Making an ejection baffle for the DEFCON 1


Contributed by Rich DeAngelis

I took this picture to better show you what the baffle is like. Already installed in the baffle's tube coupler is the lowest baffle as seen from the bottom (engine side). Above that will be the baffle to the right, shown right-side-up. Ejection gas that makes it past this stage can't move towards the center until it passes the small 13mm tube glued to the top of the second baffle. Positioned just above that 13mm tube will be the top baffle where gas ejects from the center hole. This whole baffle assembly will be positioned as far to the top of the body tube as possible, while allowing room for the parachute, shock cord, bulkhead and a little bit more. There are two reasons to have it as far up as possible. 1) Improve stability by keeping as much weight towards the nose of the rocket, and 2) Allow plenty of space for the ejection gas to cool and prevent over-pressurization of the body tube in a too-small lower section. Worst-case, a extra strong ejection charge could cause the lower chamber to burst wide open. If that were the case the parachute would not eject but that really doesn't matter at that point because all you'd get back is a pile of cardboard and balsa scrap.

Notice also the small hole on the top baffle piece. This is supposed to hold the Kevlar cord, which will be knotted and glued to the bottom side of this baffle piece and the string passes through and up the body tube.


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