It has only been a week since the last launch so we took the old Polaron G2 rocket for a spin. During the week I replaced the FC V1.6 in the nosecone with an STII timer as this is easier to operate during launch. The V1.6 used a separate remote-arm cord that needed to be pulled before launch and then used the G-switch to detect launch. With the STII we used the break wire option to detect launch and so there is no need for a separate arming action.

 

In the backup deploy mechanism, the power switch on the prototype STII was faulty and because I didn't have a spare one I decided to make one of those simple screw switches. They are very easy to make, lightweight, easy to mount, and will not accidentally turn off due to vibration or things moving past them.

 

Screw Switch

Instructions on how to make one are available here: http://archive.rocketreviews.com/reviews/all/scratch_home_made_screw_switch.shtml

They are also available commercially here:

http://shop.featherweightaltimeters.com/product.sc?productId=3&categoryId=1

 

I made ours from an off-cut from an old PCB, and simply soldered a nut to one side. I also put a thick layer of solder on the contact area so that when you tighten the screw it digs into the solder for a good contact.

 

We extended the G2b rocket by a spliced quad to get the original full length G2 rocket as we first flew it back in Jan 2011 with the inline deploy mechanism,

 

Because of the issues with the #16 camera we taped the older #11 to the side. I am still waiting for the higher class SD cards to see if that will fix the problem with the #16.

Flight Day

Setup was straight forward and again we filled up the lower half of the rocket on the pad first with 4 L of water and then screwed on the top section. Because the new spliced quad had not been pressure tested yet we decided to launch the rocket at a lower 220psi just to be on the safe side.

 

Timer delay was set for 8 seconds which was a little past apogee for this pressure, but at least it also gave the back up uMAD deployment a chance to fire. It's better that the rocket comes down under 2 parachutes than on 1. If we deploy the main too early and the rocket stays pointing up, the uMAD never triggers.

 

The rocket took off fast and again made a lot of noise as it powered up into the sky. You can never get tired of the higher pressure launches :). The rocket flew fairly straight, although it did roll a little bit. It pitched over nicely at apogee and deployed the backup parachute as designed, shortly followed by the main. As the main deployed it twisted the rocket body around and wrapped the back up parachute shock cord once around the body of the rocket. This had the effect of moving the back up parachute attachment point further down the rocket, and as a result the rocket came down with nose angled towards the ground rather than tail first. The rocket landed well though in the grass without any damage.

 

The altimeter recorded 726 feet (221m) which was considerably less than what the simulator had predicted.

 

 

I'm not sure why that was, but perhaps due to increased drag from the parachute door? I don't think there was a leak on the rocket, at least we couldn't hear one from where we were standing.

 

Because the rocket drifted too close to the trees again due to the wind direction, we decided not to launch the G2 again.

 

We launched the Axion IV rocket a couple of times using foam. It's always fun to watch the slow launches as the rocket accelerates. These were only pressurised to around 120psi.

 

Paul also decided to build himself a water rocket from the spare parts we bring along for each launch. Within 10 minutes he assembled himself "Pod 3" and launched it. He also managed to fly 3 of his pyro rockets on the day and get them all back, so he was a happy.

 

What about progress on Shadow 2? .... more on that in the next update. :)

 

Here is a highlights video from the day:

Launch	Details
1	Rocket   Flygon (Paul's Aspire) Motor   D12-7 Altitude / Time   ? / ? seconds Notes   Great straight flight with streamer deployed just past apogee. It went high.
2	Rocket   Polaron G2 Pressure   220 psi Nozzle   16mm Water   4000mL Flight Computer   ST II - 8 seconds, uMAD backup Payload   HD cam #11, zLog, STII+uMAD Altitude / Time   726' / 43.66 seconds Notes   Good flight with parachute deployment after apogee. Backup deployed first and then main about 1 second later. Good landing.
3	Rocket   Pod 2 Motor   C6-5 Altitude / Time   ? / ? seconds Notes   Good flight and good landing.
4	Rocket   Axion IV Pressure   125 psi Nozzle   9mm Water   1500mL + foam Flight Computer   ST II - 5 seconds Payload   Jet foaming spacer Altitude / Time   ? / 27.8 seconds Notes   Good flight with slow takeoff and parachute deployment right at apogee. Good landing.
5	Rocket   Pod 3 Pressure   120 psi Nozzle   9mm Water   1000mL Flight Computer   ST II - 3 seconds Payload   None Altitude / Time   ? / 14.8 seconds Notes   Good flight with parachute deployment right at apogee. Good landing.
6	Rocket   Axion IV Pressure   125 psi Nozzle   9mm Water   1500mL + foam Flight Computer   ST II - 5 seconds Payload   Jet foaming spacer Altitude / Time   ? / 29.86 seconds Notes   Good flight with slow takeoff and parachute deployment right at apogee. Good landing.
7	Rocket   Thunderbee Hero Motor   A3-4 Altitude / Time   ? / ? seconds Notes   Good flight and good landing.