Instrumenting the thrust stand
Being that I intend to be use this thrust stand to completely profile my rocket motors, I have been spending a lot of effort building the microcontrollers, software and data acquisition modules. In a sense, I feel like I am playing catch up for all of the work I didn't do on my first motor.
Since there are no moving parts in a pressure-fed liquid rocket motor, there are only a few places you can collect valuable data and even then you must interpolate it into something meaningful. One module in particular affords a lot of insight into the performance characteristics of the motors and that is the mass flow rates for the fuel and oxidizer.
 |
| Mounting rail for the load cell |
I fashioned a bracket out of a 1 ft length of 2 inch wide 1/8 steel flat bar. I welded it to a 1.5" c-channel that is welded to the top of the frame.
 |
| Back of the mounting bracket |
I wanted the load cell hanging from the mounting bracket and bolted to the top of the skate so I welded a pad onto the top of the bracket.
Next the skate is made of a 1ft piece of 4 inch 1/8" steel flatbar with 2 1/2" square tubes holding a piece of 1/4" steel flat bar that is threaded for the m4 bolts that fit my v-groove bearings.
 |
| Skate the the tank is mounted to |
Once assembled the grooves in the skate bearings slide over the 2" flat bar mount to provide a sturdy linear bearing.
 |
| Linear bearing |
 |
| Load cell mounts |
The load cell is mounted between the two tabs seen in the picture above.
 |
| Load cell mounted |
 |
| Closer picture of the load cell |
I zip tied the tank on until I figure out a better way to hold the 2ft long tank against the skate.
 |
| Holding the tank that I made back in Ohio. |
Now that I see the concept works, I am making another taller one that will have a universal mount to allow me to hold a variety including CO2, N2O and flight ready tanks.
