# Spitfire + Sabre: any facts/opinons?



## tomo pauk (Sep 12, 2011)

People, was such a combo ever considered, Spitfire with Napier Sabre? 
How do you feel about such a plane, flying from 1943 (so Sabre's bugs are sorted out)?


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## Mustang nut (Sep 12, 2011)

If it didnt nose over it would be rejected by Supermarine as too ugly


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## tomo pauk (Sep 12, 2011)

Griffon engined Spits made no nose-overs to speak of, IIRC  
BTW, why ugly?


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## Tartle (Sep 12, 2011)

Who said Sabre's bugs were sorted out by 1943. Devons in his book 'Planning in Practice' talks of the delicacy, in June 1944, of telling Napier of the forecast numbers of engines required to the end of '45 would likely drop.... however the MAP were reluctant to rock the boat as Napier Sabre was still experiencing a high maintenance rate, which resulted in there always being a large stock undergoing or awaiting repair at any one time. Repair capacity was insufficient and slow to build up so new engines were being used to keep Typhoons and Tempests on the air. The MAP were concerned that reduction in orders would have two effects:
1. lowere morale so Napiers were even slower at tackling issues, and
2. Typhoons would be grounded just as they were at their operational peak with grouns support in Europe.
So for me I would go for the Griffon in the Spitfire; technically if we pretend the engine worked then its high altitude performance would have limited the scope of the Spitfire in an interceptor role and although it would have been an exciting aircraft would it have been able to lift extra weapons... certainly it couldn't go faster as the Mcrit on wing prevents this, let alone control reversals etc. Maybe a Spiteful wing would help?


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## Mustang nut (Sep 12, 2011)

tomo pauk said:


> Griffon engined Spits made no nose-overs to speak of, IIRC
> BTW, why ugly?


 
Put that chin radiator on a spitfire?


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## Ratsel (Sep 12, 2011)

Mustang nut said:


> Put that chin radiator on a spitfire?


ever see the "tropical Spitfire"?


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## Coors9 (Sep 12, 2011)

I luv the trop spit, probably my favorite .


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## davebender (Sep 12, 2011)

State of the art engine in an outdated airframe. Why would you want such an aircraft?


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## Edgar Brooks (Sep 12, 2011)

A state-of-the-art engine which lasted until 1950, in an outdated airframe, which lasted until 1954; it doesn't really make sense, I agree.
Edgar


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## Shortround6 (Sep 12, 2011)

tomo pauk said:


> People, was such a combo ever considered, Spitfire with Napier Sabre?
> How do you feel about such a plane, flying from 1943 (so Sabre's bugs are sorted out)?



Sabre weighed about 2500lbs. A two stage Griffon weighed about 2075lbs

and just like the R-2800 thread, what do you use for a prop? The 3 bladed prop on the Early Typhoons was 14 ft in diameter as was the later 4 bladed propeller. You are really going to need a contra rotating prop and/or a big fin to keep it pointed straight.


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## davebender (Sep 12, 2011)

Just because an airframe remained in operational service until 1954 doesn't mean it is up to date. There are still DC-3 transports in operational service yet I doubt anyone would build new DC-3s powered by modern turbo prop engines.


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## Edgar Brooks (Sep 13, 2011)

The questioner asked about 1943; anyone who contends that the Spitfire airframe was outdated, at that time, really is allowing his anti-British feelings full rein.
Edgar


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## davebender (Sep 13, 2011)

The Spitfire airframe design dates back to 1934. 1935 to 1943 was a period of rapid technical advances both in airframe design and aircraft engine power output. 

British aircraft engineers are not stupid. Why wouldn't they take advantage of the latest airframe technology for their newest aircraft engine?


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## Shortround6 (Sep 13, 2011)

Some airframes aged better than others. The Spitfire aged pretty well, the 109 didn't age too bad, the P-36/P-40 not quite so well, the MS 406 not at all well (even though variants were built quite late in Switzerland) and so on. Type of construction, airfoil (wing section) and size all figured into it. The Spitfire wing was better for high speed than the Typhoon wing which was several years later. If the Spitfire had NOT been adaptable it would have been dropped from production much like the Hurricane.


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## TheMustangRider (Sep 13, 2011)

The Spitfire did not remain a front-line fighter until the end of hostilities for no reason.
It was a superb aircraft which throughout its career contended pretty well with much newer designs.


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## Edgar Brooks (Sep 13, 2011)

davebender said:


> The Spitfire airframe design dates back to 1934. 1935 to 1943 was a period of rapid technical advances both in airframe design and aircraft engine power output.


Many people make that basic mistake; the Spitfire prototype was built to 1934 specs, but the production aircraft were built to 16/36DP, dated 28-7-36, incorporating an extra two years of technological and metallurgical advancement. 
The last normal use, for the Spitfire, was with the P.R.XIX, until June, 1957, but the last operational use was in 1963; not bad for an outdated airframe.
Edgar


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## claidemore (Sep 14, 2011)

What specifically would make the Spitfire airframe outdated? In any year, but particularly in 1943?


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## davebender (Sep 14, 2011)

Internal fuel capacity too small and it cannot be easily increased. Airframe and narrow track undercarriage not designed for engines producing 2,000+ hp. 

Essentially the same problems as the German Me-109 series. Would these aircraft have remained in mass production to 1945 without the equipment demands of WWII? I doubt it. Both aircraft were state of the art during 1939 but obsolescent by 1945.


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## Marcel (Sep 14, 2011)

davebender said:


> Just because an airframe remained in operational service until 1954 doesn't mean it is up to date. There are still DC-3 transports in operational service yet I doubt anyone would build new DC-3s powered by modern turbo prop engines.


Like this?
Basler Turbo Conversions, LLC  Basler Turbo 67 Aircraft


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## Ratsel (Sep 14, 2011)

davebender said:


> Internal fuel capacity too small and it cannot be easily increased. Airframe and narrow track undercarriage not designed for engines producing 2,000+ hp.
> 
> Essentially the same problems as the German Me-109 series. Would these aircraft have remained in mass production to 1945 without the equipment demands of WWII? I doubt it. Both aircraft were state of the art during 1939 but obsolescent by 1945.


everything was obsolete with the advent of the Me262.


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## Shortround6 (Sep 14, 2011)

the Me 109 more so.

The Spitfire could and was upgraded (although not as much as it could have/should have been at times). Spitfire started with 84 gal Imp (?) and with a 9 gallon larger lower front tank, two 14 gallon wing tanks and 33 gallon rear fuselage tank (all of which were used at one time or another on MK VIII and IX aircraft) internal fuel might have been able to go to 154 IMP gallons. An 83% increase. Some Spitfires could carry an extra 74 imp gallons in rear fuselage tanks alone but that is for ferry purposes and not combat. Granted the fuel selector may get a bit tricky. I would note that if you limited the lower rear tank to just 19 gallons this tankage of the Spitfire would hold exactly the same amount of fuel as a FW 190D-9 which was using is aux tank for fuel and not MW-50. Not a huge amount of fuel but certainly not lacking when compared to German or Russian aircraft. 
The Spitfire, more through luck than design, had less problems with compressability than some aircraft designed 2-4 years later.
Spitfires armament also stayed closer to first rank. Both guns and bomb load. Granted 1000lbs isn't huge but it beats 550lb by a good margin. 

And I haven't gotten to the MK 21/22.


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## Ratsel (Sep 14, 2011)

how exactly was the Me109K-4 more obsolete then the Spitfire in say late 44? Cause the fuel argument is a weak one. the Me was not designed for Long range.


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## Shortround6 (Sep 14, 2011)

well, according to Mr Bender niether was the Spitfire. And once you start sticking 1800-2000hp engines in the same airframe the range (endurance) gets even shorter unless you can up the fuel quantity somewhat. 

Spitfire carried heavier armament, maybe not better, but certainly heavier. Spitfire could carry a bigger bomb load, Spitfire could self ferry over longer ranges. By 1944 there were certainly other planes that could do what the Spitfire could do and in many jobs do it better but the Spitfire could still at least DO a number of jobs. The Me109K-4 was turning into a one trick pony. We can argue about the endurance of a 109K in regards to time in the air but the if the MK 108 had only 60 rounds then the firing time is just under 6 seconds before the armament is down to a pair of rather weak 13mm machine guns. Two firing passes and then land?


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## Tante Ju (Sep 14, 2011)

I think it would be error to turn this into another 109 - Spit debate. Those very bore.. but I note your thesis was disproofed some time ago about 109 range. 



Shortround6 said:


> well, according to Mr Bender niether was the Spitfire. And once you start sticking 1800-2000hp engines in the same airframe the range (endurance) gets even shorter unless you can up the fuel quantity somewhat.



It did not seem to reduce on other aircraft, _just Spitfire_. 109G/K certain did not reduce range. 190D - do not think so it did? P-51? I do not think so either.



Shortround6 said:


> Spitfire carried heavier armament, maybe not better, but certainly heavier.



So it was good for what? Heavy guns with little ammo? Standard Spitfire was two 20 mm cannon. 240 round. 109F+ was one-three 20mm cannon, 200 - 490 20 mm round.. Four cannon Spitfire was not practical.



> Spitfire could carry a bigger bomb load, Spitfire could self ferry over longer ranges.



I fear this is untrue both account too. Spitfire had record problems with wing bombs and E-wing integrity. Self ferry - yes, special outside tanks. But such version exist on 109 too, I believe more used than ultra large tank on Spitfire. Used once at Malta?



Shortround6 said:


> By 1944 there were certainly other planes that could do what the Spitfire could do and in many jobs do it better but the Spitfire could still at least DO a number of jobs. The Me109K-4 was turning into a one trick pony.



I respect opinion but I disagree. In what area(s) was late XIV Spitfire better than 109K-4? Range? No (XIV shorter range). Bombload? No. (500 kg vs 454 kg) Fighter recon version - both exist. 

Simply not true there was issue with it, nor evidence presented that Spitfire increased tankage because range was increasing short exact because airframe did not take upgrades too well - drag increase greatly, so range decrease. Range did not decrease on 109, so no need for more fuel. Which in opinion of mine was possible. For example - what technical reason not to enlarge main fuselage tank? Be careful - actually done twice already on 109.. or what technical reason not to have two small wing tank in place of gondola bay (where gondola ammo was). I do not see such. Take off weight certain not issue. 



Shortround6 said:


> We can argue about the endurance of a 109K in regards to time in the air but the if the MK 108 had only 60 rounds then the firing time is just under 6 seconds before the armament is down to a pair of rather weak 13mm machine guns. Two firing passes and then land?



MK 108 was choice of weapon for bombers. Yes two firing pass with devastate results on target, then land.. this armament was optimal for German need and tactical situation - escort did not permit more, not even a second pass was likely. Got problem with that, sure why not, technical possibility was there to replace MK 108 with MG 151, put two MG 151 into/under wing and you have very heavy armed fighter.. but this armament was for bomber. German estimate 4 MK 108 rounds for a bomber vs 20 20mm round.
So that firepower for 15 (very theoretic) possible bomber shotdowns with singe MK 108 vs 12 possible bomber shotdowns with two 20mm on Spit. Of course - you could still add two other 20mm on 109K, with 290 round: + 14 possible bomber shotdowns. Total 15+14=29 for 109K, 12 possible shotdown for Spit. There is no question, _for this task_, which was better. So what is ground for criticizm?

IMO biggest problem with Spitfire as airframe was large drag to start for designer. Inferior to all other front aircraft in this respect - Jakovlev, Lavockin, Mustang, 109, even radial Fw 190. This made it keeping competitive increased difficult. Fortunate for RAF, excellent work of Rollce Royce was available. Without extreme powerful engines, Spitfire would be very unsuccessful soon phased out like Hurricane. IMHO it was success of Merlin and Griffon engine despite or rather than success of Spitfire airframe!


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## jim (Sep 14, 2011)

Mr Tante ju
While a properly built and equiped K4 was equal or superior in combat with anything , we must admit that 109 could not reach the evolution of Spitfire 24 or Seafire 47. some final improvements were possible (Db605 L ,the wings guns , the improved propellers, perhaps high pressure MW50) but the end was near. The Spitfire was bigger.


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## Edgar Brooks (Sep 14, 2011)

Shortround6 said:


> Spitfire started with 84 gal Imp (?) and with a 9 gallon larger lower front tank, two 14 gallon wing tanks and 33 gallon rear fuselage tank (all of which were used at one time or another on MK VIII and IX aircraft) internal fuel might have been able to go to 154 IMP gallons.


No, not quite; the Mk.I carried 85 gallons, and by the war's end the IX/XVI carried 160/161 gallons internally.
Tante Ju, your piece is so full of errors, it's difficult to know where to start. No Spitfire, after the very first experimental Mk.Is in 1940, carried only 2 cannon. The armament was always (at least) 2 x 20mm + 4 x .303" or 2 x .5" Brownings, with the Vc capable of 4 x 20 mm + 4 x .303". Decry the .303" if you like, but a pilot with a .303" bullet in the head is just as dead as one hit by a 20mm shell. If the 4 x 20mm Spitfire was "not practical," how did the Mk.21, 22, 24, and Seafires 45-47 manage to carry them?
Once the wings were wired to carry bombs, the Mk.V onwards was quite capable of carrying 1000 lbs (455k) of bombs, with 1 x 500 under the fuselage, and 1 x 250 under each wing, as could the IX, XVI XIV, all without difficulty. The so-called "problems" were largely due to over-cautious pilots, and pulling out of a dive before dropping the wing bombs, which was not supposed to happen.
Every resupply flight to Malta used a ferry tank, and that went on well into 1943, when Malta's siege had been lifted.
The basic design of the Spitfire never changed, so the issue of extra drag is a nonsense, in fact it decreased, with better smooth rivetting, smooth paint, etc. Ways (successful, too) were always being sought to increase the overall speed. Interestingly (well, to some, anyway,) in 1940 tests, it was found that a Spitfire I a Me109E, at full throttle, stayed absolutely level in a protracted dive, which begs the question, "what drag?" Also, if the Spitfire had such high drag, how were the P.R. Spitfires able to outrun every other aircraft, apart from the 262 (and the pilots found that, at the height at which they operated, the 262 couldn't stay with them in any sort of turn.)
You really should read some of the tests done in the U.K. As early as July, 1942, it was found that the Spitfire IX could out-climb, and turn inside the Fw190A, hardly likely if it suffered from high drag. It also was superior to the Mustang in a turn. The XIV could outclimb, outdive, and turn inside the 109G, in fact it was classed as superior in every respect. Even with a 90-gallon tank still attached, it could turn inside the the 190A 109G.
Talk of "bomber shootdowns" is something of a mystery to me, after all the Spitfire was only ever conceived as a dogfighter, since the Hurricane could cope with most German bombers. A couple of 20mm cannon shells, in a 109 or a 190 was usually considered sufficient, so a 30mm was pointless.
The Spitfire's range increased throughout the war; it did not decrease.
Edgar


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## Ratsel (Sep 14, 2011)

Not so fast... are you 100% positive the The XIV could outclimb, outdive or outrun a Me 109G-10?


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## wuzak (Sep 14, 2011)

tomo pauk said:


> Griffon engined Spits made no nose-overs to speak of, IIRC
> BTW, why ugly?


 


Mustang nut said:


> Put that chin radiator on a spitfire?



The Spitfire would have, I'm sure, continued to use the underwing radiators if it had used the Sabre.

But the Sabre was some 10in wider than the Griffon/Merlin, and as tall as the Griffon. So the graceful lines would be spoiled by the extra wide front end blending into the thinner regular fuselage.

The Griffon barely fit - as can be witnessed by the rather large bulges over the cam covers.


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## Shortround6 (Sep 14, 2011)

Edgar Brooks said:


> No, not quite; the Mk.I carried 85 gallons, and by the war's end the IX/XVI carried 160/161 gallons internally.



You may have researched this better than I but I have seen from 83-85 Imp gallons listed. I don't know if this is due to translation from IMP gallons to liters and back again or if it is the difference between full tanks and "usable" capacity. There is always a gallon or two that they can't get out of the tank. I was also trying to be conservative on the upper number and show what might have been possible in a combat situation. I believe that the rear tank/s were supposed to empty or nearly so before going into combat, much like the rear tank in the Mustang or even the rear tank in a P-40. Combat radius depending on the fuel you have left after you drop the tank and fight for a number of minutes. The Spitfire does seem to be one of the few planes that could fight with a drop tank (small one?) still attached. 
I also wanted to stay pre Spitfire 21 because the 109 fans usually complain that the Mk 21 was so different it should have had a new name.
I have no idea what sized fuel tanks were used in the Pacific but even 90 gallon drop tanks allow for better in theater ferry range than a 66 gallon tank under a 109. 

The fighter designer rarely gets to specify the armament. His job is usually to design a Plane that can fly at XXXmph at YYYYft and go ZZZ miles while carrying AAAAguns and ammo. From a design standpoint the guns and ammo are the useful load along with the fuel. If the guns and ammo weigh 800lbs it makes little difference to the designer if they are 12 .303s, six .50s or Four 20mm. Granted he has to allow for gun receivers, drag from barrels, and space for gun bays and loading hatches but it doesn't really affect the square footage of the wing or the first rough calculations ofr empty weight and such. After all, it is just a problem of carrying 800lbs (or pick weight) with a enough fuel to fly for XX hours at YYY speed while meeting the top speed, climb and ceiling requirements. What is usually for gotten in these discussions is that there is usually a stalling or landing speed requirement or field length requirement. 

I do doubt however that the Spitfire was designed as a dogfighter with the Hurricane as the bomber destroyer, it may have worked out that way when possible but I doubt that was in the designers minds in 1935-36 for either the Spitfire or Hurricane.


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## wuzak (Sep 14, 2011)

Shortround6 said:


> I do doubt however that the Spitfire was designed as a dogfighter with the Hurricane as the bomber destroyer, it may have worked out that way when possible but I doubt that was in the designers minds in 1935-36 for either the Spitfire or Hurricane.



No doubting that both were designed as interceptors, mainly for defensive operations.


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## claidemore (Sep 15, 2011)

Ratsel said:


> Not so fast... are you 100% positive the The XIV could outclimb, outdive or outrun a Me 109G-10?


 
Outclimb? Mk XIV @18lb boost had an initial climb rate of 5110 ft per minute. Only the 109 K4 with 1.98 ata could match that, and that is an assumption based on projected graphs only. 
Outdive? The 109 had a quicker initial dive speed, but the Spitfire (any MK) could match the max dive speed, and the Spit pilots were confident of pulling out at higher speeds and steeper angles than the average 109 driver. Arguable point. 
Outrun? Spitfire Mk XIV 18lb boost, sea level - 363 mph ,5000ft - 391mph. At 26000ft - 445 mph. (from Mike Williams site)
Compare to G14 1.7 ata with MW30, sea level - 356 mph, 5000 ft - 343 mph, 26000ft - 393 mph. (from Kurfursts site)
A MK IX or VIII could match a G10 or G14, a Mk XIV could run circles around them.


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## Edgar Brooks (Sep 15, 2011)

Mustang nut said:


> Put that chin radiator on a spitfire?


It isn't a radiator; it's the carburettor air intake, and you'll find that all engines need air to mix with the fuel.
Regarding the fuel, I deliberately stayed with internal fuel, since what extra you hang on an airframe depends on a specific task. The Mustang carried 269 U.S. gallons, and the normal figure is that a U.S. gallon is .83 of an Imperial gallon, so 269 becomes 224, still an impressive (and useful) difference of 63 gallons.
The comparison trials were carried out by the Air Fighting Development Unit, which comprised seasoned ex-combat pilots. During the same trials, they found that, up to 10,000', the Tempest was 20mph faster than the XIV; up to 22,000' there was little to choose, and, above that height, the XIV was 30-40mph faster, and could reach a height 10,000' higher than the Tempest.
This daft "It isn't really a Spitfire" remark, about the 21, surfaces every so often, but it had the same fuselage and tail surfaces, with (if you compare drawings) the same basic wing shape, but with a wider centre section (which widened the track - something so often forgotten, or ignored,) and the wingtips (sort of) clipped.
Edgar


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## wuzak (Sep 15, 2011)

Edgar Brooks said:


> It isn't a radiator; it's the carburettor air intake, and you'll find that all engines need air to mix with the fuel.



The chin intake on the Typhoon and Tempest were for the radiator, oil cooler and air intake.


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## Edgar Brooks (Sep 15, 2011)

wuzak said:


> The chin intake on the Typhoon and Tempest were for the radiator, oil cooler and air intake.


He referred to "chin radiator on the Spitfire," which it never carried. With perfectly serviceable radiators/oil cooler under the wings, the Spitfire would never have needed the larger chin intake.


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## wuzak (Sep 15, 2011)

Edgar Brooks said:


> He referred to "chin radiator on the Spitfire," which it never carried. With perfectly serviceable radiators/oil cooler under the wings, the Spitfire would never have needed the larger chin intake.


 
He referred to "that" chin radiator, and what it would do for the looks of the Spitfire. "That" chin radiator refers to the radiator fitted to the Typhoon and Tempest, the only two Sabre powere aircarft to see service in WW2.

I made the same point about the Spitfire using the underwing radiators.


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## Ratsel (Sep 15, 2011)

claidemore said:


> Outclimb? Mk XIV @18lb boost had an initial climb rate of 5110 ft per minute. Only the 109 K4 with 1.98 ata could match that, and that is an assumption based on projected graphs only.
> Outdive? The 109 had a quicker initial dive speed, but the Spitfire (any MK) could match the max dive speed, and the Spit pilots were confident of pulling out at higher speeds and steeper angles than the average 109 driver. Arguable point.
> Outrun? Spitfire Mk XIV 18lb boost, sea level - 363 mph ,5000ft - 391mph. At 26000ft - 445 mph. (from Mike Williams site)
> Compare to G14 1.7 ata with MW30, sea level - 356 mph, 5000 ft - 343 mph, 26000ft - 393 mph. (from Kurfursts site)
> A MK IX or VIII could match a G10 or G14, a Mk XIV could run circles around them.


again, not so fast. I said nothing of the *G-14*. The *G-10 *with the DB 605D was almost as fast as the K-4, the G-10 can dive at at speeds of Mach .87. The climb to 30,000 I'll get back to you on that.


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## Mustang nut (Sep 15, 2011)

wuzak said:


> He referred to "that" chin radiator, and what it would do for the looks of the Spitfire. "That" chin radiator refers to the radiator fitted to the Typhoon and Tempest, the only two Sabre powere aircarft to see service in WW2.
> 
> I made the same point about the Spitfire using the underwing radiators.


 
Hey guys I was only joking, a plane doesnt get rejected for being ugly though the blackburn Rok should have been. The point I was really making is it isnt just a question of slotting in a new engine. The Sabre was completely different in weight and power. If it could be slotted into a spitfire there would need to be so many mods it wouldnt be a spitfire any more. With a spitfires internal fuel it may need a drop tank to clear the airfield perimeter.


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## Shortround6 (Sep 15, 2011)

Tante Ju said:


> I think it would be error to turn this into another 109 - Spit debate. Those very bore.. but I note your thesis was disproofed some time ago about 109 range.



While the late 109s may have had better range than I thought part of that "disproving" used some questionable fuel consumption figures. While a 2000hp airplane may use little more fuel than 1000hp airplane if both are using 600hp to cruise the 2000hp plane will use more fuel if it uses it's 2000hp. 




Tante Ju said:


> It did not seem to reduce on other aircraft, _just Spitfire_. 109G/K certain did not reduce range. 190D - do not think so it did? P-51? I do not think so either.



Off all the aircraft in the world *ONLY* the Spitfire reduced it's range by fitting a bigger engine? AS for the P-51, a complicated question. The Merlin powered ones certainly carried more fuel, they usually cruised higher where the air is thinner (less drag) and needed less fuel for the same speed over ground. You have to make sure that you are comparing apples to apples. 




Tante Ju said:


> So it was good for what? Heavy guns with little ammo? Standard Spitfire was two 20 mm cannon. 240 round. 109F+ was one-three 20mm cannon, 200 - 490 20 mm round.. Four cannon Spitfire was not practical.



We are back to the morphing 109 again. one cannon or three? granted the speed didn't change much but why weren't all 109s given 3 cannon if it didn't change performance much? Shortage of cannon or (like a 4 cannon spitfire) climb, ceiling, initial roll rate and turning circle all suffered much more than straight line speed? There is some question on the 200rounds for the engine cannon too. was it 200 rounds for the 15mm gun and 150 rounds for the 20mm gun or all always 200rounds? or 200 rounds on the planes with 7.9mm machineguns and 150rounds on the planes with 13mm machine guns? 

It is also not up to the airframe designer to design the armament (at least not usually). He designs a plane to hold the armament specified by the purchasing group. One reason the Spitfire was a bit more adaptable than a 109 was that it as designed to carry eith machine guns and their ammo and not the 2-4 machineguns or 1 cannon/1cannon-2MG armament of the early 109s ( the earlier cannon didn't work so B-D 109s got 2,3 or 4 machine guns). Once a plane is in production it often becomes a case of seeing what "new" guns can be crammed in. But again the aircraft designer doesn't get a lot of choice, The air staff/ministry says "here is new gun XXX, how many can you fit in, by the way, we would would really like 4 or maybe 6" 




Tante Ju said:


> I fear this is untrue both account too. Spitfire had record problems with wing bombs and E-wing integrity. Self ferry - yes, special outside tanks. But such version exist on 109 too, I believe more used than ultra large tank on Spitfire. Used once at Malta?



There may have been problems but we do have photographs of Spitfires carrying 3 bombs on operations, any records of of a 109 carrying 3 100kg bombs in combat? or one 250Kg and 2 100kg. Problems doing it vs not doing it at all. I have no doubt that the Germans used a lot of 300liter drop tanks and used them for moving planes form one base to another. British seem to have used a lot of 90 Imp gallon tanks and used the 170s a lot more than once. 




Tante Ju said:


> I respect opinion but I disagree. In what area(s) was late XIV Spitfire better than 109K-4? Range? No (XIV shorter range). Bombload? No. (500 kg vs 454 kg) Fighter recon version - both exist.



You can certainly disagree but based on what facts? range rather depends on fuel tanks fitted to Spitfire to both. Does the Spitfire use the 33 gal rear tank for a capacity of 145 Imp gallons? does the K-4 use the auxiliary tank for fuel or engine boost? does the Spitfire use what sized drop tank (30,45 or 90 gal). Bomb load? what 109 carried 500KG? 


Tante Ju said:


> Simply not true there was issue with it, nor evidence presented that Spitfire increased tankage because range was increasing short exact because airframe did not take upgrades too well - drag increase greatly, so range decrease. Range did not decrease on 109, so no need for more fuel. Which in opinion of mine was possible. For example - what technical reason not to enlarge main fuselage tank? Be careful - actually done twice already on 109.. or what technical reason not to have two small wing tank in place of gondola bay (where gondola ammo was). I do not see such. Take off weight certain not issue.



Aside from this mysterious great increase in drag on the Spitfire ( yes later models with bigger engines had bigger radiators and oil coolers causing more drag but how much?) can you please point out the increases in the 109s fuel supply? aside from (one) the increase when they went from the 700hp Jumo to the 1100hp DB 601 and the (two) increase they get when they use the MW-50 tank for fuel? Small (?) tanks well out in wings will affect initial roll rate and are usually rather heavy for the amount of fuel they hold if they are self sealing. A rather high surface to volume ratio. Take-off weight not an issue???? I guess they just kept fitting bigger, fatter tires to later model 109s because they had so much extra rubber to get rid of? And those lumps and bumps on the wing to fit them in were just to employ out of work tin knockers? 




Tante Ju said:


> MK 108 was choice of weapon for bombers. Yes two firing pass with devastate results on target, then land.. this armament was optimal for German need and tactical situation - escort did not permit more, not even a second pass was likely. Got problem with that, sure why not, technical possibility was there to replace MK 108 with MG 151, put two MG 151 into/under wing and you have very heavy armed fighter.. but this armament was for bomber. German estimate 4 MK 108 rounds for a bomber vs 20 20mm round.
> So that firepower for 15 (very theoretic) possible bomber shotdowns with singe MK 108 vs 12 possible bomber shotdowns with two 20mm on Spit. Of course - you could still add two other 20mm on 109K, with 290 round: + 14 possible bomber shotdowns. Total 15+14=29 for 109K, 12 possible shotdown for Spit. There is no question, _for this task_, which was better. So what is ground for criticizm?



Now this part is just plain silly. Nobody hit with every round and for 99.9% of the pilots it wasn't even close. The Germans figured that the "average" pilot hit with 2% of rounds fired and so needed 750-1000 rounds of 20mm ammo in the plane to get a kill, this was impossible with a single engine fighter. They figured that 3-4 hits were possible with with the 30mm guns/s and 150-200rounds of 30mm ammo was possible to put in a plane. 

It also rather glosses over the fact that the "German need and tactical situation" was a bit different than other nations and while the 109K was a useful defensive interceptor it was no longer a general purpose fighter like it had been in 1940-41 and it's capabilities in other roles had not increased as well as some other fighters. While the MK 108 was a devastating weapon, if it hit, there is no deigning that the combat endurance of the 109 was a bit lacking when it was fitted. Needing bomber attack fighters to be 'escorted' by by anti-fighter fighters is an admission that your fighter is lacking something. Just like the British in the BoB. If teh Spitfires take on the 109s to leave the Hurricanes to attack the bombers it is rather an admission that the Hurricanes were not up to taking on the 109s by themselves. Or it is sign that while the Hurricane could still do useful work it was obsolete as an air superiority fighter. Spitfire carried the same armament so it didn't NEED the Hurricanes to take out the bombers except there were not enough Spitfires. When you have different 109s carrying different armaments to attack either fighters or bombers and need both to do the job 0f attacking escorted bombers, it is a sign that the 109 was getting obsolete. 


Tante Ju said:


> IMO biggest problem with Spitfire as airframe was large drag to start for designer. Inferior to all other front aircraft in this respect - Jakovlev, Lavockin, Mustang, 109, even radial Fw 190. This made it keeping competitive increased difficult. Fortunate for RAF, excellent work of Rollce Royce was available. Without extreme powerful engines, Spitfire would be very unsuccessful soon phased out like Hurricane. IMHO it was success of Merlin and Griffon engine despite or rather than success of Spitfire airframe!



Larger, more capable aircraft usually do have more drag. without larger more powerful engines many of the types you mention would have been phased out too. Lavockin certainly didn't stay with the 1100-1200hp V-105 engine. Mustang didn't stay with the 1100-1300hp Allison. The 109 certainly didn't stay with the 1100hp DB 601. Radial Fw 190 started a number of years after the Spitfire and started with over 1500hp didn't it? and if it stayed at 1500-1600hp how useful would it have been in 1944-45? 

what was the bomb load of the Jakovlev? or it's armament (and the Russians had very good guns on a gun power to weight ratio) How well did it do at 25,000ft? 
what was the normal range or endurance? 

I am afraid this argument doesn't stand up very well.


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## Mustang nut (Sep 15, 2011)

The Hurricane was obsolete as soon as it rolled off the production line except that being a modified monoplane Hawkers knew they could build a lot quickly.
The hurricane was down on performance against the 109 but certainly not a sitting duck, they certainly downed enough 109s during the BoB. The spitfire soldiered on through the war because there wasnt anything obviously superior to replace it, even the Tempest wasnt better in all respects at all altitudes. Without engine development any plane became obsolete very quickly in WW2.

Would a spitfire be able to take off with a Typhoon prop on the front?


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## davebender (Sep 15, 2011)

They had to employ counter-rotating props to keep prop size managable and to counter torque steer on the ground. Clever and well done but how much worse would the problem have been with an even larger engine? Why not put the larger engine in the larger and combat proven Mustang airframe?


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## Ratsel (Sep 15, 2011)

Ratsel said:


> ...The climb to 30,000 I'll get back to you on that.


4950ft/m. 452mph @ 19,685ft. So no a mark XIV couldn't run circles around a G-10.


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## Edgar Brooks (Sep 15, 2011)

davebender said:


> They had to employ counter-rotating props to keep prop size managable and to counter torque steer on the ground. Clever and well done but how much worse would the problem have been with an even larger engine? Why not put the larger engine in the larger and combat proven Mustang airframe?


They had to do no such thing; the only Spitfire with a contraprop was the 21. Not all the airframes had one, and many were converted back (easily) to a standard 5-blade unit. The wider tracking of the 21-series took care of the ground handling, as well.
If the Sabre lacked power at height, what would be the point of putting it in an escort fighter, which needs all the height it can get, and needs to be able to fight on level terms, at that height?


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## tomo pauk (Sep 15, 2011)

A nice table, or a chart (Sabre's power @ altitude) would've been nice


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## Ratsel (Sep 15, 2011)

claidemore said:


> Outclimb? Mk XIV @18lb boost had an initial climb rate of 5110 ft per minute.
> Outdive? The 109 had a quicker initial dive speed, but the Spitfire (any MK) could match the max dive speed, and the Spit pilots were confident of pulling out at higher speeds and steeper angles than the average 109 driver. Arguable point.
> Outrun? Spitfire Mk XIV 18lb boost, sea level - 363 mph ,5000ft - 391mph. At 26000ft - 445 mph. (from Mike Williams site)
> Compare to G14 1.7 ata with MW30, sea level - 356 mph, 5000 ft - 343 mph, 26000ft - 393 mph. (from Kurfursts site)
> A MK IX or VIII could match a G10 or G14, a Mk XIV could run circles around them.


According to various sites that I frequent, the Standards for a Spitfire Mark XIV are:

~ "S" gear 439mph @ 24,500ft
~ "M" gear 404mph @ 11,000ft
~ Climb rate of 4,580ft/min


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## wuzak (Sep 15, 2011)

http://www.spitfireperformance.com/spit14speedchart.jpg

http://www.spitfireperformance.com/spit14climbchart.jpg

http://www.spitfireperformance.com/spitfire-XIV-ads.jpg

Spitfire Mk XIV Performance


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## wuzak (Sep 15, 2011)

davebender said:


> They had to employ counter-rotating props to keep prop size managable and to counter torque steer on the ground. Clever and well done but how much worse would the problem have been with an even larger engine? Why not put the larger engine in the larger and combat proven Mustang airframe?



Because the Griffon was in the Spitfire before the Mustang was combat proven?


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## davebender (Sep 15, 2011)

US Warplanes
618 Mustang Mk.Is were produced for Britain during 1941 at the Inglewood, California plant. I've got to assume they were in RAF service during 1942. 

When was the first RR Griffon engine installed in a Spitfire airframe?


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## Jabberwocky (Sep 15, 2011)

davebender said:


> US Warplanes
> 618 Mustang Mk.Is were produced for Britain during 1941 at the Inglewood, California plant. I've got to assume they were in RAF service during 1942.
> 
> When was the first RR Griffon engine installed in a Spitfire airframe?



The RAF only got 30-odd Mustangs by the end of 1941, most delivered in November/December.

First Mustangs entered squadron service for the RAF in January 1942, flying their first combat missions in February and scoring their first kills in May. 

First Griffon powered Spitfire flew in November 1941. The Mk XII entered squadron service in February 1943, flying their first combat missions and scoring their first kills in April.


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## Shortround6 (Sep 15, 2011)

First Mustang combat operation by a British squadron was on May 10th 1942. First Mustang arrived in England Oct 24th 1941, in a crate. Sea voyage from San Diego via the Panama Canal rather slows down deliveries. 

First Spitfire prototype with Griffon engine (MK IV) flies in Nov 1941. 750 Griffon powered Spitfires were ordered on August 23, 1941 but none of this order were completed with Griffon engines. 

Second Spitfire prototype with Griffon engine (MK XX) flies in Aug 1942. with a Griffon II single stage engine, it is later rebuilt with a two stage engine to become the prototype Spitfire XXI. 

P-51B is ordered into mass production in Jan 1943. 

First P-51B comes of the production line a the beginning of May 1943.

Griffon powered Spitfire XIIs start to enter squadron service in the Spring of 1943. 

Second MK 21 prototype first flies in July 1943. 

First Merlin powered P-51B arrives in England in Sept 1943.


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## claidemore (Sep 15, 2011)

Ratsel said:


> 4950ft/m. 452mph @ 19,685ft. So no a mark XIV couldn't run circles around a G-10.


 What's your source for those figures? 
I know you said compare to G10, not G14, but I have no charts for G10 so I used G14. I could just as easily have used K4 @1.8 ata, and the Spit XIV would still come out ahead. There have been discussions many times before on this forum where arguments were made for combat use of K4's with 1.98 ata, and those protractors insisiting that it not be compared to the XIV @ 21 lbs boost. I prefer to compare apples to apples, so it's the Mk XIV @ 18lbs boost to the K4 (or G10 with same engine) at 1.8 ata. Any charts or reports you can share on the G10 would be much appreciated. 
Of course none of this has any bearing on a Sabre engine on a Spit, but any discussion of a Spitfire tends to include comparisons of it's principle opponent the Messerschmitt, and so it should.


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## wuzak (Sep 15, 2011)

Shortround6 said:


> First Mustang combat operation by a British squadron was on May 10th 1942. First Mustang arrived in England Oct 24th 1941, in a crate. Sea voyage from San Diego via the Panama Canal rather slows down deliveries.
> 
> First Spitfire prototype with Griffon engine (MK IV) flies in Nov 1941. 750 Griffon powered Spitfires were ordered on August 23, 1941 but none of this order were completed with Griffon engines.
> 
> ...



Spitfire XIV prototype first flew in January/February 1943, and first production machine came off the line in October 1943.

The XXI, or 21, had the new, strengthened wing. The XX was the same as the IV, but renamed, IIRC.


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## wuzak (Sep 15, 2011)

Changing the Mustang to the Griffon engine may only have been possible if Packard, or another US manufacturer, was building Griffons under licence. The production rate for Griffons was very much less than for Merlins.


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## claidemore (Sep 15, 2011)

davebender said:


> Internal fuel capacity too small and it cannot be easily increased. Airframe and narrow track undercarriage not designed for engines producing 2,000+ hp.
> 
> Essentially the same problems as the German Me-109 series. Would these aircraft have remained in mass production to 1945 without the equipment demands of WWII? I doubt it. Both aircraft were state of the art during 1939 but obsolescent by 1945.


I'm not aware of any increase in landing or takeoff problems with Griffon Spitfires compared to Merlin spits. The MkXIV was considered one of the best fighters in 1945, definately not obsolescent, and the Mk21/22 and Mk24 were yet to come! The Mk21 had the same basic airframe as the MkXIV, with the following improvements, redesigned stiffer wing, different and larger ailerons, and wider track undercarriage (by 7 3/4 inches). The Mk 22 was in use by RAF until 1955, the Mk 24 by RAF until 1952, and with the Hong Kong airforce until 1955. 
As for fuel capacity, the Mk24 could carry up to 186 gallons of internal fuel (with wing tanks and two rear tanks), which is 120% increase over the Mk1's 85 gallons of fuel. 

For me, an airframe that is outdated would be one that could not use the latest improvements in engines or weapons, or could not match the performance of other fighters in use at the time in question, and the Spitfire was always able to do that.


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## Shortround6 (Sep 15, 2011)

wuzak said:


> Spitfire XIV prototype first flew in January/February 1943, and first production machine came off the line in October 1943.
> 
> The XXI, or 21, had the new, strengthened wing. The XX was the same as the IV, but renamed, IIRC.



Thank you for the MK XIV information. One book I have claims that DP845 was the airframe that was the MK IV which was redesignated MK XX before becoming a MK XII prototype.

DP851 was supposed to be the MK 20 (which, I guess is NOT a MK XX !!) with the single stage engine and became a MK 21 when re-engined with a two stage engine. 

My apologies for the confusion.


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## wuzak (Sep 15, 2011)

Shortround6 said:


> Thank you for the MK XIV information. One book I have claims that DP845 was the airframe that was the MK IV which was redesignated MK XX before becoming a MK XII prototype.



I think that is correct. 

The MkIV designation was changed because another project was using or had used that identification, and the name was changed to avoid confusion.


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## Edgar Brooks (Sep 16, 2011)

There were two Spitfire IV airframes, DP845 DP851, which were powered by the Griffon II. There were engineering aspects of the Griffon II which Rolls-Royce didn't like, so it was taken back, and redesigned into the Griffon III, which powered the Spitfire XII; DP845 became the XII prototype, and the Mark IV was renumbered XX (along with the planned name-change to "Victor") before the prototype flew. 
Supermarine had an understandable habit of issuing Mark nos as soon as work started on the drawings; if you ever get a chance to look at a Spitfire drawing, its designation consists of 5 numbers, the first three of which denote the Mark (e.g. 300-- = Mark I,) and the susequent pair denote the area (e.g. 08 = wings.) The Mark XII was Type 366, so drawings were 366--, followed by the Sheet no., in the series.
In January, 1944, the Air Ministry tried to preempt any more confusion, by issuing, in advance, blocks of Mk. nos, so 21-30 were Griffon-powered, 31-40 were Merlin-powered (and never used,) 41-50 were Merlin or Griffon-powered Seafires.
The Mk.IV/XX designation disappeared largely because its original engine no longer existed, and, when the P.R.IV got its designation, Mark XII was the next number, once the Griffon III came available; DP851 went on to become the prototype 21, and, following its crash, PP139 took over the task. At some stage, "Victor" was dropped, and "Spitfire" continued.
Edgar


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## Ratsel (Sep 16, 2011)

claidemore said:


> What's your source for those figures?


- Source: Radinger/Otto/Schick: "Messerschmitt Me 109", volumes 1 and 2, Eric Brown: "Testing for Combat". Mercedes-Benz AG, Archives, Stuttgart, Germany



claidemore said:


> I know you said compare to G10, not G14, but I have no charts for G10 so I used G14. I could just as easily have used K4 @1.8 ata, and the Spit XIV would still come out ahead. There have been discussions many times before on this forum where arguments were made for combat use of K4's with 1.98 ata, and those protractors insisiting that it not be compared to the XIV @ 21 lbs boost. I prefer to compare apples to apples, so it's the Mk XIV @ 18lbs boost to the K4 (or G10 with same engine) at 1.8 ata. Any charts or reports you can share on the G10 would be much appreciated.
> Of course none of this has any bearing on a Sabre engine on a Spit, but any discussion of a Spitfire tends to include comparisons of it's principle opponent the Messerschmitt, and so it should.


Some G-10s used DB 605 DC and Improved 605 DM, standard MW-50 equipment, up to 2000 PS, C3 fuel. Compared to the two-stage two-speed and turbo-charged engines of the western powers it is im-pressive what Daimler-Benz could achieve with the single-stage DB 605. By comparison the two-stage Merlin engines had a rated altitude ranging from approx. 5.8 km to 7.9 km. At the combat altitudes of 1944 the performance of the DB 605 rivalled that of the high altitude Spitfire and the Mustang. While the conventionel mechanical superchargers consisted of one or two compressors driven via a two-speed gear, Daimler-Benz utilised an ingenious barometricly controlled hydraulic clutch which adjusted the compressor speed and thus the charging of the engine according to the needs at a given altitude. The conventional method results in a relative loss in efficiency below rated altitude, because the compressor uses energy to produce surplus charging.


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## Shortround6 (Sep 16, 2011)

Ratsel said:


> Compared to the two-stage two-speed and turbo-charged engines of the western powers it is im-pressive what Daimler-Benz could achieve with the single-stage DB 605. By comparison the two-stage Merlin engines had a rated altitude ranging from approx. 5.8 km to 7.9 km. At the combat altitudes of 1944 the performance of the DB 605 rivalled that of the high altitude Spitfire and the Mustang. While the conventionel mechanical superchargers consisted of one or two compressors driven via a two-speed gear, Daimler-Benz utilised an ingenious barometricly controlled hydraulic clutch which adjusted the compressor speed and thus the charging of the engine according to the needs at a given altitude. The conventional method results in a relative loss in efficiency below rated altitude, because the compressor uses energy to produce surplus charging.



This has been gone over many times before and it not anywhere near so amazing as many people think. The "hydraulic clutch" is little more than the torque converter from an automatic transmission. What you are comparing is a single speed transmission with a torque converter to a two speed transmission with a manual clutch. The torque converter "slips" to provide low gear or more properly a range of low gears. When it is locked up it can provide no higher gear ratio than a two speed transmission and it certainly can't drive the the compressor faster than the design of the compressor will allow for and get any benefit. It certainly will NOT turn a single stage compressor with a limit of, say, 3.2 Pressure ratio into a compressor with a 5.1 compression ratio (which is what the 2 stage compressor on a Merlin 61 could do) A two stage compressor will take less power to compress the air to a given pressure ratio and it will heat the intake charge less while doing so. The Two stage is heavier, bulkier and more expensive though. It is also harder to get the airflows to match through the superchargers without choking or surging. 
The hydraulic coupling, while offering a more efficient speed or the impeller at low altitudes was more expensive than a two speed drive and while the impeller and intake system were operating more efficiently the hydraulic coupling itself , at maximum slip, could be using up 40-60hp in friction and truning it to heat that the engine oil system had to get rid off through the oil cooler. Some engines with these coupling used a separate oil system and not the engine oil in which case they need their own oil tank/cooler.


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## Ratsel (Sep 16, 2011)

For 1940's technology it was SUPER impressive. The barometricly controlled hydraulic clutch gave much more 'flexibility' at all altitudes. My hydraulic clutch in my Skidoo slips like crazy (like its designed too).. but I promise its faster then most 100K+ ferraris at 0-60mph / 0-100mph / 0-135mph (top speed).


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## davebender (Sep 16, 2011)

Not sure what that means. 

However if you look at a torque curve chart for DB601 and DB605 engines it's very smooth over a broad altitude band. Compared to most engines with 2 stage superchargers which had a jagged torque curve. The smooth torque curve provided a significant advantage for fighter aircraft when using Boom Zoom tactics.


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## Shortround6 (Sep 16, 2011)

Why was it SUPER impressive? 

Lets take an engine and fit it with a hydraulic "clutch/torque converter" and another identical engine and supercharger with a two speed box. Lets say we set up the Hydraulic unit to give a max gear ratio of 10.39 to 1 and a minimum gear ratio and maximum slip of 7 to 1, and yes there was a minimum speed ratio. Then we set ou the mechanical drive set up with a set of 10.39 to 1 gears and another set of 7 to one gears. Now with Engine "A" (hydraulic clutch) at minimum slip (98-100%) it has a full throttle height of 5,000 meters. Engine "B" with it's two speed box in high gear will also have a full throttle height of 5,000 meters. Both supercharger impellers are turning the same speed. At sea level both engines will give the same power, or nearly so. Both engines will require their throttles to be partially closed to prevent over boost. As both engines climb to say 1800 meters the throttles can be opened (automatically in both cases by a barometric capsule) until they are fully opened and again both engines are making the same power or nearly so. Both superchargers are taking just under 1/2 the power to drive them than will be needed at 5000 meters. Engine "A" may deleiver a fraction less power to the prop because of the power lost in the Hydraulic clutch at maximum slip. As both engines climb higher engine "B"s power falls of in a straight line. It's impeller is turning at a fixed speed which is no longer fast enough to keep up with the thinning air. Engine"A" on the other hand is having it's barometric capsule (second one) adjust the hydraulic clutch to less and less slip and so speeding up the impeller to keep the boost constant or nearly so. At some point, lets call it 3500meters, Engine "B" shifts supercharger gears to high ratio. It's throttle is part closed to prevent over boosting because it's impeller is now turning maximum revolutions. The loss in efficiency in the supercharger is balanced by the loss of power if the engine had continued to use low gear in the the thinning air. This is the low point seen on the power graph of two speed engines between the two peaks. This is also the point of PEAK advantage of the hydraulic clutch. It's supercharger is turning at an almost optimum speed instead of being at the point of worst compromise in the two speed system. However as the two engines continue to climb engine "B" gains power as it's throttle is opened more and more until, at 5,000 meters both engines have fully opened throttles and are making the same power. As the engines climb above this point they both loose power at the same rate because the supercharger is already maxed out and cannot supply any more air. 

That is the advantage of the hydraulic clutch as a supercharger drive, it eliminates the big dip in the power curve or turns it into a curve instead of a "V". It's onther advantage is that the pilot does not have to manually shift or select "hi' or 'Low" supercharger while in combat. 
It does nothing for take-off or sea level power and does nothing for power above the rated altitude of an engine and it does not change the rated altitude from what the engine would have with a fixed gear ratio that was the same.


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## Ratsel (Sep 16, 2011)

I understand how a mechanical supercharger works. That said, I agree 100% in davebender comment. As far as "super" impressive technology for the 1940's well a difference of opinion I guess, save for the fact of the forced air induction delivery system. The skidoo example I used for a slipping clutch is to show that its really nothing of concern.


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## Shortround6 (Sep 16, 2011)

Since just about every aircraft engine of 500hp or more (and quite a few below) used a "forced air induction delivery system" in WW II, I am still not getting why this is "Super" impressive? 

There are reasons why the single stage German engines could almost match the British/american two stage engines at times during WW II, it is just that the hydraulic drive wasn't one of them.


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## Ratsel (Sep 16, 2011)

The German technology employed with the use of a bariometric controller the wet clutch. Which, IMO is a superior.


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## Edgar Brooks (Sep 16, 2011)

None of which has the slightest bearing on trying to fit a Napier Sabre into a Supermarine Spitfire.


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## Shortround6 (Sep 16, 2011)

trying to stick Napier Sabre into a Supermarine Spitfire wasn't going to happen. The Sabre being about 400-500lbs heavier than a 2 stage Griffon without the bigger prop and radiators/oil coolers. That, the 1/3 more width and no two stage supercharger should pretty much kill any interest in the idea.


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## Ratsel (Sep 16, 2011)

Edgar Brooks said:


> None of which has the slightest bearing on trying to fit a Napier Sabre into a Supermarine Spitfire.


yup. its sure dosn't. thanks for pointing that out and my appologies for offending the great and powerful spitfire


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## tomo pauk (Sep 16, 2011)

Edgar Brooks said:


> None of which has the slightest bearing on trying to fit a Napier Sabre into a Supermarine Spitfire.



Thanks, Edgar 
Perhaps you have a nice table, or chart re. Sabre's performance vs. altitude, to share with us?



> Shortround6 said:
> 
> 
> > trying to stick Napier Sabre into a Supermarine Spitfire wasn't going to happen. The Sabre being about 400-500lbs heavier than a 2 stage Griffon without the bigger prop and radiators/oil coolers.
> ...


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## Shortround6 (Sep 16, 2011)

better power to weight ratio where? 

for takeoff?
for 10,000ft 
for 25,000ft?

Here is a power chart for a Sabre IIa engine.

http://www.wwiiaircraftperformance.org/tempest/sabrecurve.jpg

Note that the almost 2400 hp at 4000ft(?) decreases to 1600hp at just over 22,000ft. Also note that this is with 400mph of ram into the carburetor intake which means that power levels are going to be down several thousand feet for climb performance. 

A Griffon 61-69 was rated at about 2000-2010hp at 6750-7000ft in low blower at 21lbs boost and 1810-1820hp at 21000ft in hi blower. At any altitude over about 1900ft it is making more power and it weighs about 83% of what the Sabre does. on a power to weight basis they are often within about 1% of each other until those altitudes are over 20,000ft. Then then the Griffon runs, not walks away, having a better power to weight ratio by 30% or more . 

Props and radiators/oil coolers have to be sized for the best power condition (worst cooling load, the extra 350-400hp of the Sabre ?. High altitude cooling may be a problem for the Griffon?)


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## Edgar Brooks (Sep 16, 2011)

tomo pauk said:


> 1/.Perhaps you have a nice table, or chart re. Sabre's performance vs. altitude, to share with us?
> 
> 2/.I do see issues about sticking an even heavier engine into Spit's airframe, but I can't see why the prop oil system should differ from 2-stage Griffon? Plus, we should save some weight drag because of lack of intercooler (feel free to correct me on this issue).
> 
> ...


1/. No, I don't, but I have a comparison report, for a Tempest, against a Mustang III, Spitfire XIV, Fw190 with BMW801D, and Me109G (no idea of suffix, but probably an early one.) It's far too big to put it here.
Mustang - Tempest 15-20 mph faster up to 15,000', level up to 24,000', 30 mph slower up to 30,000'; Spitfire XIV - Tempest 20mph faster up to 10,000', level to 22,000', 30-40 mph slower up to 30,000' (Tempest's ceiling, but Spitfire capable of 40,000'.) ; Fw190 - Tempest nearly 50 mph faster at all heights, slower in climb at all heights above 5,000'; Me109G - Tempest 40-50 mph faster up to 20,000', but difference rapidly lessens above that height; almost identical in the climb to 5,000', but slower above that height.
2/. The intercooler is part of the Griffon engine; do you mean the intercooler radiator? It's a common mistake to think that the radiators create drag, but the designer was another genius; the radiators worked in the same way as that of the Mustang, and actually increased speed, not reduce it.
3/. If the Sabre was heavier than the Griffon, it's unlikely that extra fuel could have been carried in front of the CoG.
4/. The two-stage "blower" cuts in in stages, which enables the aircraft to increase speed at heights at which single-stage engines begin to lose "oomph." It was the second stage which made the Spitfire XIV so much faster than the Tempest above 22,000'.
Edgar


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## davebender (Sep 16, 2011)

IMO that has no bearing on this discussion as the Spitfire was not designed for a radial engine.


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## Ratsel (Sep 16, 2011)

What about the DB 605 that the Germans put into that captured spitfire. I have the pic somewhere. Best engine version yet for the spit IMO


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## davebender (Sep 16, 2011)

What version of the DB605 engine? IMO the DB605D was the only version clearly superior to the RR Merlin.


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## Ratsel (Sep 16, 2011)

Dunno off hand, I have to find the relevant info.


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## stona (Sep 17, 2011)

Ratsel said:


> Dunno off hand, I have to find the relevant info.



DB 605A-1 engine (Wk-Nr 00701990).







The Rechlin test group reckoned that the new engine increased the performance of the Spitfire,most notably raising its ceiling to 41,600 feet.

The Royal Yugoslav Airforce (JKRV) flew a DB601A powered Hurricane in 1941 which displayed better take-off performance and climb rate than either the Merlin III powered Hurricane or the Bf 109 E-3 and was only slightly slower than the latter.

Steve


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## davebender (Sep 17, 2011)

With a proper German paint job it looks a lot like the He-112.





They should have given this Spitfire to Galland as he was always making wise cracks about wanting to trade in his Me-109 for a Spitfire.


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## Ratsel (Sep 17, 2011)

[


stona said:


> DB 605A-1 engine (Wk-Nr 00701990).
> 
> The Rechlin test group reckoned that the new engine increased the performance of the Spitfire,most notably raising its ceiling to 41,600 feet.
> 
> ...


Yah thats the one. I heard the same about the 40k-ft+ ceiling, but the pilot couldn't stay at that altitude for long. Thanks Steve for the information on her.



davebender said:


> With a proper German paint job it looks a lot like the He-112.
> 
> They should have given this Spitfire to Galland as he was always making wise cracks about wanting to trade in his Me-109 for a Spitfire.


He did like the spitfire.. thats for sure.


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## wuzak (Sep 17, 2011)

I think if Supermarine were to do a fighter around the Sabre it would have been a new airframe.

It may have looked something like the Supermarine Type 391 proposal for the RR Eagle 22

http://gallery.kitmaker.net/data/18138/15SM391_.jpg
http://gallery.kitmaker.net/data/18138/16SM391_.jpg


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## davebender (Sep 17, 2011)

Supermarine Seafang - Wikipedia, the free encyclopedia
"a Spitfire too far."


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## fastmongrel (Sep 17, 2011)

wuzak said:


> I think if Supermarine were to do a fighter around the Sabre it would have been a new airframe.
> 
> It may have looked something like the Supermarine Type 391 proposal for the RR Eagle 22
> 
> ...



That is an awesome looking beast. I spoke to a chap at the RNAS Yeovilton Fleet Air Arm Museum who had worked on the Westland Wyvern with the RR Eagle engine and he said it was a smooth powerful engine that sounded superb. The Eagle never had the bugs worked out because gas turbines had stolen its reason for existence but he reckoned with some RR magic it would have been the new Merlin fitted in virtually everything that flew.


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## tomo pauk (Sep 17, 2011)

Shortround6 said:


> better power to weight ratio where?
> 
> for takeoff?
> for 10,000ft
> ...



Many thanks for the link; guess next time I should put more effort to find stuff on the 'net by myself 
Re. 2-stage engines for Spitfire, I was commenting onto '2-stage engines for Spitfire' - and only 2-stage engine is Spit (operative squadrons) in 1943 was Merlin. Griffon was single stage engine back then, hence my sentence about greater power-to weight ratio of the plane.



> Props and radiators/oil coolers have to be sized for the best power condition (worst cooling load, the extra 350-400hp of the Sabre ?. High altitude cooling may be a problem for the Griffon?)



Agreed; so the Sabre would have 'more' coolers, but no intercoler - slightly more drag than XII, but less than IX XIV?

added: the chart you've provided the link is for Tempest (Sabre uses +11 lbs boost under FTHs, with 150 grade fuel) - not available in 1943?


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## tomo pauk (Sep 17, 2011)

Edgar Brooks said:


> 1/. No, I don't, but I have a comparison report, for a Tempest, against a Mustang III, Spitfire XIV, Fw190 with BMW801D, and Me109G (no idea of suffix, but probably an early one.) It's far too big to put it here.
> Mustang - Tempest 15-20 mph faster up to 15,000', level up to 24,000', 30 mph slower up to 30,000'; Spitfire XIV - Tempest 20mph faster up to 10,000', level to 22,000', 30-40 mph slower up to 30,000' (Tempest's ceiling, but Spitfire capable of 40,000'.) ; Fw190 - Tempest nearly 50 mph faster at all heights, slower in climb at all heights above 5,000'; Me109G - Tempest 40-50 mph faster up to 20,000', but difference rapidly lessens above that height; almost identical in the climb to 5,000', but slower above that height.



Thanks 



> 2/. The intercooler is part of the Griffon engine; do you mean the intercooler radiator? It's a common mistake to think that the radiators create drag, but the designer was another genius; the radiators worked in the same way as that of the Mustang, and actually increased speed, not reduce it.



Did not know that Spits radiators took advantage of Merredith effect; could you point me/us to a something on-line re. that?



> 3/. If the Sabre was heavier than the Griffon, it's unlikely that extra fuel could have been carried in front of the CoG.



I was under impression that Spit's hull tanks were at CoG, so making them wider wouldn't make any issues?

4


> /. The two-stage "blower" cuts in in stages, which enables the aircraft to increase speed at heights at which single-stage engines begin to lose "oomph." It was the second stage which made the Spitfire XIV so much faster than the Tempest above 22,000'.
> Edgar



I agree with your words, but only British 2-stage engine in service in 1943 was Merlin...*



davebender said:


> IMO that has no bearing on this discussion as the Spitfire was not designed for a radial engine.



People were complaining that a wider engine would've messed up Spits aerodynamics/looks/etc. I was pointing out that back in WW2 other airforces were installing even wider engines, with benefits outweighting shortcomings. 
Hence it has a bearing on this discussion.

added: Spit XIV was far lighter, with less drag, and with more power above 22K - all 3 factors contributing for better performance vs. Tempest at hi-alt?


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## Shortround6 (Sep 17, 2011)

tomo pauk said:


> People were complaining that a wider engine would've messed up Spits aerodynamics/looks/etc. I was pointing out that back in WW2 other airforces were installing even wider engines, with benefits outweighting shortcomings.
> Hence it has a bearing on this discussion.



Since the aircooled engines also lost the radiator the installed engine weights were closer than they first appear. Radials are shorter so the center of gravity of the engine is closer to the center of gravity (which should be close to the center of lift) of the airplane. Some air forces that installed radials in place of V-12s did so because their '2nd generation' V-12s didn't work. Radial was the only option left. Lets not forget that not only the engines but the installations were constantly evolving. A 1944 radial installation would have lower drag in just about any country than a 1941 installation. P&W managed to get a P-40 airframe equipped with an R-1830 (sort of a reverse P-36) up to 379mph (?) in the late fall of 1942. Which means a production version may have been possible by spring/summer of 1943 but the liquid cooled installations were getting better too. 


tomo pauk said:


> added: Spit XIV was far lighter, with less drag, and with more power above 22K - all 3 factors contributing for better performance vs. Tempest at hi-alt?



All true, don't forget, it can take months to change a production line from one major version of a plane to another and it can take several years for a major (not minor) revision of an engine. Production planning schedules have to be done months if not 1-2 years in advance.


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## Edgar Brooks (Sep 18, 2011)

tomo pauk said:


> 1/. Did not know that Spits radiators took advantage of Merredith effect; could you point me/us to a something on-line re. that?
> 2/. I was under impression that Spit's hull tanks were at CoG, so making them wider wouldn't make any issues?
> People were complaining that a wider engine would've messed up Spits aerodynamics/looks/etc. I was pointing out that back in WW2 other airforces were installing even wider engines, with benefits outweighting shortcomings.
> 3/.Spit XIV was far lighter, with less drag, and with more power above 22K - all 3 factors contributing for better performance vs. Tempest at hi-alt?


1/. No, sorry, the vast majority of my information comes from 50 years of collecting books and magazine articles. The man's name was Frederick Meredith, and he worked for the Royal Aircraft Establishment in Farnborough.
2/. The Spitfire was designed around the Merlin, and frame 5 (the engine bulkhead) has very short stub spars, to which the ends of the wing spars are attached. Widening the fuselage would have, of necessity, increased the wingspan, so any fuel increase would have to go forwards, since taking it backwards would shift the pilot back, as well, and play havoc with the CoG. The answer is fairly simple really, widen the fuselage, and lengthen it, to allow for the extra weight of the engine, then fit elliptical wings, and it would be so different, you'd really need a new name, "Tempest" perhaps? Frame 5 is the "keel" round which the Spitfire is built, so any extra width would have to go in front of it, making a very weird tapered front indeed.
The Sabre was deeper, too, which would have added depth to the fuselage, underneath, since you couldn't add it on top, because the pilot's view was restricted enough, already. Deepen the fuselage, and the ground clearance reduces, which needs a longer oleo leg, which wouldn't fit into the wheel wells, unless you have a wider wingspan.
3/. Definitely, as test reports show.
Rolls-Royce, and Supermarine, expected great things from the Griffon, which (apart from length) could fit into the same available space as the Merlin. The RAF had enough hassle with the extra work involved in use of the Packard Merlin, with the need for a new Mark, and separate stores facilities. Two Merlin Spitfire ranges, the Griffon family, and a Sabre set-up, with two more totally different Sabre airframes already in existence, would have been a nightmare. 
You only have to look at how quickly the R-R Merlin was discarded, immediately at the end of the war, leaving just the Packard (to use up surplus stocks,) and the Griffon, to realise the strain on the RAF's resources, especially with the post-war demobilisation, if there had been any other types. Even the Typhoon was being built, trundled across the airfield, and scrapped, immediately after the war. The Sabre was always seen as an expedient, until the Centaurus became available.
Edgar


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## tomo pauk (Sep 18, 2011)

I'd like to return back to this:


Shortround6 said:


> better power to weight ratio where?
> 
> for takeoff?
> for 10,000ft
> ...



The 150 grade fuel is 1944 stuff; Sabre should with +9 lbs boost attain cca 1850 BHP @ 18kft (full trottle height for high blower?)?



> A Griffon 61-69 was rated at about 2000-2010hp at 6750-7000ft in low blower at 21lbs boost and 1810-1820hp at 21000ft in hi blower. At any altitude over about 1900ft it is making more power and it weighs about 83% of what the Sabre does. on a power to weight basis they are often within about 1% of each other until those altitudes are over 20,000ft. Then then the Griffon runs, not walks away, having a better power to weight ratio by 30% or more .



While I'd agree that Griffon was a superb piece of machinery, declaring that it 'runs' vs. Sabre (above 21kft) is hardly true - advantage is 100 HP (give or take), or 5-7%, depending on altitude. The power to weight ratio of entire plane is what counts, and such would've been better by some 12%, but available a year later.



> Props and radiators/oil coolers have to be sized for the best power condition (worst cooling load, the extra 350-400hp of the Sabre ?. High altitude cooling may be a problem for the Griffon?)



Sabre in 1943 requires 50 % more cooling (has 50% more HP) [EDIT: at 6-7kft] than Griffon II (1-stage) 

A simple chart is attached, feel free to correct me 

added: Spit XII was good for 393mph @ 18K, with only 60% of power Sabre was capable at same alt, or with some 1130-1150Hp up there. Sabre was delivering 1200HP at some 27-28K. All in 1943.

NOTE: THE graph for Griff II is valid for static power (no ram effect), while the one for Sabre is with ram effect, hence the whole chart should not be taken as gospel.


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## tomo pauk (Sep 18, 2011)

Hi, Edgar,

Many thanks for the insights 
I've read a thing or two about Mr. Meredith, and I'm really interested to find out if 'his' effect was purposely applied at planes other than P-51.


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## Edgar Brooks (Sep 18, 2011)

tomo pauk said:


> The 150 grade fuel is 1944 stuff; Sabre should with +9 lbs boost attain cca 1850 BHP @ 18kft (full trottle height for high blower?)?
> 
> While I'd agree that Griffon was a superb piece of machinery, declaring that it 'runs' vs. Sabre (above 21kft) is hardly true - advantage is 100 HP (give or take), or 5-7%, depending on altitude. The power to weight ratio of entire plane is what counts, and such would've been better by some 12%, but available a year later.
> 
> added: Spit XII was good for 393mph @ 18K, with only 60% of power Sabre was capable at same alt, or with some 1130-1150Hp up there. Sabre was delivering 1200HP at some 27-28K. All in 1943.


Quite simply you're fixating on the wrong thing; talk to any WWII pilot, and his sole interest was speed, not brake horsepower, compared to his opponent. Below 20-22,000' the Sabre had the edge, but above that the Spitfire XIV did run away from it, to the tune of 30-40mph. Those aircraft were designed as fighting machines, at all heights, and the Spitfire won by a country mile, above 25,000'. 
Using the Spitfire XII is the proverbial red herring, since it was only ever intended for low-level use, and the Griffon II never saw service in a Spitfire, so I fail to see what that's doing here. Forget all this talk about BHP, since it's meaningless; talk speed at various heights, because that was what mattered.
Edgar


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## Shortround6 (Sep 18, 2011)

tomo pauk said:


> I'd like to return back to this:
> 
> 
> The 150 grade fuel is 1944 stuff; Sabre should with +9 lbs boost attain cca 1850 BHP @ 18kft (full trottle height for high blower?)?



I think it all depends on EXACTLY when you draw your time line and EXACTLY which version of which engine you are talking about. The Sabre II appears to have been limited to 3700rpm and with 9lbs boost had 1880hp at 15,250ft. The Sabre IIA could turn 3850rpm and at 11lbs boost was good for 2045hp at 13,750ft. The discrepancy between this number and the chart you are going by is that the Chart included the 'boost' provided by 400mph worth of ram effect going into the air intake, While this power is available for level flight it is not available for climb. If the power figures for the Griffon II do not include RAM effect then the altitude is going to be several thousand feet too low, As the Griffon IIB was rated at 1495hp at 12lbs boost at 14,500ft with NO ram. As installed in the aircraft And using a climb speed of 240mph true it could hold the full 12lbs to 15,300ft. But it could hold 12lbs of boost (and the full 1495hp) to 17,800ft in level flight when doing 397mph true. 

If what is wanted is power at high altitude The MK IX with the Merlin 61 already provided it. 1340-1390hp at 23,500 at 15lbs depending on your source, again without ram. In a combat climb using 3000rpm and 15lbs boost the MK IX could hold the 15lbs (and the 1390hp) to 25,200ft at a 239mph climb speed and for level flight could get the full 15lbs of boost at 27,400ft. A Merlin 61 is one heck of a lot lighter than a Sabre. 

The Sabre couldn't provide anything at high altitude they weren't already getting from the Merlin and the two stage Griffon promised to be that much better, and a whole lot less trouble to stick in a Spitfire. 

The Spitfire is claimed to use the Meredith effect but there is a world of difference between some mathematical formulas and some sketches and getting measurable performance in the real world. There is also quite a difference in getting a little bit of "thrust" (say, getting 20% of your cooling drag back) and actually getting "positive thrust" (thrust exceeds cooling drag).


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## wuzak (Sep 18, 2011)

A book I have about the Spitfire says that the radiators on the Spitfire were designed with the Meredith effect in mind, but they weren't as effective as they might have been - all to do with the inlet and exhaust area, and the adjustable flap. IIRC the flap on the Spitfire's radiator ducts was, at least for some versions, a two position device, which would in some instances give too much cooling if it were open, and not enough if it were closed.

I suspect Supermarines were too busy making improvements in other areas of the airframe to have time and resources to investigate the radiator ducts.


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## Shortround6 (Sep 18, 2011)

All to true.

To get the maximum results from the Meredith effect requires not only a variable 'nozzle' for different flight conditions but a carefully designed duct giving the right changes in cross section to adjust the speed of the air flow both before and after it goes through the radiator. Too high a speed hitting the radiator front surface will cause excess drag. The actual size of the radiator is also critical. A larger cross section radiator will give less drag as the air flows through it. But hiding large cross section radiators is harder than small section ones (which may be thicker front to back) and they are heavier. The air has to pick up sufficient heat while flowing through the radiator to create the desired expansion and then the duct has to reduce in size to compress the airflow to accelerate it up to the desired exit speed. It is asking a lot of a short duct or radiator housing to handle those changes in air flow speed compared to a much longer duct. Look at a cross section of the duct in the Mustang for an idea of changes in cross section they used.


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## wuzak (Sep 18, 2011)

The other issue I have wondered about with the Spitfire's radiators is the lack of a boundary flow splitter. The P-51 has one. The original XP-46 (and XP-40?) had a ventral radiator, but no boundary layer splitter and it wasn't very good. Same with the Hawker Tornado.


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## tomo pauk (Sep 19, 2011)

Edgar Brooks said:


> Quite simply you're fixating on the wrong thing; talk to any WWII pilot, and his sole interest was speed, not brake horsepower, compared to his opponent. Below 20-22,000' the Sabre had the edge, but above that the Spitfire XIV did run away from it, to the tune of 30-40mph. Those aircraft were designed as fighting machines, at all heights, and the Spitfire won by a country mile, above 25,000'.



Sorry if you feel I'm splitting hairs, but:
-I was under impression that BHPs (among other stuff) provide speed.
-Wouldn't it be fair to say that Spit XIV would run away from Tempest - from it's surplus ton of metal greater drag, and then from Sabre?



> Using the Spitfire XII is the proverbial red herring, since it was only ever intended for low-level use, and the Griffon II never saw service in a Spitfire, so I fail to see what that's doing here.



This document says Griffon II was powering Spit XII:
http://www.spitfireperformance.com/spitfireXII-ads.jpg
It's the only Griffon that saw service in 1943 in RAF service?



> Forget all this talk about BHP, since it's meaningless; talk speed at various heights, because that was what mattered.
> Edgar



Covered above 


Shortround6 said:


> I think it all depends on EXACTLY when you draw your time line and EXACTLY which version of which engine you are talking about. The Sabre II appears to have been limited to 3700rpm and with 9lbs boost had 1880hp at 15,250ft. The Sabre IIA could turn 3850rpm and at 11lbs boost was good for 2045hp at 13,750ft. The discrepancy between this number and the chart you are going by is that the Chart included the 'boost' provided by 400mph worth of ram effect going into the air intake, While this power is available for level flight it is not available for climb. If the power figures for the Griffon II do not include RAM effect then the altitude is going to be several thousand feet too low, As the Griffon IIB was rated at 1495hp at 12lbs boost at 14,500ft with NO ram. As installed in the aircraft And using a climb speed of 240mph true it could hold the full 12lbs to 15,300ft. But it could hold 12lbs of boost (and the full 1495hp) to 17,800ft in level flight when doing 397mph true.



Thanks for setting my numbers straight; the doc linked above doesn't mention it's 'static' power (no ram). 



> If what is wanted is power at high altitude The MK IX with the Merlin 61 already provided it. 1340-1390hp at 23,500 at 15lbs depending on your source, again without ram. In a combat climb using 3000rpm and 15lbs boost the MK IX could hold the 15lbs (and the 1390hp) to 25,200ft at a 239mph climb speed and for level flight could get the full 15lbs of boost at 27,400ft. A Merlin 61 is one heck of a lot lighter than a Sabre.
> 
> The Sabre couldn't provide anything at high altitude they weren't already getting from the Merlin and the two stage Griffon promised to be that much better, and a whole lot less trouble to stick in a Spitfire.



Again, thanks for the data 



> The Spitfire is claimed to use the Meredith effect but there is a world of difference between some mathematical formulas and some sketches and getting measurable performance in the real world. There is also quite a difference in getting a little bit of "thrust" (say, getting 20% of your cooling drag back) and actually getting "positive thrust" (thrust exceeds cooling drag).



Well put; for a radiator to put Merdith's effect to use, it's about narrow inlet, well widening towards the radiator core itself, and again narrowing towards exit?


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## Ratsel (Sep 19, 2011)

Thrust means air leaving the radiator is faster the air entering it. Very hard to do with a big block of copper tubes and cooling fins in the way. The 'Merdith effect' is moot at this point. Exhaust thrust is much more prevelant, yet nowhere near effective on prop driven a/c during WWII. I read something like 2-5mph at full boogy with a DB 605D in a Me 109G-10.


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## Shortround6 (Sep 19, 2011)

It was possible and it was done. The Mustang used both. and it is not the speed of the air entering and leaving the radiator but entering and leaving the radiator duct. Sort of like a ramjet but using the radiator as a heat source. The problem with figuring effect for exhaust "thrust" ( and 2-5mph at full boogy is pretty poor) is that it varies with altitude (back pressure on the exhaust outlets), quantity of exhaust ( full throttle height gives most exhaust but not the most thrust) and speed of the exhaust compared to the speed of the plane. A Spitfire would get more benefit than a Hurricane at the same altitude and throttle setting because the Spitfire is moving faster and the exhaust speed and aircraft speed are a better match. Exhaust thrust doesn't do much for low level climb.


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## Ratsel (Sep 19, 2011)

yah, and theres a big ole' radiator in the way. so the air stream has to go either up and over / down and under / around the radiator or all three. slowing the airflow even further. In front of the radiator housing there is a high pressure buildup, caused by the interuption of the airflow ( ie: the radiator ), out back after the air passes will be hot tubulant votecies, negating any sort of thrust. P-40's had that problem which caused latteral instability.


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## Shortround6 (Sep 19, 2011)

and that is why it took a while, and good engineering, to get the theory to work. Any air in the duct that isn't going though the radiator and being heated is a dead loss. It isn't helping with thrust and if it is not going though the radiator it isn't helping with cooling. It is only adding to the drag.


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## Edgar Brooks (Sep 19, 2011)

tomo pauk said:


> Sorry if you feel I'm splitting hairs, but:
> 1/.-I was under impression that BHPs (among other stuff) provide speed.
> -Wouldn't it be fair to say that Spit XIV would run away from Tempest - from it's surplus ton of metal greater drag, and then from Sabre?
> 
> ...


1/. For initial power, that's true, but the Griffon, in the XIV, had a two-stage blower, so it continued to give increased power to the engine as it climbed, unlike the Sabre, which gave out in the mid-20s. If the Sabre had had some extra blower(s) behind it, who knows what it could have done at height? Without knowing drag coefficients, it's impossible to say how the airframes would have behaved, given equal power.
2/. I suspect that form is for DP845, the XII prototype, which was fitted with a Griffon IIB, and began testing in September 1942. The Griffon II was the Firefly engine; the Griffon III was redesigned. Some XIIs did have a Griffon II, but the designated engine was thye Griffon III, with some getting the Griffon IV. Those Griffons were the only engines to see service use in Spitfires, in 1943, though six Mk.VIIIs were converted, that year, into prototype XIVs, with some using Griffon 61s, and one a Griffon 65.
3/. That's precisely how the Spitfire radiator(s) work; the housing widens to left and right, and upwards, but remains straight aft of the matrix, all of which means that the air, when heated, expands, and leaves faster than it came in. However small the effect might be, it means that, contrary to popular belief, the radiators were not a source of drag. 
I don't feel that you're "splitting hairs," but there was a lot more to squeezing extra speed out of an airframe than just the raw power of the engine. Mr. Ratsel is dismissive of an extra 2-5 mph, but, to a pilot, that can mean life or death. Whether you choose to believe it, or not, is immaterial, since it's well documented that the radiators made the Spitfire go faster, and the radiator matrices are a honeycomb, through which air readily passes (check a car's radiator,) not "a mass of tubes."
In 1942, tests were carried out on a Vb, to see what effect various alterations made. The multi ejector exhausts, in place of the three ejectors (airily dismissed by Mr. Ratsel) actually increased the speed by 7 mph. Removing the ice and stone guard, in front of the carbuettor intake, added 8 mph (standard Mk.VIIIs, IXs XIVs used a lengthened intake, with a "tropical" filter; on take-off the air was directed through a filter, then, when clear of the ground, it was redirected straight into the carburettor. A new style of mirror added 3 mph.
In late 1942, Supermarine persuaded the Air Ministry to go over to synthetic, rather than cellulose, paints, since they'd found that they could get a genuine smooth finish. They also began to fill panel lines, and rivet divots, on the wing l/e, plus primer, and smoothing down, to give a perfectly smooth surface, which gave a further 6 mph increase. By the time all of these changes had been made, the aircraft was over 28mph faster.
Edgar


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## Ratsel (Sep 19, 2011)

not dismissed, the overall design of the rad housing contributed to less drag. not any sort of thrust produced. 5mph gain from exhaust thrust is outstanding.


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## Edgar Brooks (Sep 19, 2011)

Ratsel said:


> yah, and theres a big ole' radiator in the way. so the air stream has to go either up and over / down and under / around the radiator or all three. slowing the airflow even further. In front of the radiator housing there is a high pressure buildup, caused by the interuption of the airflow ( ie: the radiator ), out back after the air passes will be hot tubulant votecies, negating any sort of thrust.


Yah, and that big ole radiator had big hexagonal holes through it, through which the air easily flowed, and the matrices were tightly fitted, in box-like structures, so that the air couldn't go up/over/down/under/round, but had to go through. The radiator installation was the only component which was tested in a wind tunnel, so it wasn't a hit-and-miss system (the British don't use knotted string for everything.) Supermarine/Farnborough's tests showed a gain in air speed, and therefore thrust; do you have figures to disprove that? There were no turbulent vortices aft of the radiator(s) either, otherwise the airflow, over the flaps, would have been disrupted, causing havoc.
Edgar


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## Ratsel (Sep 19, 2011)

yah some NASA windtunnels use the same honeycomb setup for directional flow.. for curbing those unstable vortecies.. nothing for thrust. guess I'll have to agree to disagree. thanks for your explanations.


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## wuzak (Sep 19, 2011)

Juast in case any of us thought that Supermarine were averse/immune from building ugly aircraft.

http://1000aircraftphotos.com/Contributions/Braas/4175L.jpg

The Supermarine Type 322 "Dumbo"


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## wuzak (Sep 19, 2011)

Ratsel said:


> yah some NASA windtunnels use the same honeycomb setup for directional flow.. for curbing those unstable vortecies.. nothing for thrust. guess I'll have to agree to disagree. thanks for your explanations.



The thrust comes from the heat added to the airflow. The intake needs to be expanded in front of the radiator to slow the flow down for better heat transfer, which also increases the static pressure. The heat from the radiator increases the energy in the air. The air is then exhausted through a converging duct, increasing its velocity. If done right and at certain conditions the exhaust airflow thrust will exceed the drag from the duct intake.

A similar principle was being tested for the US nuclear aircraft program. The heat from the reactor was to be transferred to a modified jet engine. The Jet engine had a compressor and a turbine. The compressor does what it always did, then the heat is transferred from the reactor to the airflow, after which it was expelled through the turbine, to power the compressor, and jet nozzle to create thrust.


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## Ratsel (Sep 19, 2011)

ok yah I guess I was looking at this wrong. If it was employed to _allow the aircraft to achieve zero cooling drag_.. ie: the trust produced counteracts the drag produced, then yes it works very well. I though the argument was that it increased overall speed.. which imo is false. my appologies for the confusion.


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## wuzak (Sep 19, 2011)

Ratsel said:


> ok yah I guess I was looking at this wrong. If it was employed to _allow the aircraft to achieve zero cooling drag_.. ie: the trust produced counteracts the drag produced, then yes it works very well. I though the argument was that it increased overall speed.. which imo is false. my appologies for the confusion.



Yes, it counteracts cooling drag, and can, under optimum circumstances, provide some extra thrust. It increases speed overall because it reduces the drag produced.

de Havilland had calculated that the leading edge radiator in the Mosquito was worth around 5-10mph (IIRC) compared to an installation that didn't use the effect.

Incidently, the Meredith Effect is a core feature of the better air-cooled radial installations (and liquid cooled engines with annular radiators).


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## claidemore (Sep 21, 2011)

Just checked 'Spitfire, The History' by Morgan and Shacklady. Meredith himself made suggestions for altering the radiator on the Spitfire, and those suggestions were used in the Type 300 which became the Spitfire Mk I. Trials were done at the Farnborough wind tunnel on 1/4 scale models. Meredith also suggested different exhaust stubs, and a relocation of the carb intake, both suggestions were used. 
Interestingly, the last fighter design that Reginald Mitchell worked on was the Type 312, which was a 4 cannon fighter with a nose postion _ventral _radiator.


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## tomo pauk (Sep 23, 2011)

A question to the knowledgeable people: was the cooler layout in P-39 P-63 any better than that of the Spit, 109, P-40, Tempest etc? I'm pointing into Meredith effect usage, cooling drag etc.


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## Readie (Sep 23, 2011)

davebender said:


> State of the art engine in an outdated airframe. Why would you want such an aircraft?



History is rather at odds with your views dave.
The 'outdated' airframe lasted quite a long time in front line service.

The Napier was good but, not as good as the Merlin / Griffon.

Cheers
John


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## Mustang nut (Sep 23, 2011)

The tempest was a fine aeroplane and in its final Fury Sea Fury variant one of the best of the last piston engined fighters (beautiful too) I am finding readies dissing of everything not spitfire merlin and griffon and jibes about other nationalities tiresome and very Fawltyesque so I have put him on ignore.


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## Readie (Sep 27, 2011)

Mustang nut said:


> The tempest was a fine aeroplane and in its final Fury Sea Fury variant one of the best of the last piston engined fighters (beautiful too) I am finding readies dissing of everything not spitfire merlin and griffon and jibes about other nationalities tiresome and very Fawltyesque so I have put him on ignore.



I was responding to Mr benders remark. The Merlin / Griffon was the best engine for the Spitfire.
The Tempest / Sea Fury were fantastic planes and took piston engined fighters to the next level in the pre jet age.
Fawltyesque = tongue in cheek humour.
If that offends you, what can I say ? some of your remarks are annoying too but, we should be able to rub along together.
John


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