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Postage costs have become absolutely insane over the last few years. Inline with the "efficiency" we were all promised after privatisation... stuff like post, gas and electricity do not lend themselves to market forces... for very, very obvious reasons (i.e. virtually impossible to form a competitor). To send my book anywhere outside the UK costs about 80% of the cover price of the book, unless you pick "economy" which is anything up to 3months transit time (i.e. surface-only). Its total madness.
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.
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?Compared to a gear driven SC, it saves about 10% of engine power at take off actually.
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.
Yep, page 94 and 95 will start you off.
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.Compared to a gear driven SC, it saves about 10% of engine power at take off actually.
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.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.
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.
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.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.
"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.
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.DB 601/603/605 used butterfly throttle, despite the hydraulic coupling.
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 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 guidances i believe and this also appeared in the Jumo 213.
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.
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.