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.

Tuesday, September 02, 2008

Multi-stage rocket

We flew our new two stage rocket with drop away boosters last Saturday. While things didn't go exactly according to plan, we still learned a lot from the two flights.

The full update is available here along with photos and video:



Anonymous said...

Hi George
Have you already found out why the staging mechanism failed? Maybe it's because of the higher G-forces created by the drop away booster?
regards christian

George Katz said...

Hi Christian,

No we don't have the root cause yet. We still need to put it up on the test stand and fire the whole configuration. We have been busy doing non-rocket related stuff last week, but are back to it this week.

We tested it the night prior to launch day and was all ok. I'll post the results when we find out.


- George

Tom Stanton said...

hi george

mabey it didn't sperate because the elastic bands weren't tight enough.


George Katz said...

Hi Tom,

It may be that the rubber bands weren't strong enough, although we are pretty sure that the stager was properly released when the parachute had opened on the sustainer, as it staged at that point without issue. If it as still locked it would not have released.

The leading theory at the moment is that it actually wasn't the stager at all. We suspect that it was the stabilising carbon fiber rods that kept the rocket in place. As the rocket is pressurised the bottle expands and it pushes the rods further appart. This would have caused them to become wedged in the tubes the rods are inserted in. Even with all the pressure gone in the booster, the sustainer still would be stretched continuing to hold the rocket in place even after the staging mechanism deployed. (we did have silicone grease on the rods for exactly this reason) The parachute opening would have caused enough force on the rods to pull them out of the tubes causing the staging. The other piece of the puzzle that fits this theory is that after the first flight we increased the piston spring force so the stager would release at a higher pressure and hence earlier and it did not make any difference. If the rods were doing the holding then any changes to the stager would not have made a difference.

We will test this theory on the pad sometime in the next couple of weeks.