Development and repairs

We spent this weekend in the workshop repairing J4 II after its explosion last week. We basically replaced all the bottles with new ones, as some of them had been in use for 6 months or more. All the brass couplings were replaced with new Aluminium ones, reducing the rocket weight further.

We also taped all the inter-bottle rings to the rocket with a wide flexible tape, similar to electrical tape. This made the rocket much more solid.

We also reconfigured Hyperon III into a 3 bottle configuration as it will fly a long payload section when the weather clears up. Hopefully next weekend.

We also finally ordered a couple of altimeters last week, so I am hoping they will arrive this week. If they arrive in time, we should be able to fly them on the next launch opportunity.

We've also been working on a new simple and compact electrical pressure switch which we hope to test in the next few days. The prototype only weighs 10 grams but it should be possible to reduce that down further. The purpose of the switch is to serve the same role as the TDD, but without the exposed external moving parts. We use a TDD to detect when the pressure drops inside the rocket (at burnout) to activate the staging mechanism.


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Flight computer V1.3.2 test flights

We had a chance to fly a couple of rockets this weekend. It was mostly about testing a new flight computer and doing some foam flights just for fun. We got some good onboard video as well.

http://home.people.net.au/~aircommand/day44.htm

... oh and got a good wakeup call on water rocket safety ...
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Hyperon Flights at Damo's space port

We had an excellent weekend launching rockets with Damien Hart from Damo's Water Rockets. It was good to finally meet him and his family in person. The weather was well behaved and so were the rockets. (Well mostly)

We took turns in launching rockets, and as a grand finale we combined Damo's booster with our sustainer for a two stage flight.

The full details of the flight day are available here:

http://www.AirCommandRockets.com/day43.htm

and Damo's great write up of the day is here.

We'll have to do that again.
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Deployment systems

This weekend I spent time making the deployment systems around the two new flight computers. These will be fitted to 90mm rockets. One of them will be fitted to J4II instead of the NOAA deployment system we have been using. The other will be a spare for one of the three rockets (Tachyon II, J4 II and Hyperon). The new flight computers are now using the CR123A lithium batteries.

I also spent time this weekend building and testing a circuit that is going to form the core of a data acquisition system for our rockets. It is again based on the PIC16F628A microcontroller we have been using for the flight computers, but this one will be dedicated for collecting in-flight data. The part of the circuit that I tested was the RS-232 communications between the PIC and my PC through RS232. This way we will able to download the collected data from the unit. Eventually this RS232 interface could also be connected to a telemetry stream back to a base station. Each of these data acquisition units will record one or two channels based on the sample frequency required. It is planned that any number of these small units will be able to be placed on the rocket to gather as many channels of data as required.

I am also hoping to use one of these acquisition modules in our static thrust measuring rig for when we test new rockets.

Hopefully on Sunday we will get to fly more rockets again.
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