require it. I have no idea what the situation is for the Foxbat, etc. This is (inter alia) why being able to look up the Type Certificate Data Sheet is so important - as I pointed out in my thread "Caveat Emptor". (Does this give you some idea of the expertise the RAA TM needs?)

 

In answer to your third question: Yes, all "normal" category aircraft must meet this requirement. However they usually have somewhat higher stall speeds than are permitted for recreational aircraft. Since the way the flight envelope limiting speeds are determined is based on the flaps-up stall speed (in a roundabout sort of way), the design diving speed (normally 111% of Vne) for recreational aeroplanes is usually fairly low; however gravitational acceleration is not similarly scaled down for them. As a consequence, when you have one of these pointed vertically downwards, it will very quickly exceed its maximum design velocity - whereas a higher stall speed GA aeroplane takes a bit longer. So whilst it was perhaps not too unreasonable to allow incipient spin training in normal category GA aeroplanes, mindlessly carrying that over to recreational aeroplanes is considerably less reasonable, from my experience. Also, do bear in mind that most of the common 4-seat GA trainers had either dual certification - normal category at MTOW, and utility category at a reduced weight corresponding to two occupants - or, in the case of the C150/152, were utility category at all weights - so they had higher limiting airspeeds than a minimum "normal category" aircraft.

 

Therefore, in answer to your second question: I think you are correct; in most RAA aircraft it is unwise to go beyond a stall with wing drop - which as somebody pointed out, usually involves only about 90 degrees of rotation. And yes, this constitutes a deficiency in these aircraft as trainers, in my view.

 

I did my basic training on Chipmunks, which were of course fully aerobatic aircraft, with "classic" spin characteristics. Full spinning was part of the PPL syllabus, back then (1963). I've taught many students spinning, as a gliding instructor. My personal view is that it is important to expose students to the full spin experience sufficiently to allow them to cease to be disoriented by it and start to react automatically; about three or four spins of maybe two full turns will usually achieve this. Gliders are good for getting over the disorientation, because they spin a trifle more slowly than short-span ultralights. The fastest-spinning aircraft of my experience was the Ultrabat (22 ft wingspan), which rotated at about 360 degrees per second; I was able to recover by rote, but the world did several barrel rolls afterwards (I simply followed it, and eventually it all stopped - but one does NOT want to expose a student to that sort of thing.)

 

I also think that normal training procedure has a serious defect, in that it does not train people to recover from any stall situation by "unloading the wing"; the training patter talks about lowering the nose & regaining speed, which imparts very little if any understanding of the actual aerodynamic process involved in regaining attached airflow over the wing. One "unstalls" the wing by reducing the angle of attack; and since there is normally some hysteresis in the process, one often needs to reduce the angle of attack significantly. If you "punch" the stick forward sufficiently to rapidly reduce the angle of attack by five degrees or so, you will unstall the wing with almost no loss of height. The conventional patter achieves this, but in slow motion, and requires a much larger departure from the flight path accordingly. That's OK for the initial exposure to stall recovery, but the training should not stop there, in MHO.

 

 

[David Isaac]

Thank you Dafydd,

 

A very clear explanation. I know the concerns you share in your last paragraph are shared my many knowledgeable instructors. Thanks again.

 

 

[motzartmerv]

the training patter talks about lowering the nose & regaining speed,

It does? I hope not..

 

 

[facthunter]

Plenty of instructors would allude to the fact of the nose dropping and the plane becoming unstalled, I would think, but that would not be a pilot initiated recovery action by itself. I would be talking somewhat of a forward movement of the stick which controls the angle of attack of the WING as distinct from the attitude of the aircraft itself, but this is not an easy concept to get across. The way stalling is frequently taught, it is associated with a high nose attitude which may give a false sense of security to pilots who know no better. It also gives an acceptance of a large height loss being normal . NOT SO..Nev

 

 

[motzartmerv]

Question: What speed does it stall at?

 

Answer: What speed would you like me to stall it?

 

 

[facthunter]

Yes it is a silly question if you don't qualify it. Most pilots are $#!t scared of getting slow. That is OK in it's own right but hardly likely to aid getting the pilot to fly at speed close to the stall, safely. Shall we mention Stick Stall Position? ( as a concept). Nev

 

 

[David Isaac]

Or an angle of attack meter, now that concept blows a lot of minds.

 

Stick stall position is a great concept not always taught and you can easily exceed it at considerable speed, but when familiar with it you know what is happening.

 

 

[djpacro]

Stall stick position is not very useful in something like this Lancair 360.

 

 

Treat the vertical scale as stick position.

 

 

[facthunter]

That's why I said as a concept. If you reconfigure the plane. Flaps, GEAR, C of G, Change Horiz.stab trim etc it doesn't apply except to each separate condition standing alone. Since the elevator(s) are the main way the pilot controls angle of attack and the pilot is usually the one who stalls the plane, the pilot's actions re the elevator position is the cause and the cure of the problem. Thrust or power comes into it as well, but few mention it. Nev

 

 

[Oscar]

Stall stick position is not very useful in something like this Lancair 360.[ATTACH]23931[/ATTACH]

Treat the vertical scale as stick position.

The Lancair 340/360 is, statistically, one of the most deadly things ever to take off (after, possibly, the Messerschmidt 163, though I believe it may well have flown better than a Lancair..). Read the original CASA flight testing report; from memory, it dropped a wing violently to 70 degrees or so in a stall, repeatedly, with a highly-experienced test pilot doing the testing. About the only really safe position for the stick in one of those is to put it in a small concrete bunker and leave it there.

 

 

[David Isaac]

I think Uncle DJP is sh!t stirring to be honest. I can see the smirk on his face as he wrote that ... he knows how bad they are ... LOL

 

 

[djpacro]

No,seriously, I have come across people who have done some advanced stall training - no flaps, single CG position and in an aeroplane with ample longitudinal static stability - and happy to proceed to stake their life on Stall Stick Position applying in aeroplanes with characteristics like that, blithely unaware of the limitations that Nev outlined. The concept is not new - see the Chapter "The Silver Chain" in Wolfgang's excellent book from 1944, Stick and Rudder.

 

The so-called “elevator” is really the airplane's speed control, or, if you want to state it accurately, its Angle of Attack control. This shows how you can keep yourself from stalling or spinning in!

Stalls and spins are caused by having too low a speed or—what is practically the same thing—too high an Angle of Attack. All right, simply do not move the stick into the position where it will force the airplane to fly at stalling speed (or at stalling Angle of Attack). Simply do not let that hand creep back. For an airplane cannot stall and cannot spin unless the stick is held back in the stalling position! Remember this simple fact. It is of the utmost importance for every pilot; unless the stick is in the stalling position, an airplane cannot stall and hence cannot spin. Stalling position of the stick in most airplanes is nearly all the way back if the power is off, and perhaps about two-thirds back if the power is on. Just what it is in your airplane it is very much your business to find out.

 

Now from this you might easily get the idea that to keep yourself from stalling and spinning in all you'd have to do would be to buy 10 cents' worth of wire and tie the stick loosely to some structural part of the airplane; so that regardless of how confused or panicky you might become in ome emergency, you simply could never pull the stick farther back than so far—say to the position for 15 degrees Angle of Attack or say a speed of 10 m.p.h. Above stalling speed. Thus, you might think, the airplane would be rendered unstallable. This would then solve one of the biggest problems of aviation, the terrific death rate from accidents, since most fatal accidents involve a stall. And it would also cut out much tedious training—all the practice of stalls and spins. You might think you had a big idea there!

 

THE FOOLPROOF AIRPLANE

 

The strange thing is that you would be right! Ten cents' worth of wire will make any airplane unstallable, will solve one of aviation's biggest problems, and will simplify flight training enormously.

It is very worthwhile to read the rest of the Chapter, if not the whole book.

[Oscar]

I think Uncle DJP is sh!t stirring to be honest. I can see the smirk on his face as he wrote that ... he knows how bad they are ... LOL

I'm positive he does! - but there is a deeper message, I think - and one to which DJP alludes above: that simply training to 'go through the motions' in sequence in a benign aircraft does not necessarily render you immune from entering a really bad situation in something with quite different and far more savage characteristics. Obviously any decent familiarity with the basics is way better than none at all - but that familiarity ought to be reinforced with some decent and reliable information about the characteristics of something that will 'bite'. By way of example: drivers who are entirely familiar with sliding a front-weight-biased car safely, used to find themselves facing the wrong way in an early Porsche 911s very, very quickly (and uncatchably!). The situation was already happening before the tell-tales became obvious.