My 9” motor uses two pieces of phenolic tubing 34.75” in (nominal) length
as liner for 67.5” of case bonded propellant. This means that the joint
between the two pieces of liner is exactly at the center of the propellant
grain.
Given that some hot gas will—intentionally—fill any voids between the liner
OD and the tube ID, it follows that such gas could ignite the back of the
propellant grain at the joint unless that joint is sealed.
Is there an experience in sealing such a joint against hot (or, at that
location, probably just warm) gas?
Thanks,
Bill