SMALL - SMALL - Telemetry SMALL - Radio
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Old Apr 22, 2014, 05:15 PM
Life is a Hobby
Canada, ON, Delhi
Joined Aug 2012
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Full scale airplanes use "handed" engines - one clockwise, the other counter clockwise. Full scale pilots describe the rotation as seen from the cockpit. Normal setup is both props rotating inwards to negate an engine-out situation.

Some WWII fighters such as the P38 had the props rotating outwards. Something to do with gunnery. I have never seen a good explanation of the outward-handed props helping gunnery but a human pilot can react a lot faster inside the cockpit to an engine out and has the training to handle it.

As for R/C models, inward-handed props are very easy with electric, just reverse two connections on one motor. Place the normal counter-clockwise prop on the left engine and the right engine would be reversed with a pusher prop. That is how I have my 7 foot PBY set up.

O.S. used to offer a reversed crankshaft for their two strokes so a twin aircraft could be set up with handed props. Probably still do.

I am gasser now and one is a DLE 20 RA. I haven`t looked into a reversing crankshaft for DLEs. Would get rid of the crazy off-thrusts if they do.

Otherwise there is obvious expertise in this thread as to how to handle offset twin gassers in an R/C model with both rotating counter-clockwise as seen from the front.

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Old Apr 22, 2014, 06:43 PM
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epoxyearl's Avatar
United States, MD, Elkton
Joined Oct 2011
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I believe that a little too much 'theory' is offered, and not enough experience with actual flying.....

If a model airplane pulls 'left' on take off, right rudder is needed to correct the direction...simple enough....No one has to explain that engine torque,precession, the higher angle of attack of the descending blade ,and the amount of manifold pressure can cause this individually, or combined....just give it right rudder.

In a full scale plane you can immediately sense which engine is failing, or has failed.
Standing on the ground, with the model 1/4 mile away, you don't always know which engine is out, until the plane has reacted to the asymmetrical thrust. If you practice engine outs, you can adjust the proper rudder offset for either engine, if it fails.....immediately trimming into the 'live' engine can allow you to continue safe flight........You can only learn how much by practicing.

Guys who don't spend some time doing unusual attitudes usually watch their aircraft auger in. It is going to lose an engine- be ready.
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Old Apr 22, 2014, 07:30 PM
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ace4rc's Avatar
Joined Nov 2007
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Our gas engine's run just as well reversed as forward. The only thing that need's to be changed is the pickup magnet, it has to be relocated for the opposite rotation timing.
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Old Apr 22, 2014, 07:37 PM
Life is a Hobby
Canada, ON, Delhi
Joined Aug 2012
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Ace...........thanks for the info on reversing a gasser.

Short, factual posts like that are always the most useful.

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Old Jul 06, 2014, 09:59 PM
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USA, IN, Seymour
Joined Oct 2009
240 Posts

Originally Posted by epoxyearl View Post
Yes, I'm sure the modern radios have provisions to set up 'linked' throttles where one channel can be controlled separately..
I'm old school ,still flying 72 series equipment.

Twins are a mental challenge, akin to walking and chewing gum.
Double your pleasure
Double your fun
Get yourself two engines, instead of just one.
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Old Jul 06, 2014, 10:07 PM
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splinterz25's Avatar
Baltimore MD USA
Joined Jan 2011
4,763 Posts
Here try this this is where I got the best advice on twins,

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