A Critical Analysis of the RAF Air Superiority Campaign in India, Burma and Malaya in 1941-45

Schweik said:

Kevin J, I really don't understand why you hit "Disagree" on this, I was just asking a question. What is there to disagree with? I wasn't asserting anything.

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Oh yea yea yea yea yea. BP Defiant, crap manoeuvrability compared with Hurricane. Estimated 360 mph top speed without turret that only cost 25 mph. Someone's been smoking the whacky backy? PR Hurricane I without guns did 350 mph so how would a Defiant with guns do 360 mph?

I never said it did...? Why do people seem determined to put words in my mouth?

Schweik said:

I never said it did...? Why do people seem determined to put words in my mouth?

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I agree, it was Boulton Paul, not you. Now me, I like the Defiant. So, move the radiator to the nose, get 20 mph, wing folding like the Spitfire, arrestor hook, catapult attachments, replace 2nd crew member with fuel tank, put the guns in the wings and maybe you get navy fighter with same speed, range as Zero but not so manoeuvrable. Better still build Miles M20 navy fighter. Better still buy Corsair.

Why I would moving the radiator to the nose make it faster? I still don't understand why you clicked 'disagree' on my original question on this. It was just a question and made no claims, so what is there to disagree with?

Schweik said:

Why I would moving the radiator to the nose make it faster? I still don't understand why you clicked 'disagree' on my original question on this. It was just a question and made no claims, so what is there to disagree with?

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The Hotspur had its radiator in that position and was faster. The production P-40 as opposed to the prototype moved the radiator and was faster. I disagreed with your suggestion that it would be a better Hurricane than the Hurricane.

I wasn't suggesting I was asking. I didn't claim to know, which is why I stipulated that it was probably a stupid question - you are more than entitled to disagree, but tagging a post with a negative flag is a bit much. If we can't ask a question without being dinged how can anyone have a conversation here?

As for the chin radiator thing, I'm not sure I agree that is the actual reason. I thought the mid-fuselage / underwing location was the more aerodynamic / less draggy place to put the radiator, ala Spitfire or P-51.

I have found the following written by the RAF in a review of the air combat in the far east.

'The Hurricane longest in operation is now completely outclassed by the Japanese fighters, and it is confined to ground attack in which its specialised bombing technique had made it a remarkable success. '

Later in the paper when discussing allied tactics:-

The basis of the allied tactics is avoidance of in-fighting with the Japanese whose manoeuvrability gives them a clear advantage. All allied fighters except the Hurricane at present enjoy advantages of dive, straight and level speed, zoom and in the case of the Spitfire climb, when compared to all but the latest types of Japanese aircraft.

In another paper written in 1942 the RAF are clear that as long as they don't get into close in fighting they are definitely superior to the Japanese type 97 (Ki 27) fighters, but the Type O fighters (Ki 43 misidentified as Zero) has a performance almost equal to the Hurricane but cannot match it in a dive and zoom combat. These would have been early Ki43's which did have a problem with the strength of the wing.
Unfortunately for the RAF, close in combat was the order of the day as the Japanese realised that the RAF fighters often couldn't gain altitude and once the Radar cover was made ineffective, started to position the escorting fighters below the bombers so the RAF had to climb through the escort before they could attack the bombers.

Kevin J said:

I can't find your 330 mph figure anywhere. RCAFson's look to be more accurate. The 30 gal slipper combat tank should only reduce speed by 5 mph. I think the 341 mph top speed is when the 45 gal slipper drop tank is fitted.

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http://darwinspitfires.com/index.php?page=spitfire-vc-versus-the-zero The Merlin 46 engined MkV's and A6M both maxed out at 330 mph at 15-16,000ft, the Merlin 45 MkV's on the other hand were doing 375 mph at 19,000ft.

PAT303 said:

http://darwinspitfires.com/index.php?page=spitfire-vc-versus-the-zero The Merlin 46 engined MkV's and A6M both maxed out at 330 mph at 15-16,000ft, the Merlin 45 MkV's on the other hand were doing 375 mph at 19,000ft.

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No, 354 mph with tropical filter, 337.5 mph with 90 gal tank, all at 17,400 feet with Spitfire VB and Merlin 45. You're not comparing like with like. From what I can find the 30 gal tank cost about 10 mph speed loss on a Seafire Iic. The Seafire Iic is about 20 mph slower than a Spitfire Vc with Merlin 46 because of navy equipment, but no volkes filter which would cause a 5% loss in speed and 8% loss in rated altitude. Go look at www.spitfireperformance.com/spittest.html and press the Seafire IIc button.

If a MK Vc with a Merlin 46 could not do 375 mph at at 19,000 the chances of a Vc with a Merlin 45 doing it are about zero.

from a test of a Spitfire V using a Merlin 45 with the "combat rating" of 16lbs.

" In level flight below 13,000 ft. the maximum level true airspeed is higher by about 35 m.p.h. using combat rating than at the same height using normal rating. The maximum level speed is 369 m.p.h. at 13,000 ft. Above this height the increase in speed is less and falls to zero at 19,900 ft., the full throttle height at normal rating, where the speed in either rating is 360 m.p.h. "

The test of the Spit VB with the fuel injected Merlin 46 is a special test engine and no production Merlin 46 used fuel injection or any production Spitfire V for that matter,

PAT303 said:

http://darwinspitfires.com/index.php?page=spitfire-vc-versus-the-zero The Merlin 46 engined MkV's and A6M both maxed out at 330 mph at 15-16,000ft, the Merlin 45 MkV's on the other hand were doing 375 mph at 19,000ft.

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They only gave speeds for the SpitV at 15K ft but that was not the full throttle height of the SpitV/M46 which as the comparison states was " ...21 000 feet...". In the comparison the SpitV is denied the use of overboost and max boost in the test was limited to 9lb and this has the effect of reducing SpitfireV/M46 speeds by about 20-30 mph at 15k ft.

Shortround6 said:

If a MK Vc with a Merlin 46 could not do 375 mph at at 19,000 the chances of a Vc with a Merlin 45 doing it are about zero.

from a test of a Spitfire V using a Merlin 45 with the "combat rating" of 16lbs.

" In level flight below 13,000 ft. the maximum level true airspeed is higher by about 35 m.p.h. using combat rating than at the same height using normal rating. The maximum level speed is 369 m.p.h. at 13,000 ft. Above this height the increase in speed is less and falls to zero at 19,900 ft., the full throttle height at normal rating, where the speed in either rating is 360 m.p.h. "

The test of the Spit VB with the fuel injected Merlin 46 is a special test engine and no production Merlin 46 used fuel injection or any production Spitfire V for that matter,

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Fuel injected gave a top speed of 368 mph above 20000 feet, 8-10 mph higher.

Shortround6 said:

If a MK Vc with a Merlin 46 could not do 375 mph at at 19,000 the chances of a Vc with a Merlin 45 doing it are about zero.

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The MkV which was tested which the injected 46 did 368 mph at 22,500, the report states the condition of the plane added 10 mph, a standard 45 engined MkV did 374 mph at 20,800ft, nothing was said about the condition. The data is from Boscome Down.

Kevin J said:

No, 354 mph with tropical filter, 337.5 mph with 90 gal tank, all at 17,400 feet with Spitfire VB and Merlin 45. You're not comparing like with like. From what I can find the 30 gal tank cost about 10 mph speed loss on a Seafire Iic. The Seafire Iic is about 20 mph slower than a Spitfire Vc with Merlin 46 because of navy equipment, but no volkes filter which would cause a 5% loss in speed and 8% loss in rated altitude. Go look at www.spitfireperformance.com/spittest.html and press the Seafire IIc button.

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The RAAF did their performance trials around 20,000ft over Darwin, I can only assume they did because that was the most common combat height they fought at during that battle. My whole argument revolves around the fact the Merlin 46 was the wrong engine in that situation because it only starting showing it's advantage well above that height, resulting in the poorer performance it showed when compared to the P40E and A6M.

PAT303 said:

The MkV which was tested which the injected 46 did 368 mph at 22,500, the report states the condition of the plane added 10 mph, a standard 45 engined MkV did 374 mph at 20,800ft, nothing was said about the condition. The data is from Boscome Down.

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We really need to try to compare like to like as a lot of things are not adding up.

Yes, a MK V Spit with with a Merlin 45 did make 374-375mph at 20,800ft at Boscombe Down, however it was a MKVa with eight .303 guns and was operating at 6450lbs at take-off.
Spitfire Mk VA X.4922 Report
A later MK VB did 371mph at 20,100ft at 6525lbs and the drag of the cannon barrels/cannon drum fairings.

A tropical MK Vb did 354mph at 17,400ft at 6695lbs and with the cg 1in further back than the early Vb,
In addition to the tropical filter the plane's set up was "An aerial mast was fitted in the usual position on top of the fuselage, and I.F.F. aerials were fitted between the tail plane tips and the fuselage. An external mirror was fitted above the front of the hood. The aircraft was finished in desert camouflage. "

earlier tests make no mention of the radio mast, the IFF aerials or the external mirror one way or the other, they may have been fitted (the radio mast especially) or not.

The Spitfire performance site has no test of the Spitfire MK VI which is a MK V fitted with a Merlin 47 (Merlin 46 fitted with a cabin compressor for pressure cabin) the pressure cabin, a four bladed prop
and the extended wing tips.

However the book "The Spitfire story" by Alfred price gives test reports of both a Spitfire Va (tropical) fitted with a Merlin 46 (aircraft X4922), a MK VI (AB200) and a comparative tactical performance of a MK VI ((BR289) VS a standard MK Vb.

The Va tropical did 363mph at 20,800ft and 353 at 26,000ft at 6,440lbs

The MK VI did 356mph at 21,800ft and 343mph at 28,000ft at 6,740lbs

The MK VI in the in the comparative trial was (at 6,738lbs) was slightly slower below 20,000ft but 6mph faster at 22,000ft which was it's rated altitude.
Below 10,000ft it was bit slower in climb and and climbed at a less steep angle. from 10,000ft to 20,000ft there was little difference although the MK VI was slightly faster in climb. From 20,000 to 30,000ft the MK VI is about 1 minute faster than the test Vb. From 30,000ft to 35,000ft the MK VI takes half the time of the MK Vb.

Unfortunately no boost levels are given in any of these tests but the tactical trial was flown in May of 1942 with a plane from the middle of the production batch. The test with Aircraft AB200 was flown in Feb 1942 and AB 200 was the 2nd production MK VI and the test of the MK Va with Merlin 46 was flown in early 1942.

If combat with the Japanese over Darwin had been below 20,000ft then the Merlin 46s might very well have been part of the problem, bu if the combats were over 20,000ft then the problems were something other than the engines fitted.

edit, the Spit Va Tropical referred to was actually the same aircraft in the report linked to above but the tests were done about 8-9 months apart, the engine changed, the guns taken out and ballast used,and the gun ports sealed over. The same aircraft is reported to have made 355 1/2 mph at 20,800ft with a mock up of the 90 imp gallon jettisonable fuel tank and ballasted to 7,420lbs, max climb rate of 2050fpm at 14,600ft and service ceiling of 35,000ft.

Shortround6 said:

We really need to try to compare like to like as a lot of things are not adding up.

Yes, a MK V Spit with with a Merlin 45 did make 374-375mph at 20,800ft at Boscombe Down, however it was a MKVa with eight .303 guns and was operating at 6450lbs at take-off.
Spitfire Mk VA X.4922 Report
A later MK VB did 371mph at 20,100ft at 6525lbs and the drag of the cannon barrels/cannon drum fairings.

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3rd of March 1942 a Spitfire Vc with 4 20mm Hispano's did 374 mph at 19,000ft at an all up weight of 6,916 Lbs http://www.spitfireperformance.com/aa873speed.jpg

True but then

"The aeroplane was fitted with universal wings, 4 - 20 m/m guns and an internal bullet-proof windscreen.

No snow-guard was fitted during the tests.

A rear view mirror was mounted on top of the pilots hood outside, and triple-ejector exhausts were fitted (without fishtails).

I.F.F. aerials, a W/T mast, and aerial were installed."

Italics mine. Plane was also running at 9.3lbs boost which is not going to make a big difference over 9.0lbs of boost.

This plane was down to 349mph at 25,000ft which also shows some of the difference between the Merlin 45 and 46/47 for fighting at over 20,000ft.


Sorry, the idea that the RAAF was handicaped by the Merlin 46 vs the Merlin 45 does not hold up. Too many of the comparisons use the wrong altitudes for comparing power or the wrong boost limits. Why the Australians were limiting the boost to 9lbs is a question that doesn't seem to be answered. The Merlin 45,46 and 47 had all been cleared to use 60 1/2 inches ( 15lbs ? boost ) in Jan 1942.
http://www.wwiiaircraftperformance.org/merlin-ratings_3jan42.jpg

Would there be any differences in performance in a temperate climate and a tropical climate?

Yes

There seems to have been a considerable difference between the air at Boscombe Down and the air in Australia

I would note that there also seemed to a considerable difference in the air in Buffalo NY and Wright field and the Air in North Africa and the South Pacific when one looks at the tests for the P-40 and P-39 and the combat reports of the pilots.