Japanese aircraft were behind in timing to Allied aircraft.

[Shortround6]

So here again, M.20 looks better to me.

First, don't trust Wiki.

• Service ceiling: 31,400 ft (9,600 m)
• Absolute ceiling: 35,500 ft (10,800 m)
• Rate of climb: 3,200 ft/min (16 m/s)
• Time to altitude: 20,000 ft (6,100 m) in 9 minutes 36 seconds

They don't agree, 20,000ft in 9 minutes 36 seconds averages 2,083fpm.
The Machine gun armed Hurricane IIs would hit 20,000ft in around 8.5 minutes, they also had ceilings several thousand ft higher.
British times to altitudes were done at a 30 minute rating, for Merlins that often meant 2850rpm and 9lbs of boost (individual aircraft varied a bit on boost)
Without knowing the conditions of the 3200ft/min climb of the M.20 things look a bit dubious.
You can get Hurricanes to climb faster than 2700ft/min, just use 3000rpm

Somewhere the M.20 was noted as having a not too nice stall. Let's also remember that they were NOT thinking of use the M.20 as a normal carrier fighter.
They were thinking of using it as CAM fighter, catapult launched and ditching at sea, one idea was to detach the landing gear when the plane was mounted on the catapult and since the plane was going to ditch in the sea anyway the landing gear needed to be jettisoned. Page 293 of the "British fighter since 1912."
Maybe they have it wrong but there seems to be a crap load of contradictory information about this airplane.

Something else that doesn't line up well.

• Empty weight: 5,870 lb (2,663 kg)
• Max takeoff weight: 7,758 lb (3,519 kg)
• Fuel capacity: 154 imp gal (185 US gal; 700 L) fuel

You have 1888lbs of "pay load" but you have 1108lbs of fuel. which leaves 780lbs of weight for the oil (76lbs) , the 200lb pilot, the radio gear (just over 100lbs) and oh yeah, the guns and ammo (571lbs?) and bit of misc (flares. gun sight?)
Either the thing carried less fuel, or it carried less ammo or they raised the take-off weight or a combination. BTW the Spitfire and Hurricane used about the same amount of oil for 85-84 gallons of fuel so the oil weight is off for 154 gallons.

 

[GrauGeist]

To steer this back to aviation, it can maybe be said that the IJA and IJN were a bit ahead of the Allies (and other Axis powers) in using all around vision canopies on their fighters. However, that's mixed, because some had them (Zero, Ki-43, a good number of Ki-27s) and some didn't (most Ki-61s, production J2Ms, etc). Oddly, USN fighters didn't get bubble canopies until the F8F Bearcat and the Goodyear Super Corsair (though a version of the F6F was designed to use one, but never made it into production).

But the IJA and IJN planes that had the bubble canopies had them as early as 1940, maybe even earlier. The Hawker Typhoon wasn't flown with one until 1942, and wasn't standardized until 1943. A Spitfire VIII flew with one in 1943, but Spitfire FR 14s and F 16s didn't get them until 1944 (and it took until after the war with the F/FR18 and F22 to standardize). Even the iconic P-51D Mustang didn't fly in prototype form until 1943, and enter production in 1944. It also took a while for P-47s to go from razorback to bubble top.

Ironically, the Miles M20 "emergency fighter" had one in 1940, and even the 1937-38 era Gloster F5/34 had a bubble-ish canopy.

The Fw190 and Me262 both had full-view canopies, the Me309 also had a canopy based on the Me262's design.

 

[Wild_Bill_Kelso]

First, don't trust Wiki.

I did have another source, and quoted from it.

• Service ceiling: 31,400 ft (9,600 m)
• Absolute ceiling: 35,500 ft (10,800 m)
• Rate of climb: 3,200 ft/min (16 m/s)
• Time to altitude: 20,000 ft (6,100 m) in 9 minutes 36 seconds

They don't agree, 20,000ft in 9 minutes 36 seconds averages 2,083fpm.
The Machine gun armed Hurricane IIs would hit 20,000ft in around 8.5 minutes, they also had ceilings several thousand ft higher.

In the field, at least in North Africa, China, Russia and the Pacific, Hurricanes didn't seem to climb that swiftly. Regardless, all I see here is some quibbles with the quoted stats. Sure we don't know the conditions of each test which produced each benchmark, but you have to start somewhere.

British times to altitudes were done at a 30 minute rating, for Merlins that often meant 2850rpm and 9lbs of boost (individual aircraft varied a bit on boost)
Without knowing the conditions of the 3200ft/min climb of the M.20 things look a bit dubious.
You can get Hurricanes to climb faster than 2700ft/min, just use 3000rpm

Like I said, maybe in England, they didn't seem to in Egypt or Rangoon.

Somewhere the M.20 was noted as having a not too nice stall. Let's also remember that they were NOT thinking of use the M.20 as a normal carrier fighter.
They were thinking of using it as CAM fighter, catapult launched and ditching at sea, one idea was to detach the landing gear when the plane was mounted on the catapult and since the plane was going to ditch in the sea anyway the landing gear needed to be jettisoned. Page 293 of the "British fighter since 1912."

That's a good point, I missed that, 80 mph stalling speed doesn't sound good for a carrier regardless. But on the other hand, a fighter with a 1200 mile range instead of a 600 mile range sounds excellent, and would have been a big help in Burma and North Africa. It would be helpful in a hypothetical British vs. Japanese scenario as well, because you could put these on islands and they could escort bombers to attack enemy shipping or bases.

And if it makes 350 mph with feet sticking out, how fast it is with retractable landing gear?

Maybe they have it wrong but there seems to be a crap load of contradictory information about this airplane.

Isn't there a lot of contradictory information about just about every WW2 airplane?

Something else that doesn't line up well.

• Empty weight: 5,870 lb (2,663 kg)
• Max takeoff weight: 7,758 lb (3,519 kg)
• Fuel capacity: 154 imp gal (185 US gal; 700 L) fuel

You have 1888lbs of "pay load" but you have 1108lbs of fuel. which leaves 780lbs of weight for the oil (76lbs) , the 200lb pilot, the radio gear (just over 100lbs) and oh yeah, the guns and ammo (571lbs?) and bit of misc (flares. gun sight?)
Either the thing carried less fuel, or it carried less ammo or they raised the take-off weight or a combination. BTW the Spitfire and Hurricane used about the same amount of oil for 85-84 gallons of fuel so the oil weight is off for 154 gallons.

I mean, ok, but you can always pick apart the stats. All we can say for sure is that the M20 looks much better than the Hurricane in pretty much every respect except ceiling. I think they made a mistake not following up on it. Given the performance in 1940, who knows where that plane could have been in 1942 or 1943. Could have been another 'wooden wonder' like the Mosquito.

 

[ThomasP]

Miles M.20 link on Wiki:

"Miles M.20 - Wikipedia"

NOTE that there are 3 different maximum speeds listed for the M.20 in the Wiki article, ie 350 mph, 345 mph, and 333 mph. The 333 mph is listed as at "combat load".

M.20 maximum speed is 333 mph "combat load" vs 335 mph for the Hurricane Mk IIB (A&AEE tests at 7330 lbs with full fuel and ammo)
M.20 maximum range is listed as 870 miles vs 470 miles for the Hurricane Mk IIB (both on internal fuel while cruising at ~200 mph at 20,000 ft)

Engine, flying weight, and maximum speed are about the same clean with full combat load, so Initial Rate of Climb of 3200 ft/min is physically impossible at any realistic flying weight. The M.20 would have to weigh about 6250 lbs to reach 3200 ft/min using the normal Climb rating of 1120 BHP (2850 rpm at +9 lbs) for the Merlin XX. If using TO power of 1260 BHP (3000 rpm at +12 lbs) the M.20 could achieve 3200 ft/min IROC at about 7250 lbs, while the Hurricane Mk IIB at 7330 lbs would have an IROC of about 3100 ft/min.

The main advantage of the M.20 is the range with internal fuel, but was this with SSFT or not?

 

[BarnOwlLover]

Most sources I've read about the M20 give a top speed of 330-335 mph and a range (radius?) of 580 miles. This is from such sources as Swanburogh's Fighters and Jane's Aircraft of World War II (modern reprint of Jane's All the World's Aircraft of 1946). Of course, such info can be outdated. And when possible I rely on something more than just Wikipedia, such as sources linked to on said pages. And of course, newer sources tend to be more accurate, though that also depends on what's survived over the years.

I believe that our resident authors and such can attest to what research can uncover--as well as difficulties in finding such info. For the M20, at least Miles' brochure on the aircraft survived (and is posted somewhere on here). Not 100% sure how accurate it is, and is probably based to at least some degree on performance estimates, but since the M20 did fly, I'd bet that a good chunk of that info was at least based on flight testing results, including estimates.

 

[WARSPITER]

Probably a case where it wasn't needed as a quick build fighter after the Battle of Britain and wasn't
needed for catapult ships as surplus Hurricanes were already available.

Couple that with not being markedly better than others in production there wouldn't have been much
of a case to build another type of fighter.

 

[Geoffrey Sinclair]

Hurricane I Merlin II weights, tare weight 4,743 pounds includes 18 gallons of coolant. Load:
423 pounds, 8 Browning, 2,660 rounds including links.
200 pounds, pilot and parachute
88.5 pounds, instruments, gun sight and gun camera
49.5 pounds, pyrotechnics
15 pounds, oxygen
3 pounds, first aid
57 pounds, radio, (TR1133 radio 79 pounds)
836 pounds, total before 87 gallons of fuel fuel 7.5 pounds per gallon and 7 gallons of oil at 9 pounds per gallon. The Merlin XX used 100 octane, around 7.11 pounds per gallon.

Miles M.20 is quoted as having room for 12 machine guns, photographs show 8 fitted, useful load quoted at 501 pounds, but the difference between tare and all up weight is given as 1,888 pounds, the tare weight is 1,127 pounds more than the Hurricane I and 403 pounds more than the Hurricane IIB with the same engine and provision for 12 machine guns. In the Hurricane weights the instruments etc. come to 213 or 225 pounds depending on the radio fitted. Miles M.20 all up weight 7,758 pounds is 1,888 pounds more than tare weight while 432 pounds of armament, plus 200 pounds of pilot plus 1,110 pounds for 156 gallons of 100 Octane fuel plus 77 pounds for 8.5 gallons of oil is 1,810 pounds. By the looks of things the M.20 tare weight is just about everything less pilot, armament, fuel and oil, unlike the Hurricane figures.

In the Hurricane IIB 12 machine guns plus 3,990 rounds of ammunition comes to 611 pounds, or 188 pounds more than for 8 machine guns.

The idea of the M.20 as a catapult fighter would look appealing for a time but then it was found launching the fighter when the ship returned to Britain was a much better way of doing things, saving the time and effort to unload, giving the crew practice and cutting the risk of handling damage.

Miles Aircraft since 1925 by Don L. Brown. Wing area 234 sq feet, aspect ratio 5.1 wing root NACA 23021, tip 23009. Maximum speed clean 350 mph at 20,600 feet, in service condition 333 mph, stall 101 mph flaps up, 80 mph flaps down, take of run 810 feet (30 degree flap) to clear 50 foot obstacle 1,350 feet, initial rate of climb 3,200 feet per minute, service ceiling 31,400 feet absolute ceiling 35,500 feet, range at economic cruise 550 miles, duration 2 hours, absolute range 870 miles at 9,000 feet duration 5.2 hours. Shall we say interesting range figures.

As of early/mid 1941 the Hurricane was due to be replaced soon by the Typhoon.

Phillips & Powis (Miles Aircraft) started Master production in August 1939, ending Magister production in January 1941, Martinet production began in August 1942, Master production ending in February 1943. The Martinet being the target tow version of the Master to a 1941 specification, prototype first flown 24 April 1942.

The RAF Aircraft Performance charts give the Master I weights as 4,206 tare, 5,350 loaded as of 1941.

Master I 39 feet by 30 feet 5 inches, wing area 235 square feet, empty 4,370 pounds, loaded 5,573 pounds (Useful load 444 pounds) 68 gallons of fuel, 7 of oil, Kestrel XXX 715 HP, 226 mph, range economic cruise 484 miles, duration 3 hours
Master II 39 feet by 29 feet 4 inches, wing area 235 square feet, empty 4,293 pounds, all up 5,573 pounds (Useful load 521 pounds) 68 gallons of fuel, 7 of oil, Mercury XX 870 HP, 242 mph
Master III 39 feet by 30 feet 2 inches, wing area 235 square feet, empty 4,217 pounds all up 5,573 pounds (useful load 597? pounds) 68 gallons of fuel, 7 of oil Wasp Junior 825 HP, 231 mph
Miles M.20 34 feet 7 inches by 30 feet 1 inch, wing area 234 square feet, tare 5,870 pounds
Martinet 39 feet by 30 feet 11 inches, wing area 242 square feet, empty 4,640 pounds, all up 6,750 pounds (Useful load 659 pounds), 130 gallons of fuel, 8.5 of oil, Mercury XXX 870 HP, 240 mph, range 694 miles, duration 5 hours

The M.20 wing is quite different to the others, no kink or dihedral. The Master and Martinet wings were NACA 23024 to 23006.

 

[Shortround6]

Like I said, maybe in England, they didn't seem to in Egypt or Rangoon.

Ok, we have talked about "hot and high" conditions before. Everybody's aircraft did worse in tropical conditions. some did somewhat worse and some did a lot worse but,
Chances of plane A being better than plane B in England but worse in Egypt or Rangoon are about zero.
The M.20 was only tested in England and the British usually tried to modify the test results to "standard conditions" (59 degrees F and standard pressure).

And if it makes 350 mph with feet sticking out, how fast it is with retractable landing gear?

Apparently it never did 350mph. It may have been an estimate?
British Fighters from 1912 says the modified version only did 333mph under test, the same as the unmodified version. Modified version was supposed to have a more streamlined spinner nose, the smaller landing gear and the catapult spools. Not sure what else was different.

Basically the M.20 was not faster, it took longer to climb to 20,000ft carrying eight .303 guns than the Hurricane II did with four 20mm guns, it had a lower ceiling and needed more runway, maybe only bit.

If it won't perform well in trials why would anybody believe it was going to do better in service?

The British did make some mistakes in procurement. The M.20 was not one of them.

 

[Wild_Bill_Kelso]

Ok, we have talked about "hot and high" conditions before. Everybody's aircraft did worse in tropical conditions. some did somewhat worse and some did a lot worse but,
Chances of plane A being better than plane B in England but worse in Egypt or Rangoon are about zero.

That would seem not to be the case - the P-40 clearly lost less in terms of performance from it's baseline, and did fairly well in North Africa, whereas the Hurricane did not. This is one of the main reasons why the British ultimately decided to double down on the Kittyhawk as their main fighter for the region, even though it meant a much more complicated logistics tail for them. In part this was because it was apparently easier and less troublesome / performance crippling tropical filter for the engine, (both the Allison with the air intake on the top, but also with the Merlin XX for reasons I still don't fully understand), But it also apparently had something to do with the physical characteristics of the aircraft, the wings or something.

The Wildcat also seems to have lost relatively little in terms of performance in the tropics. Which may be one of the secrets of it's somewhat inexplicable success.

The P-39 seemed to be the opposite, and performed much better in cold weather environments .

The M.20 was only tested in England and the British usually tried to modify the test results to "standard conditions" (59 degrees F and standard pressure).

One potential issue with the M.20 is that being wood (and cloth?) it may have had more trouble in tropical and especially high humidity environments, such as the Mosquito did in Burma.

Apparently it never did 350mph. It may have been an estimate?

Geoffrey Sinclair's post above seems to contradict that. Maybe it was an early test with a lightened bird.

But here is the thing. Fixed undercarriage imposes quite a drag burden. Like 20-30 mph at least. So if the top speed is ~330 mph with fixed undercarriage I'd expect 350-360 without, even with a "full combat load" and antennas and bomb shackles and extra gun farings (once they put in 20mm) etc.

Hurricane IIC with tropical filters were just barely making 300 mph in the Western desert, as was revealed during the big Hurricane vs Martlet debate thread.

British Fighters from 1912 says the modified version only did 333mph under test, the same as the unmodified version. Modified version was supposed to have a more streamlined spinner nose, the smaller landing gear and the catapult spools. Not sure what else was different.

Like I said above. Two lingering questions are (as someone asked upthread) did the longer range include protected fuel tanks, and also was the larger fuel tanks possible in part due to no retractable landing gear?

The wing looks a big, so I would think they had room maybe for even more fuel.

Basically the M.20 was not faster, it took longer to climb to 20,000ft carrying eight .303 guns than the Hurricane II did with four 20mm guns, it had a lower ceiling and needed more runway, maybe only bit.

I don't think you have proven that it had inferior rate of climb, at least not yet. It did seem to have a lower ceiling.

If it won't perform well in trials why would anybody believe it was going to do better in service?

The British did make some mistakes in procurement. The M.20 was not one of them.

Well I think it could have been very helpful. We disagree on the Whirlwind too!

I suspect they didn't bother because the Hurricane was quite good in the Battle of Britain, and they thought the Typhoon would arrive soon. But I think not pursuing this a bit further was in deed a mistake. I think the M.20 was a promising design which filled a gap in the English panoply of warplanes.

 

[Shortround6]

That would seem not to be the case - the P-40 clearly lost less in terms of performance from it's baseline, and did fairly well in North Africa, whereas the Hurricane did not. This is one of the main reasons why the British ultimately decided to double down on the Kittyhawk as their main fighter for the region, even though it meant a much more complicated logistics tail for them. In part this was because it was apparently easier and less troublesome / performance crippling tropical filter for the engine, (both the Allison with the air intake on the top, but also with the Merlin XX for reasons I still don't fully understand), But it also apparently had something to do with the physical characteristics of the aircraft, the wings or something.

The Wildcat also seems to have lost relatively little in terms of performance in the tropics. Which may be one of the secrets of it's somewhat inexplicable success.

The P-39 seemed to be the opposite, and performed much better in cold weather environments .

Well, the P-40s didn't get tropical filters or got a much simpler one. The P-40s that got them could cut them in and out during flight. Not sure about the radiators, The British had a entire tropical package which often gets shortened to just "vokes filter". Tropical package included such things as emergency rations and survival gear, they may have swapped out the dinghy?
British would have stuck a filter on the M.20. There was quite a bit of trouble with the P-40F with the Merlin engine, in part because it had no filter. In part because the US didn't order enough spare engines to begin with (or rather didn't allocate enough engines as spares). The British are supposed to have given 600 used Merlins to the US to provide spare parts for overhaul but we know this cannot be true because the British Merlins weren't built to the same tolerances as the Packard Merlins

P-39 had several differences, the smaller wing for one, and that air intake seems to have needed help. in test reports the nominally identical engines in the P-39 and P-40 always seem to have a bit lower full throttle height in the P-39, and this is with the P-39 flying faster which should give a bit more RAM. It may need more investigation.
The F4F has a big wing, about the same as the Hurricane and it also has the two stage supercharger so you have more power at the higher altitudes. It is still going to worse at 20,000ft in hot air but you may have a bit of compensation by the supercharger and intercoolers.

But here is the thing. Fixed undercarriage imposes quite a drag burden. Like 20-30 mph at least. So if the top speed is ~330 mph with fixed undercarriage I'd expect 350-360 without, even with a "full combat load" and antennas and bomb shackles and extra gun farings (once they put in 20mm) etc.

They don't seem to have fitted the test airframes with any extra stuff. Even the 12 .303s may have been a bit speculative. Hurricanes got a bit of a double whammy with the 20mm guns, the four 20mms and ammo weigh around 170lbs more than twelve .303s but the 20mm guns on the Hurricane have got to be about the highest drag installation of any four 20mm gun installation seen on a single engine fighter. There is a reason the Spitfires got fairings.

Hurricane IIC with tropical filters were just barely making 300 mph in the Western desert,

See above, not quite comparing apples to apples.

I don't think you have proven that it had inferior rate of climb, at least not yet. It did seem to have a lower ceiling.

OK you got me. M.20 Taking 1 minute and 6 seconds longer to climb to 20,000ft proves the M.20 had a superior climb rate to the Hurricane IIA or IIB.
I cannot argue with that logic.

Well I think it could have been very helpful. We disagree on the Whirlwind too!

I rather like the Whirlwind, I just doubt that you could hang two Merlins on plane that had a wing 6.8% bigger than the plane (M.20) in question.
Now we get into arguments as to "easily modified" really means.

 

[Wild_Bill_Kelso]

Well, the P-40s didn't get tropical filters or got a much simpler one. The P-40s that got them could cut them in and out during flight. Not sure about the radiators, The British had a entire tropical package which often gets shortened to just "vokes filter". Tropical package included such things as emergency rations and survival gear, they may have swapped out the dinghy?

Both the Vokes type filter and the one on the P-40, as well as the later (improved) type of tropical filters used by the RAF, were all capable of being cut out or bypassed in normal flight, I believe. Someone can correct me if I'm wrong on the Vokes. The 'tropical package' you are referring to here was applied to all the DAF aircraft including water etc., so this stuff was also included in the Tomahawks and Kittyhawks.

British would have stuck a filter on the M.20. There was quite a bit of trouble with the P-40F with the Merlin engine, in part because it had no filter. In part because the US didn't order enough spare engines to begin with (or rather didn't allocate enough engines as spares). The British are supposed to have given 600 used Merlins to the US to provide spare parts for overhaul but we know this cannot be true because the British Merlins weren't built to the same tolerances as the Packard Merlins

The shortage of Merlins for the P-40 F and L was simply due to USAAF not ordering enough, and the strict rules of the contract in terms of how many went to US and to UK (i.e. Canada) aircraft production. I think they may have mainly used the 600 extra engines for spare parts initially but then did re-engine some with these. Anyway it seems to have alleviated the problem considerably, for a while.

P-39 had several differences, the smaller wing for one, and that air intake seems to have needed help. in test reports the nominally identical engines in the P-39 and P-40 always seem to have a bit lower full throttle height in the P-39, and this is with the P-39 flying faster which should give a bit more RAM. It may need more investigation.

Interesting.

The F4F has a big wing, about the same as the Hurricane and it also has the two stage supercharger so you have more power at the higher altitudes. It is still going to worse at 20,000ft in hot air but you may have a bit of compensation by the supercharger and intercoolers.

Also interesting! The tradeoff seems to be - theoretical top speed of 350 or 360 mph for P-40, in the field turns to 340 or 350 mph depending on type (from tropical filter in part, but mostly due to things like bomb shackles, antennas etc., and that whole 'tropical package'). Speed for the Hurri goes from 340 or 350 to 300. Speed for the Wildcat IV goes from theoretical 330 or 320.

They don't seem to have fitted the test airframes with any extra stuff. Even the 12 .303s may have been a bit speculative. Hurricanes got a bit of a double whammy with the 20mm guns, the four 20mms and ammo weigh around 170lbs more than twelve .303s but the 20mm guns on the Hurricane have got to be about the highest drag installation of any four 20mm gun installation seen on a single engine fighter. There is a reason the Spitfires got fairings.

Yeah the 20mm armament configuration doesn't seem ideal for either plane but especially the Hurricane.

See above, not quite comparing apples to apples.

OK you got me. M.20 Taking 1 minute and 6 seconds longer to climb to 20,000ft proves the M.20 had a superior climb rate to the Hurricane IIA or IIB.
I cannot argue with that logic.

I'd say we need a bit more data

I rather like the Whirlwind, I just doubt that you could hang two Merlins on plane that had a wing 6.8% bigger than the plane (M.20) in question.
Now we get into arguments as to "easily modified" really means.

No, I agree. It needed peregrines which is why it was probably doomed.

 

[Wild_Bill_Kelso]

As you know, the British had a very efficient and large scale aircraft repair depot system in the Western Desert.

 

[BarnOwlLover]

The discussion on aircraft in the MTO is obviously worthy of it's own thread. However, Hurricanes and Spitfire Vs did use the big Vokes filter commonly in the Pacific, which the main problem with it was that the fairing for it produced a lot of drag. And I mean a ton, as in it could knock as much as 8-10% off a plane's top speed potentially.

Of course, the Spitfire IX/VIII and the Mosquito did a lot better with integrating air filters into their intakes (just an extension of the supercharger intake essentially). Other designs did it better, though (at least in my opinion). The Merlin Mustangs with their ram air supercharger intake that began just behind the prop spinner was long enough that the filters could be just added internally to the supercharger intake trunk (that's what the cheese grater panels were on P-51B/C/D/K/H and F-82s were).

Also interesting was that the later Griffon powered Seafires (namely the Mk 47) used a similar intake (though without the side mounted filter intakes), the Spiteful/Seafang went back and forth between a Spitfire XIV/22/24 supercharger intake and a Seafire 47 type intake, and the Sabre powered Hawker Fury had a Mustang type under spinner intake (outer sections fed the oil coolers that were mounted at the back of the engine, center section fed the supercharger, which had filter intakes on the underside of it).

I also believe that the cheese graters on the side of the noses of P-40s were air filters.

 

[ThomasP]

The war-time Vokes filter most widely used on the Hurricane and Spitfire Mk V had no bypass capability relative to the air filter, so there was no possibility of RAM effects.This resulted in a lowering of both the aircraft and engine critical altitudes.

The later Universal Vokes filter used on the Mosquito and Spitfire Mk VIII/IX and later had a bypass capability

The Aboukir filter had a bypass capability (I think).

 

[EwenS]

The discussion on aircraft in the MTO is obviously worthy of it's own thread. However, Hurricanes and Spitfire Vs did use the big Vokes filter commonly in the Pacific, which the main problem with it was that the fairing for it produced a lot of drag. And I mean a ton, as in it could knock as much as 8-10% off a plane's top speed potentially.

Of course, the Spitfire IX/VIII and the Mosquito did a lot better with integrating air filters into their intakes (just an extension of the supercharger intake essentially). Other designs did it better, though (at least in my opinion). The Merlin Mustangs with their ram air supercharger intake that began just behind the prop spinner was long enough that the filters could be just added internally to the supercharger intake trunk (that's what the cheese grater panels were on P-51B/C/D/K/H and F-82s were).

Also interesting was that the later Griffon powered Seafires (namely the Mk 47) used a similar intake (though without the side mounted filter intakes), the Spiteful/Seafang went back and forth between a Spitfire XIV/22/24 supercharger intake and a Seafire 47 type intake, and the Sabre powered Hawker Fury had a Mustang type under spinner intake (outer sections fed the oil coolers that were mounted at the back of the engine, center section fed the supercharger, which had filter intakes on the underside of it).

I also believe that the cheese graters on the side of the noses of P-40s were air filters.

It wasn't all good news with the change to the Seafire 47 intake.

The first aircraft, PS944, flew with the old style intake from the Mk.45/46.

PS945 with the new intake was test flown in comparative performance trials against 2 Seafire F.46 fitted with the same engines and propellers. It was found to be 15mph slower. The old style intake "was superior in all performance aspects". It was thought "the extended Mk 47 air intake was less efficient than that of the Mk 46 due, it was thought to the air flow into the intake caused by the large blade roots of the contra props and the larger wheel well blisters. Tests were also made with the Mk 47 fitted with the Spiteful type intake."

That last comment suggests more differences between the F.21/22/24 intake and that of the Spiteful than might at first seem to be present.
Morgan and Shacklady "Spitfire the History"

 

[Wild_Bill_Kelso]

Didn't the Vokes filter also carry a lot of oil? (I don't know why it would, but I remember reading that somewhere... possibly hallucinated)

 

[EwenS]

Didn't the Vokes filter also carry a lot of oil? (I don't know why it would, but I remember reading that somewhere... possibly hallucinated)

All you need to know about the Vokes filter on the Spitfire is here (including the extra oil tank needed in the tropics)

Volkes filter - what's inside?

I'm tinkering with the KP Spitfire Vc (tropical) and as I was assembling the Volkes filter, it dawned on me that all the various kits I've seen or assembled that had a Volkes filter, represented the 'chin' as a vast, empty cavern with a hole in front. Surely there's a screen or grill inside that ...

www.britmodeller.com

 

[Wild_Bill_Kelso]

Thanks. it's quite interesting that the real problem was mainly the elmination of the Ram air effect. Do you know when they switched over to the Aboukir type?

 

[EwenS]

Thanks. it's quite interesting that the real problem was mainly the elmination of the Ram air effect. Do you know when they switched over to the Aboukir type?

AFAIK there was not a general switch to the Aboukir type. It was purely a local modification made in Egypt.

Aboukir was an RAF base in the Nile Delta from pre-war days on which was based an RAF MU. Their filters were an effort to improve on the Vokes type which was standard on the Spitfire V Tropical versions manufactured in Britain for overseas use. I don't think it has ever been clear just how many were converted. One other suggestion I've seen is that the need for a local modification became apparent with the arrival of the first PR Spitfires in the Med. These PR. IV arrived without the Vokes filter.

Spitfire Aboukir filter vs Vokes?

Does anyone know why the Aboukir filter should be any better than the Vokes one? Both rely on passing the air through a convoluted filter, which removes any of the pressure recovery that could have been expected from a well-designed intake. The Vokes has greater surface area, hence more skin...

www.key.aero

And it seems that there were at least 2 types of Aboukir filter

Abukir filters

Dear Forumites I'm almost 100% sure that similar question has occured before but UG hasn't help me with it. That's why I decided to ask it here as there are lots of people who have huge knowledge about Spitfires. I have a question about famous "custom" dust filters made by MU in Abou Kir/Abukir. ...

www.britmodeller.com

 

[Reluctant Poster]

Perhaps drifting too much into naval stuff, but the above is very interesting, any explanation why they chose a 6000 ton design instead of an 8000 ton one?

Good read, however inevitably one can see a bias there. Adding the 1943-44 torpedo launch/hit figures when the IJN was increasingly loosing it's edge due to ship and men losses, faced with an ever increasing and adapting USN is a bit misleading imo. Rather the 1942 statistics, when IJN was at it's peak are a much better indication as to how the hypothetical decisive battle could have went. Note that in 4 of the 6 battles with a large numbers of torpedoes launched (i discount the below 10 numbers for now), IJN scores hovered around 12-13%. The outliers are Java sea (launched from too far?) and second Guadalcanal (not quite sure what happened there, just pure luck for the american BBs not to be hit?).

If the IJN has a really good day during this hypothetical kantai kessen and the hits are hovering in the region of 12-13%, they might just about pull it off!

The interesting conclusions that the author draws is that long range torpedo fire was not a winning proposition. The most successful torpedo attack was Tassafaronga and there the torpedoes were launched at close range, certainly with range of US torpedoes.

One of the myths is that the Japanese doctrine was to launch their torpedoes and then wait for them to strike before opening fire. I cannot find too many examples of that. In most instances they did both at the same time or waited for gunfire to weaken the enemy first.

Based on the attached study I did an analysis of the action at Savo Island
The only Japanese cruiser to launch before opening fire was the Chokai. During the attack on the southern group the Chokai launched 4 at 10,000 yards all of which missed. 8 minutes she opened fire.
The Canberra was not hit by any Japanese torpedoes. Her damage was exclusively due to gunfire. The Chicago was hit by two torpedoes (1 was a dud) fired by Kako at a range of 3600 yards. The Chicago was not taken out by the hit as the damage was minimal. The Chicago took herself out of the battle. Her captain was due to be censured for his poor performance and this resulted in him committing suicide.

During the attack on the northern group the Chokai launched 4 at 9,500 yards. 3 minutes later she opened fire. The torpedoes arrive at the Vincennes 5 minutes after the gun battle had begun. At this point uncontrollable fires were raging and extensive damage to the Vincennes had been done by Kako's gunfire. There are debates on how many torpedoes hit with one certain and 1 or 2 more which may have actually been shell hits below the water line. I'm inclined to believe that two or three torpedoes hitting out of 4 is a highly unlikely event.

The torpedoes which struck Quincy (1 Type 93 and 2 21 in) were launched well after the gunfire commenced and at a range of only 3,000 yards. An additional Type 93 stuck the Vincennes 15 minutes after that battle started and it was fired from a range of only 2,400 yards.

Reading through the attached document it becomes clear that the real problem for the US at Savo Island was the total lack of communication. It is breath taking to see the total confusion within the US forces. Ships did not announce they were under attack or that they had spotted enemy. They all seemed to think that everyone saw what they saw and everyone heard the same radio messages. If was as if no one ever studied the night actions at Jutland. Even within the ships vital information was not passed along to the Captain. The Commander of the southern force went to a conference but didn't make it clear who would command in his absence. The Commander of the northern force expected that there might be a night attack and put his ship in a higher state of readiness but didn't bother to tell the other ships in his command. There are more examples.
The USN didn't suffer such a grievous defeat due to superior Japanese torpedoes or superior Japanese optics or superior tactics. They lost because they were in total disarray due to a lack of effective communications. As Strother Martin said:

View: https://www.youtube.com/watch?v=V2f-MZ2HRHQ