PMN1
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Joined: Tue Jun 19, 2007 8:32 pm

Junkers EF100

Tue Jul 24, 2007 3:14 am

The Junkers EF100 was planned for post war use but would there have been the passenger capacity pre WW2?

http://www.luft46.com/junkers/juef100.html

http://www.geocities.com/hjunkers/ju_ef100_a1.htm

[Edited 2007-07-23 20:16:41]
 
CiC
Posts: 75
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RE: Junkers EF100

Fri Dec 14, 2012 7:36 pm

Meanwhile is a very good book in German available, the author has information from an Ex-Junkers-Engineer as source.

In my view the EF100 should have had in 1945 the same performance as the Lockheed L-1649A Starliner of 1955...
The original plan was a first flight in 1943 for the EF100, but then postponed to "after the war".
Performance: Up to 100 pax, up to 9.000kms range... even the B-377 and the L-1049 series/ DC-7 couldn't reach such performance... maybe the DC-7C, and only the big Lockheed...
The unique advantage of the EF100 were the 6x 2.500hp engines, operated with Diesel (!) and not 100/110 octane gasoline.

Something parallel with the Ju 252, only a few were built, but with better performance than the Convairliners...
 
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Aesma
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RE: Junkers EF100

Fri Dec 14, 2012 8:30 pm

Did the diesel aero engines of the time get significant usage showing good reliability (for the time) ?
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Jetlagged
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RE: Junkers EF100

Sat Dec 15, 2012 1:21 am

Quoting Aesma (Reply 2):
Did the diesel aero engines of the time get significant usage showing good reliability (for the time) ?

Reliable with very good fuel consumption. No need for high octane fuel either. Pre-war Junkers diesel aero-engines were two stroke and used horizontally opposed pistons (two crankshafts at either end of the cylinder bank, geared together) with no valves, just inlet and exhaust ports uncovered by the pistons. They were used successfully for long range applications where rapid acceleration wasn't required, flying boats and especially for airships due to the reduced fire risk of diesel oil.

http://en.wikipedia.org/wiki/Junkers_Jumo_205

http://www.enginehistory.org/Diesels/CH4.pdf

The Jumo 223 engines planned for the EF100 had four crankshafts geared together and four banks of cylinders in a rhomboid configuration.

http://en.wikipedia.org/wiki/Junkers_Jumo_223

[Edited 2012-12-14 17:25:14]
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prebennorholm
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RE: Junkers EF100

Sat Dec 15, 2012 4:00 am

Quoting CiC (Reply 1):
The unique advantage of the EF100 were the 6x 2.500hp engines, operated with Diesel (!) and not 100/110 octane gasoline.

Something parallel with the Ju 252, only a few were built, but with better performance than the Convairliners...

Reality is that only one single 24 cylinder Jumo 223 test engine was ever built. It is believed to have ended up in Russia in 1945.

Before the war, however, British Napier & Son got a licence to produce the much smaller 6 cylinders Jumo 204 engine. As the Napier Culverin it saw limited use on some military Blackburn and Fairey biplanes.

After the war they used that technology to develop the 18 cylinders Napier Deltic diesel engine. It used three crankshafts arranged in a triangle instead of the four crankshafts in diamond on the Jumo 223. It became rather successful in torpedo boats - was even sold to the German Navy. Maybe the most successful utilization of the Napier Deltic was in the British Rail Class 55 locomotive which pulled express trains for many years.

This Junkers invention of opposed piston two stroke diesel engines seemed so right for aviation. But it came to a dead end in the 70'es when the last Deltic engines in trains and ships were retired.
Always keep your number of landings equal to your number of take-offs
 
prebennorholm
Posts: 6447
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RE: Junkers EF100

Sun Dec 16, 2012 4:04 am

Quoting CiC (Reply 1):
The original plan was a first flight in 1943 for the EF100, but then postponed to "after the war".

Somehow it did in fact fly in 1943.

The Ju-390 maritime patrol aircraft was in fact a military version of the EF100. Only major difference was that the Ju-390 used six 1700 HP BMW 801 radial engines instead of the 2500 HP Jumo 223.

The number of Ju-390s, which has actually flown is believed to be two only, maybe only one. Some sourced claim a somewhat higher figure, but it is most likely that they count unfinished planes in 1944 when the program was cancelled. One plane was destroyed Dessau in February 1945 by US bombers. The fate of any other finished planes is unknown.

Quoting CiC (Reply 1):
Performance: Up to 100 pax, up to 9.000kms range... even the B-377 and the L-1049 series/ DC-7 couldn't reach such performance... maybe the DC-7C, and only the big Lockheed...

These estimates are based upon the assumption that the Jumo 223 engine would be successful and perform according to estimates.

Since the engine was never developed, then it all remains guesses.

Napier in Britain did spend a lot of resources on the concept, but with their Deltic engine they never came close to the (optimistic?) weight estimates made by Junkers. Consequently the Deltic designs never made it to become aircraft engines, but performed well on ships and trains.

Developing the Jumo 223 into an aircraft worthy product would have been a huge undertaking, which even in peacetime easily could have lasted so long time that turbine engines would have eliminated its relevance.
Always keep your number of landings equal to your number of take-offs

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