Spitfire and the Merlin 100 Series

Shortround6 said:

It is easier, Just don't expect the same results with over 10% less power and with more weight than the engine, radiator, prop from the base line MK IX.

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Weight is rarely of a concern for the top speed. Drag is cruel (copyright drgondog ), on the other hand.
I don't expect 445 mph, more likely 420 mph on a basic Mk.IX fuelage, and up to 430 mph with retractable taiwheel and covered wheel wells.

So the answer is a Spitfire with a Rolls Royce Crecy…………………

tomo pauk said:

Weight is rarely of a concern for the top speed. Drag is cruel (copyright drgondog ), on the other hand.
I don't expect 445 mph, more likely 420 mph on a basic Mk.IX fuelage, and up to 430 mph with retractable taiwheel and covered wheel wells.

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The Spitfire PR XI (similar to the Mk IX aside from no armament, increased fuel (fuel essentially replaced guns), and retractable tail wheel) had a top speed of 430 mph with the Merlin 60 series engine and no fully-enclosed wheel covers. The PR XI also had a less streamlined nose (bulged to make room for a larger oil tank). I wonder what a Spitfire could do with not just a Merlin 100, but also maybe either Spiteful-type radiators (or Hawker Tempest I or Fury Sabre leading edge radiators), and a laminar flow wing that would imitate the Spitfire's stall characteristics.

BarnOwlLover said:

I wonder what a Spitfire could do with not just a Merlin 100, but also maybe either Spiteful-type radiators (or Hawker Tempest I or Fury Sabre leading edge radiators), and a laminar flow wing that would imitate the Spitfire's stall characteristics.

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An ideal (big word, I know) Spitfire with a perfect radiator set-up (again big words) - probably close to as Mustang with same power?

BarnOwlLover said:

The Spitfire PR XI (similar to the Mk IX aside from no armament, increased fuel (fuel essentially replaced guns), and retractable tail wheel) had a top speed of 430 mph with the Merlin 60 series engine and no fully-enclosed wheel covers. The PR XI also had a less streamlined nose (bulged to make room for a larger oil tank). I wonder what a Spitfire could do with not just a Merlin 100, but also maybe either Spiteful-type radiators (or Hawker Tempest I or Fury Sabre leading edge radiators), and a laminar flow wing that would imitate the Spitfire's stall characteristics.

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Where did you get that top speed for the PR.XI?

Top speed was 417mph with Merlin 63, 422 with Merlin 70.


The PR.XI also had the more streamlined screen without armoured glass.

In comparison, the Spitfire PR.XIX with Griffon engine had a top speed of 457mph.

The PR.XIX was, essentially, the PR.XI with a Griffon fitted.

The biggest difference between the two seems to be the cruise performance.

PR.XI
Most Economical - 260mph @ 30,000ft
Max Weak Mixture - 388mph @ 30,000ft

PR.XIX
Most Economical - 360mph @ 35,000ft
Max Weak Mixture - 405mph @ 35,000ft

I cliped this from another thread, but maybe could give some fuel for the fire (or confusion) for this discussion:

"Now, maybe to add to the discussion, or at least confusion, I dug out my DH Hornet and Sea Hornet book that I bought quite a few years ago. Notably, I decided to check the weight specs. It turns out the Hornet F1 had a normal takeoff weight of just above 14,000 lbs, and normal max take off was less than 17,000 lbs. I don't know how accurate those figures are, though that book also notes that most sources do get the Hornet's dimensions wrong, namely length (based on DH plans, the Hornet is at least a foot longer in overall length than often stated). So, I do assume that the same type of research was done on the Hornet's weights."

Also, the XP-51F/G weighed about the same as a Spitfire IX. But that's clean and normal take off weight. Also, those Mustangs gave up armament (4x.50 mgs) to keep range similar to the D/K models. But the XP-51G was powered by a Rolls Royce Merlin RM.14SM (basically a Merlin 130 with an updraft supercharger intake). IMO, that does make me thing with a lightweight late Spitfire for Spiteful powered by later Merlins could do.

As per others already and Morgan and Shacklady. Griffon Spitfire proposal in November 1939, little done for a while then the contract for two prototype mark IV placed on 26 May 1941, though the mark number had been reserved earlier, the first Spitfire V was around in January 1941. Mark IV DP845 maiden flight 27 November 1941, second prototype DP851 the next month. Ultimately DP841 was the mark XII prototype, DP851 the mark 20 prototype.

Griffon II production began in April 1942, Griffon 65 in December 1942 but by the end of 1943 only 74 Griffon 61, 65, 71 and 75 production engines had been built, including 35 in December 1943.

Merlin 100 series to end 1945, 16 Merlin 100, 2 Merlin 101, 7 Merlin 102, 102 Merlin 104 (100 in August/September 1945), main production versions Merlin 113 from August 1944, Merlin 114 from October, Merlin 130 from January 1945, Merlin 131 from June. There were 164 production Merlin 100 series engines built in 1944, so while production began nearly 2 years after the two stage Griffon, "mass" production was under a year behind.

Michael Bowyer in British Interceptor Fighters reports the Merlin 65 was type tested in mid 1942 at 2,300 HP at 500 feet and 2,060 HP at 15,750 feet. First production Spitfire XII in October 1942, first production mark XIV in October 1943. Bowyer notes the Merlin 65 was two months too late but by mid 1942 the Griffon was the allocated engine for the Spitfire, the war situation and the capacity of the British economy meant the decision was effectively locked in.

Merlin 85 production from January 1944 to June 1945, 1,420 built plus 14 Merlin 85T, the engines were reported to have enough problems the RAAF substituted Merlin 60 series engines on its Lincolns.

Are the power figures accurate for the Merlin 65? The 2300 hp is a Griffon-like figure and the 2060 hp figure is more like the Merlin 130 series.

Geoffrey Sinclair said:

Michael Bowyer in British Interceptor Fighters reports the Merlin 65 was type tested in mid 1942 at 2,300 HP at 500 feet and 2,060 HP at 15,750 feet.

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The power and altitude line up perfectly with Griffon 65 running on 150 octane fuel.

I was thinking that, too. I highly doubt that the Merlin was making 2300 hp in 1942 unless it was some super-sprint spec. The Packard V-1650-9 approached that, but that was war emergency/sprint power and wouldn't come until 1944/45.

BarnOwlLover said:

I wonder why this wasn't considered, aside from the fact that the first Griffon powered Spitfires came before the Merlin 100 was fully developed. The Merlin 100 series of course powered the de Havilland Hornet (130 series) most notably, and I believe formed the basis of the Packard V-1650-9/11/23/25 that powered the P-51H Mustang and the XP-82/F-82B Twin Mustangs. I think that if it was workable, a Merlin 100 powered Spitfire would've been an interesting proposition.

Only thing is that, like the Griffon versions, fuel capacity would've had to have been increased, since the Merlin 100s were capable of making about 300+hp more than the Merlin 60 series engines. Not to mention that more power does also usually mean more strengthening, which generally means that the resulting aircraft will be somewhat heavier, though the power should hopefully offset that.
But I do wonder why this wasn't seriously pursued in war time (I'm betting that some Spitfires flying today are using later engines based on the 100 series that were sold commercially), aside from the fact that the Griffon Spits took the lead in development terms after the Mk IX and Mk VIII were developed.

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Sad Story.
One of the first Spitfires fitted with a Griffon was given to an experienced WAAF (I think that is right) for delivery to it's squadron.
Unfortunately no one told her this Griffon, maybe all, run counter clockwise. At take off in a single engine plane with powerful engine you have give it left stick to counter the equal and opposite force. When she gave it the usual left stick the plane rolled completely and she died.

BarnOwlLover said:

I wonder why this wasn't considered, aside from the fact that the first Griffon powered Spitfires came before the Merlin 100 was fully developed. The Merlin 100 series of course powered the de Havilland Hornet (130 series) most notably, and I believe formed the basis of the Packard V-1650-9/11/23/25 that powered the P-51H Mustang and the XP-82/F-82B Twin Mustangs. I think that if it was workable, a Merlin 100 powered Spitfire would've been an interesting proposition.

Only thing is that, like the Griffon versions, fuel capacity would've had to have been increased, since the Merlin 100s were capable of making about 300+hp more than the Merlin 60 series engines. Not to mention that more power does also usually mean more strengthening, which generally means that the resulting aircraft will be somewhat heavier, though the power should hopefully offset that.
But I do wonder why this wasn't seriously pursued in war time (I'm betting that some Spitfires flying today are using later engines based on the 100 series that were sold commercially), aside from the fact that the Griffon Spits took the lead in development terms after the Mk IX and Mk VIII were developed.

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I was under the impression that the de Havilland Hornets ran on 150 octane fuel. Most of the top speeds of P-51Fs, Gs and Hs involve 150 octane fuel and water injection. The top speeds quoted for Spitfire XIVs and P-51Ds are with 100/130 octane fuel and nothing injected into the fuel air mixture.

The Rolls Royce Griffons benefited from 150 octane fuel too. Their quoted performance figures do not account for this.