Building an Explosion-Proof Rocket Motor Test Stand
HTML-код
- Опубликовано: 31 окт 2022
- Support Me On Patreon: / projectsinflight
In this video I show how to build a Rocket Motor Test Stand capable of collecting thrust data from rocket motors! I even attempt to make it resistant to unplanned motor failures.
DISCLAIMER: The videos on this channel feature materials, equipment, and activities that may be hazardous. By choosing to replicate or participate in any demonstrated activities, you acknowledge and assume all associated risks. You the viewer are responsible for your own safety. ProjectsInFlight and its creators are not liable for any resulting harm or damages.
Parts:
Load Cell: www.amazon.com/gp/product/B01...
Code: github.com/projectsinflight/R...
Schematics: drive.google.com/file/d/15JAz...
Drawings:
Base: drive.google.com/file/d/1tMfD...
Motor Holder: drive.google.com/file/d/1ZqO5...
Full Assembly: drive.google.com/file/d/1p-fy...
STL Files:
Base: drive.google.com/file/d/1vUhJ...
Motor Holder: drive.google.com/file/d/1rQkr...
Electronics Box: drive.google.com/file/d/1rFB2...
Correction:
10:58 Make sure you are following all relevant laws for your area! 
Наука
I don’t understand anything about rockets, but I still found this all to be interesting. Great delivery!
Came here after watching your tube furnace video and enjoyed this one just as much.
More videos please! 🙂
I took the same journey and feel the same way. Please and thank you for your fantastic content!
I'll do my best! Got a few upcoming in the next month or two
Can't wait! Just subscribed! @@projectsinflight
that note about load cells is spot on.
a lot better than my model rockets, and you've actually fired motors, which is more than i can say
Back in the age of dinosaurs, you could actually find and purchase professionally produced design handbooks for Amateur built rockets (Not 'model' rockets, but high power scratch built), and one paperback book that I still have is 'Rocket Manual for Amateurs' by Capt. Bertrand R. Brinley (1960) from Ballantine Books (price then was $0.75 new). Deals with all aspects of rocket design, fuels, testing, safety, ranges etc.
incredible video. I really like to see more of these type of equipment making video.
This is awesome! - Jay
Awoo! That was amazing!
Good videos; interesting and well made.
Very cool!!
Cool!
Don't forget to check the gap with a piece of paper or something.
Since even a small grain of sand can become stuck in it and throw off the measurement.
That's a good point yeah. I should do that
Cool project. Your lathe reminds me of my lathe.
Looks like the same model to me
Good shit
You have an unusual thrust curve. The burn looks progressive for the first 0.7 seconds then increases from 2.5N to 12N in the next 0.1 seconds. The thrust continues to increase progressively to 24N at burnout over the next 0.4 sec. I have no knowledge of your propellant configuration but most should not exhibit that burn profile.
Propellant burn rate is usually a function of pressure (r=b×p^n where b and n are characteristics of the propellant). Pressure is a function of burn front area to nozzle throat area and the burn rate.
Given those, there are 2 main causes of unpredicted thrust, burn front area to nozzle area and high burn rate exponent, n greater than 1 = boom!
Likely causes of this thrust profile are:
1) Assuming a cored grain, ignitition didn't start at the head of the fuel grain(s). This can cause the fuel to burn at very low pressure until the rest of the grain ignites.
2) Propellant started burning where it shouldn't, e.i. between the grain and the housing.
3) Propellant porosity makes burn rate unpredicable.
oh yeah that motor was definitely exhibiting some kind of problem. i suspect a crack in the propellant or something
Really amazing thing man, loved it. i think this can be replicated in poor man's way too.
Most of it can- I'm currently looking into a way to do metalization that DOESNT require a thousand dollars of high vacuum gear
Thats really fascinating, looking forward for that video. By the way, will you upload more content related to these rocket motor? I really love the way you make your content. Amazing, please always keep it up!
You're a machinist, electrical engineer, mechanical engineer and write programs. 🤯
Almost every mid level rocketry hobbyist is a sum of all the above.
@@jacks19822Fr fr can attest
Question regarding these types of test stands: Aren't you also measuring the weight of the motor as well as the thrust? Obviously you can calibrate the load cell to the initial motor mass but as the rocket burns, your weight is decreasing in a non-trivial way and it would seem difficult to subtract that from your thrust measurements.
you are correct. usually the weight of the motor introduces a small error, which can be approximately removed by assuming a linear burn rate or mass removal rate i guess. i didn't bother because the mass of the motor was more than an order of magnitude less than the thrust and i didn't get to the point where i needed the extra exactness of the measurements
smart AF
Do you think this design would withstand a cato’d 1” ID whistle motor?
My first thought would be to build a slightly gapped support for the motor mount itself (limit vertical travel) instead of limiting the load cell deflection. In the old version, just having a bolt coming out the bottom the motor mount could limit travel to stay within safe limits?
Yeah, the old one definitely could have been modified with a travel stop like you said. I like the S-type load cell mostly for it's simpler mounting
Inspired questions:
Is fire 🔥 electricity in slow motion ?!
What over the counter substance could I add to my gas for more bang 💥 bang !?
Your thoughts.
I thought this was a chip-fab channel... This explains the channel name and logo though :) Eagerly awaiting whatever projects you decide to work on.
I used to have a different name but no one could spell it. I changed the name in order to make it easier for people to search/spell. I chose the first name i could find that was entirely dictionary words and wasn't already taken and had some relevance to my work
@@projectsinflight It's a good name :)I think it will go far :)
I have the same type of load cell as you, a compression and tension one. I am using your code and wiring but the output is the tension not the compression... Whats can I do?
does it measure compression at all? if it's backwards that would be relatively easy to swap in code. otherwise i'd think maybe the wiring is different than the one i have.
@@projectsinflight I figured it out i had the white and green wires swapped! Thanks
Hey cool vid, could you share what software you used to design this.
Seems like a much easier cad software then what I am trying to learn.
Fusion 360
Could the motor burn and output be controlled a bit better with a nozzle?
There's a rammed-clay nozzle in there. It's not the best but it is definitely the easiest nozzle to make
Did you used mathlab for these plots?
engagement
Great video but unfortunately none of your links work
Why do none of the links work
As far as i can tell, youtube breaks your links for "security" reasons until your channel reaches a certain size
Context: Deflection is highly dependent on the location of the force [Strain = Force * (distance^3) / (3*Modulus of Elasticity* second moment of inertia)]
Problem: The rocket holder spreads the force over a large area, and the contact area will change with the deflection.
Possible misunderstanding: There may be a gap between the holder and the gauge, although I am unable to confirm from the video.
Possible Solution: Use a washer to concentrate the load only near the mounting hole.