A newbies impression of the 109 and spit

[Glider]

Originally Posted by Crumpp

Wow....



Everything is covered in the Operating Notes. The RAE and the NACA were in agreement about the longitudinal stability and control.

Granted, the RAE had no standards outside of opinion so they did not know they were in agreement with the NACA conclusions at the time. Interesting paradox regarding stability and control engineering history.

Everything the NACA concludes is listed right there in the Operating Notes published by the Air Ministry as a caution for Operating the aircraft.

You seem to have missed the rest of that posting:-

The early Spit 1 pilots notes say that intentional spinning is banned also go on to say that its easy to recover from an accidental spin as long as you allow enough height and ensure your speed is 150 mph. I am sure Crumpp who has extensive spinning experience will agree that the two golden rules are a) make sure you have sufficient height, b) Get your speed up to a safe level

With your experience do you agree that the two golden rules are as stated?

If so, then what is dangerous in the pilots notes about spinning?

[Glider]

This might be of interest

thought I remembered reading an interview on this subject many years ago- and finally found it in a yellowed copy of Alfred Price's 'Spifire At War' (published 1974). It's germane to this discussion (as my teacher used to say) because the person being interviewed is none other than Mr Eric Newton who spent the war with the Air Accident Investigation Branch. He was still employed by them as an investigator in 1974- the time of the interview- so presumably still had the facts at his fingertips. This body was, and is, independent of the RAF.

Mr Newton was called in to investigate Spitfire crashes which could not be immediately attributed to pilot error (the same crashes which are detailed in Morgan and Shacklady). He says:

"Out of a total of 121 serious or major accidents to Spifires reported to us between the begining of 1941 and the end of the war, 68 involved structural failure in the air. Initially the most common reason for such failures, with 22 instances in 1941 and 1942, was aileron instability. The symptoms were not at all clear cut: the aircraft were usually diving at high speed when they simply fell to pieces. Only after one of the pilots had survived this traumatic experience and parachuted successfully were we able to find the cause. During his dive he saw both of his ailerons suddenly flip up, producing an extremely violent pitch- up which caused the wing to fail and the aircraft to break up. In collaboration with RAE we did a lot of tests and found that aileron up- float was made possible by stretch in the control cables; in those days tensioning was a hit or miss affair with no compensation for temperature. On our recommendation the RAF introduced a tensometer which ensured accurate tensioning of the controls; this, and the simultaneous introduction of metal surfaced ailerons ('42/'43), cured almost all the cases of aileron instability in the Spitfire.

The next most serious cause of structural failure in the Spitfire was pilots overstressing the airframe. She was extremely responsive on the controls and one must remember that in those days there was no accelerometer to tell the pilot how close he was to the limit. So it was not difficult to exceed the aircraft's 10G ultimate stress factor (what was the 109's?-) during combat or when pulling out from a high speed dive; during the war we were able to put down 46 major accidents to this cause, though undoubtedly there were many other occasions when it happened and we did not see the wreckage. Incidentally, if there was a structural failure in the Spitfire it was almost inevitably the wing that went; the fuselage was far less likely to fail first (the same for most low wing monoplane fighters?-except the Typhoon?- Berkshire).

I once asked a very senior RAF officer why the accelerometer- technically a simple instrument- was not introduced during the war. He replied that he was sure it would have an adverse effect on the fighting spirit of the pilots (same was said re the parachute in WW1!- Berkshire).

Whether that would have been so I cannot say. But I do know that when they finally introduced the accelerometer into service in the Hunter in 1954, and began educating the pilots on structural limitations and the dangers of overstressing, accidents to this cause virtually ceased.

After structural failure the next largest category of accidents proved on investigation to have followed loss of control by the pilot (36 cases). Of these 20 occured in cloud and could be put down to pilot error; one must remember that in the rush to get pilots operational instrument training was not up to peacetime standards. A further 13 accidents were shown to have been caused by oxygen starvation; the oxygen system had been used incorrectly with the result that the pilot had passed out and the aircraft had crashed. As a result of our investigations the system was modified to make it easier to operate.

The remaining 3 accidents in the loss of control category were initiated by the pilot pulling excessive G and blacking himself out.

Engine failures and fires contributed a further 17 accidents, and the remainder could be put down under the 'miscellaneous' heading.

As I have mentioned we investigated a total of 121 Spitfire accidents during the war. The causes did not always fit simply into neat categories mentioned above. For example, a pilot might lose control in cloud and his aircraft then broke up in the ensuing dive due to aileron instability- in that case the accident would have been listed under two categories. There were one or two accidents caused by the light- weight plastic bucket seats fitted to some batches of Spitfires. The trouble was they were not strong enough and if there was a heavy pilot who pulled a bit of G they tended to collapse- on to the elevator control runs which ran underneath. We soon had that type of seat replaced.

In the nature of my work I tend to concentrate on an aircraft's failings and ignore its good points; but how safe was the Spitfire? I think the figures speak for themselves; a total of more than 22,000 were built, and we were called in on only 130 occasions- and in not all of those was the Spitfire at fault. If one considers that she was not a simple trainer built for ease of handling, there can be no doubt that the Spifire was a remarkably safe little aircraft."

To summarise:
There were 121 Spitfire crash investigations between 1941 and May 1945 involving serious structural failure:
22 aileron instability
46 pilot overstressed airframe
20 pilot error in cloud
13 misuse of oxygen system- pilot error
3 pilot blacked out
17 engine failure/fire

Breaking up in a spin doesn't even get a mention,

I should add that this is copied but I cannot find who the original poster was, but the comments are of interest. If anyone should know please let me know as they deserve any credit

[Crumpp]

With your experience do you agree that the two golden rules are as stated?

Yes and just as the Operating Notes warn, it is the recovery that is dangerous to the airframe.

Understand?

46 pilot overstressed airframe

46 pilots died from it.

loss of control by the pilot (36 cases).

Loss of control is not very well defined, Glider. A spin accident though IS a loss of control accident.

Moreover, 41 percent of those
fatal accidents ended with a stall/spin.

Stalls and spins continue to be a significant
part of LOC-I.

http://www.faa.gov/news/safety_brief...r2012Pilot.pdf

Statistically, a very high percentage of those loss of control accidents is a spin.

[bongodriver]

46 pilots died from it.

not from spin recovery

[Crumpp]

Breaking up in a spin doesn't even get a mention,

It is the second highest catagory of accidents in your investigation. You really did not know that as a pilot?

[Crumpp]

not from spin recovery

Sure they did, not all of them of course but if you get the details a significant number of those Loss of Control accidents resulted in overstressing the airframe from recovery.

Just as the Operating Notes warn.......

[bongodriver]

Originally Posted by Crumpp

Sure they did, not all of them of course but if you get the details a significant number of those Loss of Control accidents resulted in overstressing the airframe from recovery.

Just as the Operating Notes warn.......

all aircraft operating notes warn about overstressing, Spit notes 'do not' say spin recovery 'causes' overstressing.

[Crumpp]

all aircraft operating notes warn about overstressing

Not really bongodriver.

You would have a very hard time overstressing the Bf-109 for example. Especially if you followed the later instructions and did not trim the aircraft during the dive.

It was designed that way through good stability and control engineering.

[Igo kyu]

Originally Posted by Crumpp

You would have a very hard time overstressing the Bf-109 for example.

An example chosen entirely at random perhaps?

[robtek]

The first that comes to mind is that the stick forces in the 109 were too high to pull out of a high speed dive without using trim.

Too high or even high stick forces make a involuntary overstressing really tough work.