Snap roll a Spit?

[Lumps]

Came across 'Pilots Notes' for the Spitfire (on the Internet) []Flying a Spitfire (http://www.historylearningsite.co.uk/flying_spitfire.htm) and right at the end of giving speeds for various manoeuvres it says 'Flick manoeuvre – Flick manoeuvres are not permitted'

Anyone know the reason for this? I would of thought an aircraft built for combat would be strong enough to withstand the forces of a flick roll - is the reason structural? I'm guessing it would have happend many time unintentionally in combat.

In this I am assuming the pilots notes were (A) genuine and (B) written at the time of production, not for the few aircraft flying now for which I can totally understand this limitation. Both assumptions could be shaken easily but... go ahead if you can!

[PappyJ]

Although the Spitfire was known as a very good aerobatic aircraft - qualities which are beneficial to a combat aircraft - it is not, nor ever was, an "unlimited" category aerobatic craft.

Manoeuvres such as "snap rolls, flick Rolls" or whatever you chose to call them, are high stress violent manoeuvres. I recall that the Spitfire has sensitive elevators and there is a warning that if the control column is brought back too rapidly in a manoeuvre such as a loop or steep turn, stalling incidence may be reached and a high-speed stall induced. It's warned that when this occurs there is a violent shudder and the aircraft tends to flick over laterally resulting in a loss of control (similar to a Lomcovak).

Military combat manoeuvres are typically of a steady G-load type, and typically not "violent" manoeuvres.

Also, limitations are not always based on structural limitations. Its possible that this limit may have been due a system - possibly the cooling system - which as you know was a liquid system.

That's my pennies worth.

[Lumps]

Thanks, plausible but then the first flick roll ever demonstrated to me was in a 152 aerobat! You seen what is holding the tail on on those things?! A flick roll at say 80 knots in a Spitfire, I would have thought, would not be overly stressful for an aircraft designed to handle dynamic forces far in excess of what a 152 can handle.

Also I can say from first hand experience that hitting wake turbulence while close behind another aircraft pulling 4-5 g's (I'm sure that the lads in ww2 pulled well in excess of that during combat) is surprisingly violent.

And then I find this...

Kilmartin had said, "See if you can make her talk." That meant the whole bag of tricks, and I wanted ample room for mistakes and possible blacking-out. With one or two very sharp movements on the stick I blacked myself out for a few seconds, but the machine was sweeter to handle than any other that I had flown. I put it through every manoeuvre that I knew of and it responded beautifully. I ended with two flick rolls and turned back for home. I was filled with a sudden exhilarating confidence. I could fly a Spitfire; in any position I was its master. It remained to be seen whether I could fight in one.

[Wizofoz]

Clearly, there were Pilots who hadn't read the book.

In RR Stanford Tucks biography, there is a description of him impressing a group of American Pilots (or, at least, convincing them the he was crazy) by doing a snap-roll on final approach.

[Centaurus]

As a former flying instructor on the Australian Wirraway trainer (looks like a Harvard only more powerful), we often did flick-rolls more out of fun rather than a serious training manoeuvre. If I recall correctly, the Wirraway had a strong wing 6 G or similar. The manoeuvre was conducted in level cruise flight at 120 knots and the stick was pulled hard back to its limit. It was a mighty uncomfortable manoeuvre and a series of violent rolls could occur. We were stupid to do it in retrospect although I don't think it was a prohibited manoeuvre. But in those days RAAF trainee pilots were taught to be able to recover from unusual attitudes and from that angle the flick roll was a useful method of inducing a violent wing drop common in a high speed stall which is what was happening. I don't recall ever doing it on Mustangs though.

But to do that in a Cessna aerobat? Bugger that for a joke...

[John Farley]

I would of thought an aircraft built for combat would be strong enough to withstand the forces of a flick roll

At what speed? Aerodynamic loads are related to V squared.

[Brian Abraham]

The pilots notes are genuine. The Spit was not allowed to be snapped/flicked. It would be reasonable perhaps to suggest that the reason might be the transportation joint immediately forward of the fin/tailplane. I make the suggestion as flick/snap maneovers were not permitted on the T-28 for that reason.

Snap/flick is not permitted on the P-51 either. The reason being that they do not do a good snap, and usually end up in a power on spin. The manual warns against making intentional power on spins because it may take up to six turns and 9,000 feet to recover.

[mcdhu]

It's been a long time, but I'm pretty sure that, in the UK military, there was a general prohibition of flick manoeuvres in MODFOs which were superseded by JSP318.
Perhaps a current UK military pilot could bring us up to date.
mcdhu

[Machinbird]

As one who has snap rolled a Luscombe that was equipped with a surplus WWII horizon and DG, the gyros definitely did not like the maneuver.

Had to repair the gyros at least once as a result.

Depending on entry speed, the snap (flick) roll did not have to be a particularly violent maneuver. Basically it is just an accelerated spin entry that you stop after one rotation.

[AerocatS2A]

I'd think there'd be some pretty strong gyroscopic forces transmitted through the crank shaft from the prop if you were to flick roll a spitfire. The other general issue with rolling manoeuvres is that the up-going wing sees more g forces than the g meter in the cockpit is reading. I don't know if that is a significant factor in why you shouldn't flick a spitfire, but it's worth remembering that just because the g meter says 4g, that doesn't mean your wings are only doing 4g, one will be doing less and the other more.

[Brian Abraham]

Done little research, and thanks for asking the question Lumps, has been interesting. My original assumption re transport joint is obviously incorrect.

Air Publication 1565B Pilot’s Notes Spitfire IIA and IIB dated July, 1940
Flick manoeuvres are not permitted
Air Publication 1565B Pilot’s Notes Spitfire IIA and IIB date uncertain
The high speed variety of flick roll or flick half roll must ON NO ACCOUNT be done. It is liable to cause severe strain, is clumsy and uncomfortable, and, being extremely easy, has no training or other value of any kind. But a flick roll at low speed, and low RPM done very gently, is a useful exercise in timing and control at low speeds, and prevention of spin. It is done by throttling well back, slowing down to about 140 mph ASI, and then very gently easing the stick back and, at the same time, applying rudder. The nose will rise and yaw, and, as the control angles are steadily increased, the aeroplane will suddenly start to “auto rotate”, or flick. If the stick is kept back the aircraft would then spin, but, as soon as the aeroplane approaches an even keel (at about the moment when the wings are vertical) the stick is put forward, and, as the flick ceases, the controls used to steady the aeroplane until the roll is completed. If this is done too late the aeroplane will continue to flick, until it does part of a turn of a spin; if done too soon the flick will stop, and the rest of the roll must be done by aileron control, in the normal way.

ON NO ACCOUNT CARRY OUT FLICK MANOEUVRES EXCEPT AT LOW SPEEDS, but remember that low speed makes spinning more likely if the controls are mishandled. Ample height should be allowed.
Air Publication 1565J Pilot’s Notes Spitfire IX, XI and XVI 3rd edition September 1946
Flick manoeuvres are not permitted
“Challenge in the Air” By M. Liskutin

Miroslav Liskutin of the Czechoslovakian 313 Squadron came under attack at Dieppe by a FW 190.
I saw two glowing white rods just above my head. My reaction was quick and I think completely instinctive, to get out of his gunsight! I stepped on the rudder, applied full ailerons, throttled back the engine, and pulled back on the elevators. My Spitfire performed a violent flick roll. Never before had I experienced violence like it. Keeping the controls in extreme positions I continued deliberately with a spin.

The manoeuvre worked, the FW 190 had disappeared. He discovered then that level flight could only be maintained with full aileron deflection, which required enormous physical effort, and did not think he could sustain such effort from Dieppe back to England. Almost overcome by paralysing cramp, by using the crowbar on the door he was able to wedge it between the side of the fuselage and the stick to relieve him of the strain. To his elation he was able to reach his base at Redhill, Surrey, and land (at 165 mph) without incurring further damage.
Miroslav obviously found out that the The high speed variety of flick roll or flick half roll must ON NO ACCOUNT be done. It is liable to cause severe strain, is clumsy and uncomfortable was correct. The wings certainly had a bit of twist if 165 mph was as slow as he could get.

Alex Henshaw
I loved the Spitfire in all of her many versions. But I have to admit that the later marks, although they were faster than the earlier ones, were also much heavier and so did not handle so well. You did not have such positive control over them. One test of manoeuvrability was to throw her into a flick-roll and see how many times she rolled. With the Mark II or the Mark V one got two-and-a-half flick-rolls but the Mark IX was heavier and you got only one-and-a-half. With the later and still heavier versions, one got even less.
AerocatS2A, the rolling "g" limit is generally taken as two thirds of the symmetrical load - but check your manual.

[Lumps]

Thanks Mr Abrahams, I guess that clears it up - the notes i read made no mention of speeds which made me scratch my head.

[bubbers44]

I used to enjoy pulling straight up into a puff cloud snap rolling until it fell off into a spin coming down. Not really much point to it but it sure was fun in that little biplane. The Bailey Bitty Bipe was the only one ever made so if anybody knows who owns it now tell him to try it. It took two fingers to do a roll.

As previously stated a snap roll is simply an accelerated stall into a spin maneuver. We taught snap rolls on top of a loop in a Citabria so don't see why a Spitfire would have a problem with it unless it is an engine related gyroscopic problem.

[3holelover]

I was thinking just that Bubbers... Slow and easy. As for gyro related problems? Maybe in one direction, but if so, then the other way should happen pretty fast.

I'm curious to know if indeed a "flick roll" is just a British name for a "snap roll"? I'd never hear that term before.

[DB6]

3hole, yes it is. Flick roll (UK) = snap roll (US). Also stall turn (UK) = hammerhead (US) but that's getting off-topic.

[haughtney1]

My grandfather described rather vividly in person (as well as in his logbook) snap rolling his Spit VB whilst on the receiving end of a 190's 20mm shells, the experience mustn't have been too horrific as he used the same manoeuvre almost 3 years later in a Tempest V to escape the attentions of another 190 that had his name on it.
Having said all of that, after the war he never flew again, preferring to go back to milking cows.

[bubbers44]

We also did hammerhead stalls. They are quite lazy maneuvers so do not think gyroscopic forces would be involved.

[3holelover]

Thank you DB6.

[High_Expect]

Of note the RAF Tutors were cleared for flick manoeuvres for a while..... Perhaps that is why they have been ground for the last 6 months + after props started falling off. :eek:

[djpil]

...But to do that in a Cessna aerobat? Bugger that for a joke...The Cessna is a great snapping airplane. I wouldn't snap a Decathlon which is supposedly a more serious aerobatic machine (and not due to concerns over loads on the crankshaft flange).

I can remember asking some-one at Pilatus many years ago why their displays did not include lomcevaks whereas the Tucano did. The answer I was given was that a PT-6 could only withstand a small number of them.

Even Pitts were shedding props at one time.

[barit1]

I know of two prop departures on Wasp Jr. - powered Stearmans in the 60s, one during a triple-snap, and the other suspected likewise (no witnesses, however). After each case there was an AD to inspect threads on the crankshaft.

Now I believe there is an AD prohibiting aircraft w/ Wasp Jr. power (and with the heavy H-S prop??) from snap or spin maneuvers. Considering the millions of snaps and spins these fine engines endured during WWII training duty, and for 6+ subsequent decades, I regard such an AD as overkill. :rolleyes:

[con-pilot]

Even Pitts were shedding props at one time.

Had that happen to one of my best friends. While performing at an airshow in his S-1, the prop came off during a series of snap rolls. The CG shifted back to somewhere back of the tail and he could barely control the aircraft with full forward stick. He glanced off the roof of one hangar and crashed into an open hangar.

He replaced the S-1 with a special built single seat S-2.*

His injuries, a really bad bruise on his inner left thigh. The wreckage fitted in the back of a pickup. But, if you looked into the cockpit and no where else, there was not a bit of damage. Course you had to ignore the fact that the wings were wrapped around the fuselage.

He was latter killed in an airshow in Oklahoma City flying his new single seat SU-29.



* This S-2 was a single seat aircraft that was specially built for him at the Pitt's factory. He sat down on the floor, they took his measurements, he was vertically challenged (short) guy and then they built the S-2 around him.

[Lumps]

So in conclusion flick rolls at high speeds where prohibited due to the chance of structural damage (airframe) and could apply to many aircraft. It is the simplest, most logical answer - are we saying this is it? Id like to know more about any potentially damaging gyroscopic forces from prop through crankshaft and gearbox but where is the evidence?

[Yankee Whisky]

Think of the enormous disk area and weight of 5 blades on the later model Spits. Changing this spinning disk's plain of rotation suddenly causes an extremely high gyroscopic bending force on the prop shaft, to the point where, if a previous stress failure crack is present, the prop shaft will break off the engine. This will be the case in all props when, over time and numbers of violent maneuvers, a failure will result.

[GQ2]

Coming back to the original query;- The writers of the 'Pilots Notes' were well aware that the skills of the average young Spitfire pilots were nowhere near those of experts like Henshaw. Remembering my own early clumsy attempts at flick-rolls, I found them disorienting and getting any consistency of exit very difficult. As ever, low-level aerobatics were responsible for a significant proportion of air-accidents. Inexperienced pilots trying flicks in a Spit' at low levels would have been bad for the accident stats....
That said, Henshaw, as I recall, used to perform them during a vertical climb during his normal display and regarded the manoeuvre as unremarkable.

As for flicking 152 Aerobats....a mere bagatelle...but not at low level...:). Much more fun in an S1 though...! :ok:

[bubbers44]

Snap rolls are really fun maneuvers and doing them in many aircraft never considered them anything but fun. Maybe some aircraft can't handle the twisting gyroscopic forces.

[flyboyike]

It's good to see pertinent, immediately-relevant quetions like this posted on pprune, what with so many of us going though Spitfire training and all...

[OBX Lifeguard]

I for one would give up every hour I've got in jets to fly a spitfire.

I was cautioned against doing too many snap rolls in my Great Lakes biplane because of a tendency to break engine mounts. I enjoy doing them...but I kinda cringe when I open the cowling afterwards...:sad:

[Lumps]

Done many snap rolls flyboy?

[mikedreamer787]

Excellent post on the last page BA, but I thought flick manouvers
were prohibited due to the telescopic spar of the Spit (evidenced
in that 165kt approach Liskutin did).

Does the spar in fact play a part in these manouvers being banned?

[flyboyike]

Done many snap rolls flyboy?


Negative, that's the kind of flying that almost sounds like work. I became a pilot precisely because I despise the very concept of work.

[Brian Abraham]

mikedreamer787, my post here should answer your question

http://www.pprune.org/tech-log/443530-limit-load-factors-ww2-fighters-eg-spitfire-mustang.html

[John Eacott]

I found that rolling a Spit was...interesting. Nose up until the pedals were on the horizon, then into the roll and by the time we were all the way round the nose had dropped back to level flight. Not a snap roll, but indicative of the issues involved. Light on the ailerons but heavy in pitch and twitchy on the rudder, all-in-all well worth the dosh for the experience :cool:

[mikedreamer787]

Thanks for that BA. I copied and printed your part
of the thread and added it to my Mk IX manual.