ORIGINAL: B.L.E.
Richen up the mixture if you are using a 4-stroke glow engine. Loctite comes in three strength grades. Blue, Red, and Green. You want to use the Blue Loctite.
No - you
DON"T want to use Loctite
PERIOD, on a propshaft.
What engine do you have?
If the nut keeps coming loose, there is something else wrong. Find the problem and fix it, don't cover it up and create MORE problems.