216th_Peterla Posted October 2, 2015 Posted October 2, 2015 Pretty nice demonstrative video. It certainly works!
EAF19_Marsh Posted October 2, 2015 Posted October 2, 2015 Out of interest, what is with the varying prop spin on the engine - is it semi-seizing owing to an oil leak?
Finkeren Posted October 2, 2015 Posted October 2, 2015 (edited) Out of interest, what is with the varying prop spin on the engine - is it semi-seizing owing to an oil leak? Nope.The engine is dead. But the prop isn't feathered, and as the air speed increases the airflow over the prop blades becomes powerful enough to overcome the vacuum in the cylinders and force the prop to start rotating again. The reason it slows down the moment the pilot starts to pull out only to kinda start turning a bit again as the plane levels out, I think has to do with the fact that during the pull out, the airflow over the blades comes in at a different angle and therefore has a harder time turning the prop, which then stops turning. After the pull out the airflow comes straight over the blades again, and the prop starts turning a bit, because air speed is still very high. The plane slows down quickly in level flight though, so the prop doesn't really get to spin properly, before it slows down again. That's my take on it anyway. Edited October 2, 2015 by Finkeren
6./ZG26_Emil Posted October 2, 2015 Posted October 2, 2015 Which raises a question....can we feather props in BOS?
Finkeren Posted October 2, 2015 Posted October 2, 2015 I think you can, yeah - on the planes that had the option, which for instance the Pe-2 hadn't - but I'm not certain. Will have to check the key setting next time I play.
6./ZG26_Gielow Posted October 2, 2015 Author Posted October 2, 2015 (edited) Yes we can !!! Left Ctrl + F I am not sure if it is default but it is what I have here. Select desired engine pressing 1 or 2 keys if you don´t have a lot of joysticks hehehe. Reduce throttle and propellers to idle/0%. Press E to shut down engine and then Ctrl + F. The fire only extinguished after shutting down the engine. The two times that I got a fire and dived it was a wing fire, not an engine fire. If you pay close attention the blades were feathering when they start to rotate again, Edited October 2, 2015 by =[Coffin]=Gielow
Finkeren Posted October 2, 2015 Posted October 2, 2015 If you pay close attention the blades were feathering when they start to rotate again, Ah, so that's why they stop rotating again the second time? I just asumed it was because air speed dropped.
6./ZG26_Gielow Posted October 2, 2015 Author Posted October 2, 2015 (edited) Here you can see it feathered clearly. Just another regular day for a bomber crew Uber pilots check rudder effectiveness before shutting down an engine Edited October 2, 2015 by =[Coffin]=Gielow
=362nd_FS=Hiromachi Posted October 2, 2015 Posted October 2, 2015 And I was wondering why yesterday so many AI Ju-52 managed to extinguish as Ai once hit severely drops the altitude from its designated to the deck and tries to fly to base. Now I see that steep dive they did allowed to extinguish fire.
Finkeren Posted October 2, 2015 Posted October 2, 2015 (edited) And I was wondering why yesterday so many AI Ju-52 managed to extinguish as Ai once hit severely drops the altitude from its designated to the deck and tries to fly to base. Now I see that steep dive they did allowed to extinguish fire. I don't know if it's modelled, but I would imagine, that it would be quite a bit easier for a Ju 52 to extinguish an engine fire (not fuel fire) due to the fact, that the engines are pretty much just hanging out there in the air flow with very little shielding. Edited October 2, 2015 by Finkeren
EAF19_Marsh Posted October 2, 2015 Posted October 2, 2015 Ah, so that's why they stop rotating again the second time? I just asumed it was because air speed dropped. If the slowed because airspeed stropped then the modelling would have been very poor; there is now way the acceleration / deceleration was significant enough to case the change in RPM seen unless the pitch changed or something similar occurred - hence my question.
Finkeren Posted October 2, 2015 Posted October 2, 2015 (edited) If the slowed because airspeed stropped then the modelling would have been very poor; there is now way the acceleration / deceleration was significant enough to case the change in RPM seen unless the pitch changed or something similar occurred - hence my question. Well, actually the pitch did change, as Gieglow said, but even if it hadn't a slow down of the air flow would actually lead to the prop stopping rather fast. Remember, that the prop isn't just windmilling freely, it's actively fighting against the vacuum in the cylinders, and requires quite a bit of force from the air flow to keep spinning. As soon as the air flow drops below the point where it can overcome the resistance in the engine, the prop slows down very rapidly. That's why at low airspeeds the prop can seem to stop almost instantly, if the engine cuts out. Edited October 2, 2015 by Finkeren
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