Diesel engine sounds?

[Drzook]

Hey all,
I just re-discovered Hauke Keitel's amazing Dornier Do-26. During the course of researching the aircraft I found that it is powered by four Junkers Jumo 205 Diesel engines. The plane's sound is aliased to the default DC-3. Now call me crazy but I am pretty well convinced that a Jumo 205 doesn't sound anything like a Pratt & Whitney Twin Wasp. Does anyone know of any aircraft diesel sounds? I would think this would help for some other diesel powered aircraft (Dornier Do-18, Blohm und Voss BV-222). Thanks in advance.

[fliger747]

Take your eyephone down to the local truck stop?

T

[Drzook]

If I had anything resembling talent in sound files I'd do something like that.
Looking at the stats on the Jumo 205, found some interesting things here: www.enginehistory.org/Diesels/CH4.pdf

• It's a Diesel engine (but we knew this already)
• It's a two-stroke diesel-no valves
• It has two pistons per cylinder and two crankshafts connected by gears
• It is started by a Coffman-style cartridge system

Based on that so far the best sound-alike would be the Napier Sabre-like the Jumo it has more pistons than one would think and has several crankshafts that are connected by gears. IIRC it also seems to have that 'marbles-in-a-can' sound. We'll see what happens

[robert41]

The engines in trucks are mostly 6 cyl 4 cycle's. The Jumo 205 was a 2 cycle. Could not find any sounds for the 205 after a quick search. But maybe could use the sounds from the Detroit 2 cycle diesels?

[Drzook]

It's a thought. Unfortunately I have no clue how to turn sound files into FS sound files. I did have a revelation/weak rationalization about using the Napier as a stand-in however:
Napier Sabre: 24 cylinder four stroke
Jumo 205: 6 cylinder 12 piston two stroke
A two stroke engine gets a power stroke every revolution as opposed to the four stroke getting one every other revolution. A Sabre and a Jumo running at the same rpm would theoretically be getting the same number of explosions if you consider the explosion in a jumo's cylinder counts as two explosions due to it pushing two pistons.
I just listened to a Detroit two stroke in a grader (http://www.youtube.com/watch?v=pDepeBOSGng). Sounds fast but it was actually turning a relatively slow rpm. It was only sounding like high rpms due to the nature of a two stroke engine getting combustion/power every revolution.
Granted, a Napier Sabre puts out a LOT more horsepower. It's also a bigger engine though. I found Lawdog's Napier sound and will modify the sound.cfg file for four engines and see what happens.

[Maarten -]

I'm not what one would call an expert when it comes to diesel engines, but have a look at and listen to some of these videos on youtube. My search was "Junkers Jumo 205".
http://www.youtube.com/results?searc...umo+205&page=1
Maybe it puts you into the right direction.

Cheers,
Maarten

[Willy]

Fairbanks-Morse also makes an opposed piston 2 stroke diesel. Most of those that I've seen are 12 cylinders and would fill your living room. The US Navy seems to really like the F-M engines as they buy a lot of them.

[fliger747]

The USN subsidized the Deiselization of the US Railroads in the 30's just to develop a reliable Sub Diesel. In practice this was amazing forethought, ours were far better than the MAN (Machinefabric Augsburg Nuremburg) ones that the Germans used and we tried not too sucessfully in a pre war class.

Anyone know what the RPM of the Jumo's was? Typically diesels run a bit slower with more toprque (given the compression ratio).

T

[srgalahad]

Anyone know what the RPM of the Jumo's was? Typically diesels run a bit slower with more toprque (given the compression ratio).

T

According to the same ref. DrZook quoted above, http://enginehistory.org/Diesels/CH4.pdf
A Power/fuel graph is supplied

PERFORMANCE STATISTICS
The Jumo 205-C Diesel which was used extensively in1936 and 1937, was rated at 600 h.p. at 2,200 r.p.m.and cruised at 510 h.p. at 2,100 r.p.m. Since then its

power output has been raised by increasing its r.p.m., until nowthe Jumo 205-E model is rated at 700 h.p. at 2,600 r.p.m. The Jumo 205-D, which is a military engine, develops a maximum output of 880 h.p. at 3,000 r.p.m. The specific fuelconsumption of these three engines is approximately the same, namely, 0.35 lb. per h.p. per hour at cruising speed and 0.37 lb. per h.p. per hour at full load (Fig. 46). These performances are obtained without a supercharger. When the engine is supercharged with an exhaust-driven supercharger the gear-driven blower is retained for starting purposes. The Jumo 207, as the engine then is known, develops 1,000 h.p. for take-off and maintains this output at an altitude of 20,000 feet

[Volker Böhme]

Hi,

the Chieftain tank had an opposed-piston engine as well, maybe youtube footage will have sound of the engine running with the tank stationary. When moving, it would sound quite different, though.

Back to aero engines: The Jumo 205 had been quite successful with long-range aircraft, but was a failure for military models. With frequent power changes neccesary, formation flying, for example, it would not be as reliable as required. One of the problems of opposed-piston designs is to get the power from to crankshafts on a single driveshaft again - the same also applies to other engine designs that more or less bolt two independent engines together. Junkers designed the engine to have one crankshaft drive the propeller and the other one to drive all the accesories first and only add the surplus power to the first crankshaft, made the transfer of load much less failure-prone.

Best regards,
Volker

[stansdds]

Detroit Diesel Series 71 and Series 92 are two-stroke engines and are commonly found in trucks and buses.

[Drzook]

I discovered some interesting facts about the Do-26 today. The fuel capacity was 7300 liters of diesel. The range with full fuel (and nearly nothing else) was 9000 km. At cruise speed of 290 km/h this works out to an endurance of 31.1 hours with an average fuel burn of 62.12 gph. When one figures this is spread out over four diesels this works out to 15.53gph/engine. That's about the same fuel burn as a Continental O-520 at cruise on a Cessna 182.:isadizzy:
(in my best Keanu voice...WHOA)

[stansdds]

Diesel engines can be very fuel efficient.