Fuel grain geometry

[magnitude_and_direction]

Hey guys, I'm currently into building my own motors and was wondering if anyone else out there currently uses star grains? I currently use a bates grain configuration (basically multiple toilet paper roll shapes stacked together with a slight gap between each) but I end up taking a long time to make each grain and then shape it to get the right geometry. I was wondering how many people out there make star grains and how they do it? Particularly interested in any thrust and pressure calculations that can be done, as my casing is currently designed to handle 1000 psi.

If it helps, the propellant I use is RNX-57 (a Richard Nakka development).

Thanks!

 

[Banzai88]

This thread probably belongs in the Research topic.

 

[3stoogesrocketry]

Hey guys, I'm currently into building my own motors and was wondering if anyone else out there currently uses star grains? I currently use a bates grain configuration (basically multiple toilet paper roll shapes stacked together with a slight gap between each) but I end up taking a long time to make each grain and then shape it to get the right geometry. I was wondering how many people out there make star grains and how they do it? Particularly interested in any thrust and pressure calculations that can be done, as my casing is currently designed to handle 1000 psi.

If it helps, the propellant I use is RNX-57 (a Richard Nakka development).

Thanks!

First do not mention any formulas or ingredients anymore . Second , is there a reason you need a star grain geometry? What are you trying to accomplish?

Eric

 

[tim cubbedge]

Contact cwbullet for access to Research Forum. Not much will be discussed here.

 

[magnitude_and_direction]

Alright will do. Was not my intention to violate any rules my apologies.

 

[djs]

my casing is currently designed to handle 1000 psi.

Not sure how you determined the casing strength, but generally this is too low.

Also, assuming you're in the US, try to find a local Tripoli prefecture and learn from people who are already making motors.

This is assuming you are 18+, of course.

 

[heada]

By "star" I assume you mean finocyl, correct? Most core designs, BATES, moon, finocyl, etc. are made using a mandrel and casting or pressing the grain around it. Some grains are harder to make than others. Finocyl are harder for several reasons but I fear I can't go into detail without the thread being removed. As others have said, if possible, join the research sub-forum here and there you can discuss details.

 

[G_T]

Star grain is a little different than finocyl. There are many grain geometries used to essentially keep the burning surface area near constant, beyond just Bates.

Gerald