GrauGeist
Generalfeldmarschall zur Luftschiff Abteilung
There was a lend-lease agreement, wich stated that Packard manufactured Merlins for Britain with the stipulation that the US was allowed to get a percentage license-free for the duration.
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There was a lend-lease agreement, wich stated that Packard manufactured Merlins for Britain with the stipulation that the US was allowed to get a percentage license-free for the duration.Those factions also weren't helped by the fact that Packard ended mass production of the Merlin shortly after World War II, Rolls-Royce wanted the US Gov't to pay a $6000 licensing fee per engine that was waived for most of World War II due to Britain's economy being in the crapper, no huge military demand for piston engines (be it Merlin or Griffon), and dealing with the lag time/transition to jets for military and ultimately civil use.
And I do appreciate the fact that engines like the ultimate developments of the Merlin eventually were capable of making 2600+hp. However, that was with 150 octane fuel, ADI, 3300 rpm and 36 lbs of supercharger boost. Essentially, it was a WEP/sprint rating. The RM.17SM was intended to be rated 2380hp for take off and 2200 normal max power.
Packard Merlin V-1650-9 - 2,270 BHP
Allison V-1710-14X - 2,250 BHP
Service limit for operational planes with Merlin-66 at 25 lbs boost exceeded 2000hp in January 1942.Packard Merlin V-1650-9 - 2,270 BHP
Allison V-1710-14X - 2,250 BHP
I think in a hypothetical scenario where the war would have dragged on for a few more years, and jets would also have been delayed a few years, we could very well have seen Griffon powered Mustangs. It seems to me that because the war was drawing to a close and jets being on the imminent horizon, there was never the same effort spent in improving the Griffon as the Merlin. But considering that Griffon was essentially a scaled up Merlin, to a rough approximation it should have been able to produce an equal amount of power per liter as the Merlin.I usually favor engines like the Merlin because of it's efficiency and size as shown in the Mustang (I doubt a P-51 with a Griffon would've been much better aside from maybe being a better interceptor, which most versions of the Mustang that made it into production weren't optimized as except the P-51H, and even that was primarily intended to be an escort fighter).
In hindsight we can see how sleeve valves were not such a great idea. But at the time, it was of course different, especially with a guru figure like Ricardo being a proponent. Would we have ever known that sleeve valves were a Jonah if not for Roy Fedden, Frank Halford and teams spending years tearing out their hair trying to make them work (and even then only managed to produce maintenance nightmares that perhaps entered service only because of wartime desperation?)? In a sense it's just standard R&D, you try a lot of different things, most of which turn out to not be such a good idea.But broadly sleeves had reached the limit of boost and been found wanting (big problems with liner distortion and also thermal issues due to the obviously
appalling conductivity through the sleeve. I dont think you`ll ever get more than was gotten from the Sabre with water injection.
As far as comparisons to today, as far as I know except for some novelty engines which don't appear to be used for much, nobody is using sleeves for anything.
Problem with the Griffon is that it was larger and heavier than the Merlin (fit in the same box in terms of length and width, but was taller and significantly heavier), and the larger displacement meant more cooling (ie, the much larger radiators on the Spitfire 14 vs the Spitfire 9) and being more fuel thirsty. Sadly, I don't think the "bigger engine, more torque, lower revs mean potential for better fuel mileage" that works with cars works the same way for airplanes. Also, the larger displacement should in theory mean less supercharger boost needed for the same power, but Griffon 60 and 80 series engines by war's end were running the 18 and 25 lbs boost ratings that the Merlins were, and, strangely, not making the amount of power that having 10 more liters of displacement would suggest IMO.I think in a hypothetical scenario where the war would have dragged on for a few more years, and jets would also have been delayed a few years, we could very well have seen Griffon powered Mustangs. It seems to me that because the war was drawing to a close and jets being on the imminent horizon, there was never the same effort spent in improving the Griffon as the Merlin. But considering that Griffon was essentially a scaled up Merlin, to a rough approximation it should have been able to produce an equal amount of power per liter as the Merlin.
I think in a hypothetical scenario where the war would have dragged on for a few more years, and jets would also have been delayed a few years, we could very well have seen Griffon powered Mustangs. It seems to me that because the war was drawing to a close and jets being on the imminent horizon, there was never the same effort spent in improving the Griffon as the Merlin. But considering that Griffon was essentially a scaled up Merlin, to a rough approximation it should have been able to produce an equal amount of power per liter as the Merlin.
Actually putting 500lbs ahead of the CG would have balanced out the weight aft and turned the plane into a lamb.
Except the ferocious torque of the Griffin would have made the P-51's already 'exciting' tendency to drop a wing and roll as it unstuck even more 'exciting' - it was a borderline dangerous plane until it got moving and gained enough control authority.
Problem with the Griffon is that it was larger and heavier than the Merlin (fit in the same box in terms of length and width, but was taller and significantly heavier), and the larger displacement meant more cooling (ie, the much larger radiators on the Spitfire 14 vs the Spitfire 9) and being more fuel thirsty. Sadly, I don't think the "bigger engine, more torque, lower revs mean potential for better fuel mileage" that works with cars works the same way for airplanes. Also, the larger displacement should in theory mean less supercharger boost needed for the same power, but Griffon 60 and 80 series engines by war's end were running the 18 and 25 lbs boost ratings that the Merlins were, and, strangely, not making the amount of power that having 10 more liters of displacement would suggest IMO.
Thanks for the explanation.Well I wrote a sizable book which already explains it in quite some detail.
But broadly sleeves had reached the limit of boost and been found wanting (big problems with liner distortion and also thermal issues due to the obviously
appalling conductivity through the sleeve. I dont think you`ll ever get more than was gotten from the Sabre with water injection.
Jumo 213 only became superlative with the 4-valve head, although it was already drastically more advanced than the Merlin (until the 100 series) in most respects (water cooled
exhaust valve guides, swirl throttle, crankshaft nose oil feel, oil centrifuge and so on. All of which are on all Formula One engines on the grid right now (although Renault used
to make do without a centrifuge, by having a bigger and more complex oil tank, but they probably have a centrifuge now).
Broadly the 213 reached about the same max boost pressure as the Sabre throughout the war but on 87 Octane fuel. Which is quite extraordinary
and shows how much better the cooling of the combustion chamber/piston/bore walls must have been. The Sabre made decent power but
at least in part by running at high rpm. The 213J ran only 300rpm slower and "apparently" was planned to exceed 4000rpm eventually. Which I can
believe looking at the internal parts (much lighter than 213A).
As far as comparisons to today, as far as I know except for some novelty engines which don't appear to be used for much, nobody is using sleeves for anything.
As I said, every F1 engine on the grid has virtually every major design aspect of the 213.
The 213 has a pretty quirky design for the liner attachment which I don't think I`d use myself, but otherwise, if I were to design an aero engine now,
I`d pretty much scale down a 213J and maybe just opt for a Merlin 2-piece block sandwiched liner attachment.
Sabre was definitely obstructed and strangled by people at RR and the Air Ministry (F. R. Banks), but, was basically a very expensive and mostly unreliable novelty
which was in hindsight, the wrong technical path. The component design is very good, but the sleeve concept was a mistake. Quite possibly a poppet
valve Sabre would have been quite a hard thing to beat.
The 213 pointed to the future in nearly every respect, and aside from the slightly odd liner clamps, and in "J" form, is vastly technologically superior in general concept to
anything else which flew in combat in WW2. The power it extracted from bog standard B4 fuel is quite remarkable, if you were to downrate Allied engines to run on
87 octane, nothing would have been close to a 213 on a per-litre basis. Wartime problems, materials shortages, fuel shortages and so on together with the significant failure to
get a 4-valve head into combat production on the 213 prevented it from becoming a world-beater. Its an unbelievably advanced engine in concept, an entire generational leap
ahead of the DB600 series.
Wrt fuel burn, I don't recall any figures but I'd be surprised if Griffon had very different BSFC compared to the Merlin. Of course, given identical BSFC a more powerful engine will burn fuel faster than a smaller one at max power. At identical cruise power I'd expect both of them to be fairly close. Of course, a Griffon plane would need to haul around a heavier engine and draggier radiator, but I wouldn't think those would have a dramatic impact.Problem with the Griffon is that it was larger and heavier than the Merlin (fit in the same box in terms of length and width, but was taller and significantly heavier), and the larger displacement meant more cooling (ie, the much larger radiators on the Spitfire 14 vs the Spitfire 9) and being more fuel thirsty. Sadly, I don't think the "bigger engine, more torque, lower revs mean potential for better fuel mileage" that works with cars works the same way for airplanes. Also, the larger displacement should in theory mean less supercharger boost needed for the same power, but Griffon 60 and 80 series engines by war's end were running the 18 and 25 lbs boost ratings that the Merlins were, and, strangely, not making the amount of power that having 10 more liters of displacement would suggest IMO.
Putting an engine in the Mustang that dry weighed 350 or so lbs more than the Merlin would've played havoc with CG and range on internal fuel. Granted, the P-51 usually had issues with full rear fuselage tanks so that might have cancelled the nose-heaviness out to a degree, especially as the radiator and fuselage tanks probably would have to be made larger, though that also brings about it's own design issues. The Mustang's cooling system already had to be heavily modified to go from the single stage Allison to the two stage Merlin. And going to the Griffon would mean round two as far as those mods, just like when the Spitfire went from from the single stage Merlin to the two stage Merlin, to the Griffon.
Well I wrote a sizable book which already explains it in quite some detail.
But broadly sleeves had reached the limit of boost and been found wanting (big problems with liner distortion and also thermal issues due to the obviously
appalling conductivity through the sleeve. I dont think you`ll ever get more than was gotten from the Sabre with water injection.
Jumo 213 only became superlative with the 4-valve head, although it was already drastically more advanced than the Merlin (until the 100 series) in most respects (water cooled
exhaust valve guides, swirl throttle, crankshaft nose oil feel, oil centrifuge and so on. All of which are on all Formula One engines on the grid right now (although Renault used
to make do without a centrifuge, by having a bigger and more complex oil tank, but they probably have a centrifuge now).
Broadly the 213 reached about the same max boost pressure as the Sabre throughout the war but on 87 Octane fuel. Which is quite extraordinary
and shows how much better the cooling of the combustion chamber/piston/bore walls must have been. The Sabre made decent power but
at least in part by running at high rpm. The 213J ran only 300rpm slower and "apparently" was planned to exceed 4000rpm eventually. Which I can
believe looking at the internal parts (much lighter than 213A).
As far as comparisons to today, as far as I know except for some novelty engines which don't appear to be used for much, nobody is using sleeves for anything.
As I said, every F1 engine on the grid has virtually every major design aspect of the 213.
The 213 has a pretty quirky design for the liner attachment which I don't think I`d use myself, but otherwise, if I were to design an aero engine now,
I`d pretty much scale down a 213J and maybe just opt for a Merlin 2-piece block sandwiched liner attachment.
Sabre was definitely obstructed and strangled by people at RR and the Air Ministry (F. R. Banks), but, was basically a very expensive and mostly unreliable novelty
which was in hindsight, the wrong technical path. The component design is very good, but the sleeve concept was a mistake. Quite possibly a poppet
valve Sabre would have been quite a hard thing to beat.
The 213 pointed to the future in nearly every respect, and aside from the slightly odd liner clamps, and in "J" form, is vastly technologically superior in general concept to
anything else which flew in combat in WW2. The power it extracted from bog standard B4 fuel is quite remarkable, if you were to downrate Allied engines to run on
87 octane, nothing would have been close to a 213 on a per-litre basis. Wartime problems, materials shortages, fuel shortages and so on together with the significant failure to
get a 4-valve head into combat production on the 213 prevented it from becoming a world-beater. Its an unbelievably advanced engine in concept, an entire generational leap
ahead of the DB600 series.
Hypothetical scenarios always seem to favor one side over the other. With the war dragging on, where do you draw the line as to Allies on the mainland or not? On the mainland range of fighters becomes less worrisome (and performance goes up as fuel loads can be decreased and or smaller drop tanks made / utilized), and the ability to generate both air to air and air to ground sorties goes up (ASD - average sortie duration) length goes down. Put bombers on the mainland and their bomb loads go up, and time over bad guy territory goes down (so does risk to a degree). Allies on the mainland equals greater force brought against the Germany. Allies not on mainland, Russians somehow held off, German economy somehow still able to produce soldiers, weapons, food, and fuel (on going problem for years) and improvements needed on long range escorts. As Stalin is oft quoted as say, "Quantity has a quality all of its own". Or the Allies could have just produced more fighters. This allows you to fly over Germany and set up caps above their airfields, and or do sunrise strikes, and effectively keep the "higher performing" German fighters on the deck. Enough fighters and you could do this all day (logistically fuel, food, men and aircraft can be supplied which Germany couldn't keep up with).Wrt fuel burn, I don't recall any figures but I'd be surprised if Griffon had very different BSFC compared to the Merlin. Of course, given identical BSFC a more powerful engine will burn fuel faster than a smaller one at max power. At identical cruise power I'd expect both of them to be fairly close. Of course, a Griffon plane would need to haul around a heavier engine and draggier radiator, but I wouldn't think those would have a dramatic impact.
But all the same, what's the alternative? In the hypothetical scenario I outlined with the war dragging on and jets not in sight, Germany would likely have been deploying things like Do-335 and Ta-152 in nontrivial numbers, and the Allies would have needed more top speed to keep up, slightly worse fuel burn at cruise be damned.
And yes, this would certainly have required a heavily modified plane just like the Spit was modified to accommodate the Griffon. But just based on the Mustang being a bigger and heavier plane than the Spit, I'm sure it would have been doable.
I dont have "a letter" saying "we didnt do this because xyz" but you can infer a probable reason.Is it known why Jumo engineers doesn't changed much earlier to 4-valve-heads, as example with the precedessor models 210 or 211?
Why didn't Hispano switch to 3 valve heads instead of keeping using 2 valve (and a bad two valve layout at that)?Is it known why Jumo engineers doesn't changed much earlier to 4-valve-heads, as example with the precedessor models 210 or 211?
When that reduction of boost took place?Also, perhaps strangely, later Merlin 130 series engines were derated to have a normal boost of 18 lbs vs 25 lbs, though that reduction only knocked about 40 hp out of those Merlins (and had no impact on the Hornet's performance, though as far as the specs I did read, very slight performance differences--+/- 1mph and +/- 10 fpm climb rate--occurred due to a prop design change).
The Sabre eventually got to 25 lbs of boost, but that wasn't until late-war/post war development versions.
And all German engines could've benefited from better supercharging, but the lack of steady supplies of 100+ octane fuel prevented this.