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.

Thursday, August 20, 2009

Acceleron Photos from 4th July

A big thanks goes to Andrew from NSWRA for shooting the following photos of the Acceleron V booster in flight. We didn't get any still photos of the launch on the day as we were busy shooting video. (click on the images for a higher res version)

In the first one you can see the turbulent flow from the red and blue nozzles, whereas the green nozzle has very nice laminar flow (seen further down the plume).

The second photo is my favorite one with the air pulse starting and the sun reflecting from the sustainer.

The last one shows the rocket shortly after staging occurred. The black fins of the sustainer are about to clear the nose of the booster.

I'll post some of the other photos of the flight in next main page update.



Sparthir Kiwiwarrior said...

Firstly your site and everything you folks are doing is awesome! Keep going.

1. Have you guys ever though of constructing near identical rocket systems at the same time so if you loose one or want to compare minor design changes it is easier? You may even be able to fly simultaneously in the same conditions for better comparisons.

2. If producing a laminar flow is the desired effect have you considered the design and fitting of a type of fluid flow control system? Not sure how these might work but either something before the nozzle or directly after it to slightly improve the fluid dynamics might help? I'm also thinking that something before the nozzle in the main chamber to reduce gases entering the fluid flow might be worth looking at.

George Katz said...

Hi Sparthir,

Thanks for the questions.

1. We actually do this quite often on a component by component basis. If we are building something we will build 2 or 3 of them since we already have the materials and tools at hand, it makes it more efficient that way then setting up again next time. We usually keep these for spare parts if we damage the main component.

Comparison flights are always valuable, but with the limited time we have for trying out different things we often don't do as many comparison flights as we should.

2. Laminar flow is nice if it can be achieved but not at the expense of efficiency. We normally get reasonably laminar flow from all three nozzles, but the problem with this flight was that we had a couple of protruding seal washers in the nozzle flow and that's what caused the turbulence.

It may be a worthwhile test to see if a fitted flow control system would achieve any better efficiencies.

Bubbles in the water definitely cause drops in thrust. On some of our rockets we have fitted a baffle that redirects the air coming from upper bottles to prevent air mixing with the water.

There are still lots of unknowns about what is the optimal way of managing the complete flow of water/air/foam based on nozzle profile and materials used. Hopefully people doing experiments in this area will help shed more light on the subject.

Sparthir Kiwiwarrior said...

Hmm sounds like there should be software that might be able to help model that for you. If not then there sure should be someone out there that could help write it.

The initial modelling etc could be done to narrow down some designs.

I think that your trials and tests are probably going to be the best way to measure this in real world situations. Doing thrust tests for power and duration is more than likely going to work best.

If I find any software to do this I'll post a link for you guys. :)