Author Topic: WWII Inline engines: Daimler Benz vs Rolls Royce vs Allison vs Klimov vs Jumo  (Read 29312 times)

Offline Captain Virgil Hilts

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WWII Inline engines: Daimler Benz vs Rolls Royce vs Allison vs Klimov
« Reply #45 on: May 24, 2007, 06:04:59 PM »
Quote
Originally posted by Angus
Virgil Hilts: Please please explain to me P51 had to be powered by a merlin to get alive above 15k.


Once again, in simple, easy to grasp terms. The Allison, as required by the USAAF and the War Production Board, was produced with a single speed supercharger. Without the ability to increase the speed of the supercharger, there was not enough boost available to make horsepower at higher altitudes.
The Merlin had a two speed supercharger. At low altitudes it ran at a low speed, and at higher altitudes it ran at a higher speed to produce more boost in the thinner air at higher altitudes. Around 20,000 feet or so, the Merlin supercharger went from low speed to high speed.
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Offline OdinGrunherze

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WWII Inline engines: Daimler Benz vs Rolls Royce vs Allison vs Klimov
« Reply #46 on: May 24, 2007, 06:14:16 PM »
So, The R4360 would blow them all away anyway.
So there ya go!!!!

OG

Offline Captain Virgil Hilts

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« Reply #47 on: May 24, 2007, 06:18:06 PM »
Quote
Originally posted by gripen
Well, you see the problem in that logic; historically the Allison had problems to do 1600hp reliably while the Merlin did quite well 2000hp. That was the situation at spring 1944.

Besides, the Allison design went towards the concepts used in the Merlin like lower compression ratio and mechanical supercharger etc. In practice the developement of the Allison was couple years behind the Merlin during war.


No, the Allison, with the correct fuel, and properly tuned, could easily produce in excess of 1800HP reliably. In spring of 1944, actually winter 43-44, the P-38J had well over 1600HP at critical altitude. That was the under rated HP from the first of the J model P-38 as delivered. In late spring and early summer of 1944, the P-38L arrived, rated at 1725HP.

The Allison was designed to run with 6.6:1 compression and with a centrifugal supercharger from the beginning. It didn't "go towards Merlin concepts". It had the low static compression from the very beginning. It also had dual overhead cams, 4 valves per cylinder, pent roof combustion chambers, dual spark plugs, forged pistons, roller cams, and roller rocker arms.

And NO, the Merlin was NOT that reliable. The first P-51's delivered to the 8th AF fighter groups were notorious for cracked heads, that dumped coolant out. As soon as the head cracked and the coolant left, you had 30 seconds of power, after which it seized. They were also at least as bad if not worse for fouling spark plugs as the Allison ever was. Sorry, but the vaunted Merlin power and reliability was as big a myth as the Mustang being the plane that beat the Luftwaffe. It just ain't so. The new Merlin equipped P-51B had severe teething issues when it was introduced. Now, this is the same Merlin that you speak of, that was NOT a new engine, but rather the same engine that had already been in the war since 1939. So four years later, it was STILL cracking heads, fouling plugs, and seizing crankshafts, and on a regular basis. At least according to the guys who flew them.
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Offline 2bighorn

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WWII Inline engines: Daimler Benz vs Rolls Royce vs Allison vs Klimov
« Reply #48 on: May 24, 2007, 06:41:17 PM »
Quote
In 1940 Packard Motors of Detroit began building the two-speed Merlin V-1650-1 (Merlin 28) under license from Rolls Royce. This engine had 1170 horsepower in high blower with a critical altitude of 21,000 feet. Lockheed ran a study comparing a Merlin XX powered Lightning with a standard V-1710 powered variant. The reported speed difference was over 25 mph, favoring the Merlin powered airplane. Climb performance was similar to the Allison powered machine.

Another Merlin vs. Allison comparison in 1942 involved the V-1710-89/91 Allisons (engines used in standard P-38J) and the Packard V-1650-3 two-speed, two-stage Merlin used in the P-51B/C. Utilizing Military Power speed was almost identical.

Yet another study in 1944 compared V-1710s producing 1725 bhp and "advanced" Merlins using "special" fuel and producing 2000 bhp (no altitude specified). The Merlin powered version could supposedly attain 468 mph at 30,000 feet, which was considerably better than the Allison powered version.

These studies were all conducted by Lockheed and exhibit a certain amount of optimism in regard to maximum speed for both types, but the consensus clearly shows better performance with the Merlin powered Lightning.

Offline Wolfala

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WWII Inline engines: Daimler Benz vs Rolls Royce vs Allison vs Klimov
« Reply #49 on: May 24, 2007, 07:42:52 PM »
Quote
Originally posted by Captain Virgil Hilts
Actually, the use in racing has EVERYTHING to do with the quality and superiority  of the engine design. The Allison had far more room to grow in power without sacrificing reliability. The Allison was rated by the manufacturer at well over 1800HP, the USAAF down rated it. Further, the same basic engine was used later with compound turbosupercharging to reliably produce around 3000HP. The only problem with that engine was the exhaust temperature was too great for the typical aircraft exhaust system. But the engine itself tested beautifully.



Should mention the Allison V-1710 Turbocompound engine.

An attempt to recover some of this energy resulted in the turbocompound V1710 shown at the bottom of the page. It was identified as the V1710‑E22 by Allison, and as the V1710‑127 by the government. A turbocompound engine collects all of the exhaust gasses and runs them through a turbine, with all of the power generated going back into the crankshaft and ultimately to the propeller. It differs from a turbosupercharged engine, which uses exhaust gas energy to increase the pressure of incoming air. Work on this engine began in about 1944 and continued until 1946, when Allison asked that it be cancelled because turbine engines had greater promise. It was the first successful turbocompound engine, and probably one of only three to ever be built. This engine was designed to power the XP63H, which, as it turned out, never flew. The V1710‑E22 had a military rating of 2320 hp, and a War Emergency Rating with water/alcohol injection of 3090 hp.


http://www.enginehistory.org/v1710tc.htm


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Offline Angus

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WWII Inline engines: Daimler Benz vs Rolls Royce vs Allison vs Klimov
« Reply #50 on: May 24, 2007, 07:54:46 PM »
Woo-hoo:
"Sorry, but the vaunted Merlin power and reliability was as big a myth as the Mustang being the plane that beat the Luftwaffe. It just ain't so. The new Merlin equipped P-51B had severe teething issues when it was introduced. Now, this is the same Merlin that you speak of, that was NOT a new engine, but rather the same engine that had already been in the war since 1939. So four years later, it was STILL cracking heads, fouling plugs, and seizing crankshafts, and on a regular basis. At least according to the guys who flew them."

And the Allisons flew just very nice? Of course many more Merlins failed, after all the hours in service were many times as many. Probably many more than any inline engine.
More of reliability of the engine 4 years in service? Well, the power was pushed up from 1000 hp to close 2000, with 1700 as an easy go, and those are figures of front-line fighters in big numbers.
What of the reliability of the Allison powering the P38 in the ETO? Problems because of the atmosphere AFAIK.
BTW, a P38 smacked into a hill close to where I live. Engine failiure leading to fire. A guy dug up the engine blocks and keeps them in a secret place, or so it's told.


And:
"At least according to the guys who flew them."
Well, who? I knew one who clocked 2+ TOD's in WW2 (combat) as well as instruction, without as much as a hic-up.
It was very interesting to carry out the flight trials at Rechlin with the Spitfire and the Hurricane. Both types are very simple to fly compared to our aircraft, and childishly easy to take-off and land. (Werner Mölders)

Offline Tails

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WWII Inline engines: Daimler Benz vs Rolls Royce vs Allison vs Klimov
« Reply #51 on: May 24, 2007, 10:42:45 PM »
Quote
Originally posted by Wolfala
Should mention the Allison V-1710 Turbocompound engine.

**Snip text and sexy engine pic**


Got any info on how much that beast weighed? Already sounds like it'd blow a turboshaft out of the water (Pratt PT-6 being the one in mind) on power alone.
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Offline gripen

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WWII Inline engines: Daimler Benz vs Rolls Royce vs Allison vs Klimov
« Reply #52 on: May 24, 2007, 10:59:57 PM »
Quote
Originally posted by Captain Virgil Hilts
No, the Allison, with the correct fuel, and properly tuned, could easily produce in excess of 1800HP reliably. In spring of 1944, actually winter 43-44, the P-38J had well over 1600HP at critical altitude. That was the under rated HP from the first of the J model P-38 as delivered. In late spring and early summer of 1944, the P-38L arrived, rated at 1725HP.


Hm... There has been several theories why the Allisons were so unreliable at high altitudes. Anyway, high altitude problems were not limited in ETO, there were similar issues with the F-5s in the MTO (see America's 100000) so fuel theory can be rejected quite easily (there were no Js before summer). IIRC Tony Levier blew something like 30 Allisons during summer 1944 when trying to solve the problem so the problem was there and apparently never fully solved because P-38s were not tried again in the high altitude operations.

Quote
Originally posted by Captain Virgil Hilts

The Allison was designed to run with 6.6:1 compression and with a centrifugal supercharger from the beginning. It didn't "go towards Merlin concepts".


Actually it did in the G-series Allisons, see the "Vee's for Victory".

Quote
Originally posted by Captain Virgil Hilts

And NO, the Merlin was NOT that reliable. The first P-51's delivered to the 8th AF fighter groups were notorious for cracked heads, that dumped coolant out. As soon as the head cracked and the coolant left, you had 30 seconds of power, after which it seized. They were also at least as bad if not worse for fouling spark plugs as the Allison ever was. Sorry, but the vaunted Merlin power and reliability was as big a myth as the Mustang being the plane that beat the Luftwaffe. It just ain't so. The new Merlin equipped P-51B had severe teething issues when it was introduced. Now, this is the same Merlin that you speak of, that was NOT a new engine, but rather the same engine that had already been in the war since 1939. So four years later, it was STILL cracking heads, fouling plugs, and seizing crankshafts, and on a regular basis. At least according to the guys who flew them.


There were problems in the beginning; the P-51B was rushed in the service due desperate need. However, the problems were soon solved, IIRC one P-38/P-51 pilot once said: "I have landed P-38 one engine running several times but I have allways landed P-51 one engine running".

Offline Knegel

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WWII Inline engines: Daimler Benz vs Rolls Royce vs Allison vs Klimov
« Reply #53 on: May 24, 2007, 11:53:58 PM »
Quote
Originally posted by gripen
Well, the question was about the best, not about the most advanced. The Merlin was there when needed and giving very good performance. And regarding the reliability, the other inlines are far behind; even the civil version of the two stage Merlin were rated for 2000hp while the military versions of the Allisons and DBs were really hard pushed at that output.



So was the DB601 and DB605, despite the less good fuel, the DB engeeners always found a way to get to a very similar stage of power.

To say the "Merlin was by far the best developed" engine is not true, at least much overdone.
1st the DB601A was ahead of the MerlinII, then the brits got better fuel and the Merlin had a WEP advantage, then the germans did use better fuel and the DB601N was ahead again, then the Brits got a new engine, then the DB601E and so on.
Only in mid 1942- mid 44 there was a advantage for the merlin, cause the germans gave all the good fuel to the BMW´s. Later, with MW50 and GM1 the DB605 was on paar again, while the fuel still was the main problem(next to the typical late war production problems).

The DB603 and Jumo213 also was very good designs.

There simply is no best engine, there are airframes where the engines fit in and turn to be very good and there are tactical situations where the engine need to fit.
The high alt performence of the allied engines wasnt much worth while a tactical airwar in MTO and russia, while the great Ash82 and BMW801 was bad while interceps in high alt.

Offline Captain Virgil Hilts

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WWII Inline engines: Daimler Benz vs Rolls Royce vs Allison vs Klimov
« Reply #54 on: May 25, 2007, 02:42:58 AM »
Quote
Originally posted by gripen
Hm... There has been several theories why the Allisons were so unreliable at high altitudes. Anyway, high altitude problems were not limited in ETO, there were similar issues with the F-5s in the MTO (see America's 100000) so fuel theory can be rejected quite easily (there were no Js before summer). IIRC Tony Levier blew something like 30 Allisons during summer 1944 when trying to solve the problem so the problem was there and apparently never fully solved because P-38s were not tried again in the high altitude operations.

 

Actually it did in the G-series Allisons, see the "Vee's for Victory".

 

There were problems in the beginning; the P-51B was rushed in the service due desperate need. However, the problems were soon solved, IIRC one P-38/P-51 pilot once said: "I have landed P-38 one engine running several times but I have allways landed P-51 one engine running".



I'm not aware of Levier blowing 30 engines, and especially not during the summer of 1944. I have no idea where you got that. In fact, after Levier came to England, the engine failures were greatly reduced, as was fuel consumption. Funny you should bring up Levier, in fact. It was Levier who solved the problems with burned valves, runaway turbochargers, excessive fuel consumption, and performance at high altitude. Suggest you read "The Lockheed P-38 Lightning" by Warren Bodie, and the other version by Steve Pace. They have Levier's reports on operational issues from his tour of the 8th AF, and the causes thereof. The causes thereof happen to be: incorrect fuel mixture setting at cruise, incorrect prop pitch settings at cruise, improper adjustment of the turbocharger oil regulators and waste gate, and irregular fuel quality. After proper instruction of both the pilots and crews, pilots who had been returning from missions on one engine and with 10 gallons of fuel were returning with two healthy engines and as much as 100 gallons of fuel.

A perfect example would be Lt. Loenhert's P-38, "California Cutie" which flew some 300hours of combat on one pair of Allisons. The ones that came with the plane.

After Levier's tour, the P-38's DID in fact fly full high altitude missions in escort of the bombers. The P-51 DID NOT replace the P-38, or even equal it in numbers, until APRIL 1944. Only AFTER the P-51 reached numerical parity with the P-38 were the P-38 units completely relieved of escort duty, and released to ground attack. And the P-38 was in fact the first U.S. fighter over Berlin, and in numbers. BOTH the 20th AND the 55th made it to Berlin before a P-51 unit even came close.

The ORIGINAL V-1710 Allison had around 6:1 compression. They varied between 6:1 and 6.6:1 more or less. It was designed to be supercharged. It was ALWAYS supercharged, and had low static compression. The F series in the P-38 had 6.5:1 compression.

I hate to break this to you, but the P-38J-1-Lo entered service with the 8th AF in NOVEMBER of 1943. The P-38J, in all versions from J-1-Lo to J-25-Lo served with the 8th AF from November 1943 to July 1944. The P-38L entered service in July 1944, although most, but not all squadrons switched to the P-51 instead. Some squadrons in the ETO did not switch.

The Merlin was already supposedly a proven high altitude engine, supposedly superior to the Allison, and in service over Europe for over 3 years before an Allison equipped P-38 even arrived. But in late 43 and early 44, more than 3 YEARS after they entered combat service, they evidently weren't so superior or proven, since they blew up in P-51's on a regular basis.

Oh, and the Allison equipped P-38's were rushed into service before the P-51's, with FAR less operational training and indoctrination, with FAR fewer experienced combat pilots and officers. The 20th and 55th were rushed into service after "Black Thursday", a lot sooner than the P-51 units, and in a bigger hurry. So that excuse doesn't wash for the P-51. They had more time to go operational, and the supposedly superior engine had already BEEN in operation at high altitude over Europe for 3 years.

Yes, many P-38's returned on one engine. But P-51's that lost one engine NEVER returned at all.

If you want to quote pilots, I'll quote one for you, and give you his name. Captain Arthur Heiden, flight leader, 79th FS, 20th FG.

From Captain Heiden, who flew BOTh the P-38 and the P-51:

"P-38 units from the moment of going on initial operational status were committed to MAX EFFORT. No two ways about it. No time to shake things out, to discover your problems. You got there and zap, you were in up to your eyeballs. This meant that everything flyable went and everything that still had wings would be made flyable. No matter what. This in effect was the same as demanding, by direct order, that everyone and everything must have, immediately if not sooner, 100 percent combat capabilities. Like Casey Jones, the pressure was all the way up without any margins whatsoever."

"Despite these revolting developments, the pilots of the 8th knew that the P-38 could outturn, outclimb, outrun and outfight anybody's airplane in the air so they set about rectifying their problems."


And:

"Nothing, to these pilots, after the hard winter of 1943-44 could be more beautiful than a P-38L outrolling and tailgating a German fighter straight down, following a spin or split-S or whatever gyration a startled, panicked and doomed German might attempt to initiate. You just couldn't get away from the P-38L. Whatever the German could do, the American in the P-38L could do better."

On the P-51:

"The P-51 was a new airplane and we were eager to fly it and were happy with it. It was so easy and comfortable to fly. The P-38 had kept us on our toes and constantly busy--far more critical to fly. You never could relax with it. We were disappointed with the 51's rate of climb and concerned with the reverse stick, especially if fuel was in the fuselage tank, the rash of rough engines from fouled plugs, and cracked heads which dumped the coolant. With the 38 you could be at altitude before landfall over the continent, but with the 51 you still had a lot of climbing yet to do. The 38 was an interceptor and if both engines (were healthy), you could outclimb any other airplane, and that's what wins dog fights. When you are in a dog fight below tree tops, it is way more comfortable in a 38 with its power and stall characteristics and, for that matter at any altitude."

Finally:

"Feb 44 we went back to Schwienfurt with acceptable loses. March 3rd the 20th & 55thFGs went to Berlin--Bombers were recalled. March, April, and May brought vicious battles, often with heavy loses. However, Germany were throwing their valuable flight instructors and 100hr students in to the battle. The Luftwaffe was at last starting to die."

"The 8th was, at last, being flooded with Mustangs and well trained pilots. The Mustang was a delight to fly, easier to maintain cheaper to build and train pilots for, and had long legs. In those respects you can rightfully call it better, but it could not do anything better than a P-38J-25 or L. Just remember who took the war to the enemy and held on under inconceivable odds. Enough of the crap."


Note The above quotes from Captain Arthur Heiden, from Dr. Carlo Kopp's article "Der Gabelschwanz Tuefel", at C. C. Jordan's "Planes and Pilot's of World War II".
"I haven't seen Berlin yet, from the ground or the air, and I plan on doing both, BEFORE the war is over."

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Offline Angus

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« Reply #55 on: May 25, 2007, 04:24:18 AM »
Gunther Rall flew captured allied aircraft in mock-up fights against students. He was fascinated by the Merlin, both the sound, and power as well as the engine showing little wear (with som 90 hrs on the overhaul clock) while the DB was loosing power very shortly.
That P51 he flew had a very tight engine he said, while his 109 did not, - in only 10 hours you could turn the prop easily.
Could be a material issue rather than design though, - after all it was war and 1944...
It was very interesting to carry out the flight trials at Rechlin with the Spitfire and the Hurricane. Both types are very simple to fly compared to our aircraft, and childishly easy to take-off and land. (Werner Mölders)

Offline gripen

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« Reply #56 on: May 25, 2007, 04:31:47 AM »
Quote
Originally posted by Captain Virgil Hilts
I'm not aware of Levier blowing 30 engines, and especially not during the summer of 1944.


I don't remember where I got that number, however he certainly experienced several "Allison time Bombs" during his tour in Britain which ended in the beginning of June. He tried to solve problem there and the testing continued in the states as well.

Quote
Originally posted by Captain Virgil Hilts

I have no idea where you got that. In fact, after Levier came to England, the engine failures were greatly reduced, as was fuel consumption.


It's quite logical that the problems were reduced when the air temperature increased in spring and the P-38 started fly more low altitude missions.

Quote
Originally posted by Captain Virgil Hilts

The P-51 DID NOT replace the P-38, or even equal it in numbers, until APRIL 1944.


Actually it did, all P-38 units of the 8th AF converted to the P-51. And even in MTO and pacific the P-51 took over high altitude missions.

Quote
Originally posted by Captain Virgil Hilts

The ORIGINAL V-1710 Allison had around 6:1 compression. They varied between 6:1 and 6.6:1 more or less. It was designed to be supercharged. It was ALWAYS supercharged, and had low static compression. The F series in the P-38 had 6.5:1 compression.


Please read the "Vee's for Victory"; the G-series V-1710 had CR 6.00:1 ie same as in the Merlin.

Quote
Originally posted by Captain Virgil Hilts

I hate to break this to you, but the P-38J-1-Lo entered service with the 8th AF in NOVEMBER of 1943. The P-38J, in all versions from J-1-Lo to J-25-Lo served with the 8th AF from November 1943 to July 1944.


Please read my post, there were no Js (in the MTO) before summer 1944, however, there were J based F-5s in the MTO at winter 43/44 which experienced similar problems as Js in the ETO so local fuel can't explain the problems.

Quote
Originally posted by Captain Virgil Hilts

The Merlin was already supposedly a proven high altitude engine, supposedly superior to the Allison, and in service over Europe for over 3 years before an Allison equipped P-38 even arrived. But in late 43 and early 44, more than 3 YEARS after they entered combat service, they evidently weren't so superior or proven, since they blew up in P-51's on a regular basis.


Well, once introduced to the service the P-51 with Merlin quickly replaced the P-38.

Quote
Originally posted by Captain Virgil Hilts

Yes, many P-38's returned on one engine. But P-51's that lost one engine NEVER returned at all.


Well, that underlines the reliability problem of the Allison; it would have been removed from service if it had been in the single engined fighter. However, the reliability of the Merlin was certainly acceptable because it eventually replaced the P-38.

It can be said that the 8th AF found a quick fix to the high altitude problems of the P-38 (Allison was just one of the problems), the fix was called the P-51.
« Last Edit: May 25, 2007, 05:14:02 AM by gripen »

Offline gripen

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« Reply #57 on: May 25, 2007, 04:38:02 AM »
Quote
Originally posted by Knegel
So was the DB601 and DB605, despite the less good fuel, the DB engeeners always found a way to get to a very similar stage of power.


Hm... The DBs had restrictions most of time and often problems to reach claimed performance also the TBO was short. Infact the DB603 was used mostly for the twins due to continous problems. There were similar problems wth the Jumos as well.

Offline Charge

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« Reply #58 on: May 25, 2007, 04:49:25 AM »
"The DBs had restrictions most of time and often problems to reach claimed performance also the TBO was short."

Because of material problems/shortages. Technically the engine could deliver comparable power given proper fuel and plugs.

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Offline Masherbrum

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« Reply #59 on: May 25, 2007, 06:09:17 AM »
Quote
Originally posted by gripen
Hm... The DBs had restrictions most of time and often problems to reach claimed performance also the TBO was short. Infact the DB603 was used mostly for the twins due to continous problems. There were similar problems wth the Jumos as well.


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