I've never had to bother with vibration with my electric systems but I'm getting a lot of air bubbles in the fuel line in one of my nitro birds. I'm hoping that I don't need to use the foam clunk that I've just bought because I've also bought a prop balancer and can see that one blade on the APC prop is definitely heaver than the other. I've read that you can sand some prop away, paint on some varnish, or even stick a little bit of tape to the prop. Surely sanding can only weaken the prop or change the geometry. I'd prefer the latter. Would this be ok ? Also, is it true that the prop is balanced if it stays settled in any position apart from when the blade is resting on the bench ?

If you're talking about a 14" prop or smaller, then if the prop rests at a 3 O'Clock and 9 O'Clock position, that's good enough.

Sanding the back side of the prop all along the edge and along the thickest part of the center of the prop (not the core but along a center line from the "center to the tip" will remove what you need to remove for proper balance. APC's are generally pretty good, and either don't require balancing or require very little. It won't hurt the prop.

If, though, it's really bad, then throw it away and replace it.

CGr.

Paint is better...and grass to rebalance everything after you get done mowing the runway.

Don't mess with sanding the props ...especially wood props.

I generally just sand the leading edge of Master Airscrew props to get rid of the molding seam...that's it.
After a couple of nose over...that's about all the time and work I'll do to props.lol

Wrap soft foam (somthing like your mouse pad or softer) around your fuel tank.

Also re inspect all of the screws for the engine mount. Use BLUE loctite (so you can remove the screws later) or
use NYLOCK type nuts.

Put foam (such as seal strips for windows or doors) either on the wing or the fuelage for the wing's saddle.

nail polish works well for adding weight to the light side of a prop it sticks well and drys fast.

What few APC prop's I've had to balance, I've just sanded a little stock off and they worked just fine. I have one on my OS 1.20AX and it's been on there now for about 8 months (my Venus II) without a problem. Sanding is just fine as long as you don't over do it.

CGr

Don't forget to balance your spinner too!

And if you've reamed the prop hole slightly off center, you may have an out of balance problem that the prop balance will not easily catch.

The prop may appear to balance, but one side will always appear to be "down".

I've been using the aluminum prop-spinner nuts (they (Dubro) also make brass ones that are heavier if that's needed). They work fine, altough don't look as neat as a full spinner. They are functional (won't wear or gore with the electric starter cone) and add a little bit of nose weight where it's needed most (if you need it, that is). And, they don't need to be balanced.

CGr.

I can't put foam round the tank as there is simply no space between the formers and the tank. May have to install that foam clunk but it will be a PITA to get the tank out.

Blue locktite ? Every time thanks ;-)

Those sintered ( sp? ) brass anti-foaming clunks that Dubro sells have worked fairly well for me.

You may want to give them a try.

They act as a filter too.

Yeah.. I am pretty much sold on those things. They certainly cover building/assembly mistakes..err..whatever..

I had one plane that was not doing well after about 1/3 of the tank had been consumed. It would get lean and quit. So, someone suggested getting those anti-foaming clunks.. think it may have been here on RCU, but I can't remember, it was quite some time ago. I swapped it out and the problem simply disappeared. Now, removing and replacing the tank may have had something to do with that, but I would prefer to attribute it to the anti-foaming clunk and let it go at that. If it works, don't fix it, right?

CGr

how do i balance my Cf spinner which has no hole in the tip, due to the fact that the cone is attached to the backplate using screws around its base?