This would be interesting. In fact, if SoW gives us improved engine modelling then controlling pitch/RPM will become more important that throttle for the German planes.
The reason is that the German aircraft didn't have constant speed propellers. Correct me if i'm wrong, but i think i read somewhere that they were simple variable pitch propellers. But what's the difference?
Well, constant speed props automatically vary the pitch to keep the RPM at the value you set. This is usuallly done through a hydraulic system contained in the spinner of the prop, with oil pressure inside the mechanism working against the air resistance that the prop faces. When the air resistance is low the oil pressure inside the mechanism overcomes it and changes the propeller pitch one way. When the air resistance overcomes the oil pressure inside the propeller governor, the pitch changes the other way. Essentially by moving the pitch lever you are not directly affecting prop pitch, you are probably setting the oil pressure inside the governor and each oil pressure value corresponds to a certain RPM value via the function described above.
So, with constant speed props you select your desired RPM and the prop does the rest, within some limits of course. For example, if you downthrottle too much the RPM will still drop as there's not enough power to maintain it, if you go too fast in a dive the RPM will rise as the automatic pitch system reaches its gimbal lock limit.
However, things are different for a variable pitch prop that is not constant speed. These don't maintain a selected RPM, you simply select your desired prop pitch angle by moving the lever, directly affecting prop pitch. That means if your airspeed rises and you want to maintain RPM and prevent over-revving, you'll have to do it yourself as the prop won't do it for you. Similarly, if you start climbing and losing airspeed, you'll have to adjust pitch to prevent the RPM from dropping. Essentially, this prop is variable in pitch but needs constant monitoring of RPMs.
The way i see it, it would be nice if we could have separate control profiles for different aircraft. Then, people with a single throttle would be able to save different profiles, so that when for example i'm flying a 109E i can assign my slider to prop pitch, as this is the one that can fry my engine if left unattended, and use the keyboard for my throttle settings. In fact, there's only 2-3 main throttle settings in each aircraft: max(take-off/WEP), climb, max continuous cruise. However, if i'm flying an aircraft with a constant speed prop, then it would be more convenient to revert to the classic control scheme and control the throttle with the slider and the prop RPMs with the keyboard.
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07-14-2010, 12:38 PM
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