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.

Monday, January 23, 2012

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.

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.


Rodrigo said...

Nice!, this beautifull rocket must fly on the good way!
Good luck!

Douglas Nulty said...

Hey George,

Its all building up to next weekend for the shadow now then, I wish you the best with its flights =]

He He yeah Murphy's law would have it that way!


MrZ said...

I'm glad to hear that the development of the Polaron is going on.

This Shadow thing looks very nice, but to me a massive multi stage rocket is way more spectacular.

Anyway, your work is AMAZING...

Keep going!

George Katz said...

Thanks guys. The weather so far isn't looking all that great for this weekend. Predictions of rain for the rest of the week and on the weekend. :( We'll know better closer to the weekend.

Jan said...

Hi George,
What kind of rocket will the Polaron G2 - Phase 2 be?
To get a force of 3000N, you need a high pressure and/or large surface for all the nozzles together.

The rocket I' planning will be launched at 8 bar with max 3x Ø22mm nozzles and 1x Ø9mm nozzle. That makes only 962N of pulling force.

It seems that you can't launch on Saturday due to the weather conditions.
If we can believe it, next weekend (04/02) it will be dry and with not too much wind...
A good site for weather prediction :

George Katz said...

Hi Jan,

Ooops that was a typo, that should have said 2000N. Thanks for pointing it out, I've gone back and fixed it in the post. We are designing it so we could use full bore (22mm) nozzles on the boosters, as well as a larger central nozzle. The target launch pressure is 250psi (~17 bar).

A Karman said...

Hi George,

I'm a big fan of your site, I'm checking it daily, sometimes more than once,to see if there's another update. Can't wait to see the first video of "the shadow".

Good luck!


George Katz said...

Thanks Arjan. The launch video of the Shadow will have to wait a bit longer, as the launch for this weekend has now been cancelled due to the weather. Our launch windows are dependent on the NSWRA launch schedule, as that is when we get access to the launch site and have the altitude clearance.