Try both.  From the history that I have the P-38 was designed with the props rotating with the tips going together at the top, so that if one engine went out the torque and yaw effects would tend to cancel.  Then they found some nasty turbulence effects over the horizontal stab that they solved by swapping the engines.  It guaranteed that the handling would be vicious no matter which engine went out, but when both were going the plane worked just great.

Thanks for the replies:

Tim, Trial and error is tried and true. It is just that after umpteen hours of building I want to avoid an ERROR that re-kits my model! 

John, I understand the pusher prop use on a single motor model has advantages. However, (and I could be wrong) my understanding is that the line tension in maneuvers is the result of the way the slipstream from the prop impinges on the wings and tail feathers. With a twin and two slipstreams I am confused as to what the effects (if any) are going to be. That is why I am wondering if others who have electric twins have experience in this regard.

Ya know the only combo I would avoid is two RH tractor props!

I read where the original P-82 Twin Mustang was set up "normal" (RH prop on left side, LH prop on right side) with the tops of the props coming together - it would not take off because the props downwash over the center section.  They swapped the motors side to side to fix.  My Brodak F-82 is set up that way to be "scale".

Also consider this: if that carried into your twin, it would suggest that your airplane might turn better one way or the other, and swiching the props would counteract that?

I am also on John R's page, can't say that you will really need it but two LH props should maximize the effect - but will that be too much?

 

I very much doubt that the effect will be enough to crash.  I kinda doubt that, if I were the guy on the handle, that I'd be able to tell at all.

So I think you're safe playing some games with it, as long as you always make sure that you have the right props on.

Tim,  Check my signature below!!!   

Bob Hunt was working on a twin.  I'll give you the same advice I gave him.  Beware of getting the polarity of the props and motors mixed up:

motor 1 rotation   motor 2 rotation   prop 1  prop 2  outcome
        L                       L                  L         L         OK
        L                       L                  L         R         bad
        L                       L                  R         L         bad
        L                       L                  R         R         bad
        L                       R                  L         L         bad
        L                       R                  L         R         good
        L                       R                  R         L         bad
        L                       R                  R         R         bad 
        R                       L                  L         L         bad
        R                       L                  L         R         bad
        R                       L                  R         L         good
        R                       L                  R         R         bad
        R                       R                  L         L         bad
        R                       R                  L         R         bad
        R                       R                  R         L         bad
        R                       R                  R         R         OK

I wouldn't risk it.

Hi John,
You will enjoy the same benefit as with a single, with both motors and props as pushers.
The two spiralling airstreams essentially merge into one as long as they are not too far apart.
later,
Dean

John,
I don't think rotation direction will make a great deal of difference on a C/L airplane, especially one that is not trying to fly a competition pattern. With your motors it is easy enough to experiment.

Pat