I am in need of a data logger to measure the thrust of a rocket Vs Time. I have the test stand (or sensor) which is a simple resistive sensor. I plan on running a voltage across it, in which the voltage will correspond to the amount of thrust produced.

I have picked out these 2 data loggers; Im kinda on a budget here.

http://www.omega.com/ppt/pptsc.asp?ref=OM-EL-USB-1

I was thinking of USB-3. I like portablity, and I dont want to get a laptop.

or this:http://www.sparkfun.com/commerce/pro...roducts_id=752

But it seems like Id have to decode the ascii with that one.

I dont want to have to pay for software either. Does any one have any other suggestions? I basically need to record voltage. My current setup involves the camera recording a ohm meter, but it seems the meter might not catch "spikes" in the thrust (and it doesnt seem too fast to me).

 

Loggers can be nice, but since the experiment taks place in a short time, why not use an A to D converter to read the thrust directly into the computer? Might save some unnecessary hardware that way.

Unless the rocket motor might go pop, in which case the logger is a better sacrifice.

 

Well I have found a 8 bit data logger that would be perfect for my application, it uses the parallel port which I dont mind, and it doesnt cost a ton of money. Plus Id have to solder the thing myself, So its an added bonus!

I would have to run a long cord from the computer to the test stand, I thought parallel started to get funky after 25ft.

The engine shouldnt blow, the worst that can happen is a hole would burn through some where on the engine, causing a release of gases. But that wouldnt effect the logger in anyway.

Unless I found a cheap laptop, something like a 400Mhz comp would be all I need.

 

No question that the logger will record data. Do you get enough resolution out os 8 bits? that's only 256 discreet levels. If you are also looking for transients in the thrust, can it sample at frequent enough intervals to catch the spikes?

 

Well I dont want to have too many bits, or else I'll have too many data points to graph.

http://www.dataq.com/products/startkit/di194rs.htm

When ever I searched google, dataq was always #1 on the list. To tell you the truth, Most people who test their engines use dataq loggers. I Also figured that I wouldnt have to run a long serial/parallel port cord from the test stand to the computer, I can just run a long cord like so:

Computer-Data logger---------------------Test stand

Instead of

Computer---------------------Data Logger-Teststand.

Since Im only measuring voltage, theres only a distance of about 40 feet between the test stand and the computer. In worst case scenario, I would have to design a circuit to get rid of the noise. However, I Do have a mini computer (Old HP 400Mhz) thats pretty small. I could set it on a table and use that instead of a lappy.

Motor Burn times are Very short, and are around .1 seconds to 1 second (but it depends on how long the motor is, how wide it is, propellant grain, and what type of propellant is used). An added bonus is it comes with 4 channels, so if there was a need to measure other things, I could. And at 25 bucks, I dont think you could beat that kind of a deal.