Allied Gold-Match II

RG,

Why would the Spitfire hold an advantage over 30K? I would have thought that the Bearcat would have waxed the Spitfire at any altitude.

And which Spitfire was the best model to become operational prior to 1946? I noticed that you mentioned the XIV.

DAVIDICUS said:

RG,

Why would the Spitfire hold an advantage over 30K? I would have thought that the Bearcat would have waxed the Spitfire at any altitude.

And which Spitfire was the best model to become operational prior to 1946? I noticed that you mentioned the XIV.

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I doubt it would make much difference to go up to the Spit 21. The version of this plane used in WWII had the Griffon 61 or 64 with a five bladed prop. Only a few post-war units were built using the Griffon 85 and two 3 bladed contra-rotating props, and I don't know if any of these were operationally deployed or if they were produced before the end of 1945. In any case they didn't perform that much better than the Spit XIV.

The F8F supercharger was optimized for relatively low altitude - peaks being at about 17,000 and 25,000 feet. Against the Japanese there was no need to worry about higher altitudes. If you look at the BHP curves for the R-2800 (c) vs. the Griffon I posted in the original Allied Gold-Match thread (Spit XIV vs. F4U-4) you can see that the Spit power curve is likely to match the R-2800 at about 30K. Also, the 5 bladed prop has advantage at high altitude as the shorter blades will not exceed mach when the longer blades of the R-2800 start to.

=S=

Lunatic

RG the Spit Mk.21 had an intirely new WING for christs sake !! It was thicker, stronger, and had an even better armament (4x20mm Hisp's)

The Spit Mk.21 would most likely out-turn the Bearcat, aswell as out-climb it ! (Even the Mk.XIV has an initial climb rate of over 5,000ft/min !)

And about the test with the F6F and Spit V, Source please ?! British tests showed that the Spit Mk.IX turned just as well as the Spit Mk.V, while the Mk.XIV turned just as well as the Mk.IX !!

So there goes your theory about the Spit Mk.XIV not turning as well as the Spit Mk.V !

yes and i fail to see how rate of climb has much of an effect on the outcome of this............

Soren said:

RG the Spit Mk.21 had an intirely new WING for christs sake !! It was thicker, stronger, and had an even better armament (4x20mm Hisp's)

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Stronger yes... thicker no.

The new wing was similar in plan, but was stronger, carried more fuel, housed a longer landing gear (which allowed a larger diameter propeller), and carried four 20mm cannon.
http://www.chuckhawks.com/spitfire.htm

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The Spit Mk.21 had exactly the same airfoil as virtually all of the Spitfires,

Supermarine 368 Spitfire 21 - NACA 2213 (root), NACA 2209.4 (tip)
Vought V-166 F4U Corsair - NACA 23015 (root), NACA 23009 (tip)
http://www.aae.uiuc.edu/m-selig/ads/aircraft.html

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the only real difference being the tips were squared off.

Also, as to an earlier comment you made about the Spit wing being about the same thickness as that of the Corsair. The way the NACA numbering system works for both 4 and 5 digit wings is that the last two digits represent the thickness as a percentage of the chord. Therefore at the root the Corsair wing is 15% as opposed to 13% of chord thickness, and the chords are almost the same (the Corsair's being a little longer), but at the tip the Spitfire's is 9.4% vs. 9% for the Corsair, but the chord of the Corsair's wing is quite a bit longer so it is still thicker. The tip section for the F8F is the same as the Corsair's, but the root section is a 23018, a little bit thicker.

Soren said:

The Spit Mk.21 would most likely out-turn the Bearcat, aswell as out-climb it ! (Even the Mk.XIV has an initial climb rate of over 5,000ft/min !)

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The Spitfire 21 weighs more than the Spitfire XIV, has the same airfoil, and the same power level, and a decrease in gear ratio to 0.45:1. Here is the +21 lbs boost climb chart for it (from the 4th fighter group site):



Climb performance is not even close to 5,000 fpm. The highest climb rate I've seen quoted was 4850 fpm, no source for the data provided. Time to climb to 20,000 feet is 5.15 minutes - worse than the Spitfire XIV! The Spitfire 21 running +21 lbs boost was a half minute slower to 20,000 feet than the XF8F running at only 59 inches of boost! Even if the Spitfire 21 were to be able to manage 5000 fpm climb, it still would be over 1000 fpm slower than the Bearcat (at full boost).

The Spitifire 21 and the F8F represent totally opposite development directions. Where the Spitfire 21 represents Supermarine's efforts to move its fighter from being an interceptor to being a patrol/escort plane, the Bearcat represents Grumman's effort to evolve the Wildcat/Hellcat line from being a patrol plane to being a pure interceptor. The Spitfire's range and weight are increasing compared to its forerunners, where the Bearcat's weight and range are decreasing.

The two planes have virtually identical wing area and very close wing loadings (Spit = 243.6 sq-ft/9250 lbs, F8F = 244 sq-ft/8800 lbs), but the powerloading advantage is with the Bearcat in a big way. So how do you figure the Spit 21 is going to out-turn or out-climb the F8F. It does not make any sense at all.

The F8F had every advantage over the Spitfire 21 (except at very high altitudes), with the execption of firepower which goes to the Spitfire but not by a whole lot. The Spitfire 21 had 4 x 20mm Hispano II cannon firing at 600 rpm / gun = 2400 rpm, vs. the F8F-1 with 4 x .50 M3 BMG's firing at 1200 rpm / gun = 4800 rpm.

Soren said:

And about the test with the F6F and Spit V, Source please ?! British tests showed that the Spit Mk.IX turned just as well as the Spit Mk.V, while the Mk.XIV turned just as well as the Mk.IX !!

So there goes your theory about the Spit Mk.XIV not turning as well as the Spit Mk.V !

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Everything I've seen indicates the Spit V turned better than the IX which turned better than the XIV. Same wing.. heavier plane. I have no source (though I'll look for one) concerning the RN's comparision of the F6F-3 vs. the Spit V - just the general comment that the RN was impressed that the Hellcat could turn with the Spit (but not climb with it), and the tests were done in 1943.

While I'm looking for those tests, perhaps you can provide a reference to the Spit IX turning as well as the Spit V, or the Spit XIV turning as well as the Spit IX (which implies it turned as well as the V)? Everything I've ever read disputes this!

=S=

Lunatic

Didn't any of the Bearcats that became operational prior to '46 have 4x20mm's?

RG Im really beginning to question your credibility as your Climb info for the Spit Mk.21 is just flat wrong, and must have been "Home made"

The true climb rate for the Spit XXI is 7.85 min to 30,000 ft !! And a Max climb rate of 4800 ft/min at 7,700 ft !

The Spit XIV with less sustained climb rate than the Spit Mk.21, has a max climb rate of 5,040 ft/min. at 2,100 ft. !

While I'm looking for those tests, perhaps you can provide a reference to the Spit IX turning as well as the Spit V, or the Spit XIV turning as well as the Spit IX (which implies it turned as well as the V)? Everything I've ever read disputes this!

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Then you havent read anything !

Spitfire IX tactical comparison with Spitfire VC:

Manoeuvrability
The Spitfire IX was compared with a Spitfire VC for turning circles and dog-fighting at heights between 15,000 and 30,000 feet. At 15,000 feet there was little to choose between the two aircraft

At 30,000 feet there is still little to choose between the two aircraft in manoeurvrability, but the superiority in speed and climb of the Spitfire IX becomes outstanding. The pilot of the Spitfire VC found it difficult to maintain a steep turn without losing height, whereas the pilot of the Spitfire IX found that he had a large reserve of power which enabled him to maintain height without trouble


Spitfire XIV tactical comparison with Spitfire IX:

Turning Circle
The turning circles of both aircraft are identical.

Turning stall
The Spitfire XIV gives less warning of a stall in a tight turn than a Spitfire IX, though the same pre-stall characteristic ("shuddering") occurs. This is a good point as it allows sighting to be maintained nearer the stall. This aircraft tends to come out of a dive in a similar manner to other Spitfires.


Spitfire XIV JF317 and Spitfire VIII test results:

In spite of heavier controls the Spitfire XIV is more manoeuvrable than the Spitfire VIII in turns at all heights.

The Spitfire XIV is superior above 25,000 and with its better turning characteristics it is more than a match for the Spitfire VIII.

Stronger yes... thicker no.

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Please don't use Chuck hawks as a source !

Can you give the source of that data please?

Please look at the NACA wing profiles - they prove beyond any doubt that the Spit 21 wing was no thicker than the Spit XIV (or IX) wing.

RG_Lunatic said:

Can you give the source of that data please?

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Take a look at the 4th Fighter-group site.

--------------------------------------

And about the Spit Mk.21:

1. Introduction.

This report summarizes the results obtained on the prototype Mark 21 fitted with a Griffon 61 engine.

2. Summary of Results

At an all up weight of 9000 lb. and wtih combat rating of 2750 r.p.m. and 18 lb. boost:-

(a) Maximum level speed 455 m.p.h. at 25,600 ft.
(b) Maximum rate of climb 4800 Ft./Min. at 7700 ft.
(c) Time to 30,000 ft. 7.85 mins.
(d) Service ceiling 42,800 ft.
(e) Coolant and oil suitabilities: Full tropical under combat climb conditions.

DAVIDICUS said:

Didn't any of the Bearcats that became operational prior to '46 have 4x20mm's?

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Maybe maybe not. The F8F-1b's were delivered in early 1946. There may have been some night fighter versions delivered in 1945?

However, all F8F's had universal gunbays, and could fit either .50's or M3 20mm.

=S=

Lunatic

Soren said:

RG_Lunatic said:

Can you give the source of that data please?

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Take a look at the 4th Fighter-group site.

--------------------------------------

And about the Spit Mk.21:

1. Introduction.

This report summarizes the results obtained on the prototype Mark 21 fitted with a Griffon 61 engine.

2. Summary of Results

At an all up weight of 9000 lb. and wtih combat rating of 2750 r.p.m. and 18 lb. boost:-

(a) Maximum level speed 455 m.p.h. at 25,600 ft.
(b) Maximum rate of climb 4800 Ft./Min. at 7700 ft.
(c) Time to 30,000 ft. 7.85 mins.
(d) Service ceiling 42,800 ft.
(e) Coolant and oil suitabilities: Full tropical under combat climb conditions.

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That data is Vickers tests for a prototype aircraft and it's dated May 1943! It may well be estimated performance based upon static tests.

If you page down you will find the actual test data on a real Spitfire 21 production unit conducted during the Spring and Early summer of 1945 which reads:

Aeroplane and Armament Experimental Establishment
Boscombe Down
10 October 1945
Spitfire F. Mk. 21 LA.187
(Griffon 61)

Climb and Level Speed Trials


Summary.

...........Climb and level speed performance trials have been completed on this aircraft, the first production Spitfire 21. The salient results were as follows :-


Rate of climb at full throttle height, MS gear, +21 lb/sq.in., 2750 rpm = 4440 ft/min. at 4900 ft.
" MS gear, +9 lb/sq.in., 2600 rpm = 2740 ft/min. at 14,200 ft.
" FS gear, +21 lb/sq.in., 2750 rpm = 3615 ft/min at 19,200 ft.
" FS gear, +9 lb/sq.in., 2600 rpm = 2125 ft/min. at 29,000 ft.


Estimated service ceiling, 2750 rpm = 43,400 ft.
" 2600 rpm = 42,400 ft.


Combat level speed (+21 lb/sq.in., 2750 rpm) = * 406 mph at MS gear full throttle height (7000) ft.
* 442 mph at FS gear full throttle height (21,800 ft.)
446 mph at FS gear full throttle height (22,600) ft.)

For the full report click HERE

http://www.spitfireperformance.com/spit21.html

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This test clearly shows 5.15 minutes to 20K and 8.85 minutes to 30K as shown in the table I provided before.

====================

Soren said:

RG Im really beginning to question your credibility as your Climb info for the Spit Mk.21 is just flat wrong, and must have been "Home made"

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Soren you can just go to hell! I used data from the SAME SOURCE YOU DID! However, unlike you who simply chose to present the best data available as fact I read through all of it and it is absolutely clear that the 1945 AAEE data from a real production plane is much more legitimate than the Vickers data based upon prototype testing/estimates by the manufucturer in EARLY 1943!

You need to read the front page of the Spitfire performance testing website, in particular:

An Air Ministry document from 29.10.43 details the protocol to use in arriving at performance figures for aircraft:

NOTE ON THE USE OF PERFORMANCE ESTIMATES

1. There are 4 main stages in the evolution of performance for a new aircraft:-

(1) Original Estimate - based on drawings and expected engine powers.
(2) Flight Tests - Performance of actual aircraft - (a) Prototype, (b) Production, when built
(3) Provisional Performance Curves - Adjustments of (1) in view of (2)(a).
(4) Final Performance Curves - Based on (2)(b) and subject to variation with the condtion of the aircraft.

2. The limits within which the Stage (1) estimate can be guaranteed depend on whether the new aircraft is -

(i) A development of an established type whose characteristics are well known (e.g. Spitfire XIV); or
(ii) A new type, about which little or no confirmed information is available, (e.g. F2/43, with Centaurus engine).
(Note:- The addition of new factors, e.g. Contra-rotating props. to an aircraft in Category (i) would probably transfer it to Category (ii).)

3. With "Development" aircraft, original estimates should be accurate to within 1-2% in speed, and 50-100 ft./min. in rate of climb. With "New Type" aircraft, however, the error might be up to 6-7% in speed, and 200-250 ft./min. in climb.

4. Flight Test figures, by themselves, should be treated with considerable reserve, since they may be obtained under non-standard conditions, and the aircraft flown may differ from production machine.

5. From the prototype trials, Provisional Performance Curves can be obtained, modifying them, if necessary, to allow for the effect of the difference between the prototype and production machine.

6. Only when trials with representative production machines have been carried out under known conditions can the Final figures be issued. These figures then represent the performance expected of an average production machine of this type.

7. Any particular machine off the production line, however, may vary from the average in top speed and climb because of differences in engine power and general finish. The usual variation for single-engined fighters is up to 3% in top speed, and 150-200 ft./min. in rate of climb; heavy bombers vary up to 4% in top speed, and 150-200 ft./min. in climb. (...)

http://www.spitfireperformance.com/

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Again, you owe me an apology!

--------------

Now I want to see that data showing the Spit V, IX, and XIV all turned equally well. You realize that if this is true it throws all your wingloading arguments right out the window, as all 3 planes had exactly the same wings but weights of 6500 lbs, 7500 lbs, and 8500 lbs, respectively.

=S=

Lunatic

However, all F8F's had universal gunbays, and could fit either .50's or M3 20mm.

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which to you means of course that they all carried 20mm and even though you don't know if they used 20mm before 1946 the fact that the gun bay could take it, in your increasingly annoying eyes this means that they did carry 20mm the whole time..........

" your increasingly annoying eyes"

Lanc, his eyes are stinging from your evil breath. What do you expect?

that's not evil, that's garlic

You're a good sport Lanc. You know I'm just kidding.

of course i'm a good sport, i'm british, calling me a good sport is one of the biggest compliments you could pay me...........

Soren you can just go to hell!

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And you expect to be taken seriusly when saying such rubbish ? RG Im disappointed !

However, unlike you who simply chose to present the best data available as fact I read through all of it

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Oh really, well then you just "forgot" this part or what ?:

5.1 Due to a slight inaccuracy in the adjustment of the boost control the tests were not done in all cases at exactly the nominal boost. It is calculated that altering the boost on test to the nominal value would have increased the normal rate of climb below full throttle height by about 70 ft/min. in MS gear (boost 0.4 lb/sq.in. too low) and 100 ft/min. in FS gear (boost 0.7 lb/sq.in. too low).

Now I want to see that data showing the Spit V, IX, and XIV all turned equally well.

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RG I already gave you them !!

Now I want to see that Spit V and F6F test of yours !

You realize that if this is true it throws all your wingloading arguments right out the window, as all 3 planes had exactly the same wings but weights of 6500 lbs, 7500 lbs, and 8500 lbs, respectively

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Your actually convinced that its all about the Wing-loading as to how well a plane turns ?!!

RG what about Power-loading, Wing-aspect-ratio, center of gravity etc etc !

the lancaster kicks ass said:

However, all F8F's had universal gunbays, and could fit either .50's or M3 20mm.

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which to you means of course that they all carried 20mm and even though you don't know if they used 20mm before 1946 the fact that the gun bay could take it, in your increasingly annoying eyes this means that they did carry 20mm the whole time..........

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No, just that they could have.

BTW: the universal gunbay design came from... the British!

I believe there were a few F8F-1N's in the inital batch of F8F's, and these had 20mm. But I am not sure these were delivered before 1946.

As for the Spit Mk.21 and F8F Bearcat.

RG the Normal loaded weight for the Bearcat was 9,386 lb, and its wing area 244 sq.ft. The Spit Mk.21's normal loaded weight was 8850 lb, and its wing area was 244 sq.ft !

And according to my sources, the Spit 21's new wing gave greater lift !

Soren said:

Soren you can just go to hell!

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And you expect to be taken seriusly when saying such rubbish ? RG Im disappointed !

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When you accuse me of fabricating the data which is right there on the same site you are quoting what do you expect me to say? You deserve worse!

Soren said:

However, unlike you who simply chose to present the best data available as fact I read through all of it

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Oh really, well then you just "forgot" this part or what ?:

5.1 Due to a slight inaccuracy in the adjustment of the boost control the tests were not done in all cases at exactly the nominal boost. It is calculated that altering the boost on test to the nominal value would have increased the normal rate of climb below full throttle height by about 70 ft/min. in MS gear (boost 0.4 lb/sq.in. too low) and 100 ft/min. in FS gear (boost 0.7 lb/sq.in. too low).

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Once again you do not read very well do you?

5.1 Due to a slight inaccuracy in the adjustment of the boost control the tests were not done in all cases at exactly the nominal boost. It is calculated that altering the boost on test to the nominal value would have increased the normal rate of climb below full throttle height by about 70 ft/min. in MS gear (boost 0.4 lb/sq.in. too low) and 100 ft/min. in FS gear (boost 0.7 lb/sq.in. too low).

.....The level speed and rate of climb at combat rating would not have been affected appreciably.
http://www.spitfireperformance.com/la187.html

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The underlined words in the passage you quoted and the part you chose not to quote that follows, which I've highlighted in bold, make it utterly clear that this is irrelevant to the combat climb - which is what we are talking about right? I left that passage out because it does not have any bearing on the climb rates under discussion.

Soren said:

Now I want to see that data showing the Spit V, IX, and XIV all turned equally well.

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RG I already gave you them !!

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The source Soren? Surely you don't expect me to take your typing of selected sections of such information at face value do you? 8)

Soren said:

Now I want to see that Spit V and F6F test of yours !

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So far all I've found are references to it, not the actual data. I'm still looking...

Soren said:

You realize that if this is true it throws all your wingloading arguments right out the window, as all 3 planes had exactly the same wings but weights of 6500 lbs, 7500 lbs, and 8500 lbs, respectively

Click to expand...

Your actually convinced that its all about the Wing-loading as to how well a plane turns ?!!

RG what about Power-loading, Wing-aspect-ratio, center of gravity etc etc !

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You are the one who has pointed to wingloading over and over again to support your "this plane must turn better than that plane" arguments. Powerloading helps to sustain a turn, but it does not tighten it. The wing aspect ratios of all three models of Spitfire's are the same, and the center of gravity for the V is the best of the three. But most of all, pilot accounts relate that the Spit V was the best handling of all the versions of the Spitfire and that later models did not manuver as well because of the increase in weight.

So lets see the source data to confirm your claim. Or is it "Home made"? (sorry - I just couldn't help myself )

=S=

Lunatic