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Prop in Slot Q's

I'm building a homemade prop in slot Airplane!(I think) I haven't decided if my plane will fly like a Nutball or a prop in slot. So what do I need to know if I should decide to do prop in slot? I.E. prop rotation (tractor or pusher) CG in relation to the motor, general stuff! I really appreciate it!


G'day Mate
With "prop and slot" it doesn't matter which way you have the prop turning (pusher/tractor), use what you have.
Keep the CG in the same place as usual.
For the slot position, somewhere between the middle and the rear. The further you have the motor to the rear the more the battery will have to go forward for correct CG. BUT if the slot/motor is too far forward when you move the battery back for correct CG it may hit/be where the motor is.
The best way to work it out would be to install everything except the motor and prop and have it taped on top to test CG and adjust as needed and when the CG looks good then cut the slot.
No need for side, up/down thrust, just have it straight and level.
With prop and slot it will be a lot more noisy than tractor motor configuration at the front.


Well-known member
What shape are you aiming for?

Nutballs fly way way way different than anything else primarily due to the wing shape. Tractor (front mount) is the way to go.

If it "looks" like a plane of some sort, as mentioned, prop in slot is fine pusher, tractor, both, whatever. Nose heavy always wins for maiden and adjust the COG from there.
I'm not making an actual Nutball! I'm not sure whether my experimental aircraft would fly as a prop in slot or like a Nutball. There is a type of race boat, you can google it. They're H-1 Unlimited Hydroplanes. My dad used to drive lower class hydros. In the first picture, it's my representation of what his would have looked like if he drove unlimiteds. I'm using it as a model to scale it to fit foam board However, the boat is called a Hydro PLANE, so I want to fly it! I have never done prop in slot, but I have flown my friend's Nutball. It's a diy project, so there's no plans, and I figured that you on the forum could give me some advice on how this stuff works before I move ahead on building. Thanks for all your help

I'm going to knock out the front canard wing in the very front to do a Nutball. (on my model it says NGK) on the real ones, it does control pitch so the boat doesn't "blow over" because it would do a half loop and the thing (still going 200 mph) would hit the water inverted and that's not good
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Yea I'm down at seafair watching the real ones today. Mine isn't going to look as the one you showed. Mine is going to be a profile plane and fly like a Nutball. I was considering prop in slot but I don't think it'd really work...


Well-known member
Be prepared - I have one of these (that I need to repair...hmmm) they don't fly very well. Mine is setup in a tractor config.