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.

Thursday, March 31, 2011

Servo Timer II test flights

This weekend we went down to the local park to start the Servo Timer II trial flights. We flew a total of 7 flights with the timer and thankfully all worked well. Two of the flights included the uMAD for triggering the timer at apogee.

The full launch report along with a highlights video is here:

We are now preparing larger rockets to continue the tests. We would like to do an additional 10-15 more flights before starting a production run of the timers. Yesterday I was going to do some tests with one of the timers, and noticed that I had left the power switch ON, and completely drained the battery over the last few days. So this morning I updated the firmware to flash the LED briefly every 5 seconds to remind me to turn the power off.


MariusD said...

Hi George,
From what I saw, I think that you didn't want to change the G switch with a bigger value (e.g. 5G). How did you filter it? Probably reading consecutive values -on- (e.g. 50-100ms) and see if they are still on for 3-4 readings.
You must give some details for new ejection system. Probably you must tweak it a little because it is influencing rocket drag with that gap. At least for G2.

George Katz said...

Hi Marius,

We need the 2G g-switch because some of the foam flights have fairly slow takeoffs at around 3G so we need to be able to detect those. The filter is simply a counter that counts up when the G-switch is activated, and counts down to zero when open. If the counter goes over a threshold then a launch is detected. So far the trigger threshold seems to be working fairly well. It samples the G-switch at around 10Khz.

I'll post details of the new G2 deployment mechanism once it is tested.