Wed Sep 19, 2018 12:17 pm #1638931
Ive been reading alot about ww2 aircraft recently and i find it interesting that the spitfire couldnt keep up with its german counterparts in a dive ie me109 and fw190. The german aircraft as far as i know didnt have a typical constant speed unit more of a lever to set the pitch to where it stayed unlike a CSU where an increase or decrease in prop speed would automatically be counteracted by increasing or decreasing propeller pitch. My understanding of the constant speed propeller is that the pilot sets the prop speed by adjusting the spring pressure on the fly weights inside the CSU which control a valve either allowing oil to flow into the propeller hub increasing pitch or return from the propeller hub decreasing pitch, i understand how this works so well in normal flight but in a dive when gravity overtakes the work of the propeller in accelerating the aircraft in my mind this then makes the propeller sort of like a turbine turning the engine, so this then would reverse the effect of the CSU as when the aircraft enters a dive as it begins to accelerate under gravity the back of the propeller will become somewhat unloaded allowing a slight increase in rpm which would then cause the flyweights to slightly open the valve allowing oil into the propeller increasing the blade pitch, under these conditions increasing the blade pitch will just exaggerate this turbine effect so where the CSU is applying a coarse pitch in order to slow the propeller its actually speeding it up. Ive also read that pilots were advised to select coarse pitch before entering a dive to prevent the CSU jamming into fine pitch, going back to what i mentioned before with the propeller speeding up in a dive and with the CSU applying maximum blade pitch when the pilot pulls out of the dive this will induce a sudden perhaps harsh operation of the CSU if left in fine pitch as suddenly the engine will be dealing with high rpm with max pitch, a combination unachievable in normal flight, this to which the jamming of the mechanism could be associated with. So all this would happen at a cost in the name of drag and this would explain why the germans would get away in a dive.
Any thoughts on this?
Any thoughts on this?
Last edited by User22169 on Wed Sep 19, 2018 4:13 pm, edited 1 time in total.