March until October of 1940: fighters' ranking

[wuzak]

I am reluctant to apply the word "cropped" to something that rotates at 28,000rpm.

The low altitude Seafires featured engines with reduced superchargers.

Reduced superchargers, as in the impeller blades were cropped to a smaller diameter?

Engine power went to the propeller, not the supercharger.

You learn something new every day!

Of course the supercharger requires power to operate. Reducing the impeller size also reduced the full throttle height and power required to drive the supercharger. Which means more power to the prop.

The low altitude engines were also installed in some old, beat up, Spitfire_Vs after D-Day. The aircraft were not popular with the pilots. In France, you really wanted a Spitfire_IX or XIV.

The Spitfire LF.Vs hastily introduced in 1941/1942 to combat Fw 190s at low altitude?

 

[Shortround6]

Some Seafires were reputed to have used Merlin 46 engines.

There were 4 different (at least ?) impellers used on the single stage engines.
The standard 10.25in diameter.
The 9.75in diameter used in the Merlin 30, 32 and 34
The 9.50in diameter used in the Merlin 45M, 50M, 55M and 55MA
The 10.85in diameter used in the Merlin 46, 47, 50A, 56

For supercharger drive gears you had the standard 8.588 gears uses in the Merlin I, II, III, and others.
You had the 6.313 gears used in the Merlin VIII
And you had the 9.089 gears used in just about everything else.

Please note that a lot of the low altitude engines used the 9.089 gears with the 9.50 diameter impeller.

The Merlin 46 used the 9.089 gears with the 10.85 impeller and required the most power to to drive the supercharger. It also gave the most power at high altitude.
The Merlin 32 used the 8.588 gears with the 9.75 in impeller and that is how they got the low altitude power.

A Merlin 45 used the 9.089 gears with the 10.25 in impeller and
A Merlin 45M used the 9.089 gears with the 9.50 in impeller.

Somebody else can calculate the tips speeds.

 

[PAT303]

Test between Zero and Spitfire Mark V tropical

The son of the pilot of the Spitfire is on this forum and stated his dad bent the tail of the Spitfire 15 degrees during the test against the Zero. He first stated it was 9 degrees but he misread his dads writing, I believe in his flight log.

Your comparing a MkV Trop fitted with a Merlin 46 running 9 psi boost, at the time of this test both the Merlin 45 and 46 were cleared for 16 psi, that Spitfire did 330mph when regular MkV hit 375mph to give you an idea of it's performance loss.

 

[Clayton Magnet]

I think it has been covered many times before on this forum, but if you wanted to design a Spitfire to perform as poorly as possible, the final product would look a lot like the Spitfires used in the Australian A6M trials.

 

[pinsog]

They must have needed filters to operate in the dusty environment or they wouldn't be on there. Could they run 16 psi boost with the filter on? If my group was losing 28-5 I'd be having my mechanic turn the boost up so I didn't die.

Death trap Zero didn't have armor or self sealing tanks, does anyone know how many pilots lived out of the 28 Spitfires shot down?

Many of the Wildcats at Guadalcanal were built from the wrecks of multiple planes after being shelled by battleships and cruisers, couldn't hit 330 mph on the day it rolled off the factory floor, flown by a 100 pound woman with no guns or ammo, climbed like a brick and it still fought Zeros to a 1 to 1 ratio not including the bombers they destroyed.

 

[Howard Gibson]

The Spitfire LF.Vs hastily introduced in 1941/1942 to combat Fw 190s at low altitude?

I don't think they went nuts with LF and HF Spitfires in '41-'42. Spitfire_Vs with Merlin_55Ms were flown over France after D-Day in '44. These were known as "clipped, clapped, cropped Spitties". There were much better Spitfires out there.

Just because better technology has been introduced, it doesn't mean that everybody gets to fly it.

 

[pbehn]

I don't think they went nuts with LF and HF Spitfires in '41-'42. Spitfire_Vs with Merlin_55Ms were flown over France after D-Day in '44. These were known as "clipped, clapped, cropped Spitties". There were much better Spitfires out there.

Just because better technology has been introduced, it doesn't mean that everybody gets to fly it.

As I understand it the "clapped" refers to them being used machines that were modified. Clipped and cropped refers to them being optimised for a specific purpose, that is low altitude speed/climb and a higher rate of roll. Other Spitfires were modified with extended wing tips pressurised cockpits etc for high altitude performance but were awful to fly at lower levels and didnt like to land, preferring to float along the runway, technology is sometimes a compromise and at other times a pursuit of a single goal.

 

[wuzak]

I don't think they went nuts with LF and HF Spitfires in '41-'42. Spitfire_Vs with Merlin_55Ms were flown over France after D-Day in '44. These were known as "clipped, clapped, cropped Spitties". There were much better Spitfires out there.

Just because better technology has been introduced, it doesn't mean that everybody gets to fly it.

Clipped - clipped wings to improve roll rate to compete against the Fw 190A in 1941/42.

Cropped - supercharger impeller machined down to improve boost and power to increase low altitude power to combat low flying Fw 190A raiders in 1941/42.

Clapped - because they were used examples, war weary, if you like.

They may well have still been flying them over the D-Day beaches, as a significant proportion of Spitfires in service in 1944 were still Vs. But they were relegated to ground attack or secondary roles.

 

[pbehn]

They may well have still been flying them over the D-Day beaches, as a significant proportion of Spitfires in service in 1944 were still Vs. But they were relegated to ground attack or secondary roles.

Why not optimise the second line machines for the use you intent to put them to? D-Day was an amphibious landing, everything of importance was at ground level, by mid 1944 Spitfire Mk Vs were not going to be tasked with providing "top cover".

 

[Shortround6]

They were flying a Spitfire VB with a Merlin 50M at Boscombe Down in early 1943.
Report was written 25th of May 1943.

see; Spitfire F. Mk.VB Climb and level speed performance

Wings were not clipped.
Due to the "cropped" impeller the engine was allowed to use 18lbs of boost instead of the normal 16lbs of boost.

Please note that this was over a year before Normandy.
I would also note that the test aircraft was only 94 airframes different (newer) than the airframe used for the first VB Spitfire built as such and with full operational equipment and tested in May of 1941. How "clapped" the example used when testing the Merlin 50 engine may have been is subject to question but the airframe may have been almost 2 years old?

in any case the test Spitfire was flying within 1-2 months of the First P-47 Thunderbolt combat sorties over Belgium and France. The Idea that the cropped impeller/low altitude Spitfire V was a "D-Day" special is pretty thin.

 

[Shortround6]

Getting back to the Zero vs Spitfire over England in 1940 and the relevance of the Australian trials.

The Merlin 46 operating at 9lbs of boost was within 30-40hp of a Merlin III running at 6lbs boost until around 17,000ft is reached. The Merlin III then has less power the higher the plane goes. The Merlin 46 gets stronger until 22-23,000ft is reached.

The test makes it clear that the Spitfire has a performance edge over 20,000ft and NO TESTS over 20,000ft were performed.
The improved supercharger inlet on the Merlin 46 is overshadowed by the higher supercharger gears and the larger diameter impeller at altitudes of under 17-18,000ft.
The Spitfire Is over England in 1940 have weaker armament than the VCs over Darwin but the eight .303s are lighter in weight and don't have the drag producing gun barrels 20mm feed blisters. They also don't have the Vokes/tropical filter nor do they have the tropical radiator and oil coolers fitted. With other added equipment the RAAF Spitfire Vs were about 500lbs heavier than a Spitfire I over England in the summer of 1940 or almost 8-9% lighter.

A Spitfire I running 12 lbs of boost was good for 314mph (?) at sea level and 359mph at 11,500ft, knock 5-10mph off if you wish. If the Zero vs Spit fight descend to lower altitudes over England in 1940 the Spitfire Is will have over 300hp more power than the Darwin Spitfires did and will be lighter.
The Zero would still be dangerous but the results could very well be different.

 

[Vincenzo]

The L.F. Mk V had the Merlin 45M, 50M, 55M, a Mk V with a 50 is not a L.F.

 

[Jabberwocky]

2TAF definitely used 'L' or 'LF' modified Mk Vbs and Mk Vcs from its formation in June 1943 and into the early part of 1944, but these had nearly disappeared by the time of D-Day.

From the 2TAF's June 1944 order of battle, I make it eight Mk V squadrons. In comparison, 2TAF had 35 Mk IX squadrons in service at the same time, along with a single Mk VII squadron.

Almost all of 2TAF's Mk Vs - with the exception of some meteorological and air spotting aircraft - appear within 83 Group, but placed in reserve with ADGB. From the 83 Group intelligence summaries it appears none of their Mk Vs actually saw any combat post D-Day. There aren't any claims made or losses recorded for Mk Vs for June through to the end of August.

From my reading, early 1943 to early 1944 was the heyday for the LF Mk V.

 

[nuuumannn]

303 Squadron were certainly the highest CLAIMERS. However modern research comparing actuals to claims places 603 Squadron as top scorers, with 303 in 4th place.

Ahh, the Scots'll be pleased. 603 (City of Edinburgh) Sqn, AuxAF memorial at Edinburgh Airport, formerly RAF Turnhoose.

2007 603 Sqn Spitfire

 

[nuuumannn]

Not at all, aircraft are like any other fighting machine, there is a balance between performance firepower and protection, the Zero doesn't have that balance.

And what are you basing that on? The usual misguided prejudice?

Have fun flying either way across the channel doing 200mph at 13,000ft with 850 litres in unprotected tanks in 1940-41.

I believe you make far too much of protection and its role. As mentioned earlier, lots of Zeroes shot down lots of aircraft with armour plating and got away with being shot at themselves, so reality doesn't match your argument, Pat 308, which I've pointed out time and again, but which you just repeat without providing credible evidence.

Everything you state about the Zero has no reference to fact and is based predominantly on your disapproval of the aircraft. Suggesting it couldn't survive in Europe because of a detrimental performance compared to the PTO? Why? Where does this come from? Was there something in the air/water/fuel in Europe compared to the PTO? Did the P-38, B-25 and other types that operated in both theatres suffer the same thing? Or is this peculiar trait happen only to Japanese aircraft, specifically the Zero?

And this hare brained idea that Zeroes couldn't fly over the Ruhr because of flak and other anti-aircraft measures... Again, evidence! This entire theory makes no sense at all and is completely meaningless because it is devoid of context. You might as well say that the B-17 would have been useless over Viet Nam. Totally misplaced statement with no basis of credible reasoning at all.

Let's provide evidence instead of shooting these silly theories around.

 

[Shortround6]

The link below is a link to an evaluation of the A6M5 Model 52. It notes the controls are very good up to over 300 mph.

The later A6M3s got trim tabs for the ailerons as did all the Zeros afterwards.
The A6M2s and early A6M3s had no trim tabs for the ailerons which did affect the relative control response before the different models.

 

[SaparotRob]

I remember reading (Air Classics methinks) a B-17 was used in Viet Nam for special missions. This was because the B-17 didn't look American.

 

[nuuumannn]

I remember reading (Air Classics methinks) a B-17 was used in Viet Nam for special missions. This was because the B-17 didn't look American.

I've read the same. In the example above though, my quote was about a meaningless context as a B-17 bomber instead of B-52s, but you get that, I'm sure. Were B-17 search and rescue aircraft used in South-East Asia? Would make sense.

 

[SaparotRob]

I knew where you coming from nuuumannn. It's so rare for Viet Nam and B-17 to be in the same sentence that the line "the B-17 didn't look American" leapt to my mind unbidden. I'm glad for the confirmation, though. I've been remembering a lot of things lately that might not have happened.

 

[GrauGeist]

The B-17s used by the CIA (Air America, Civil Air Transport and Intermountain Aviation) were all phased out of service in Southeast Asia by the late 50's.

It might be of interest, though, to know the B-17 of Intermountain Aviation was the ship that snatched up James Bond at the end of the movie* with it's Fulton system.

* Sorry, should have mentioned the movie's name: "Thunderball"