turbine overspeed light and water injection

[bephanten]

over 30k ft, climbing with full throttle and rpm, turbine overspeed light is on. if i momentarily press water injection button, light turns off, turbo rpm and manifold pressure drops significantly and remains there. they increase again after nibbling with rpm or decreasing throttle. 

i tried same scenario with a new plane at same altitude. pressed water injection momentarily, mp and turbo drops but rises again without control intervention. 

turbo.trk

[grafspee]

When you engaging water injection in P-47 turbo regulator is switching in to override mode. You simply asking a lot more boost. Normally w/o water engaged turbo regulator won't allow to get very high boost.

P-47 manuals are mentioning something like "turbine surge" maybe this is what causing that rpm and boost drop. On other hand pilots were testing P-47 at higher boost probably exceeding rpm limit on turbo.

But honestly im not convinced that this sudden turbo rpm drop should happen when you attempting to over rev turbo. Afaik we can't over rev turbo due to that mysterious rpm drop.

When you flying at max turbo rpm and you press water injection you simply asking for more boost as so for more turbo rpm but in DCS when you try to do it turbo rpm drops. And only way to get back on turbo is to retard turbo boost lever or switch off water.

Edited December 2, 2024 by grafspee

[bephanten]

yes, in the manual i could not find detailed info on turbo behavior. rpm drop is undocumented. and for my case, there is two kind of behavior, either rpm drops and rises by itself,  or drops and it returns to previous state after playing with controls.