Acceleron V to 864' (263m)

We had a good launch day today at the NSWRA launch. We flew the Acceleron V 2-stage rocket a couple of times again. Both flights went great with the first reaching our new personal best of 864'. On the second flight we angled it a little away from the trees because of the wind direction. The rocket went up to 829 feet. Both flights were flown at 120psi again.

Just after the air pulse phase.

 View from just after apogee. Tiny cars!

I'm in the process of putting together an update for the main website with more photos and a highlights video. That should be finished towards the latter part of the week.

The update will also include more details on the Polaron G2 rocket.

Progress update

This week we continued with the nosecone plug and it's now ready to start forming nosecones. I need to get some mould release agent this week so we can start. The fiberglass is all cut up as well. The guys on  Australian rocketry's forum as well as the Yahoo water rocket forum have given me some really good tips on on preparing the mold and the upcoming moulding process.

We also pressure tested 3 more of the spliced quads to 270psi. We have 5 of these now ready for flight, with two more to be fiberglassed this week.  So far we are quite happy with the quads, but until we test them on real rockets with the kind of forces they will experience in flight and landing we won't know for sure.

To get an idea on what we are up against, we assembled the spliced quads into the Phase 3 main stage, and put a representative sustainer on top. The boosters and fins are not shown.Once on the pad it will sit at least another foot off the ground. We will definitely need a full size ladder for launch day. :)

Last night I also prepared the 3 fins to be used on Phase 1 of the rocket. All three of them weigh 83 grams, but will need to be attached to the removable fin can which will likely double that weight.

Nosecone, Testing and more fiberglassing

This weekend we pressure tested two of the spliced quads to 270psi. They both held well, and should be good to go for the 250psi launch pressure. I was a little concerned that they may stretch too much because of their length and leak, but there seems to be enough flex in the glue to cope with it.

We also made another couple of spliced quads which are now curing. This now gives us 5 of the spliced-quads which (if they all pass the pressure tests) will be used for the Phase 1 of the Polaron G2 rocket. 3 of the segments will be coupled together with tornado tubes and a couple as spares.

We have also started making a plug for the fiberglass nosecone. The plug is made from 10 layers of 19mm MDF. Each layer was individually machined to shape and then glued together. We have opted for the efficient ellipltical nosecone, as our rockets travel well below the speed of sound.The nosecone is 110mm wide.

 

Here is the nosecone plug before final sanding

Fins and Fiberglassing

As a part of the work we are doing with Polaron G2, we are looking at different fin materials.

This week we are comparing 3 different ones. The first one is a regular 4mm 3-ply plywood fin. This fin is very tough, but the main drawback is its weight. At 74 grams it is the heaviest. Thickness is 4.2mm.

The second one we tried making out of two 1.5mm sheets of balsa wood glued together at 90 degrees to each other with PVA glue. We then put one layer of 200gsm fiberglass on either side. Epoxy resin was used for this. The fin is quite tough and weighed in at 43 grams. The thickness is 3.9mm but the main drawback is the amount of work involved to do this and the higher cost.

 The 3 fins tested. Left to right: corriflute, balsa/glass sandwich, plywood.

The last fin is made from corriflute, the material we have been using until now. It weighed in at 25 grams, but has a thickness of 5mm. It is quite tough, and has a good finish, but the main drawback is that it is made from polypropylene and hence harder to glue and paint. The leading and trailing edges are also harder to create nice and smooth.

So far the balsa sandwich is probably a good compromise, unless we can find some nice lightweight plywood.

We have also spent some time this week getting Acceleron V rebuilt and serviced so it can be launched again. We also did a 50psi leak check. We'll try to launch it again soon just for fun.

We were supposed to go out to the NSWRA launch today, but after driving half way there in pouring rain, we decided to turn back. As we got back, the weather cleared up but the wind had picked up. So we went back to the workshop and fiberglassed 3 of the spliced-quads. We are going to give them at least 5 days to fully cure before pressure testing. We are going to try to push them to 270psi for the 250psi launch pressure. We'll see how much they'll actually hold.

 3 x 5.3L spliced quads wrapped in fiberglass.