FIT JAMSTAR high altitude ejection

[AlexBruccoleri]

Hi, Does anyone have a live link to the FIT JAMSTAR project that Bob Krech linked in a previous post? I am specifically interested in reading about sealed containers with diaphragms for high altitude ejection.

https://www.rocketryforum.com/threads/high-altitude-ejection-charge-testing.21562/
Thanks, Alex

 

[JimJarvis50]

Hi, Does anyone have a live link to the FIT JAMSTAR project that Bob Krech linked in a previous post? I am specifically interested in reading about sealed containers with diaphragms for high altitude ejection.

https://www.rocketryforum.com/threads/high-altitude-ejection-charge-testing.21562/
Thanks, Alex

Alex,

I wrote an article on the topic that started the thread you posted. The article is attached (I've posted it many times here on the forum). I have used this approach on five flights above 100K. I looked at the links at the time, but I don't recall any specifics about what was done.

Jim

 

[AlexBruccoleri]

Hi Jim, Thanks for the reply. I read your article in a past thread and its great. Thanks for publishing your projects. Unrelated to recovery, I think you are a top rate craftsman with composites!!.

I was curious what type of burst disk were used. Bob claims the "pros" use them but I could not find anything specific. For what it is worth, burst disks are tricky. You need to make sure they have the right flow rates once burst, which requires testing like anything else.

Cheers, Alex

 

[JimJarvis50]

Hi Jim, Thanks for the reply. I read your article in a past thread and its great. Thanks for publishing your projects. Unrelated to recovery, I think you are a top rate craftsman with composites!!.

I was curious what type of burst disk were used. Bob claims the "pros" use them but I could not find anything specific. For what it is worth, burst disks are tricky. You need to make sure they have the right flow rates once burst, which requires testing like anything else.

Cheers, Alex

I would be speculating, but I suspect that if you want to build pressure for the charge to fire, and don't want to use a long charge tube to accomplish that, then a burst disk would be a way to do that. It would not surprise me if the pros did that so that conditions could be controlled with varying powder levels and with a smaller package.

Contrary to what Bob said back when, with the longer charge tube, it is not necessary to have air in the tube. Most of my tests were without air and all burned 100% of the powder. Having said that, I do seal the charge with a thin cap of epoxy (not a burst disk) just so that the ematch works better. The other thing I do differently than what is written in the article is to have the ematch located closer to the top of the powder.

Jim

 

[blastzone]

Curious, has anyone done any testing with larger diameter tubes, instead of longer? To get more volume by increased diameter, but not having to have really long thin tubes?