This blog covers the day to day progress of water rocket development by the Air Command Water Rockets team. It is also a facility for people to provide feedback and ask questions.

Monday, September 15, 2008

Test stand work

It's been a fairly quiet week as we have had a number of non-rocket related engagements. This weekend I continued work on the test stand. The test stand now has the basic frame and the load cell and load cell amplifier attached. The load cell to rocket coupling is also almost finished. We still need to support the rocket under test to stop it moving from side to side, but that will be done over the next day or so. We are quite keen to try the test stand and we will likely do a few test runs this week.

My mum has also started helping out in preparing the bottles and sleeves for splicing. This has drastically reduced the amount of time it takes to splice bottles together. I was able to do 4 splices in less than an hour.

I'm also in the process of writing up the full details of the test stand, but those will only be published after we have fired the rockets a few times so we can also report on the repeatability and accuracy of the setup.

If people have suggestions for tests they would like to see results for please let us know in the comments section below.

Some of the thrust tests we have planned are:
(each test is likely to be run 3-5 times to eliminate variance in water and pressure levels)
  • 9mm nozzle with water only
  • 7 mm nozzle with water only
  • 5 mm nozzle with water only
  • 9mm nozzle with Jet foaming
  • 7mm nozzle with Jet foaming
  • 5mm nozzle with Jet foaming
  • 9mm CD nozzle
  • 7mm CD nozzle
  • 15mm nozzle with water only
  • A look at the chocking effect of Robinson coupled bottles vs full bore tornado couplings.
  • Variable nozzle performance with water
  • Variable nozzle performance with foam
  • Different foam generating techniques
  • Comparison of different foaming agents
  • Comparison of foaming agent concentration
  • Test differences in the convergent section of the nozzle


Tom Stanton said...

hi george

you could test a 13mm nozzle to see how much thrust each booster makes.


George Katz said...

Hi Tom,

How much volume will each of your boosters be, and what pressure would you be using? We can replicate something similar here so the test results are closer to what you will be flying.

One of the things we are keen to do is verify the thrust profiles against simulated ones. If they are in close agreement, then for day to day rocketeering, simulations are easier, and when trying to optimise a particular design then the test stand would be the way to go.

Tom Stanton said...

hi George,

Each of our boosters will have an 11mm nozzle and will be 2litres, we will fill the booster to 100psi and we will us 800ml of water.