A newbies impression of the 109 and spit

[NZtyphoon]

Putting the Pilot's Notes in context:
Also issued along with the Pilot's Notes were Pilot's Notes General A.P. 2095 which explain the limitations in the Pilot's Notes, and the reasons for them: (2nd ed, 1943):

Part I Note A Flying Limitations
1. Introductory.
(i.) The Pilot's Notes for each type of aircraft lay down certain flying limitations. They state, broadly speaking, the demands which it is safe to make of the airframe. Non-observance of the flying limitations may lead to increased maintenance work, or, in extreme cases, to structural failure in flight.

(ii.) In the fixing of these limitations there is of course a margin or factor of safety allowed. This factor for airframes varies according to the degree of confidence with which their strength and likely stresses can be predicted, but is commonly around 2. This means, for instance, that a wing which is intended to withstand 4g should not break until 8g is imposed, but there is increasing risk of strain and failure as g rises above 4.

(iii.) The flying limitations also involve questions of safe handling from the aspect of controllability.

(iv.) In combat and emergencies pilots must take risks with their aircraft, balancing one risk against another; limitations must be strictly observed in so far as there is no sufficient reason to exceed them.

First, the Pilot's Notes were deliberately conservative to ensure that most pilots flew well within the limitations of the airframe thus avoiding too many overstressed, high maintenance aircraft on operational service.

However, the RAF acknowledged that in combat it was up to the pilot to choose what risks needed to be taken; whatever legal status the pilot's notes had in peacetime that legality could be overruled under combat conditions because if pilots were expected to fly by the rules all the time they were easy meat. One reason so many pilots were shot during their first combat was because they hadn't yet learned how to fly their aircraft at or beyond the limits set down in the pilot's notes.

4. Manœuvres not Permitted
(i.) Intended spinning of operational aircraft is permitted only in the case of certain approved single-engine fighters within the limitations stated in the Pilot's Notes. (Normal Methods will usually effect recovery - A.P. 129 Ch. III)

(iv.) The reasons underlying these prohibitions are partly considerations of aircraft strength and partly of control. Aircraft are designed to fulfill their operational role and not to perform manœvres of no operational value...

Why spin when you don't have to?

RAF Pilot's Notes for operational single-engine fighters which permit spinning:
Spitfire VII and VIII, IX & XVI, XIV & XIX: Spinning permitted but with a height limit of 10,000 feet.
Typhoon: permitted, without bombs or drop tanks
Tempest V: not permitted until proper tests had been carried out
Mustang III: only when rear fuel tank was empty
Corsair: Spinning not permitted

[WTE_Galway]

Quote from page 46 of a book by Morgan & Shacklady taken from this discussion:

http://forum.keypublishing.com/showthread.php?t=75816


The Air Ministry was not completely satisfied with the spin recovery of the Spitfire, and at a meeting on 17 January 1938, chaired by Air Cdr. Verney, Supermarine persuaded those in attendance that no modifications be made to production aircraft apart from the addition of an anti-spin parachute. For the Air Ministry Verney said that based upon model tests at Farnborough production aircraft could not be passed for spinning even with a tail parachute. Supermarine then pointed out that Jeffrey Quill had made sixteen successful spins of eight turns in the prototype. After more discussion the DTD agreed to accept the Supermarine proposal and that the first 20 production models should be fitted with the tail parachute and undergo further spinning trials. He, DTD, would be satisfied with recovery at 15,000 ft. When the first production Mk 1 Spitfire, K9787, was completed at the beginning of May 1938 an anti-spin parachute was duly fitted and the aircraft made its first flight from Eastleigh, piloted by Quill, on 14th of the same month .

[Kurfürst]

Originally Posted by WTE_Galway

Quote from page 46 of a book by Morgan & Shacklady taken from this discussion:

http://forum.keypublishing.com/showthread.php?t=75816


The Air Ministry was not completely satisfied with the spin recovery of the Spitfire, and at a meeting on 17 January 1938, chaired by Air Cdr. Verney, Supermarine persuaded those in attendance that no modifications be made to production aircraft apart from the addition of an anti-spin parachute. For the Air Ministry Verney said that based upon model tests at Farnborough production aircraft could not be passed for spinning even with a tail parachute. Supermarine then pointed out that Jeffrey Quill had made sixteen successful spins of eight turns in the prototype. After more discussion the DTD agreed to accept the Supermarine proposal and that the first 20 production models should be fitted with the tail parachute and undergo further spinning trials. He, DTD, would be satisfied with recovery at 15,000 ft. When the first production Mk 1 Spitfire, K9787, was completed at the beginning of May 1938 an anti-spin parachute was duly fitted and the aircraft made its first flight from Eastleigh, piloted by Quill, on 14th of the same month .

Its interesting to note that the Bf 109 won the fighter tender against its Heinkel rival due to the excellent spinning and stability characteristics much desired by the Imperial Air Ministry. Green notes, that the Commission ultimately ruled in favour of the Bf 109 because of the Messerschmitt test pilot's demonstration of the 109's capabilities during a series of spins, dives, flick rolls and tight turns, throughout which the pilot was in complete control of the aircraft.

[bolox]

while not strictly related to the spit/109 debate, the fitting of elevator bob weights wasn't unique

http://p51h.home.comcast.net/~p51h/sig/TO/01-60-90.pdf

[Crumpp]

while not strictly related to the spit/109 debate, the fitting of elevator bob weights wasn't unique

Stability and Control issues were not unique in WWII era aircraft. The science was very young and there were no standards in place. Most if not all of them had some sort of issue.

It is the area WWII fighters show the most variation in performance and is just as important to their fighting abilities as the aerodynamics.

Germany was the only combatant to have standards when the war started. The United States had standards by the time it entered the war as well. Everyone else did not adopt any defined standards until after the war.

[CaptainDoggles]

Originally Posted by bongodriver

Kermode may be 'dated' by todays standards but given we are talking 1930/40's aircraft then it covers everything applicable for the time, the new deffinitions of stability you give really have come about since the advent of aircraft capable of all these different states.

The laws of physics haven't changed since the war. Stability isn't something that an aircraft is "capable of".

Originally Posted by bongodriver

if the Spitfire was dynamically unstable as I believe the Spit bashers are claiming

I don't think anyone here is claiming the spit was dynamically unstable, nor would I say anyone here is a "Spit basher".

It's not "bashing" the spitfire to say it was not statically stable. Facts are facts. If you're going to get emotionally invested in this discussion then I'd rather not engage with you.

[bongodriver]

Originally Posted by CaptainDoggles

I don't think anyone here is claiming the spit was dynamically unstable, nor would I say anyone here is a "Spit basher".

Well a 'spit basher' would say that, no point admitting to it if you hope to keep under the bias radar and hide the emotional investment in it's counterpart, ok glad we cleared the dynamic stability issue though as thats the only real stability issue which would cause significant problems.

Originally Posted by CaptainDoggles

It's not "bashing" the spitfire to say it was not statically stable. Facts are facts. If you're going to get emotionally invested in this discussion then I'd rather not engage with you.

it is 'spit bashing' if that characteristic is being used as an example of a stability problem, I don't mind if you don't wish to engage with me, please don't be under the impression I need it.

Originally Posted by CaptainDoggles

The laws of physics haven't changed since the war. Stability isn't something that an aircraft is "capable of".

understanding of physics has however, stability is an inherrent capability of an aircraft, you must realise that a Cof G shift can cause a change in stability.

[CaptainDoggles]

Originally Posted by bongodriver

Well a 'spit basher' would say that, no point admitting to it if you hope to keep under the bias radar and hide the emotional investment in it's counterpart, ok glad we cleared the dynamic stability issue though as thats the only real stability issue which would cause significant problems.

Is it your favorite aircraft or something? I've stated nothing but facts and you're calling me biased.

it is 'spit bashing' if that characteristic is being used as an example of a stability problem, I don't mind if you don't wish to engage with me, please don't be under the impression I need it.

I never said it was a problem. I just said the spitfire is not statically stable.

understanding of physics has however, stability is an inherrent capability of an aircraft, you must realise that a Cof G shift can cause a change in stability.

CG shift has nothing to do with the topic at hand.

[bongodriver]

Originally Posted by CaptainDoggles

Is it your favorite aircraft or something? I've stated nothing but facts and you're calling me biased.

I don't aim the claim at you per se, but the general feeling on these topics are mainly led by bias, my favourite aircraft.....late mark perhaps....but not a fan of early spits, couldn't say a particular favourite but I am a secret lover of the cessna 150/152 believe it or not..bloody fantastic little aircraft.

Originally Posted by CaptainDoggles

I never said it was a problem. I just said the spitfire is not statically stable.

then why was it brought up in the first place?

Originally Posted by CaptainDoggles

CG shift has nothing to do with the topic at hand.

No, but it was a response to your claim stability is not a capability of an aircraft, if it can be changed then it is a variable, which if used to advantage is a capability, now try denying that some aircraft can shift C of G to their benefit.

[CaptainDoggles]

then why was it brought up in the first place?

Because people throw terms like "stable" around without really knowing what it means, and think that because an RAF pilot said the Spitfire was "easy to fly" that it must therefore mean the Spitfire was a very stable aircraft.

No, but it was a response to your claim stability is not a capability of an aircraft

Never mind. Linguistic difference. I was just pointing out that you don't say "The P-51 is capable of static stability." You say "The P-51 is statically stable." An aircraft is designed to be stable under a particular set of conditions. If you change the conditions then the aircraft might not be stable under those conditions, but you aren't changing the aircraft.

if it can be changed then it is a variable, which if used to advantage is a capability, now try denying that some aircraft can shift C of G to their benefit.

Why on earth would I deny that and why is it relevant to the Spitfire?