Me 262 deutsch marine prototype

[FLYBOYJ]

It seems there were 3 Mk1 Meteor crashes in August of 1944, all within a 2 week period and at least one facility. There is also evidence that one of the V-1 kills occured when one of the Meterors were on some type of functional check flight possibly after an engine change. I found this interesting article about the only surviving Welland engine...

Rolls-Royce Welland (merlinv12site)

A second visit to the National Archive in Kew brought to light significant further information about the engine including an amazing photograph and periodic maintenance instructions especially prepared for engine No 183. These data, with much else, were found in a file containing exchanges of correspondence between the Ministry of Aircraft Production and the Canadian Cold Weather Test Station. where engine 183 was sent in January 1944. Shortly after the engine had arrived in Canada when it had only had a few hours running, and before serious testing had begun, the rear main bearing collapsed. There then followed a stream of secret correspondence between the UK and Canada on the possible causes of the collapse and how to proceed. The amazing photograph referred to is a picture of the remains of the collapsed bearing. It is extraordinary that such an apparently insignificant picture should have been preserved for over sixty years, but then the National Archive is itself an extraordinary asset freely available to anyone. The decision was taken that the engine could re rebuilt in Canada and the necessary spare parts were dispatched and the task completed by April 1944, unfortunately too late for any further testing as the winter had passed. The failed ball bearing was replaced by a roller bearing, other similar bearings having failed in two other early pre production engines during flight trials in October 1943. It would appear that by the time that cold weather trials could recommence during the winter of 1944/45 that trials of the Derwent I engine were given priority and the trials planned for the Welland discarded and the engine returned to Britain.

The Article sates that the rear bearing on this engine failed after 50 since new!

 

[Waynos]

FBJ, It is not in doubt that the Derwent was more reliable than the Welland, or that it was more powerful, and the piece you posted above is quite explicit as to what happened to that engine.

But I hope you can see that none of that shows the Welland in general only had a service life of about 25hrs, or about the same as the German engines of 44-45, which is what prompted this line of discussion.

I have already admitted that I cannot prove you wrong, but neither do I feel that you have proven your case either.

I am left to wonder then, why it is that the engine life of the Jumo's from 1944-45 is so frequently commented on, and yet the life of the British engines is never mentioned, not ever? This alone, while also not conclusive, at least points to the fact that the German engines were considered, even then, abnormally short lived by comparison doesn't it?

 

[parsifal]

Hi Waynos

IMO it sugests it, but it is not conclusive at all. Whats needed is an engineering assessment of the two engine designs that can conclusively point to some inherent design fault or other weakness. Some discussion has already taken place about the shortages of strategic materials for the germans, which seems logical enough, though I have some thoughts about those shortages. Its hard to believe that the Germans lacked enough reserves to produce proper turbine blades, or proper bearings or any of the other specialised components that make up an engine. Perhaps their use of forced labour, their profligate misuse of skilled tradesmen (drafted into the army at wars end, their steadily dropping QA at the end of the war has something to do with the issue?

 

[FLYBOYJ]

FBJ, It is not in doubt that the Derwent was more reliable than the Welland, or that it was more powerful, and the piece you posted above is quite explicit as to what happened to that engine.

But I hope you can see that none of that shows the Welland in general only had a service life of about 25hrs, or about the same as the German engines of 44-45, which is what prompted this line of discussion.

The 25 hour service life is not a broad brush - my point is that the early engines were not consistent in meeting their advertised service life. Some of the Wellands "might" have made 160 hours, others may have failed in 25, in fact the example I've shown shows at least one engine to fail with under an hour on it.

I have already admitted that I cannot prove you wrong, but neither do I feel that you have proven your case either.

Actually I have - the example above plus the fact you have failures in the field show that the Welland was inconsistent in meeting its advertised TBO time.

I am left to wonder then, why it is that the engine life of the Jumo's from 1944-45 is so frequently commented on, and yet the life of the British engines is never mentioned, not ever? This alone, while also not conclusive, at least points to the fact that the German engines were considered, even then, abnormally short lived by comparison doesn't it?

It does - but at the same time it seems there was little operational records kept from 616 squadron with regards to MC rates and engine reliability. I believe there was a lot of publicity and propaganda needed to show that the allies had an operational jet aircrat in the ETO any any negative press was kept to a minimum, but that my opinion only.

Hi Waynos

IMO it sugests it, but it is not conclusive at all. Whats needed is an engineering assessment of the two engine designs that can conclusively point to some inherent design fault or other weakness. Some discussion has already taken place about the shortages of strategic materials for the germans, which seems logical enough, though I have some thoughts about those shortages. Its hard to believe that the Germans lacked enough reserves to produce proper turbine blades, or proper bearings or any of the other specialised components that make up an engine. Perhaps their use of forced labour, their profligate misuse of skilled tradesmen (drafted into the army at wars end, their steadily dropping QA at the end of the war has something to do with the issue?

Well lets see - you have one proven failure of a unit with under an hour's operating time on it. 3 aircraft lost in the field, all within 2 weeks, at least one record of a flight for an "engine checkout," only 167 wellands built for the support of 12 aircraft that of which 3 were lost in the field due to non-combat operations and the remaining removed from service within 6 months. At the same time across the pond you had one highly publicised failure of a P-80 powered I-40 in which Tony LeVier almost lost his life. That engine had under 10 hours on it.

The point here is that although Rolls Royce attached the 180 hour TBO to the Welland, that was not a guaranteed number and failures could have at any time. Although there is no question that when compared to the reliability of the Jumo, these early engines were more reliable, the fact that you had these failures prove (plus the fact that the engine was quickly replaced) the reliability of the Welland is definitely questionable and to say that it had a 180 hour TBO was a crapshoot at best.

 

[mikewint]

it seems to me that any population will distribute itself in a Gaussian distribution or "bell" curve. the 180 was probably the upper end of that curve. the jumos suffered from a lack of metallurgy just like their cannon barrels when the germans ran out of molybdenum or the quality of plate armour in their tanks.
technology is a wonderful and marvelous thing but while you're trying to boot your battle computer charlie runs up and hits you on the head with a rock. i am a firm believer in the KISS principle

 

[FLYBOYJ]

it seems to me that any population will distribute itself in a Gaussian distribution or "bell" curve. the 180 was probably the upper end of that curve. the jumos suffered from a lack of metallurgy just like their cannon barrels when the germans ran out of molybdenum or the quality of plate armour in their tanks.
technology is a wonderful and marvelous thing but while you're trying to boot your battle computer charlie runs up and hits you on the head with a rock. i am a firm believer in the KISS principle

Actually Gaussian Distribution is used in engine trend monitoring in today's world. Point made earlier is early jet engines couldn't establish effecting trending because an accurate baseline couldn't be established because although manufacturer's gave TBO times, in actuality there were failures at sporatic times in service. The 180 hour TBO on the Welland was probably established based on engine test cell data. Had the engine performed in service the TBO would have been extended, but in the situation of the Welland, it wasn't - the engine was eventually removed from service.

Food for thought.

 

[mikewint]

FBJ, yes, i did indeed neglect the sample/population size. with such a limited production and experience it's still a trial and error approach and prototypes are not production models though again with limited number they're not far removed from prototype.
and going back to the 262 add in a goodly measure of desperation and lack of alternatives.
my biggest problem with designers was the quantifying of risk. i do understand risk is inherent and in some cases unpredictable but some of the dumb designs border on ridiculous.