Snap roll a Spit?

[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.

[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]

Flick rolls

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]

Spit' Flicks.

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...!

[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...

[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]

Originally Posted by Lumps

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/44353...e-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

[mikedreamer787]

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