smoke218 Posted January 14, 2009 Share Posted January 14, 2009 Hello everyone, I've got a question that's been puzzling me all day. What's bothering me is I don't understand how two engines drive one shaft or rotor shaft on a helicopter. The picture I get in my mind is the gears are being driven by one engine while the other engine doing something but I just don't know what it is. I know that the other engine is driving the rotor shaft too, but how? I guess my question is how does two turbine engines drive the helicopter's main rotor shaft together at the same time? Someone please help me understand.:helpsmilie: Link to comment Share on other sites More sharing options...
Nate--IRL-- Posted January 14, 2009 Share Posted January 14, 2009 This should get you started....... http://www.digitalcombatsimulator.com/index.php?lang=en&end_pos=1630 Nate Ka-50 AutoPilot/stabilisation system description and operation by IvanK- Essential Reading Link to comment Share on other sites More sharing options...
urze Posted January 14, 2009 Share Posted January 14, 2009 (edited) I guess my question is how does two turbine engines drive the helicopter's main rotor shaft together at the same time? They do it by using a Differential gear: http://en.wikipedia.org/wiki/Differential_(mechanical_device) Edited January 14, 2009 by urze Leftside Limited - ideas and solutions Link to comment Share on other sites More sharing options...
lucasdigital Posted January 14, 2009 Share Posted January 14, 2009 How do two legs moving in opposite directions propel a bicycle? ;-) Very clever gears! Cut to it's simplest, each engine is attached to the rotor system through a freewheel, so each engine can keep the helicopter aloft, whilst two engines working together can make it a swift S.O.B. Check out this - http://books.google.co.uk/books?id=CSmVLrllpKUC&pg=PA6&lpg=PA6&dq=twin+engine+helicopter+schematic&source=web&ots=uaotJLGnjE&sig=BWFf2lhqje5ITzRP1fiVRkUmaLk&hl=en&sa=X&oi=book_result&resnum=10&ct=result#PPA6,M1 -- L u c a s d i g i t a l Mark Lucas http://www.lucas-digital.com Link to comment Share on other sites More sharing options...
smoke218 Posted January 14, 2009 Author Share Posted January 14, 2009 Ah, the freewheel--that's how it's done! Thanks a lot folks. I would have never figured this one out on my own in a million years. You guys are the best--thanks again. Link to comment Share on other sites More sharing options...
RvETito Posted January 14, 2009 Share Posted January 14, 2009 With the only difference that the free-wheel drive is installed in the imtermediate gearbox for each engine the main gearbox of Ka-50 has roughly that schematic: The two input driveshafts transfer torque to a common gear which is the first stage of reduction (of the main GB). "See, to me that's a stupid instrument. It tells what your angle of attack is. If you don't know you shouldn't be flying." - Chuck Yeager, from the back seat of F-15D at age 89. =RvE= Link to comment Share on other sites More sharing options...
nightlynx Posted January 15, 2009 Share Posted January 15, 2009 So the shaft that holds the blades on the end, is there one shaft or two (one inside the other)? Link to comment Share on other sites More sharing options...
AlphaOneSix Posted January 15, 2009 Share Posted January 15, 2009 Two. One inside the other. Link to comment Share on other sites More sharing options...
sobek Posted January 15, 2009 Share Posted January 15, 2009 I'm not really familiar with reading this driveshaft chart. Is there a differential gear in there somewhere or is this just handled by the free wheel clutches? Wouldn't a differential gear make the free wheel clutches stop working, so far as making a flamed out turbine turn backwards? Good, fast, cheap. Choose any two. Come let's eat grandpa! Use punctuation, save lives! Link to comment Share on other sites More sharing options...
AlphaOneSix Posted January 15, 2009 Share Posted January 15, 2009 The free wheel unit comes before you even get to the main gearbox. If an engine stops turning, the clutch disengages, and the engine just stops spinning, and the main gearbox doesn't drive the engine at all. Link to comment Share on other sites More sharing options...
sobek Posted January 15, 2009 Share Posted January 15, 2009 The free wheel unit comes before you even get to the main gearbox. If an engine stops turning, the clutch disengages, and the engine just stops spinning, and the main gearbox doesn't drive the engine at all. But there is no differential gear to balance the load between the two engines, or am i wrong? Good, fast, cheap. Choose any two. Come let's eat grandpa! Use punctuation, save lives! Link to comment Share on other sites More sharing options...
RvETito Posted January 15, 2009 Share Posted January 15, 2009 No differential gear, the torque from the two input shafts are both transfered to the gear No.3- this is the first stage of reduction of the main gearbox and except that it sums the torque of the two input shafts into one shaft. In case of OEI the operating engine will spent power to drive the input driveshaft of the other engine up to the free-wheel unit which is not such a big waste. "See, to me that's a stupid instrument. It tells what your angle of attack is. If you don't know you shouldn't be flying." - Chuck Yeager, from the back seat of F-15D at age 89. =RvE= Link to comment Share on other sites More sharing options...
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