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New P38 90" wing motor mount

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New P38 90" wing motor mount

Old 11-17-2012, 06:46 PM
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Airshow
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Default New P38 90" wing motor mount

I am building the plane now and have 2 maybe problems

1# the manual shows motor as a side mount and a lot of cutting of the cowl
but there is lots of room if you mount them upside down and less cutting is this a problem?
using 2 91=4s
2# will i have to reverse one of the motors counter clock wise one of the guys at the field said I would??
not sure?
I have a Twin Star and have no problem

Thanks and have a great day[]
Old 11-17-2012, 06:57 PM
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speedracerntrixie
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Default RE: New P38 90

Running 4 cycle engines inverted should not be an issue just as long as the fuel tanks centerline is not higher then the carb center. I have run 2 strokes inverted on a couple of occasions and hated the airplanes because of it. I have not flown many twins but I have virtually never seen one with counter rotating engines. The key I would think is make darned sure that both engines are running 100% reliable and have rerasonable close RPMs at all throttle settings.
Old 11-19-2012, 03:10 PM
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Granpooba
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Default RE: New P38 90


ORIGINAL: Airshow

I am building the plane now and have 2 maybe problems

1# the manual shows motor as a side mount and a lot of cutting of the cowl
but there is lots of room if you mount them upside down and less cutting is this a problem?
using 2 91=4s
2# will i have to reverse one of the motors counter clock wise one of the guys at the field said I would??
not sure?
I have a Twin Star and have no problem

Thanks and have a great day[]
No, you will not reverse one of the motors.

As previously stated, both engines running perfectly insync, will work. Friend of mine also had a Twin Star and flew great. Even had a couple of engine outs and brought in for good landings.

Not even all full size prop driven aircraft have counter rotating props.
Old 11-25-2012, 01:23 PM
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DGM
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Default RE: New P38 90

I am on my second 90" P- 38. Electric with both props turning the same way. No problems. I considered glow power but the tanks came out quite a bit below the carb, so decided on electric. Plane is eazy to fly and looks great in air. Nice thing about electric, other than dependability, is you can climb to altitude and shut down motors and glide around. Yes it does glide well. Then start up and continue powered flight.

Flew a B-26 with glow and that worked well too. Tune each engine individually so each engine is running at its best, full speed, idle and inbetween. DO NOT try to match RPMs. A few hundred RPM difference will not affect flight.
Old 11-25-2012, 05:20 PM
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Default RE: New P38 90

This may be of a little help, below is a link to the mods I did on installing twin saito's (inverted) in a twin otter. Also, you might seriously consider installing a Twin Sync to help manage the engines and to ensure a margin of safety in the event you have an engine out. I installed one in the Otter and it has been a real pleasure to fly. Not to mention it saved my bacon once on a touch-n-go when I lost an engine.

http://www.rcuniverse.com/forum/fb.asp?m=11033547

Twin Sync
http://www.troybuiltmodels.com/items/WRCTWINSYNC.html

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