As for LW a/c which could use MW-50 water-methanol injection such as the 109G-6 & G-10 (just 2 mention 2 109's) & the Fw 190A-5 & A-8 (just 2 name 2), a maximum period of 10 mins of boost could be used at any one time, and a period of 5 mins had to elapse before boost could be applied again.Generally, MW-50 tank sizes allowd for up to 30-40mins (I have differing accounts)of boost.That's 3-4 periods of 10mins each with a minimum of 5 mins between .
Jochen, I understand that a large number of 190A-8's used their EXT tank for MW-50 instead of avgas.The oft-quoted A-8 max TAS of 408 mph takes into account MW-50 boost.Having looked at the AH performance chart for the A-8, it is obvious that EXT is used for fuel only (if I fly the 190 it is normally the A-5, so I had not even noticed).
One of the main differences between the A-7 & A-8 was the rear fuselage tank that could be used for either fuel or MW-50, and the snall disparity in max TAS between the 2 is based purely on the A-8 using MW-50.Without MW-50, there would be almost no difference between the 2.
Should AH's 190A-8 be modelled with the EXT tank using MW-50 instead of fuel?I think we should be given the choice.A significant number of A-8's used the EXT tank for MW-50.I have read different opinions from different historians, but when you consider that most A-8's used an external drop-tank, and that the EXT tank was relatively small, it makes sense that many units would have preferred to use it for MW-50 rather than avgas.
After all, the bloated A-8 often needed as much of a performance boost as possible, and as most A-8's carried a DT, what makes more sense - using the EXT tank for a small amount of extra fuel, or use MW-50 to get a performance boost? If the rear tank is already there and is going to be used, there is an equal weight penalty in using either fuel or MW-50 in the EXT tank.
That being the case, I think we should have the hangar option of using fuel or MW-50 in the A-8's EXT tank.As for the A-5, I understand both the A-4 & A-5 both used MW-50 exclusively in their rear tank.
For those who don't know how MW-50 worked, here is an explanation of how it worked in the 109 models from the G-6 to the K-4.This info can be also used when referring to the Fw 190 :
The water-methanol mixture was injected into the supercharger below the powerplant's rated altitude, acting as an anti-detonant. Boost pressure from the supercharger was utilised to apply pressure to the 25 Imp. Gal MW-50 tank, forcing the mixture along a small pipe to an injection nozzle in the eye of the supercharger.The flow of MW-50 mixture was controlled by a solenoid valve activated by an automatic throttle switch & a master switch in the cockpit, and a 4% increase in power could be obtained, even at constant boost pressure.In the DB605AM powerplant used in the G-6 & G-14, fuel was consumed at 106 Imp. gal. per hour at take-off , but when using MW-50 with higher boost pressure , fuel consumption climbed to 141 Imp. gal. per hour. So extended use of MW-50 reduced range considerably, as well as having disastrous effects on the engine's spark-plugs, but this was generally regarded as a relatively small price to pay in return for increased performance - in the G-6's & G-14's using the DB 605AM, MW-50 boosted take-off power from 1,475 hp to 1,800 hp.
As a final note, the RLM realised that MW-50 boosting was not as efficient as improved supercharging (though improved supercharging AND MW-50 could be most beneficial), and as a result, emphasis was put on building a DB 605 powerplant with increased supercharging, which resulted in the DB 605AS engine being produced which was essentially a DB 605A using the DB 603's larger supercharger.The DB 605D was, to be simplistic, an enhanced version of the DB 605AS, utilising the same larger blower from the DB 603 with some ofther enhancements.
[This message has been edited by C_R_Caldwell (edited 02-09-2001).]
