It's been mostly quiet on the rocket development side over the last few weeks with the school holidays, and being busy at work. But progress has been continuing on the Shadow. I've mostly been working on the payload bay that carries the batteries, altimeter and camera. That's now mostly complete and just needs to be secured in the rocket. I still need to drill access holes for all the electronics.
Dad and I discussed an issue yesterday about how the uMAD behaves. Due to the magnetic inclination in Sydney being about -64 degrees the uMAD detects apogee differently in different directions as you would expect. While in the "good" directions it detects apogee just as the rocket turns below horizontal, but in the worst case scenario the rocket needs to be near vertical (inverted) to detect apogee. If the rocket were to weather cock in the "bad" direction (and Murphy says it will) and flew in an arc, it may never reach the near vertical flight path in relation to the magnetic field. So we decided to include a timer back up for parachute deployment. Since there really isn't a whole lot of room for a fully redundant system, we decided to do a firmware update for the servo timer, so that it will handle both the external uMAD input as well as it's internal timer.
We are going to use the break wire option again to trigger the timer. The servo timer firmware has now been updated so that which ever event fires first the servo will be activated. The firmware listens to the uMAD even if there is a problem with triggering the timer.
We've also been looking at the Polaron G2 - Phase 2 development. One of the things that is evident in releasing the clustered rocket from a common point is that there will be about 2000N pulling on the neck of the central bottle while on the pad. This would likely damage it, and so we are re-designing how the nozzle will be attached, and likely include struts to distribute the load from the boosters.
We've had several requests now for a tutorial on how we fold our parachutes, so earlier in the month we posted a how-to fold a parachute tutorial to add to the myriad of others already on the net.
http://www.aircommandrockets.com/parachutes.htm
I've also spent some time this month re-editing some of the old videos, removing boring bits, improving the colour, and re-uploading them in higher resolution to the new YT channel. This process will take a while though before all the videos are processed.
The Shadow is currently scheduled for its maiden flight on the 28th January if the weather and winds are good. Initial launch pressure will be 330psi (~23 bar) and if the rocket survives we will try again at a higher pressure.
