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.

Wednesday, February 04, 2009

FTC rocket upgrade

We've been working on a number of rocket related projects this week. We started redoing the FTC payload bay that includes several improvements. We are replacing the split nosecone made from FTC to one made from Fiberglass. The fiberglass is a lot stiffer, but still lightweight and does not collapse like FTC does when it is cut in half.

Because we used a piece of FTC to form the half-shells, their diameter is also the right size for fitting over the FTC tube. The V1.5 flight computer used is being replaced with the smaller V1.6, and the batteries are being replaced with four AAAAs. The net result is a more compact payload section that is a little lighter than the predecesor. We are also creating smaller fins for the rocket to reduce the overall weight near the tail.

We have also tested an all-Sikaflex splice this week with the glue failing at around 130psi. The glue had given way, as both the sleeve and the bottle that was glued inside the sleeve were undamaged. The glue was left on both surfaces. This means that this glue probably should not be used for pressures above 100psi. We have a number of spliced pairs using this glue already made for the Acceleron rocket, so we will have to replace them with PL splices. We can still use them on other test rockets so we will hang on to them.

Fiberglassing is definitely a messy business but I'm getting used to it a bit more now. Last week I bought a proper respirator with organic gas filters for $45 and its really effective and I can't smell any of the resin when working with the fiberglass.

As we are working on a lot of spliced pairs at the moment, there is quite a bit of sanding to do of the surfaces to be glued. We always used to do it by hand, but we've made it a little easier now by getting a piece of PVC pipe and cutting a pair of long slits in it. We then take two rectangles of sandpaper and put them back to back and place them in the slot. The pipe then goes in the lathe. When it spins the sand paper makes a kind of S-shape and makes it much faster to sand the outside and inside of the bottles. It reduces sanding time by about 1/3 and also is alot easier on the hand strain.

Soldering up the flight computers has also been performed in the background in spare time, and documentation continues to be worked on.


1 comment:

Unknown said...

Hi George,
Thanks for the info on Sikaflex. I purchased a few lengths of T8 FTC from a local electrical supplier so it looks like I'll have to invest in some PL Premium before we start playing around with them.
Mat Gardner