We have three Land Rovers and I only buy my parts from the UK, I recently got new front carpets for one of our Defenders and they arrived in 6 days from the UK and including postage were half the price quoted here in Australia. I am on the West coast of Oz, I can get parts from Europe quicker and cheaper than from the East coast of Oz.
Jumo inverted vee's vs. Daimler-Benz inverted vee's - Pros and Cons
- Thread starter bdefen
- Start date
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We have three Land Rovers and I only buy my parts from the UK, I recently got new front carpets for one of our Defenders and they arrived in 6 days from the UK and including postage were half the price quoted here in Australia. I am on the West coast of Oz, I can get parts from Europe quicker and cheaper than from the East coast of Oz.
MiTasol
1st Lieutenant
And worse still if you buy headlight protectors for the LR Discovery in Aus the cheapest I could find were AU$360+.
In the UK they cost me AU$56 plus under AU$30 postage. The box clearly says "Made in Australia". A hand brake part cost $258 in Aus and UKP13.66 (under $25) in the UK.
The worst I know of in Aus is Microsoft Aus. For one software package the boss sent our IT manager to the US to purchase full retail in LA and saved over $5000 on the deal.
I recently bought a SSD from the USA. The price was the same in Australia (big surprise) but the postage from Sydney (2000km/1200miles) was four times higher and they quoted 14 days unless I paid even more for express post.
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Thanks for that. I'm being greedy here, but also, had you come across any reports of the Rechlin flight test reports of the JUNKERS/BOSCH Thyratron CDI ignition system that was flown in a converted fighter at war's end?
I got a winch bar shipped from the UK to Newman for $20 cheaper than the same bar shipped from Perth to Newman, how does that work?.
Dear Calum,
Did you investigate the HCCI engines BMW were developing as mention in my post #55 and this BIOS report:
http://www.fischer-tropsch.org/primary_documents/gvt_reports/BIOS/bios_1612.htm
Explore US alternatives to British sleeve valve engines (and the ramifications)
The Germans at that time refered to it as "the Ring Process".
It would seem a solution to the problems with spark plugs and producing high octane synthetic fuels. I'm also surprised we didn't hear of the Germans producing Hesselman engines in WW2.
For sure, hydraulic couplings have the advantage of allowing an engine or electric motor to start unloaded but they will yield little boost for take-off. But in transmission mode they barely exceed 80% efficiency compared with about ~90% for a well-designed gear transmission. It's an inescapable fact that a hydraulic coupling relies on slippage to transmit torque and slippage expresses itself as heat. The other parasitic losses that arise from this are the 'devil in the detail' e.g. extra oil cooler capacity, i.e. more weight and drag, etc.
I've waited a long, long time for someone to mention the Ring process. Typically German; academically fascinating but practically useless. You'd think that with all the Wright radials they'd recovered they would have 'discovered' the humble rubber O-ring and it's application to sealing the ignition system and pressurising same with supercharger air.
The ether fluid compound used in the Ring process supplied by IG FARBEN, (also makers of Zyklon B!) would have been yet another of the essential materials disrupted by strategic bombing that kept the Luftwaffe grounded.
Koopernic's reference to HCCI is right on the money. Throughout the tortured later years of research into HCCI by the car industry I was unceasingly amazed that no-one had remembered the Ring process which had achieved the one thing the latter hadn't; the engine could accelerate under load. Instead of tearing their hair out when their HCCI experimental engines stalled they should have intensively studied a Ring-process engine to discover its combustion secrets.
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FWIW - on 2400 rpm and at sea level, the Jumo 211F was making 1120 PS on 1.25 ata (30 min duration), the DB 601A did 1100 PS on 1.4 ata (5 min duration). Jumo 211B on 2400 rpm was good for 1200 PS at 1.35 ata (1 min rating)
On 2600 rpm and at sea level, the Jumo 211F was good for 1340 PS on 1.4 ata (1 min duration), the DB 601N did 1175 PS on 1.35 ata (1, or 3, or 5 minute limit?).
2500 rpm - DB 601E did 1200 PS on 1.3 ata (30 min duration) at SL.
Seems to me that 'classic' S/C drive was no worse than the hydraulic drive at low altitudes.
On 2600 rpm and at sea level, the Jumo 211F was good for 1340 PS on 1.4 ata (1 min duration), the DB 601N did 1175 PS on 1.35 ata (1, or 3, or 5 minute limit?).
2500 rpm - DB 601E did 1200 PS on 1.3 ata (30 min duration) at SL.
Seems to me that 'classic' S/C drive was no worse than the hydraulic drive at low altitudes.
Deleted member 68059
Staff Sergeant
- 1,058
- Dec 28, 2015
Yes, I`m publishing a paper on it in a few months with Professor Stefano Fontanesi at "GruppoMotori" at Modena University. We`re recreating a
DB601 test in CFD running "ringverfarhen", and you can find some more data on it in my book in the following pages:
Deleted member 68059
Staff Sergeant
- 1,058
- Dec 28, 2015
"Yield little boost for take off" ?
I dont know what that means. Anyway slipping the coupling at take-off you avoid having huge pumping losses by having to use a butterfly throttle to lower boost at sea level,
thats typically about 100>150hp in a WW2 V12. You`ll lose a fraction of that gain by needing a slightly larger oil cooler, but thats about it. Its a very substantial gain.
I did make a fairly comprehensive video about all this:
No idea where you get your efficiency numbers from but they`re totally wrong. In "transmission mode" (not a good phrase to use as they are always in transmission mode, but I`ll assume you mean "minimum slip") the couplings have about 1.5% minimum slip, which is almost entirely lost to
heat to oil. The equation for this is:
A well designed spur gear transmission will be looking at less than 1.5% total loss per mesh, you might have 3 meshes in a SC gearbox, so maybe ~5% total loss - the fluid coupling once "locked" has 1.5% slip, which is in fact almost the same loss, because slip is essentially directly proportional to loss to heat, and you`ll have at least one gear mesh step up and in the case of a DB, an additional bevel. So you`ll also have 1.5+1.5+2% = ~5% (call it 2% loss for the bevel).
At take off, you`ll have about 30% slip, which means lots of heat to oil, however, the engine and oil are cold here, so its not nearly as bad as the numbers suggest, and in fact makes quite a nice way to heat the engine up faster. Once you`re high up, the coupling is filled with out and isn't doing much, so doesn't really contribute to heating the oil further once you`ve climbed to intercept.
A torque converter does not rely on pure slippage as say an electrical induction motor, friction drive or eddy current drive. The turbo compound V1710, the two stage supercharged V1710's supercharger the turbo compounded R3350 all used these devices. So did 1930s London Daimler automatic buses.
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DB 601/603/605 used butterfly throttle, despite the hydraulic coupling.
Yes but i think the point is there was less throttling needed to control manifold pressure since the compressor(supercharger) could effectively be turned down and not over compress in the first place. The butterfly valve need only close when negative manifold pressures are desired. I suppose you could in theory turn the compressor into a turbine that both controls air flow or manifold pressure while recovering suction losses back into the main crankshaft. I suspect that's what the new electric superchargers might do. In the 1930s I would have tried that with a variable displacement hydraulic swash plate pump driven of the engine which drives a variable displacement swash plate hydraulic motor that drives the compressor. The Russians used variable inlet guidance vanes to efficiently regulate supercharger pressure/flow I believe and this also appeared in the Jumo 213.
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Deleted member 68059
Staff Sergeant
- 1,058
- Dec 28, 2015
Only for very fine tuning, the coupling slip did the bulk of the boost control work
Mikulin engines (from AM-35A to -42) used both throttle plates and variable inlet vanes, so did the VK-107 and -108.
Jumo 213 used the 'Leerlaufdrossel' (rouhgly 'idling throttle') and variable inlet vanes.
For low altitudes, the coupling slip indeed benefitted a lot. Other companies used the 2-speed S/C for the same purpose and no worse result.
The DB 603A-D, for example, used two separate throttle plates, 'reglerklappe' and 'leistungsklappe' (roughly, 'control throttle' and 'power (setting?) throttle', per color plate VI in the 'Flugmotoren und Strahltriebwerke' book).
There was a need for decrease the boost supplied by supercharger ('geblaese druck') to the manifold boost ('laderdruck'), as dictated by knocking limit.
Deleted member 68059
Staff Sergeant
- 1,058
- Dec 28, 2015
Hmm well thats really not quite true is it Tomo, all you can say is that some sort of method of driving the supercharger at a variable speed is the ideal situation (if its mechanically driven), and that one-speed is the least ideal, as the number of gears increases, the result gets closer to that of the variable speed drive.
Yes, I believe know what a DB 603 is Tomo, and the throttle plates are no different from that of a DB 601 as already discussed above.
I will not comment on 'well thats really not quite true' line.
Also I'm not sure from where the one-speed S/C drive popped out here - neither DB 601/605 nor the Jumo 211 were with the 1-speed drive.
The power graph posted there is at odds vs. the power graph posted here, or here, or here - where the effects of throttling under ~2 km are obvious. The 1st two charts are from the engine manuals.
The data sheets also show 1100 PS for take off, like this one here.
I'm sure that you know about DB 603. Some other people might not know about it's throttle plates.
Snowygrouch, I pre-ordered your book from Amazon. Received it on my birthday. I have read Smith, and Gunston, and I am about 60% through your book. Thank you! I have been wanting something like the Great Horsepower Race for years. I will admit I don't understand a lot of the detail but I plan to read it a second time. I do have one complaint. All of the quotations from memos are printed in a different font. I can understand using a different font but the one selected is too faint. I do plan to order a second copy soon. Maybe today. McFarland has a chapter in Innovation and the Development of Flight on fuel development which I also very much enjoyed and I look forward to your conclusions on fuel development. I think you need to write a text on introduction to ICE for us mechanically challenged folks.
