Western engine reliability

[Aozora]

Soviet pilot here says for example.
Interview with Vladimir Mukhmediarov

'I finished the war on Yak-9U with M-107 engine. Its engine life was 50 hours only. There also were a lot of accidents with this airplane. At high power connecting rods would break.'

So explain me please how 50 hours from Merlin 46 engine is different from 50 hours from M 107 engine. Operated by same skilled mechanics, using same oil, under same conditions.

You have no idea of the condition, the relative skills of the mechanics, or what type of oil or fuel was being fed to the Merlins; also you seem to be forgetting, there were no servicing manuals for the Spitfires or their engines...

Plus you obviously haven't read your own extracts so let me refresh your memory...

According to the account of Nikolay Isaenko, having begun to fight in August 1943 in equipment that had been worn in the process of training and ferrying, the 821st IAP entered combat work with already "problem" engines.

Taking into account that the fighter was an imported item, which began to experience shortages of spare parts for various assemblies from the beginning of use and especially of combat work, it was unavoidable that these shortages would have an impact on the material condition of the aircraft. Spare parts were in short supply for the Merlin, for the Rotol propellers, for coolant and oil radiators, wheels, and instruments.

Also noted you haven't mentioned the fact that another Soviet pilot thought the reliability of the Merlins in the Hurricane was okay.

A. S. What about the English engine, they say it was unreliable?

N. G. It was a good engine, powerful and sufficiently reliable. The engine worked very clean. It had exhaust stacks and flame suppressors, mounted like mufflers. This was very helpful because it prevented the pilot from being blinded. In this regard our own aircraft were significantly deficient.

This was the more complex Merlin XX with a two-speed supercharger.

Serious engine troubles during testing with high power - shown. An example of Griffon 65 engine lasting between 40-60 hours post war was shown. If you have other practical figures for Griffon engine - show. We all learn...

So, let's have a look at that extract from a Canadian report shall we? First engine 5672/590356 removed due to rough running and vibration, no cause shown, so that proves nothing - it was not engine failure: note: Carburettor serial No. RGA 194

Next engine 1752/334548 installed - Carburettor serial No. RGA 231. engine failed, cause noted in Sec. 201 - not shown by Tante Ju. Why did that engine fail? Was it related to damage caused by the vibrations from the propeller removed during the first stages? Do you have Sec. 201? Show us so we can all learn.

First engine 5672/590356 reinstalled with same carburettor as second, serial No. RGA 231, indicating first problems were carby related, not engine. Test session ended.
Some questions, to put this extract from a report, and the report itself, into context:
*What was the purpose of the tests? Was it the engines being tested or the airframe?
*What mark of Griffon was being tested?
*What were the concluding remarks of the test? I have to assume that if the conclusion stated that the Griffon was unreliable and showing a tendency to fail at low hours that conclusion would have been added to this thread.

Without knowing what the tests were for and what the concluding remarks were, plus the comment on the total engine failure there is no context, therefore using this to prove poor reliability is a waste of time.

As for this:

4.3 Spitfire XIV (Griffon 65)
Spitfire R.B.176, as received from Squadron, was operating at +19 lb./sq.in. boost and 2,750 r.p.m. (Griffon 65; 5-bladed Rotol propeller). It had a circular external rear view mirror with hemispherical fairing; no ice-guard on the air intake; a whip type aerial behind the hood; a radio mast projecting from the lower surface of the wing forward of the starboard aileron; another mast set in a fairing under the fuselage; small type bulges over the 20 m.m. cannon and the cannon stubs faired; the machine gun ports in the leading edge sealed. The 30 gal. auxiliary fuel tank (slipper type) was removed for the purpose of the tests.
The paintwork was in poor condition. Parts of the leading edge and inboard surfaces of the wings were very badly chipped and scored. The leading edge was stripped of paint and repainted. The rest of the aircraft was rubbed down only.
The engine was then modified to give +25 lb./sq.in. boost and one flight was made. Only two level speed measurements were obtained, as the engine became suddenly rough after about two minutes of the high boost on each level. Subsequent inspection showed that a blow back had occurred, damaging the air intake. The reduction gear was also found to be cracked and no further tests could be made with this engine.

*How many hours did the Griffon have on it before being tested at the RAE? Doesn't say.
*How often had it been put under strain possibly chasing V-1s? No mention of the engine's service life.
*Paintwork in poor condition meaning this aircraft had seen considerable service and possibly been through some debris from V-1s?
Engine blowing back "popping" into air intake? Several possible causes, not all directly engine related see below:

Engines vibrating or not delivering power:

From:

Also reports made by Allies themselves differ of your opinion.

And, clearly, from yours, http://www.ww2aircraft.net/forum/av...4-vs-la-7-vs-yak-3-a-13197-26.html#post975423

Last paragraph is interesting as it cites practical TBO 100 to 180 hours of life with 150 grade fuel (1.5 TEL) before completely destroying valves and requiring engine change.

And far higher than the 50 hours you assert here...http://www.ww2aircraft.net/forum/av...4-vs-la-7-vs-yak-3-a-13197-26.html#post975423

Not forgetting that is at high boost pressures using 150 grade fuel.

Soviet Merlin 46s were not worn out. They did not last more than about 50 hours - yes this 50 hours includes familiarisation, as usual.

So prove it, show us all solid documented evidence that this was so, apart from your opinion.

Two Squadrons contain about 45-50 aircraft in British practice. 6000 / 50 = 120 hours per plane. What is not known - how many engine changes in meantime?
610 Sqn 1,119 hrs Griffon 65 - about 46 hour per plane in avarage (note post war trial Griffon 65 lasts about this long before engine change is needed...). How many engine changes in meantime?

Had there been problems leading to a higher than average incidence of engine failure that would surely have been mentioned. The report doesn't mention a high incidence of engine changes.

 

[Aozora]

BTW Merlin also had 'awful lot of trouble' completing 100 hour tests on bench. Well known from history.

Well then, provide some evidence that this blanket assertion applies to all Merlins, and not just the early developmental prototypes.

I am curious how long Sabre lasted. I think 40 would be very generous assumption, given plague history of engine.

Up to you to prove - there's no doubt Sabres were thoroughly unreliable until Bristol stepped in and helped Napier with the sleeve valves, after which there were no major problems.

 

[DerAdlerIstGelandet]

Not long on this forum, but I have experienced other forums where threads got nasty once people started the "you tell us the provenance of that document or else" crap, plus I have had a look around here and, while finding found the likes of this thread , my overall impression is that good faith over posted documents etc is expected - or am I mistaken? And, no I have never been banned from any forum - like parsifal I loath wasting my precious leisure time on stupid, pointless arguments: that said I also value the right to take the time and trouble to post relevant material without having someone else demanding that I prove their authenticity and provenance - As it is please note I usually post my sources.

You'll have also probably noticed that us "Colonials" (from OZ and NZ) can be blunt and direct - that's just the way we are.

You also will have possibly noticed that we Mods are getting sick and tired of all the stupid bickering by people that want to do "He said, she said BS" internet fights and arguments.

Instead of calling people out, let us Mods do our job. If you have a problem with someone, instead of stoking the fire, let us know, and we will assess it and handle it.

One can debate with pointless name calling and rudeness, and instigating fights. Even if you think that something is pointless. I am not taking sides, I don't care if you are like parsifal or not. Parsifal knows that I have nothing but respect for him, and that we actually see eye to eye on most topics. I have defended him and taken his side enough for him to know this, but that does not mean I am not sick and tired of it.

So don't start doing it as well.

Is that okay?

 

[Shortround6]

Actually the Sabre was a troublesome engine until almost the end of the war (if not forever?).

Fair is fair.

Little has been said about the Hercules though. Not sure how the war time models were but the post war versions certainly racked up some impressive TBOs.

 

[GregP]

Hi Tante Ju,

We have a museum flying event on the first Saturday of every month. We have had these events for 40+ years. Since MOST of our aircraft are fighters, the vast majority of our events are about fighters, with appropriate speakers. We fly American, British, Russian, and Japanese engines, with the occasional French engine thrown in (we even have an Antonov AN-2). We fly Allison V-1710's, Merlins, R-1820's, R-1830's, R-2600's, R-2800's, a Nakajima Sakae 21, the Bristol Centaurus, the GE-IA, the GE-I16, the J33 and several others up to and including the J-47, together with a few smaller engines.

The fighter pilots who give talks on a very ragular basis tell us of their experiences with the fighters. They don't spend a lot of time on conditions since most of the visitors attending these events aren't really interesed in conditions ... they want combat stories. Almost none of the pilots who have spoken over the years had bad things to say about the engines or aircraft. Most of the sudden stoppages were due to combat damage.

So, a relatively large cross section of WWII pilots who flew combat LIKE the Allison, the Merlin, the DB 601/3/5, and the various radials. The Japanese pilots liked their radials, but not their inlines. The Germans liked their engines, too, both radial (BMW 801's, etc) and inline (DB 601/3/5 and Jumos). The conditions on the Russian Front are responsible for the lousy engine life in Russia. They didn't experience that elsewhere except in very dusty conditions (think Malta and Coral dust in an aircraft not running an air cleaner at all).

While all these engines don't require excessive maintenance, they DO require maintenance. Ask FlyboyJ or DerAdlerIstGelandet (how the hell do you pronounce that?). They know. If you don't DO it, they will probably all fail at about 40 - 80 hours. You have to do the maintenance to keep them running well. Our own Allison V-1710's with 1,200 hours on them would never make it that far without normal maintenance. You have to change oil, oil and fuel filters, plugs, set valves, torque cylinders on the Merlins, and a host of other small but vital maintenence actions. I am working right now at changing the lower oil lines on a P-47's R-2800. They haven't failed but are due to be changed. If you don't, and if they then fail, the fault is YOURS, not the engine's.

Sorry, the Allisons and Merlins that died at 50 hours were killed by unskilled users and maintainers; they weren't bad engines. Ditto for DB, BMW, Nakajima, Mitsubishi, Alfa Romeo, Junkers, etc.

I hate to make the obvious point, but bad engines usually never made it into production due to their excessive failure rate. The exception was the R-3350, which was awful when introduced, but turned into the most reliable big radial ever after the war due to developed operating and maintenance procedures.

 

[wuzak]

DerAdlerIstGelandet (how the hell do you pronounce that?).

Boss.....

I hate to make the obvious point, but bad engines usually never made it into production due to their excessive failure rate. The exception was the R-3350, which was awful when introduced, but turned into the most reliable big radial ever after the war due to developed operating and maintenance procedures.

Vulture. Sabre. Db 606 (or was that more specific to the installation in the He 177?).

 

[Aozora]

Vulture. Sabre. Db 606 (or was that more specific to the installation in the He 177?).

I don't know if I'd quite lump the Sabre in with the Vulture or DB 606/610, considering the numbers of Typhoon and Tempest pilots who put their lives on the line behind the beast. That said they did initially have a very short service life:

The Vulture had inherent design flaws, in particular the star-shaped conrod assemblies, and the use of which Rolls-Royce weren't able to deal with until too late:

The revised design, too late:

(Robert Kirby; Avro Manchester: The Legend Behind the Lancaster. Midland, 1995 83-84, 103-104) Avro Manchester: The Legend Behind the Lancaster: Amazon.co.uk: Robert Kirby: Books (excellent book

 

[wuzak]

I don't know if I'd quite lump the Sabre in with the Vulture or DB 606/610, considering the numbers of Typhoon and Tempest pilots who put their lives on the line behind the beast.

I would, in that the Sabre was in production before it was quite ready.

 

[Aozora]

I would, in that the Sabre was in production before it was quite ready.

Definitely from that perspective - an average life of 25 hours was lamentable.

 

[Marcel]

Sorry, the Allisons and Merlins that died at 50 hours were killed by unskilled users and maintainers; they weren't bad engines. Ditto for DB, BMW, Nakajima, Mitsubishi, Alfa Romeo, Junkers, etc.

Not knowing enough to participate in this technical discussion, I still might make an observation? Seem to me when reading Tante Ju's comments that he is actually not claiming that these were bad engines, although the title of the thread suggests otherwise? His claim seems to me that the Russian engines were not so bad as everyone thinks. The short lifespan of these engines seem to be caused by the conditions and lack of maintenance in Russia. And he tries to prove that by showing that, western engines did not do better under the same conditions. I think you all agree that the maintenance in Russia left a lot to be desired. in this case comparing western engines under western conditions and Russian engines under Russian conditions seems to be non-informative in my eyes. So I'm wondering what the heated discussion is all about.

But I'm not a native English speaker and I usually miss the subtilities in the language. And I also have not followed the discussion that triggered this thread. So I might have understood it wrongly.

 

[meatloaf109]

DerAdlerIstGelandet (how the hell do you pronounce that?).

The Eagle Has Landed in english. But to be on the safe side call him "Sir". Same with FLYBOYJ.

 

[Denniss]

DB 606/610 were not unreliable but the engine installation in the He 177 led to many problems - maintenance was a nightmare. Due to tight installation the mechanics could not access all vital parts without a heavy crane to dismount the engine.

 

[parsifal]

Tante I want to congratulate you on your excellent response. Well done. You proved me wrong, and Im happy.

Thats the good news. The bad news is that I still am not convinced. Others have taken you to task on that. You dont need me to spoil your day.

 

[tomo pauk]

I must thank to Aozora in providing the excerpts.

Agreed with Dennis, at least DB-610 developed no known issues/problems.

 

[Shortround6]

We maybe having language problems. I speak only English (and maybe not to well at that so I am not sure how well somethings translate.

When dealing with engines were have two characteristics we are dealing with.

Durability

Reliability

Durability is how long the engine (or major parts of it) will last.

Reliability is how likely the engine is to complete a given mission or, upon being called to start-up, can under take a mission on a given day.

For instance the DB 610 may have just as durable as the DB 605 but it's reliability would be lower, in part just because you have twice as many parts, in part because servicing is harder, in part because heat in the installation may affect smaller accessory parts.

Many engines had problems with magnetos, carburetors, pumps and other bits and pieces stuck on the out side that affected over all reliability.

Some other engines were known for putting rods through the side of the block or having the gear case fail and loosing their propellers well before their rated service life was up. One might say that in those cases durability did affect reliability

One also has to be careful in using some of those General over haul charts. To take the Allison engine, which was pretty well built chunk of engine overall( and it did change quite a bit over the years). In Europe and the MTO in US service it was used in 3 aircraft, the P-40, the P-39, and the P-38. The First wide spread combat use was in North Africa with the "F" series engines. Lots of sand and dirt, How much over boosting on the P-40s. P-38s had [/I] reliability problems due to the turbo installation AND had durability problems due to the turbo. Wartime pilots (in many air forces) didn't really understand how their engines worked. They were told (instructed) to do such and such and they did it. P-38 pilots for a long time were being "instructed" to fly (cruise) a certain way which was against the recommendations of both Allison and Lockheed. They were being instructed to fly/cruise at high rpm and low boost. Which is sort of like driving a 4 speed car in 3rd gear on the highway. It will do it, it will do it for hours or thousands of miles but it uses more fuel and will wear out the engine quicker. You also have a strange fact with the P-38s, If the pilots abuse an engine in a P-40 and blow it up they usually don't get back to base to have the engine replace/sent for overhaul. P-38s could blow up one engine and bring it back so it showed up in the statistics.

The overhaul statistics are good information but they show the engines that made it to the overhaul facilities. They may or may not give the reasons for the engine going to the overhaul facility. In the case of the Merlins and R-R it was the average of ALL engines going threw the repair organization which includes battle damage and crash damage (prop strikes). If you get in one engine with 10 hours and a prop strike and one engine with 300 hours and just worn out/hit service life limit you have a 155 hour average. Rolls-Royce and the repair organization had had worked out a particular repair for Merlins that had cracked the main gear case due to a prop strike or crash. The cracks were welded and a steel strut was added that ran from the top rear of the gear case on an angle down and back to the crankcase (not cylinder blocks). Since the engine had to be torn down for inspection it only made sense to do the small amount of extra work to do a complete overhaul.
Engines could be sent for overhaul for a variety of reasons. Low oil pressure (which changing the pump/s doesn't cure), metal showing up in the oil filters/strainers are two main ones. Some engines didn't tolerate over revving very well. "Power" diving had the potential to wreck engines. The Merlin was rated at 3600rpm in a dive but at part throttle (1/3 or 1/4?). Using large throttle openings while diving could wreck the engine. A malfunctioning propeller could also affect the life of the engine. Some propellers didn't change pitch when they were supposed to (or did after a delay) and allowed the engine to over rev.
Some of the difference between bomber and fighter engines may be due to factors like these. While bomber engines didn't have to put up with over boost much or lots of large throttle changes, they often had to put out full take-off power for 4-5 minutes to get off the ground and get the gear up followed by 20-30 minutes at max climb power to reach altitude. Fighters, unless carrying large external stores, could often throttle back a bit sooner.

 

[DerAdlerIstGelandet]

The Eagle Has Landed in english. But to be on the safe side call him "Sir". Same with FLYBOYJ.

Not necessary. Don't say such things, some might believe you.

Tante I want to congratulate you on your excellent response. Well done. You proved me wrong, and Im happy.

Thats the good news. The bad news is that I still am not convinced. Others have taken you to task on that. You dont need me to spoil your day.

And you keep picking...

 

[GregP]

Some great replies in there since my last post.

Marcel, I believe the Soviet engines WERE pretty good, expecially considering the conditions and skill of the maintainers and pilots using them. I have many stories of how they were able to operate, including building a fire under the engine after the gas and oil had been drained to keep it warm! ... and in a wooden aircraft! As I said some time before, I have several friends with Vedeneyev M-14 radials that absolutrly love them ... and they seem to last very well. Your remarks are interesting and give pause for thought.

Same for Shortround's excellent post. Relaibility and durability ARE two different things, and many people never realize it.

I am well aware of the Sabre's shortcomings and the same for some of the German experiments, but I didn't bring them up since I already had an example. I believe that there were never very many He 177's built (600 total before they realized it was a turkey?) compared with 10,000 - 20,000 of other, better designes and over 30,000 Me / Bf 109's. Still, I will admit that definitely qualifies as production of a powerplant that was hopeless. And they DID finally "fix" the Sabre. If there was one around today, I'd probably not opt to fly it if the opportunity became available simply because I'd have no way of knowing if was one of the "fixed" units or not. The knowledge has withered away on the Sabre to the point where, world-wide, I am not aware of one that is runnable. Perhaps there IS one or even several, but they aren't exactly wide-spread and I don't know of a shop that claims to be able to overhaul one.

One the other hand, we regularly fly the Merlins, Allisons, various radials, and there are enough DB 601/3/5's around that they CAN be overhauled and made to run. Finding a VDM propeller is another story ...

So, I suppose my point is that the reliable and durable engines survive to be flown today, and some of these were being touted as 50-hour engines. I beg to differ on that score, not entirely (there well might have been 50-hour Allisons and Merlins, but not many) but as a general statement. The discussion is very interesting with good information being exchanged.

 

[meatloaf109]

Not necessary. Don't say such things, some might believe you.

Yes, Sir!

 

[Juha]

Not knowing enough to participate in this technical discussion, I still might make an observation? Seem to me when reading Tante Ju's comments that he is actually not claiming that these were bad engines, although the title of the thread suggests otherwise? His claim seems to me that the Russian engines were not so bad as everyone thinks. The short lifespan of these engines seem to be caused by the conditions and lack of maintenance in Russia. And he tries to prove that by showing that, western engines did not do better under the same conditions. I think you all agree that the maintenance in Russia left a lot to be desired. in this case comparing western engines under western conditions and Russian engines under Russian conditions seems to be non-informative in my eyes. So I'm wondering what the heated discussion is all about.

But I'm not a native English speaker and I usually miss the subtilities in the language. And I also have not followed the discussion that triggered this thread. So I might have understood it wrongly.

I frankly doubt that, if one wants to make a reasonable comparison between the reliability of Soviet and Western aeroengines, IMHO right way would be compare e.g M-105 series engines to DB 601/605 series and RR Merlins, all main V-12 inline engines of respective nations. Compare M-107 known to have been problematic and Merlins which were maintaned by mechanics who didn't have access to manuals and not even had somebody who had previous knowledge of the engine to give advise. And that in a regiments which previous a/c had been powered by an aircooled radial. And then draw a sweeping conclusion on average reliability of Merlin in front-line use from that.

 

[Juha]

IMHO Sabre was reasonable reliable engine once Bristol was persuaded to help Napier with sleeve valves and Napier was put under control of the EE Group and AM finally was ready to accept paper gaskets.

Juha