- This topic has 8 replies, 4 voices, and was last updated 16 years, 1 month ago by
Tom Martin.
Tom Martin.-
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Tom Martin
I just recently joined the club, and have an interest in making some of my own sugar motors. So I decided to build a test stand. I have some good designs for load cells to do the measuring, and I think I have found a good data logger for the application. What I am missing still are a few good ideas for the stand itself. I would love some ideas for a stand that would have the motor pointed directly upward. Any one in the group done this recently and have some successes or oopses to share?
Jeremiah Johnson
I’ve got a test stand that MB built that you should take a look at if you’re in the Broomfield area sometime. Send me an email or call me at 303-502-7389 and we can arrange a time to meet and you can see what you think of the design.
edward
If you don’t want to invest the money I’ve got a stand I’ve let members in the club use. Records thrust and pressure at 10kHz. One stand is 6″ motor capable to 5000lbs thrust.
Edward
Tom Martin
Thank you for the offers. I would love to see both of these. I think I will be building my own stand primarily for the experience of it. Thanks for the offer for the use of the existing stand. I will be in contact. It may be a bit before I can get in touch with you guys. My wife is about to have a little girl.
Do either of you have photos, plans, or descriptions?????
edward
My stand has the motor pointing down as I test hybrids, but it isn’t hard to switch around. I used a piece of 1010 rail as the mount with a hinge system on a 1″ C aluminum channel to pipe clamp the motor to the channel. It works very well as there is little friction so you get accurate readings. Since I mainly test hybrids I have the option to record three variables – Chamber Pressure, Thrust and Nitrous Tank pressure all at up to 50kHz, but I generally run them at 10kHz. I’ve made my own Matlab program to reduce the data and do the calculations for me.
I also have a ballistic evaluation motor that I’ve used to determine the ‘a’ and ‘n’ numbers of different propellants.
It is hard to describe the stand and I don’t have any plans 🙂 I’m in Fort Collins and you are more than welcome to come look at them after a launch.
Edward
Bruce R. Schaefer
also have a ballistic evaluation motor that I’ve used to determine the ‘a’ and ‘n’ numbers of different propellants.
Edward, remember I gave you some of your Sorbitol back last January at the dinner, and you said you’d pass those “a” and “n” numbers on to me. Would you? I’m really interested. Thanks!
edward
Yes! I tested them at 3 different KN values. I got an ‘a’ number of .305 and a ‘n’ number of .01 .
I used potassium nitrate that I got from a co-op. These number were obtained with non-milled potassium nitrate. I also did test with potassium nitrate that was ball milled to for 120 hours. It burned considerably slower though the density was better. It also had to be packed rather than poured.
Edward
Bruce R. Schaefer
Interesting. Regardless of how fast a powder burns uncontained, how it’s packed, how much it’s milled (particle size), etc., you never really know how it’ll perform until you test it in a moter. Great data! Thanks!
Tom Martin
mrtidy I sent you a PM.
Tom Martin
Jeremiah Johnson
edward
Bruce R. Schaefer
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