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D520: Aérodiol/water, 50/50
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I was just reading that the early Merlins were designed for pure water, which caused problems with over-large radiators.
What is "Aérodiol"? Where can I find information about it?D520: Aérodiol/water, 50/50
MS 406: Ethane-Diol(ethyl-glycol)/water 40/60
Hispano Suiza prescribe, 10 to 60% glycerin, ethyl glycol, or ethyl alcool
It's just what I was reading about the development. I can't say that it's authoritative.Is there a proof for any of those claims?
It's just what I was reading about the development. I can't say that it's authoritative.
I meant earlier development, pre-deployment. The source said that the Brits got a supply of ethylene glycol from the U.S. and switched to a much more compact radiator during development. Don't know if that's accurate or not.Per manual for Fairey Battle, Merlin I engine, coolant listed is a glycol mixture.
I meant earlier development, pre-deployment. The source said that the Brits got a supply of ethylene glycol from the U.S. and switched to a much more compact radiator during development. Don't know if that's accurate or not.
I'm ... very surprised by that.The UK was just starting to switch over from pure ethylene-glycol to the 70/30 mix in 1940 with the adoption of the Merlin X and XII engines. The earlier Merlin II-VIII powered aircraft had to continue using the earlier pure ethylene-glycol unless/until their cooling systems were modified for pressurized cooling.
Ethylene glycol has a lower specific heat capacity than water. My father and I looked this up in the CRC handbook when I was curious about why the He70 would use pure E-G. I've double-checked. E-G has a slightly higher density, which makes up for this a bit. However, if the E-G system is being run well above water boiling (at 120C), the density difference is very marginal. Of course, at 120C the E-G is carrying a lot of heat, helping to make up the difference between it and pure water at 90C.Apparently pure ethylene-glycol can absorb a more heat than liquid water
I'm not aware of that and I can't think of any reason why it would be so.but cannot absorb or get rid of the heat anywhere as quickly as water.
I believe Aerodiol was a french commercial brand name for ethanediol, just with some additives making it more suitable for use in aero engines.
Ethanediol is in turn a contraction of ethane-1,2-diol.
Ethane-1,2-diol is in turn the IUPAC standard nomenclature for ethylene-glycol (C2H6O2).
The French automobile and aircraft industries were well aware of the cooling properties of the various blends of coolants - but like the US, UK, and Russia in the late 1930's - they had not yet settled on the later more-or-less standard universal mix of 70/30 (water/ethylene-glycol) mix for aero engines.
The US in 1939(?) had specified a 2/98 mix for all liquid cooled aero engines, including the V-1710 (this was a major part of the problem with getting rid of heat in the turbocharged V-1710 systems used in the early P-38s, why the non-turbo V-1710s had problems developing higher power ratings early war, and why the V-1650-1 engine charts for the P-40F&L were never rated at more than 1300 HP). AFAIK The US did not switch to a 70/30 mix until the adoption of the Merlin 60/V-1650-3 engines in the P-51B Mustang.
The UK was just starting to switch over from pure ethylene-glycol to the 70/30 mix in 1940 with the adoption of the Merlin X and XII engines. The earlier Merlin II-VIII powered aircraft had to continue using the earlier pure ethylene-glycol unless/until their cooling systems were modified for pressurized cooling.
Merlin 25 was not a low-altitude engine....
These changes, when combined with a redesigned supercharger which generated less heat in the incoming air/fuel charge, allowed even higher power outputs of ~1400 BHP, with low altitude versions like the Merlin 25 producing ~1600 BHP.