I would just like to point out that Hightech has just
agreed with me that Badboy, Ack-Ack and countless others are dead wrong about the meaning of "vertical turn" in this particular text (to my great relief!)...
This means the discussion can now actually move forward in a useful way...
Leaving aside for the moment the issue of partial power to increase the low-speed turn rate, I think it is worthwhile to emphasize the context in which this text was written, and why it is particularly significant:
http://img30.imageshack.us/img30/4716/jjohnsononfw190.jpg To begin with, it is written with the hindsight of a POST-WAR perspective, from a very combat-experienced 30+ kill ace over years of combat. So the content of his account could be interpreted as being intended to be generally illustrative, not a particularly odd anecdote of a curious day (or he would give indicative warnings that this was not typical or normal)...
Second, it is true the aircrafts in question are the Spitfire Mk V versus the what is probably an early FW-190A, the FW-190A-3 or A-4.
It thus may not be illustrative of late-war aircraft capabilities.
It is worth mentionning here that the Soviets found the FW-190A-5's displaced center of gravity (6 inch longer nose), to reduce the full-power sustained turn rate by one second over the A-4... (This is actually contrary to my short-nose theory, but, contrary to some, I don't consider theories to be absolutes, or to be absolutes in a LINEAR way, especially at full power...: All my posts are mainly about observing the natural reality, and not to hang on with a death grip to theories... As long as the rough general picture I have of the aircraft's relative performance is correct, I couldn't care less if my theories about WHY are ALL wrong...)
Another point worth noting is that Soviet full-power sustained turn rate tests found little difference between the turn rates of the Spitfire Mk V and the much more powerful Spitfire Mk IX (usually less than 1 second apart at around 19-20 seconds). Again, this is against my lower-power shorter-nose allows better turn times theory, but at full power vs lower power things may again not be LINEAR, or apply to all types...
I have several late-war examples of FW-190As out-turning P-47s late in 1944, and this much better than they did in early 1944, but that could be due to worsening P-47D Bubbletop turn performance. Not really significant, right?
Wrong. It is still very significant in light of what follows:
German evaluation of a captured P-47D Razorback (needle prop): "The P-47 out-turns our Me-109G" . From: "On Special Missions: Kg 200"
In addition, in the over 600 P-47 combat accounts that I have read on Mike William's "WWII aircraft performance" site, the P-47 ALWAYS out-turns easily the Me-109G (at worst it is a match in right turns only, and even then the P-47 still can win), something which the P-51D has a LOT of trouble doing without resorting the fancy, very specific, downthrottling/coarse prop pitch/flaps down "trinity" (this from the additional 600-700 P-51 accounts from the same site)...
Early Spitfire encounters with FW-190As are always along the lines: "The Me-109s would dive and extend away, but the FW-190As would stay and fight": IE:
"-Squadron Leader Alan Deere, (Osprey Spit MkV aces 1941-45, Ch. 3, p. 2: "Never had I seen the Hun stay and fight it out as these Focke-Wulf pilots were doing... In Me-109s the Hun tactic had always followed the same pattern- a quick pass and away, sound tactics against Spitfires and their SUPERIOR TURNING CIRCLE. Not so these 190 pilots: They were full of confidence..."
The result of that encounter? 8 to 1 in favour of the FW-190As...
So the consistency with the Johnny Johnson account is, again, very typical, and in line with a post-war reminescence
meant to be informative...
Do I need to mention Soviet evaluations of FW-190As in combat?: "Will inevitably offer turning combat at a minimum speed", "Superior to the Me-109 in horizontal maneuvers", "engages in prolonged turning combat while the Me-109s interacts with it by using "Boom and Zoom" tactics"
Yes, all this, including the Soviet accounts, is fairly early, and usually goes up to no more than the A-4 or A-5s in early 1943. But are the late-war 1944 A-8s really that different?
Ask yourself this: If the Johnny Johnson account benefits from a post war hindsight, why does he not mention that FW-190As got worse as war went on?
He only mentions that the Spitfire Mk IX redressed the balance. In fact there are accounts from German pilots that the FW-190A-8 was the most maneuverable of the entire A and D series, especially with the broad wood prop... At least one actual FW-190A-8 Western ace described, on this very board, but through a relative who did not say his name, how he, downthrottled, during an on-the-deck turning combat, gained nearly 180° per 360° on an edge-of-stalling P-51D (who must have been at full power for this to be even possible)...
I did find a late-war account of a Spitfire Mk XII being unable to get away from a FW-190A in horizontal turns, only being saved by another unknown aircraft hitting the FW-190 in the cockpit...
British RAE tests also found the FW-190A to turn much better than the Me-109G, though they likely under-estimated the 109. (The P-51B
with full drop tanks was found to also out-turn the Me-109G, but could not out-turn the FW-190A even without drop tanks...)
Then you have Johnny Johnson starting his POST-WAR article with: "They (FW-190As) seemed faster in a zoom climb than the Me-109, and also far more stable in a vertical dive. They also turned better."
I really don't know what it would take, in the face of all this, to abandon notions that the math can allow us to make predictive statements about sustained turn performance outcomes (or even unsustained ones for that matter, if our lack of previous knowledge of the 6G Corner Speed of a P-51D being actually tested at around 315-320 MPH IAS is any guide)...
I remember clearly a whole thread, long ago on this very board, about how the Tempest V had the highest sustained climb rate of all the several types tested by the RAE on a specific day, and yet compared to all the other types present had the slowest straight-line horizontal acceleration!
I don't know what it would take to make people realize that mathematics are not predictive of relative performance accross different types, and sometimes not even within the same type (if the downthrottling issue is any guide)...
When you look at all the differences between a Me-109G or a FW-190A, it is obvious to me the differences are way too vast to be within the reach of simple math calculations...
Which is why personal accounts are inherently more valuable.
Gaston