3W 42i Engine Manual
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tray. Fuel tanks, batteries, and other equipment can be mounted on top of this tray; the canister(s)
being installed below it. Close off the lower compartment at its rear with an angled former. Locate
this former 1" behind the back of the canister(s). Next cut a hole in the bottom of the fuselage just
under the rear of the canister(s). In this way the air coming from the front of the model can flow
over the canister(s) and then be deflected by the angled former so as to exit through the hole in
the fuselage. Do not forget to reinforce around this hole.
Important:
This exit area needs to be four times (4x) as large as the intake area.
Propellers
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Only use propeller brands and sizes that are approved for your engine
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The propeller blades must be of the same length
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The propeller must be flat (You can check for flatness by putting the propeller on a level
surface. The maximum difference of the blade heights should be no more than 1/64".)
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The propeller tips must have an identical shape. This is especially important when using
3 or 4 blade propellers.
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You must use a drill press to drill your propeller.
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You must drill the propeller from the rear.
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A drill guide is recommended, but the propeller washer can be used as a drill template. (Fix
the propeller washer onto the propeller in the center-bore using a bolt and nut. Drill one
hole; put one of the propeller bolts into the hole. Continue until the last bolt is used.)
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If you cannot hand tighten all of your prop bolts easily then you have not drilled the propeller
correctly. This can lead to sheared propeller bolts.
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Balancing your propeller is absolutely critical to the health of your engine. You must keep
your propeller balanced. (Propeller balancers are available from DUBRO, and others.)
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Always remember that when the engine is running every person must stay behind the line
of the rotating propeller; never to the side or the front!
