MW50 -Secondary effects were cooling of the engine .

[Kurfürst]

Originally Posted by Mustang

Many Thanks

This explains many things .

A bit more was added to that subject of 1.98ata 109K (and G-10s! people always seem to forget the G-10 had the same engine and ratings!) here: http://www.kurfurst.org/Engine/Boost...arance198.html

There are some new developments in the matter about the role of II/JG 11, but essentially the facts remain the same.

As to the question at hand - cooling effects of MW-50 - it can be stated with definite certainty that overheat of coolant should not be a problem at all. We have German datasheets of DB 605A and DB 605AM showing the max. heat transfer data of the engine (how much heat the engine generate to be carried away - max. abzufahrende Waermemenge in German table). The data shows that the 605AM, with MW-50 and operating at max boost, ie. 1.7ata / 1800 HP actually makes less heat than the MW-less DB 605A at 1.3ata / 1310 HP. I don't have that paper on my site yet, only extracts, but I think it was referred above.

Now the 109G's cooling system was effective enough to keep the temperatures down well below safe limits at around 85 Celsius in full power climbs, ei. 1.3ata / 1310 HP, when airflow through the radiators is minimum (the DB 605 manual notes the engine can tolerate around 110 Celsius coolant for 10 minutes). http://www.kurfurst.org/Performance_...es/blatt10.jpg

As noted above with MW 50 the coolant system had to cope with even less heat. Add to that that high altitude 109s (G-6/AS, G-14/AS, G-10, K-4) had larger sized oil/coolant radiators fitted. See http://www.kurfurst.org/Performance_...u4_am-asm.html

1.) DB 605 AM i = 1,685 mit MW-50
G = 3515 kg
Wasserkühler Fk = 33,6 dm2
Ölkühler Fk = 6,5 dm2
Luftschraube 3 flg. vorhanden als 9-12078

2.) DB 605 ASM i = 1,685 mit MW-50
G = 3550 kg
Wasserkühler Fk = 42.0 dm2
Ölkühler Fk = 8,5 dm2
Luftschraube 3 flg. vorhanden als 9-12159

and http://www.kurfurst.org/Performance_...t_109K_EN.html for 109K

Radiators : Coolant radiators Fk = 36 dm2
Oil cooler Fk = 8.5 "

This seems to be a general weakness in the Il-2 engine - coolant overheating was generally overdone, probably to impose some limit on using max. power or to simulate 'engine wear'. At least I can confirm that for 109s, which as per historical data very unlikely to ever reach maximum limits without closing the radiators completely or something similiarly stupid. The worst thing that can happen is that the coolant radiator flaps open.