Report on BATES grain simulation written by me :)

I had to do a lab recently for a computational science class I am in. I had to choose a model and write up a report about it. I chose Scott Fintel's Solid Rocket Motor BATES grain burn rate simulator.

Although I probably got some facts wrong, I would just like to see if anyone has input on the validity of this information, or any other comments.

View attachment FletcherLab1.pdf

Exhaust throat diameter has an effect on the performance of a motor. It should be slightly under optimum and pass through optimum to slightly overexpanded for the best result. A motor with a nozzle designed for the optimum at sea level would perform poorly at Hartsel, Colorado and it's 8800 foot altitude. Designing a proper nozzle for an experimental launch with like an AeroTech K185 would give a measurable difference in altitude especially at Hartsel.

OK. Thank you.

Nice write-up but the term BATES grain has become equated with one or more double end burning center-perforated propellant grains, but that not quite right. From the history of the Ballistic Test and Evaluation System (BATES). https://www.dtic.mil/cgi-bin/GetTRDoc?AD=ADA405742

"A BATES motor uses a double end burning center-perforated grain designed for maximum neutrality, minimum sliver, andminimum mass addition from insulation and for manufacturing simplicity. The grain is cartridge loaded in a phenolic tube. The motor also has a very low web fraction, which combined with the cartridge design places very low requirements on propellant properties."

This is a really great reference which describes exactly what a BATES motor is designed to do.

Bob

Interesting - I always thought Bates was somebody's name.

Question... what is web? I know it deals with propellant thickness.... but what dimension?

Web site the thickest part of propellant the flame front will need to progress through. In a BATES grain, the web thickness is the distance from the edge of the core to the outside of the grain. IE, if you have a 2" diameter grain with a 0.5" core, the web is 0.75". Or, web = (dia - core) / 2.

When you have two or more BATES grains, how do you know which one is the master?

grouch said:

When you have two or more BATES grains, how do you know which one is the master?

Click to expand...

...the one holding the whip?...