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

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Kevin J said:
Supposedly it could do 450 in a dive so more than a Ki-43. A Merlin 24 would give it a good low altitude performance edge. So exit manouvre would be dive then boost to run then zoom climb back. That should be okay until the Ki-43-III comes along and it's outclassed. You could then remove 2 cannon to improve the roll rate. Now that they did.
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I don't think top speed in a dive was the problem, it was the slow acceleration in a dive. If a P39 or P40 rolled into a dive it accelerated quickly, essentially it dropped like a rock. Early Spitfires and all Hurricanes accelerated too slowly and while they may eventually outpace the Japanese fighter following them, they remained within effective gun range for too long and got shot down. The P40 outrolled anything the Japanese had, so it was on its back and gone in a heartbeat.
 
pinsog said:
I don't think top speed in a dive was the problem, it was the slow acceleration in a dive. If a P39 or P40 rolled into a dive it accelerated quickly, essentially it dropped like a rock. Early Spitfires and all Hurricanes accelerated too slowly and while they may eventually outpace the Japanese fighter following them, they remained within effective gun range for too long and got shot down. The P40 outrolled anything the Japanese had, so it was on its back and gone in a heartbeat.
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I guess you're not going to refine a fighter ( Hurricane IIb ) that you expect to replace with a better one ( Spitfire Vb ) quite soon. The late 42 Sea Hurricane IIc no doubt came along because of the disappointing performance of the Seafire IIc.
 
Schweik said:
I wonder what the difference was in this test done a month earlier where it managed 370

http://www.wwiiaircraftperformance.org/P-40/Kittyhawk_II_performance_9sept42.jpg

Does anyone still upload documents to wwiiaircraftperformance.org? Did it all stop some time around 2015?
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Look at document FL220-LEVEL.JPG and you get 330 at 9800 and 354 at 20400 with air cleaner so about 5% loss in speed over Kittyhawk II with no air cleaner.
 
Kevin J said:
There's no way that a Spitfire Vc with a volkes filter was ever going to do 365 mph, it's more like the 345 mph of the Seafire IIc. A Vc Merlin 46 SU carb did 368 so take off 8 - 10 for the standard version without filter. Seafire IIc did 320 at 16000. So maybe it was an Aero vee filter.
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It was definitely a Vokes filter. The Australians spent some time building and testing their own replacement tropical cowling to replace it (they got a slight performance improvement but had problems with rough running at high altitude).

Various figures for Spitfire V aircraft with Vokes filters:

Vc - 352 at 18,500 ft (Merlin 45, as reported by the Australian Air Ministry based on UK tests)
Vb - 354 at 17,400 ft (AB320, Merlin 45)
Vc - 357 at FTH ("extensive" Australian testing of 3 aircraft with different cowlings (358.5 for locally produced cowling, 363 for temperate cowls)
Va - 363 at 20,800 ft (6,440 lbs) (test of tropical filter as reported in The Spitfire Story by Price)
Vc - 364 ("several separate tests" in Australia accord to Darwinspitfires.com)
Vc - 365 at 22,000 ft (6,870 lbs) (first Australian test, probably part of same figures from Darwinspitfires)
V - 374 (Comparative trials of tropicalised and temperate aircraft (379 for temperate). Model not given, from Spitfire the History

The 365 mph of the first aircraft tested by the Australians was higher than most, but the speed of individual aircraft varied, especially if they had a variation in FTH.

I suspect there may have been differences in the design, manufacture or fitting of the Vokes filter because some trials reported a large speed loss (15 mph or more) but others around 5 mph. The Australians devoted a lot of effort into getting temperate cowls and designing their own improved tropical version but in the end found little difference between them.
 
Kevin J said:
I guess you're not going to refine a fighter ( Hurricane IIb ) that you expect to replace with a better one ( Spitfire Vb ) quite soon. The late 42 Sea Hurricane IIc no doubt came along because of the disappointing performance of the Seafire IIc.
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I am not sure that was the case. I would love to see some memos regarding the thinking or reasoning of the time. You may be right but there is too little evidence available to say one way or the other.

we do have to make sure we are comparing like to like and both planes came with and without the Vokes filter, larger oil tanks, ice guards (in the case of the Spitfire at least)
and in one case of the Sea Spit MK IIC it was carrying four 20mm cannon and four .303 guns.

http://www.spitfireperformance.com/seafireIIc.pdf

I am not sure how many of either type aircraft got the 6 outlet exhausts instead the 3 outlet ones. There are a number of pictures about that claim to be Sea Hurricane IICs with the 3 outlet exhausts. Bad captions or the 6 outlet exhaust was limited issue/special case?

Fit Spit with the same intake as the 342mph Hurricane and the same exhausts and fit two 20mm guns and four .303s and I wonder what the results would be (use the Merlin 46 as a number of Seaspits got very low altitude engines which means their speed in the lower thicker air cannot compare to the Sea Hurricane flying at 20,000ft),
 
Shortround6 said:
I am not sure that was the case. I would love to see some memos regarding the thinking or reasoning of the time. You may be right but there is too little evidence available to say one way or the other.

we do have to make sure we are comparing like to like and both planes came with and without the Vokes filter, larger oil tanks, ice guards (in the case of the Spitfire at least)
and in one case of the Sea Spit MK IIC it was carrying four 20mm cannon and four .303 guns.

http://www.spitfireperformance.com/seafireIIc.pdf

I am not sure how many of either type aircraft got the 6 outlet exhausts instead the 3 outlet ones. There are a number of pictures about that claim to be Sea Hurricane IICs with the 3 outlet exhausts. Bad captions or the 6 outlet exhaust was limited issue/special case?

Fit Spit with the same intake as the 342mph Hurricane and the same exhausts and fit two 20mm guns and four .303s and I wonder what the results would be (use the Merlin 46 as a number of Seaspits got very low altitude engines which means their speed in the lower thicker air cannot compare to the Sea Hurricane flying at 20,000ft),
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Yes lots of different figures. IIRC there were a small number of new build Sea Hurricane IIc, so maybe only 10% of them had the individual exhausts and the higher speeds as other figures I've seen are 324/320 for the IIb/IIc.
 
Hop said:
It was definitely a Vokes filter. The Australians spent some time building and testing their own replacement tropical cowling to replace it (they got a slight performance improvement but had problems with rough running at high altitude).

Various figures for Spitfire V aircraft with Vokes filters:

Vc - 352 at 18,500 ft (Merlin 45, as reported by the Australian Air Ministry based on UK tests)
Vb - 354 at 17,400 ft (AB320, Merlin 45)
Vc - 357 at FTH ("extensive" Australian testing of 3 aircraft with different cowlings (358.5 for locally produced cowling, 363 for temperate cowls)
Va - 363 at 20,800 ft (6,440 lbs) (test of tropical filter as reported in The Spitfire Story by Price)
Vc - 364 ("several separate tests" in Australia accord to Darwinspitfires.com)
Vc - 365 at 22,000 ft (6,870 lbs) (first Australian test, probably part of same figures from Darwinspitfires)
V - 374 (Comparative trials of tropicalised and temperate aircraft (379 for temperate). Model not given, from Spitfire the History

The 365 mph of the first aircraft tested by the Australians was higher than most, but the speed of individual aircraft varied, especially if they had a variation in FTH.

I suspect there may have been differences in the design, manufacture or fitting of the Vokes filter because some trials reported a large speed loss (15 mph or more) but others around 5 mph. The Australians devoted a lot of effort into getting temperate cowls and designing their own improved tropical version but in the end found little difference between them.
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The Volkes filter was big and bulky and included an oil tank necessary when a 90 gal slipper tank was carried. This caused th 5% speed loss.
 
Kevin J said:
I guess you're not going to refine a fighter ( Hurricane IIb ) that you expect to replace with a better one ( Spitfire Vb ) quite soon. The late 42 Sea Hurricane IIc no doubt came along because of the disappointing performance of the Seafire IIc.
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Can I ask where you got the idea that the Sea Hurricane IIc was developed because of the disappointing performance of the Seafire IIc?
 
They kept building Hurricanes way after they were effective fighters and Merlin 32's were specially designed to boost low altitude performance and was designed for, and built mainly used by the FAA because of that. The Merlin 32 produced more power than the Merlin XX as fitted to the Sea Hurricane at low altitude.
 
data card for the Sea Spitfire L IIc with Merlin 32 engine (also used in the Baracuda)

seafirel2cads.jpg


From Spitfire Performance. The engine used a 9.75in Impeller (compared to the "cropped" 9.5in ones) but used the the 8.588 supercharger gear instead of the 9.089 gears of the MK Vs with Merlin 45s, 50s, 55s with the cropped impeller.
If somebody can find a Hurricane with a speed of 330mph or so at 5,000ft we might have a horse race but again we need to make sure we are comparing like to like,
The Seafire III did use the Merlin 55 and 55M (cropped rotor)

Please note with engine, despite have ing 18lbs at low level boost was down to 6.6lbs at 16,000ft including RAM from 334mph forward speed, at 20,000ft boost was down to 3.5lbs.
 
They may have built Sea Hurricanes because they were easier to land on a Carrier than the Seaspit and not because they performed better.

There is also the matter of allocations, unless you shut down a Hurricane factory and retool it to build Spitfires there are only so many Spitfires to go around. Every Sea Spit for the FAA is a land Spit not built for the RAF (not exactly but you get the point) so converting/building 400 or more Sea Hurricanes in late 1942/early 1943 may have been seen as as a way to keep from screwing up total number of fighters built.
 
Shortround6 said:
data card for the Sea Spitfire L IIc with Merlin 32 engine (also used in the Baracuda)

View attachment 547576

From Spitfire Performance. The engine used a 9.75in Impeller (compared to the "cropped" 9.5in ones) but used the the 8.588 supercharger gear instead of the 9.089 gears of the MK Vs with Merlin 45s, 50s, 55s with the cropped impeller.
If somebody can find a Hurricane with a speed of 330mph or so at 5,000ft we might have a horse race but again we need to make sure we are comparing like to like,
The Seafire III did use the Merlin 55 and 55M (cropped rotor)

Please note with engine, despite have ing 18lbs at low level boost was down to 6.6lbs at 16,000ft including RAM from 334mph forward speed, at 20,000ft boost was down to 3.5lbs.
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Hurricane V, Merlin 32, 322 at 2000.
 
No Performance figures but from "Hawker Aircraft since 1920 by Mason"

""Rolls-Royce was able to show that it was possible to ground boost the Merlin 32 to develop almost 1700hp, and it was therefore decided to combine thins engine, driving a 4 blade Rotol propeller, with the universal wing of the MK IV and alter the designation to MK V. Two conversions from MK IVs were undertaken, the first, KZ193, being flown by Lucas and Fox on 3 APril 1943'

"By the Autumn of 1943, however, with very large stocks of Hurricanes being assembled in India, it was decided that relatively modest advance in performance did not justify perseverance with a new version of the Hurricane and, although the three MK V examples underwent prolonged trials, the project was abandoned."

Unless we know the condition of the MK V prototype it's speed, while interesting, doesn't tell us much. The MK IV universal wing having a single .303 gun on each side (hardly fighter armament) and fittings/wiring/plumbing for bombs, drop tanks, rockets and 40mm AT guns in pods. Was the 322mph made with clean wings or with empty bomb racks or with ?????

This prototype performance is 17mph slower than the data card for the Seafire M MK IIC
 
wuzak said:
Can you post the full comparison and where the data comes from?

The Seafire 322mph @ 2,000ft and the Sea Hurricane?
http://www.spitfireperformance.com/mb138speed.jpg

Hurricane IIC
http://www.wwiiaircraftperformance.org/hurricane/hurricane-IIc-raechart-level.jpg

The Hurricane IIC doesn't get to 320mph until 19,000ft and FS gear (which the Seafire did not have).

Have you any better data for the Hurricane V?
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It's from wiki. Other figures from wwiiaircraftperformance.
 
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