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Did the Engines Rotate in Opposite Directions?

AmbroseAmbrose Member Posts: 3,158 ✭✭✭✭
edited July 2014 in General Discussion
In reading a story about salvaging automotive engines from larger boats, I learned that twin engines rotate in opposite directions. I would think that would be even more important on aircraft. Does anyone know if the engines on high performance WWII planes like the P38 were set up this way? What about 2 and 4 engine bombers?

Comments

  • cbxjeffcbxjeff Member Posts: 17,401 ✭✭✭✭
    edited November -1
    I believe multi-engine aircraft engines turn the same direction. The fact that they are on different wings cancel out the torque problem (as long as all of them are running). Also if I recall, we had one or more single engine fighters that had two props operating in opposite directions.
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  • mark christianmark christian Forums Admins, Member, Moderator Posts: 24,456 ******
    edited November -1
    Props on multi engine bombers like the B-17 and B-29 all ran in the same direction: clockwise.
  • mlincolnmlincoln Member Posts: 5,039 ✭✭✭
    edited November -1
    I'm 95% sure the P-38 had -handed engines which made take off and flying much easier. I don't know about the B-25 and B-26 and other such aircraft of a somewhat similar size. If MC says no, though, I'm going with that.
  • Don McManusDon McManus Member Posts: 23,460 ✭✭✭✭
    edited November -1
    Yes the P-38 hand handed engines, but it was fairly unique in that regard.

    The de Havilland Mosquito received handed engines only late in the war.

    Both these aircraft had a much greater HP to weight ratio that the B-25, etc, and also had inline engines.

    I am unaware of any of the big radials that were used in WWII being handed.
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  • Don McManusDon McManus Member Posts: 23,460 ✭✭✭✭
    edited November -1
    quote:Originally posted by dennisnielsen
    Most boats do on twin engines,otherwise it pulls.


    Do the engines rotate in opposite directions, or just the screws?
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  • nordnord Member Posts: 6,106
    edited November -1
    Boats... Clockwise and counterclockwise.
  • cbxjeffcbxjeff Member Posts: 17,401 ✭✭✭✭
    edited November -1
    When I worked at Chris Craft in the very late '50's the big Connies used Chev small blocks that ran in opposite directions.
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  • cce1302cce1302 Member Posts: 9,555 ✭✭✭
    edited November -1
    Helicopters rotate opposite. CH-46 anyway.

    Also the MV-22 Osprey.
  • AlpineAlpine Member Posts: 15,041 ✭✭✭✭
    edited November -1
    quote:Originally posted by Don McManus
    quote:Originally posted by dennisnielsen
    Most boats do on twin engines,otherwise it pulls.


    Do the engines rotate in opposite directions, or just the screws?




    On my boat and others that I observed the motors ran conventionally and the transmissions had an extra gear to rotate the prop opposite it's twin.

    On some very big boats the motors had to be stopped and started in the opposite direction to get reverse.
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  • 20gabob20gabob Member Posts: 232 ✭✭✭
    edited November -1
    The P-38 lightning had counter-rotating engines to cancel out the torque of the engines making the aircraft try to flip over. That was a heck of a lot of power on a small fighter and everything was done to make it as controllable as possible.
  • Don McManusDon McManus Member Posts: 23,460 ✭✭✭✭
    edited November -1
    quote:Originally posted by Alpine
    quote:Originally posted by Don McManus
    quote:Originally posted by dennisnielsen
    Most boats do on twin engines,otherwise it pulls.


    Do the engines rotate in opposite directions, or just the screws?




    On my boat and others that I observed the motors ran conventionally and the transmissions had an extra gear to rotate the prop opposite it's twin.

    On some very big boats the motors had to be stopped and started in the opposite direction to get reverse.








    I was on a very big boat that had to do that for a couple of years.

    Of course with steam turbines, it was actually using a separate set of blades on the same turbine shaft.[:)]
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  • bigoutsidebigoutside Member Posts: 19,443
    edited November -1
    On a boat, the effect is called "prop walk" and a skilled helmsman can turn a boat 180 degrees within a boat length by taking advantage of it.

    Less of a consideration on a plane.

    But Paul Tibbets made his decision on which way to turn based on prop rotation. I guess if it's something you're trying to get away from, you'll take your advantage wherever you can.
  • buckglovesbuckgloves Member Posts: 156 ✭✭
    edited November -1
    My Correct Craft has one engine. It turns counter clock.
    351w Ford.
  • bigoutsidebigoutside Member Posts: 19,443
    edited November -1
    quote:Originally posted by buckgloves
    My Correct Craft has one engine. It turns counter clock.
    351w Ford.


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  • buckglovesbuckgloves Member Posts: 156 ✭✭
    edited November -1
  • pwilliepwillie Member Posts: 20,253 ✭✭✭
    edited November -1
    quote:Originally posted by cbxjeff
    When I worked at Chris Craft in the very late '50's the big Connies used Chev small blocks that ran in opposite directions.
    The engines that were timed to run in the opposite direction lasted the least amount of hrs....
  • bigoutsidebigoutside Member Posts: 19,443
    edited November -1
    quote:Originally posted by pwillie
    quote:Originally posted by cbxjeff
    When I worked at Chris Craft in the very late '50's the big Connies used Chev small blocks that ran in opposite directions.
    The engines that were timed to run in the opposite direction lasted the least amount of hrs....


    What would cause that?
  • LesWVaLesWVa Member Posts: 10,490 ✭✭
    edited November -1
    Twin engine boats like some Hitachi Euclid haul trucks ran twin engines into a single transmission. In order to get the transmissions input shaft to rotate in the right direction through the gear box/coupler/bell housing. The engines had to rotate in different directions.

    Little visual aid.

    Black = Transmission input.
    Red = Left bank (engine).
    Gray = Right bank (engine).

    14524896396_e49f271dcf_z.jpg


    Some of the trucks we used had either twin 6 or 8 cylinder Cummins engines. Making the truck an actual 12 or 16 cylinder.
  • Horse Plains DrifterHorse Plains Drifter Forums Admins, Member, Moderator Posts: 39,310 ***** Forums Admin
    edited November -1
    quote:Originally posted by LesWVa
    Twin engine boats like some Hitachi Euclid haul trucks ran twin engines into a single transmission. In order to get the transmissions input shaft to rotate in the right direction through the gear box/coupler/bell housing. The engines had to rotate in different directions.

    Little visual aid.

    Black = Transmission input.
    Red = Left bank (engine).
    Gray = Right bank (engine).

    14524896396_e49f271dcf_z.jpg


    Some of the trucks we used had either twin 6 or 8 cylinder Cummins engines. Making the truck an actual 12 or 16 cylinder.
    Your grey, and red gears are rotating in the same direction
  • Don McManusDon McManus Member Posts: 23,460 ✭✭✭✭
    edited November -1
    quote:Originally posted by Horse Plains Drifter
    quote:Originally posted by LesWVa
    Twin engine boats like some Hitachi Euclid haul trucks ran twin engines into a single transmission. In order to get the transmissions input shaft to rotate in the right direction through the gear box/coupler/bell housing. The engines had to rotate in different directions.

    Little visual aid.

    Black = Transmission input.
    Red = Left bank (engine).
    Gray = Right bank (engine).

    14524896396_e49f271dcf_z.jpg


    Some of the trucks we used had either twin 6 or 8 cylinder Cummins engines. Making the truck an actual 12 or 16 cylinder.
    Your grey, and red gears are rotating in the same direction


    And the boat is listing to port.
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  • babunbabun Member Posts: 11,054 ✭✭✭
    edited November -1
    quote:Originally posted by bigoutside
    quote:Originally posted by pwillie
    quote:Originally posted by cbxjeff
    When I worked at Chris Craft in the very late '50's the big Connies used Chev small blocks that ran in opposite directions.
    The engines that were timed to run in the opposite direction lasted the least amount of hrs....


    What would cause that?


    True.
    Thrust forces designed into the original motor are now "backwards".
    Piston shirts, bearing loading, firing orders, are now "wrong" when rotation is changed.
    Small block chevy's had a piston wall oil sprayer built into the connecting rod and bearing, now it's spraying oil on the wrong side of the cylinder.
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