True, but from the point of view of a classroom textbook, which you obviously know, these things don't count in affecting the efficiency of a gas turbine. the clue is in the word ancillaries...
Which country designed the best engines for WWII?
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True, but from the point of view of a classroom textbook, which you obviously know, these things don't count in affecting the efficiency of a gas turbine. the clue is in the word ancillaries...
MiTasol
2nd Lieutenant
I totally agree but if one wants to be pedantic the ancillaries, especially the fuel control unit, are more than somewhat necessary and essential for the engines operation and performance. Accessories like hydraulic pumps no. And the intake is a borderline ancillary as well. The exhaust however is very much an essential item and I am glad that Pratt always made totally interchangeable exhausts. Unlike Rolls on the Conway where I spent a long day as part of an engine change crew (plus welder) welding and trimming the mice in the exhaust until we got the correct static takeoff rpm.
As another aside, the original GAF Nomad had a bellmouth intake which is the most efficient at providing airflow into a compressor. That intake was replaced when operators, especially in high humidity climates like PNG, had engine failures on takeoff because the bellmouth is also the most efficient producer of intake icing. In one case both engines failed due to severe icing, still evident and photographed after someone got a camera, at (from memory) 28C in the Highlands. Using anti-icing at that temperature is not intuitive for pilots and it robbed the engine of 50 (out of 400) horsepower at sea level and a lot more, percentage wise on 10,000+ ft elevation runways.
As another aside, the original GAF Nomad had a bellmouth intake which is the most efficient at providing airflow into a compressor. That intake was replaced when operators, especially in high humidity climates like PNG, had engine failures on takeoff because the bellmouth is also the most efficient producer of intake icing. In one case both engines failed due to severe icing, still evident and photographed after someone got a camera, at (from memory) 28C in the Highlands. Using anti-icing at that temperature is not intuitive for pilots and it robbed the engine of 50 (out of 400) horsepower at sea level and a lot more, percentage wise on 10,000+ ft elevation runways.
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Admiral Beez
Captain
I visited the British Science Museum last week and was surprised by how compact British jet engines were compared to their long German competitors.
I wonder what aircraft the Germans could have designed had they had Britain's compact turbines.
wuzak
Captain
Compact in length, not in diameter.
Derwent I
Rolls-Royce Derwent - Wikipedia
Diameter: 43 in (1,092 mm)
Dry weight: 975 lb (442 kg)
Jumo 004B
Junkers Jumo 004 - Wikipedia
Diameter: 81 cm (32 in)
Dry weight: 719 kg (1,585 lb)
I don't think that the length of the jets was particularly a problem, but increase in diameter may have been.
Thumpalumpacus
Captain
Drag, drag, drag. With any early jet, you need to trim that any way you can.
Admiral Beez
Captain
I do wish Wikipedia would decided on the order of weights and measures. Sometimes it's metric first, sometimes it's imperial first. It's the same for ship displacement, sometimes it's tons, tonnes, short tons, long tons or even (for old ships) bm. And volume, sometimes US gallons first, sometimes litres, often with imperial gallons randomly thrown in the mix. For speed it's sometimes kph first, or mph, with knots thrown in somewhere. I'm fine with all the terms being used, but for comparison purposes why not decide on an order? I know, information online is often worth what you pay for it, and Wikipedia is anarchical by design, so I'm asking too much.
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Admiral Beez
Captain
I suppose, but I'd put a deHaviland Vampire (first flight 1943) and it's single fat engine up against a skinny-engined Heinkel He 162 (first flight 1944) and my guess is the Brit wins hands down.
swampyankee
Chief Master Sergeant
- 3,954
- Jun 25, 2013
Wetted area and separation. The engine, itself, is not a source of drag.
Also, early axial flow engines tended to have more stability problems with their compressors.
Jagdflieger
Senior Airman
- 580
- Mar 23, 2022
I don't think that comparison sticks - especially not with wooden stripped down "Notloesung" (temporary stop-gap) solution such as a He 162
I think that the most advanced German project, the Messerschmitt P 1101 together with the Me 262 helped the USA greatly into developing it's initial first grade jet-fighter the
Sabre F-86 in conjunction with the FJ-1 Fury and exploring towards swept wing geometry with the then later called X-5.
Having the latest German experience/scientific research and designs, coupled with reliable and more powerful jet-engines plus American ingenuity automatically had to produce
the best jet-fighter by 1948.
Regards
Jagdflieger
wuzak
Captain
I assume the original measure is first and the converted measure in parentheses.
Using the above data as an example, the British engine is imperial first, the German engine is metric first.
Thumpalumpacus
Captain
Not even the frontal area?
Maury Markowitz
Airman
- 22
- Sep 9, 2021
No need to speculate, the Heinkel He 178 was based around the HeS 3, and ended up being basically identical to the Gloster E.28/39.
The Germans stopped developing the centrifugal designs as their frontal area created more drag which was working against the entire concept of a high-speed powerplant. The axial design was also obviously easier to develop in a multi-stage fashion as the compressed air exited directly onto the next stage and didn't require the weird piping you can see in the Whittle designs - and von Ohain's as well.
Thumpalumpacus
Captain
What's the cD for those designs, if we're comparing?
Maury Markowitz
Airman
- 22
- Sep 9, 2021
The rule is to use the originally provided measurement and then put conversions in parens. This avoids a loss of accuracy if you "convert the wrong way".
They have introduced a new gizmo to allow you to reverse the order so you can give metric first even if the original was imperial, but this was relatively recent so few existing articles have been updated.
swampyankee
Chief Master Sergeant
- 3,954
- Jun 25, 2013
Not at speeds below about M=0.75
Thumpalumpacus
Captain
I didn't know that. Thanks, off to read a little.
GrauGeist
Generalfeldmarschall zur Luftschiff Abteilung
Hirth's HeS 08 and HeS 030 were not large engines, the latter being the same diameter as the 003 and 004, but shorter (and lighter) with a higher thrust to weight ratio.
If it weren't for the bickering and infighting, the 030 would have matured at about (or ahead) the same time as the 003 and 004.
It was sidelined by the magic unicorn HeS 011 project, which was too ambitious for the what was going in, war-wise.
The He280 performed very well with the HeS 08 engines, though it was intended to have the 030 - *if* (and this has been stated on many occasions) the RLM had taken the jet engine development seriously from the onset and insisted in it being a priority, then the HeS 08's bugs could have been addressed early on, the He280 could have entered production when intended and the HeS 011's development would have been ready for the 280's upgrade.
If it weren't for the bickering and infighting, the 030 would have matured at about (or ahead) the same time as the 003 and 004.
It was sidelined by the magic unicorn HeS 011 project, which was too ambitious for the what was going in, war-wise.
The He280 performed very well with the HeS 08 engines, though it was intended to have the 030 - *if* (and this has been stated on many occasions) the RLM had taken the jet engine development seriously from the onset and insisted in it being a priority, then the HeS 08's bugs could have been addressed early on, the He280 could have entered production when intended and the HeS 011's development would have been ready for the 280's upgrade.
SaparotRob
Unter Gemeine Geschwader Murmeltier XIII
Blame Thomas Jefferson. I think he wanted the U.S. to go metric but he didn't follow through.
How many corrections will I receive for this post?
tommayer
Airman
Rotary? Come on. No Mazdas or Clergets in WWII.Inline it has to be the Merlin.
Rotary its a toss up between Pratt Whitney and BMW.
I voted for the Poms because of the Merlin.
Peter Gunn
Master Sergeant
Metric Schmetric, I think however, it's safe to say we CAN blame the Declaration of Independence on him...
