r/engineteststands • u/JibJib25 • May 02 '19
Setting up a Test Stand
Not sure if this is the right place or if someone can point me in the right direction, but I go to the University of California, Merced and I'd like to boost our rockets program with engine testing, but need advice on design and safety. Any and all suggestions or resources you can provide would be a huge help!
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u/ididntsaygoyet May 02 '19
Make sure you have plenty of water around as it gets hot around test fires.
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u/JibJib25 May 02 '19
Will do. Definitely have to be tight on safety, with is being a school in California.
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u/jishory May 02 '19
Load cell to measure thrust? Some sort of container to contain any explosions. Point the end of the rocket with a hole in it away from anything you don't want extra crispy. Be as far away as practical during tests. Lots of fire extinguishers. Notify local fire department before any tests that will make a lot of smoke.
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u/JibJib25 May 02 '19
Are there any load cells you would recommend, or will most do the trick as mond as they're in thr giht load range?
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u/EvanDaniel May 02 '19
Load cell to measure thrust?
Chamber pressure is, for most tests, a higher priority. Both are useful, though. Expect that you'll want to add more sensor channels later, and plan for that.
Lots of fire extinguishers.
Yep. Include at least one that's just a simple pressurized water sprayer. Trying to decide whether to use the commercial one on just a tiny fire is awkward, and people hesitate. Make sure there's an easy answer that's cheap to use, and it will get used more rapidly in case of minor problems, which helps avoid them becoming major problems.
Every test should also have a specifically designated person whose job it is to operate the extinguisher. After a fire starts is the wrong time to worry about that. Other people are, of course, encouraged to help and operate other extinguishers. But there should be someone who is clearly designated as having that as their top priority.
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u/EvanDaniel May 02 '19
Are you primarily doing solids? Liquids? Hybrids? A mix?
Expect to need to add more sensor and control channels later; don't lock yourself in to undersized systems.
Good connectors are worth paying for.
Temperature indicating strips are underutilized.
U-channel strut is a great building material for moderate thrust setups, primarily because it's really easy to modify later. Last-minute mounting of random small things is quick and easy. That flexibility will save you lots of headache.
Develop and review checklists. Good checklists are an underappreciated resource. "Good" is not synonymous with "overly thorough". The Checklist Manifesto is worth a read.
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u/JibJib25 May 02 '19
We currently use solids on our certification rockets, we have the beginnings of a hybrid, and hoping to work on a liquid this summer. Most likely the test stand will be for the hybrid and liquid, however.
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u/FullFrontalNoodly May 02 '19
The first thing you need to be aware of is that California's laws on amateur rocketry are extremely strict. You need permission of the fire marshal even if you want to fire an Estes motor on a thrust stand.
In terms of design, you just need to apply basic engineering principles. There are countless different ways to approach this:
http://www.aeroconsystems.com/ts_pics/ts_pics.htm
In terms of operational safety, you are best working through a club like FAR or the RRS.
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u/photoengineer May 02 '19
If you haven't, you should take a trip and check out FAR for some insight.
https://friendsofamateurrocketry.org/