Western engine reliability

Post #11
"they didnt have too
many good things to
say about their
practices. pilots got into
planes, as soon as the
engines were started
they were immediately
pushed to full throttle
and the plane airborne.
neither the pilots or
ground crews did any
pre-flight checks or
engine warm up. the
pilots took off in the
direction the plane was
facing at the time
regradless of the wind
direction ( cross wind,
down wind..didnt
matter) or placment of
other ac. there was no
co-ordination"
Replace plane or a/c with motorcycle and you'll have the answer.
Just humour, no big deal.

I dont get the issue about east front. Attrition to non-combat related causes for all combatants (with possibly the exception of the Finns) was exceptionally high. German attritional losses on the east front for example, ran at about 20-30% of the force structure every month, depending on the weather conditions and intensity of activity. Soviet losses were similar, so from the point of view of loss rates, engine reliability had little or no effect on Soviet force structures. Neither did it have much effect on operational readiness rates. German readiness rates according to Hayward were typically about 35-50% climbing to 60% occasionally on the eastern front. Soviet readiness rates were certainly no worse than that , usually above 50%.


Another way to look at this issue on the Eastern Front, might be to look at sortie rates.....how many aircraft were needed in a random sample to fly x amount of missions. if the number of aircraft (attached to the formations concerned) needed is higher to fly say 100 missions, then we can safely assume a lower readiness rate, and by extension, a lower level of engine reliability.

Im not aware of a lower or worse return for the Sopviets in any of these categories.


I think this whole issue is just a big crock......a beat up to try and trumpet superior german technoilogy, or to try and bring allied (and Soviet ) reliability levels back to their own (generally) miserable levels.

bobbysocks said:

and because of that would the airframes have been considered "war weary" long before the engines ( generally ) were in need of overhaul? did they ever "overhaul" an engine? with production going full tilt would they have wasted the time and effort on rebuilding an engine from the crank up or just throw that one in the junk pile and do a complete engine change?

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Please note the word "average". For every green pilot that cracked up a plane in it's first week on base another plane had to go 16 months to get an 8 month average.

British had overhaul facilities in several areas around the globe as did the US. There are pictures of a Merlin overhaul "facility" in caves near Cairo, Egypt. Units (squadrons) did not overhaul engines as a general practice, There may have been exceptions. Engine swaps were much more common but the engines swapped into the planes maybe from the factory or from an overhaul facility.

In North Africa the British broke down several hundred ( as many as 600?) Merlins in order to supply the US forces with parts for their Merlin powered P-40s. US planners had only acquired about 20% more engines than complete planes which was considered too low. Many planners thought there should be 50% more engines than complete aircraft.

I have checked a few figures and it appears in 1942 that Chevrolet in 1942 in addition to supplying 4058 R-1830s also supplied the equivalent of another 16% in spare parts and Studebaker was about the same percentage of parts over and above complete R-1820 engines. Allison was supply a much higher percentage of spare parts.

This sounds very funny. Since we build Allisons, we have the books and the records of overhaul ... and we talk with and sell to (mostly used to sell to these days) former WWII pilots who have Allison, Merlin, P&W, Wright, etc. - powered aircraft from WWII. For instance, we did the engines for Lefty Gardner and all the flying P-38's except the Red Bull unit.

According to our information, wartime TBO for the Allison was 250 - 400 hours depending on the dust conditions. Wartime TBO on Merlins was 200 - 300 hours depending on dust conditions. In typical wartime forward area airstrips, typical TBO was 250 hours for both.

Alllisons have cylinder liners that need no maintenance, but the Merlin needs the cylinders tightened up every 25 - 30 hours or so. Nothing tough about it but, if you DON'T do it, the Merlin will experience premature problems due to cylinder leakage. From the Merlins and Allison we operate today, both are very relaible and give plenty of warning when they are starting to want attention except in very unusualy circumstances.

I have had friends with P-51D Mustangs experience issues with a newly-overhauled Merlin at 40 hours ... and other friends who got 450 - 600 hours on them without a problem, but following recommended maintenance procedures and recommended operating procedures. We have some Allison customers with 1,200 hours on Allisons we have overhauled and most get 800+ hours on them if they take care of them and operate them properly. That is peacetime operation.

According to Lefty Gardner, Joe Foss, Bug Mahurin and others the Allisons, Merlins, Wrights, and P&W's were quite reliable and usually lasted to recommended TBO when maintained and operated properly. They almost never lasted LONGER than reconnended TBO because they were military and were taken out of service for overhaul when they reached TBO unless they were in a "squadron hack" in a combat zone.

Yes, you can kill a Merlin, Allison, or ANY big piston by not operting or maintaining it properly, and you can do it in less than 50 hours easily. I can kill an Allison in 20 minutes if I want to. When you give people aircraft and they operate them without training or even reading the book, I have no doubt the engines were a source of trouble.

At the Planes of Fame, we operate a Nakajima Sakae 21 engine in our A6M5 Model 52 Zero. It is the same engine the aircraft was captured with in 1944 and the same propeller. It was overhauled by Nakajima (now Fuji Heavy Industries) and we operate it per Nakajima recommendations. The people who had a Zero at the end of the war and never took the trouble to learn the book didn't have them long before they were unserviceable.

Engine reliability depends almost entirely on the use and maintenance of same. Dito the propellers and guns.

I flew radio control aircraft for about 18 years before stopping (would like to start again ...). Never had an enguine failure, but saw them regularly by people who didn't know how to run the 'engines. The worst thing I had happen was my tuned pipe fell off because I didn't tighten the bolts properly. I landed the plane (now a LOUD plane), retrieved the pipe, installed new bolts and flew it again within 10 minutes. Never happened again. It works for RC engines, too ... use and operate them correctly and you will have a good experience.

Treat them badly and you will be on the ground watching other people fly.

That is such a good post GP. What engines were designed such that they would have a shelf lif of 50 hours or less. the only types i could think of might be the cutting edge types, like the early jet engines. I would think that nearly all the WWII era internal combustion engines would represent evolutionary changes to existing proven technology. The chances of these engies having an inherent design fault that would reduce their service life to 50 hours or less seems very remote to me.

I believe that the Axis constructors began to suffer serious QA issues as they plunged closer and closer to defeat. The Germans themselves talk about these problems. Would it not be likley that given an engine that, as designed should have a service life of 250 hours, but with dodgy QA in the componentry, might not suffer a higher instance of early failure?

Thanks parsifal. You are right about early failures of Axis engines late in the war. Think Ta-152. They were all "prototypes" presed into service due to the wartime situation and never were more than about 25 flyable at one time. They didn't fly long and only two (Ta-152C's) were opertional when the war ended. But the engines might not have been the issue as much as lack of engine maintenance. We may never know. It wasn't the propellers or the airframe and I refuse to believe the Germans couldn't come up with a good radiator. That leaves the powerplant as the main culprit. I suspect maintenance since the Jumo 213 wasn't a bad engine, but DID require maintenace, just as our WWII engines do today.

I have a comment about Soviet engines. They had short TBO and still do. Part of the trouble was the way they were operated and maintained. I have seen film clips of Soviet crewmen filtering aviation gasoline through cotton just to get wood chips out of it! The Soviet gas was low octane for the most part, poorly filtered, and full of contaminants. The containters were not washed between uses and the maintenance was crude. Freezing arctic conditions certainly played a part in this, but maintenence practices practically determined the engine life.

If the Soviets got only 50 hours from an Allison or Merlin, then I have great respect for a Shvetsov radial that went 180 hours! Maybe they ain't so bad after all. If we ran them on good gasoline and maintained them properly, they might live quite well. I have several friends with Russian Yak-50 / 52's and they get VERY good lifetimes from their Vedeneyev M-14 radial, even though the TBO rating is short. I have one good friend who has been flying his for 14+ years and has had only minor issues that were easily fixed. Nice plane! I love it, at least.

One other observation. I have been a Planes of Fame volunteer since 2006. We have an annual airshow with an average of 30 WWII plane flying in it every year for two days straight (Saturday and Sunday), plus practice days before the airshow. Since 2006, in total, we have had 3 aborts. One was for an engine issue on a Tigercat. One was for a hydraulic failure of a wing fold hose on a Corsair. One was for a flat tire. Think about it. That's a total of about 30 aircaft runing from 1 to 5 flights a day for 2 - 3 days, or about an average of 1,800 flights with 3 aborts.

Not bad, huh?

Bad engine reliability? I don't think so.

The Jumo 213E's main culprit was the high alt supercharger stage, lack of strategic materials for this highly-stressed components led to many failures/non-functionality/power loss. At least this was reported during testing in late44/early 1945, I have no reliable info about what happened with them in later 45.

I believe strongly that the German engines were good engines ... but new planes have issues, almost without exception. Personally, I've seen many "first flights," and have never seen one without a squawk when the first flight was over. Ditto for the second flight. You are usually into the 4th or 5th flight before the plane is OK to fly again after s simple refueling, perhaps even farther into flying.

All the Ta-152's were essentially prototypes thrown together in desperation, and I have no doubt that with development, they would have been stellar contributors to the effort ... but never got the chance and were not produced in large enough numbers before the cessation of hostilities to do anything much for the war effort. There was also no pipeline of Ta-152 spare parts and service manuals. There was very little wrong with the Ta-152 ... but it WAS essentially a prototype pressed into service before it was ready for service as a result of the situation.

Wish we could restore and fly the one at the Smithsonian Museum.

I think the main issue affecting German reliability at the end of the war was the spiralling QA that was bound to lead to increased down times for the aircraft. everything was affected, not just aircraft. Thats not a poor reflection on German engineering, its just an acknowledgement that errors go up as the qulaity goes down, and quality was bound to go down as Germany spiralled out of control and into defeat.

Spiraling QA? Please explain.

Perhaps slave labor and the necessity to check EVERYTHING?

spiralling, as in descending uncontrollably

Slave labour would contribute to that. As would the undiscriminating draft that saw highly skilled workers in key industries drafted

there's been a distinct lack of Tante ju on this thread since it started, it'd be interesting to hear his thoughts on the subject now.

I predict he will corner one of us, probably the least well informed (that would be me), have a little rant, be extremely rude, deny everything and say while he posted good evidence, we have posted nothing and in particular say the RAF and CW contributed virtually nothing to the allied victory and then stomp off.

i hope he proves me wrong

parsifal said:

I predict he will corner one of us, probably the least well informed (that would be me), have a little rant, be extremely rude, deny everything and say while he posted good evidence, we have posted nothing and in particular say the RAF and CW contributed virtually nothing to the allied victory and then stomp off.

i hope he proves me wrong

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'Tis a pity that people get so wound up about events that happened 70 years ago- but then there are those who get wound up about events that may, or may not, have happened 3,000 years ago.

Now, where were we? Apparently the thesis behind this thread was the terrible record of Allied aero engine reliability which, according to Tante Ju, meant that the average life expectancy or TBO for all engines by 1945 was about 50-60 hours. The Merlin was cited as was the Griffon, Sabre and early Allisons ; funny thing is in Europe these engines (apart from the original Allison engined Mustangs) were using 100/150 grade fuel and high boost on operations and experiencing no problems with unreliability or low TBO:



Merlin 66: 9,268 hrs; over 6,000 hrs by two squadrons alone. (Tante Ju cites worn out Merlin 45s in Russian service.)
Griffon 65: 2,000 hrs; 610 Sqn 1,119 hrs. (Tante Ju cites 1 preliminary test and a post war test with no explanation given as to the circumstances behind the failures...)
Sabre: 2,300 hrs at +11 lbs; reducing to +9 without V-1 threat. (Tante Ju cites 1 test and Eric Brown's experience.)

The Allison V-1710-91, fitted in P-38Ls, was cleared to use the fuel after being run continuously at high boost for 7½ hours (generating 2,000 hp.)
http://www.wwiiaircraftperformance.org/p-38/Allison_V-1710-91_ENG-57-531-267.pdf

As was the R-2800:


(all WWII Aircraft Performance)

fantastic material, well done

Conflicting information it seems. Have to ask about the origin and autentizy of the three typed documents you presented Aozora?

69TA said:

Conflicting information it seems. Have to ask about the origin and autentizy of the three typed documents you presented Aozora?

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Have to ask?? From your other postings I see you have an attitude problem regarding source material that people have gone to the time, trouble and expense to search out and present on the internet so, no, I am not compelled to answer. Be satisfied that the material is genuine and leave it at that.

Wow. I asked a simple question and you talk about an attitude problem! Maybe you need to look at yourself for a while?

So, do I have to assume You made those piece of papers up or do you have some kind of "source"?

Just for interest, the modifications needed to allow engines to run on 150 grade:

http://www.spitfireperformance.com/JL165-Rolls-Royce.pdf

http://www.wwiiaircraftperformance.org/150grade/cross-channel-ops.jpg

http://www.wwiiaircraftperformance.org/150grade/cti-1659.pdf

and the problems which affected reliability of the V-1650 but not the R-2800-57s in P-47Ms:

http://www.wwiiaircraftperformance.org/150grade/atsce-28march45.pdf

Thankyou