Tuesday, April 17, 2012

Star Shaped Core

I've been trying to come up with a way to create a star shaped core without the need for a machined
mandrel and a way that would also reduce the risk of having to deal with a stuck mandrel.  The above image
illustrates what I came up with.  I'm currently making a version of this jig that has several features added in so that I can actually try to cast a grain with this set-up. The most notable features are a star shape on the base that helps seal the bottom so that propellant doesn't seep under and into the core, a hole in the center of the base to ease the installation of the tape, and a secondary top cap which helps to keep everything centered.


Ben Brockert said...

It's a cool idea, but I don't expect the tape will hold shape that well against a viscous fluid. At best it will want to be a semicircle between the posts; at worst there will be large variation in the shape through the engine.

It'd probably still fire ok, though. But if you're doing it as a concept for SS2S, Richard seems the type to really like consistency.

Randy Dormans said...

Hey Ben,
Thanks for the comments. The tape is certainly a big unknown but there are a lot of different types that I can try. I'm thinking of using plain masking tape for the first try, but may use fiber reinforced tape if the regular stuff doesn't hold up. I should have the set up ready to try soon and will definitely update with the results. And as far as consistency goes, I like it too :)