Iddons

What is the best way to install a mass to set CoG?

Epoxy down some lead ?

Where is generally the best place if tail heavy, under fuel tank, in the nose ?

Deadeye

First, move the radio gear around if you can. Any weight you don't have to add is a good thing.

If your radio gear is as far forward as you can go, and it is still tail heavy; you want to add weight as far forward as possible, like behind the firewall. You could also try a heavy Harry Higley's prop nut. This puts the weight as far forward as physically possible on a plane. The farther ahead the weight. the less you have to add.

hookedonrc

This will sound nuts, but I actually have used a small sack of gravel taped and sealed. It conformed to the fuse real well and didn't shift around. I did it only on one plane and that was because the hobby shop was closed on the day I was getting it ready to fly. It worked though.

Roby

If I need weight forward of the CG ,I will move the radio stuff around
and/or use a "heavy hub"

If I need weight aft of the CG ,again I will move equipment around ,not use the "hub"
and I will go up in the dowel size for my pushrods.

Regards
Roby

Jimmbbo

If moving equipment around won't work (the best way), and weight must be added, I use buckshot (available at gun shops) and epoxy. The buckshot fills in oddball spaces that might otherwise be unusable, and when mixed in epoxy, is unlikely to shake loose.

You can figure out how much weight you're going to need by using a baggie of shot where you think it should go (as far forward or aft as possible, to minimize the amount of weight required), and adding/removing buckshot till the model balances (will also work with cut up tire weights or fishing sinkers - smaller pieces are better). Remove the shot from the baggie, mix it in a cup with some epoxy, and pour it in.

Jim