Discards from a hole-saw carbon/balsa/carbon laminate serve as the basis for a disk to attach to a 1/4" dowel to create the piston-plunger. Turning down the laminated disk to fit inside of the bomb body with some clearance so there is no drag is accomplished by turning the disk on a fixed pivot against a sander. Locating the piston on the pushrod (dowel) is accomplished by inserting the dowel rod with piston disk positioned on the rod into the bomb nose, attaching the aft section, and - ensuring the dowel contacts the aft section, without disturbing the dowel position - pull off the aft section and push the piston disk against the back of the balsa nose section. A fillet of epoxy is applied to the union of the piston disk with the dowel at this location. Determining the length of dowel rod to leave out beyond the nose is simply a matter of pushing the piston out until it emerges the back of the center body and cutting the excess off the front even with the nose.
#1 & 2 are fabrication of the piston disk.
#3,4,5 shows process of locating piston disk on the dowel rod and bonding in place.
#6 shows bomb in complete form before "detonation".
#7 shows bomb after "detonation" - the sanding bar I'm holding represents the ground; by virtue of the relative movement of the nose and center body with respect to the piston plunger, the aft section and contents should be ejected. (you can just make out the piston peeking out at the back of the center body)
