Launch postponed

The NSWRA launch has been cancelled for this weekend due to the continued slightly damp conditions. This means we need to postpone the launch of the Shadow again until the next launch window opportunity. NSWRA is having a "show-and-tell" day instead which should be fun since we normally don't get a chance to talk to people at length during a regular launch day.

The extra time should give us an opportunity to do a little more testing before the launch.

Progress update

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.

The Shadow - Launcher video

With Christmas celebrations mostly over, dad and I put together a short video today that describes how the Shadow's launcher works and how the rocket is loaded onto the launcher. I've added the video to the latest Shadow update here:

http://www.aircommandrockets.com/shadow.htm#_171211

Other than that there really hasn't been much happening with all the lead up to the holidays. I've added a few links to Facebook and Google+ from our main website. These will be updated regularly with latest developments as well so if you prefer to receive updates that way or just want to chat about rockets then those should make it easier.

Here is The Shadow with a fresh coat of paint:

Merry Christmas!!!

We all know we want one of these for Christmas

We wish you and your family all the best for Christmas and also into the new year!

Unfortunately we've run out of time to launch The Shadow this year, but we should get a chance to launch it at the next NSWRA launch in January. The quiet time over Christmas should allow us to also complete a couple of other projects that we've been working on. I'll post more on those when done.

Now where is my helmet? ... I'm pretty sure I saw a rocket sled sized box under the tree.....

The Shadow - coming together

We've been flat out over the last couple of weeks, but have had time to work a little on the Shadow. We've now finished the launcher, and the fins are now also attached to the rocket. The nosecone and payload bay have been painted which will make them easier to find should they separate from the rocket.

In the next week or so we should have the rest of the payload bay complete with the camera, altimeter and batteries still to be mounted. The rocket at least is now starting to look like a real rocket. :)

I've update the build log with a few pictures from the last couple of weeks.
http://www.aircommandrockets.com/shadow.htm#_061211

Reefing Parachutes

This weekend we went down to the local park to fly a pair of smaller rockets to test a couple of techniques for reefing a parachute to stop it opening too quickly during high speed deploys. The first technique used the old reefing ring approach and for the second experiment we simply twisted the shroud lines. We managed to fit in a total of 6 flights before the wind picked up.

We’ve written up the results from the experiments here:

http://www.AirCommandRockets.com/day114.htm

The update includes a video that shows how the reefing works in flight.

 Reefing ring preventing the parachute from opening too quickly.

Simple break-wire trigger

We've had a number of requests now for how to add an external trigger to the Servo Timer II for the very slow launches that the built-in G-switch may have trouble detecting. I've added a tutorial on how to add a simple break-wire option to trigger the timer on launch. In most instances it should not cost anything.

http://www.aircommandrockets.com/servo_timer_V2_0.htm#_tip5