Each flight log entry usually represents a launch or test day, and describes the events that took place.
Click on an image to view a larger image, and click the browser's BACK button to return back to the page.

Date: 23rd August 2012, 5:00am - 5:30pm
Location: Kurnell, Randwick Race course, NSW, Australia
Conditions:  20 - 40km/h very windy, warm 25C, partly cloudy in the morning, overcast and stormy later
Team Members at Event:  PK and GK

TV Commercial

Last week our rocketry club (NSWRA) was approached by an advertising agency filming a TV commercial here in Sydney that involved a father and son building and launching a water rocket. They had the actors but needed some water rockets and a launcher. So we agreed on a design with a couple of options that would work for them. In order to simplify the whole shoot it was decided that no recovery system would be used. They were aware that the rocket would be destroyed after just one flight so they ordered 5 of them. They were on a tight schedule and we only had several days to get them all ready. The design was based on the Axion II rocket. Luckily we had enough parts and bottles to make up the required rockets. I think we ended up using close to 80 x 1.25L bottles on the actual rockets and spare parts.

The rockets

Each rocket consisted of 2 spliced pairs and a single bottle to give a total volume of around 5.45L. These were coupled together with normal Tornado tubes with the holes enlarged and custom washers fitted. The rockets also had coriflute fins. The nosecone was just an empty bottle with half a ping pong ball for the tip. We also taped an old C- battery onto the top bottle for extra ballast. These batteries weighed 68 grams. The whole nosecone was just spray painted red. Initially they asked for the fins to be painted silver, but the day before the shoot they asked if they could be painted red instead and so we re-sprayed them red. The entire rocket weighed approximately 450 grams.

We also prepared 3 parachute nosecones just in case they decided that they wanted parachutes on the day.

We ended up making 5 rockets + 1 spare.

Paint scheme as originally requested	Front view. There is no recovery system	Preparing all the rockets a couple of nights before.
Last minute re-spraying fins.	Instead of painting we wrapped the splices with red electrical tape	All neatly staked in a box.

The launcher

Initially they asked to use our old green launcher, but dad and I also modified our medium launcher to make it look a little more home made with a couple of wooden planks for the base. we also added the guide rails from our old green launcher so that it didn't look too complicated. On the day they decided to use the medium launcher which was a better choice because it was more stable than the old launcher especially with the taller rockets. Normally the small launcher wouldn't be an issue because we pin it to the ground with tent pegs, but because they were shooting on the rocky headland there was nowhere to hammer the pins in.

The medium launcher that was used for the shoot.	Here is the medium launcher being worked on.

Launch day

This was definitely our earliest start for a launch to date. We got up just after 3am so we could drive about 1 hour to be on location by 5am. The nice thing was that there were no cars on the road at that time.

5am Start. It was pitch black.	Sunrise on location at the headland.	Waiting for some other scenes to be filmed.
We started off with nice blue skies	but pretty windy	getting ready to set up the rockets

Due to the location being directly under the approach flight path to Sydney airport, we had to restrict the altitude of the rockets. Since the actors were going to be close to the rockets anyway we only used lower pressures.

Right under the flight path.	Dad working hard as always	Deciding on how the scene will work

The other major problem was the very strong breeze blowing out to sea. We knew we may loose a few of the rockets in the ocean. This really didn't matter as they were one flight rockets anyway.

Rocket set up on the pad	For quick set up the rockets were pre-filled with water and foam.	Director deciding how the scene will play out.
One of the camera men.		Spare rockets ready for launch

They first did several takes of the father and son setting up the rocket. After that they managed to get 2 launches in before the crew had to move on to another nearby location. Although there is a foot pump in the scene, it was never used as it would have taken too long to pump up the rockets by hand. We remotely pressurised the rockets from the scuba tank. The hose was buried under some sand so you couldn't see it.

Burying the hose to the scuba tank.	"Father and son"
	"Action"

The first rocket flew well and came down about 30 meters off the edge of the cliff and on the rocks below. The second rocket had a similar flight but the wind blew it further out and it landed in the ocean. One of the crew managed to retrieve both of them later when the second one washed up on the rocks.

We always had to wait with each launch until there were no planes coming in for a landing.

Remotely pressurising the rocket	Waiting until the plane goes past... ... and launch.

Then we packed up the gear and headed back to unit base for lunch (The catering was awesome!) while they filmed some more scenes with the father and son getting the rocket out of a car and arriving at the launch site. They wanted to get some more shots of the rockets going up into the sky, so we set them up at the local park near where we had lunch, but weren't sure if they would get through all their other scenes before filming the rockets.

Lunch with the crew.	Waiting at the local park to see if they were going to film some more.

So after 2 hours of waiting we packed up and headed to another location at the Randwick (horse) race course where they were going to be filming horses racing. They rented out the whole race track!

Setting up a camera on a boom	Off to film a horse race	Horses getting ready and doing what race horses do.

We set the rockets up in the middle of the track ready for filming should they get a chance. Finally at about 5:00pm they had an opportunity to film the rockets in flight so we launched one with foam using the Jet foaming spacer and a second one without. The light was fading fast though as a storm was approaching so I'm not sure if they'll be able to use that footage or not. Both rockets flew great and also nicely crumpled on impact. The wind was still blowing hard at around 30-40km/h. Way too strong for what we would normally launch in.

Waiting for the film crew ...	... as a storm approaches.
Launch with jet foaming spacer	Regular launch at twilight

I don't think we will get many more opportunities to launch our water rockets right in the middle of the Randwick race course. Just as we finished packing up the last of the rockets a huge storm came through with lightning and even stronger wind so we all went home. It was a long day, but a lot of fun with a very friendly crew, and it was good to see what all goes on behind the scenes of a commercial shoot.

When the commercial is finished, and if it's available on line I will post a link to it here and also mention who the client was.

Servo Timer IIs

We've been busy over the last couple of weeks soldering up more of the Servo Timer IIs. As we are making these in a greater quantity this time, we were able to get better volume discounts on the components so the timers are a little cheaper than last time.

If you are interested in using one, they can be purchased here: Servo Timer II

Components from Digikey have arrived	ST II PCBs	ST IIs ready for testing

Centrifuge

In testing of the timers we noticed that some G-switches need more acceleration than others to activate. The specification says that they activate between 2 and 4.9G. 5G may be difficult to achieve on rockets using small nozzles and foam or low pressures. So in order to characterise the G-switches we built a little centrifuge so we could see at what G-forces the G-switches actually activate. The centrifuge was built using the kids Lego Mindstorms NXT 2.0 kit. It made it easy to build and control the speed of the spinning arm. The test circuit simply consisted of a 9V battery an LED and a resistor hooked up to a socket so we could plug the G-switches into it easily. The distance of the G-switch from the center could also be adjusted to vary the acceleration force.

We used the high-speed camera to measure the actual speed of the spinning arm. We weren't looking for specific activation force, but more at the relative distribution of the activation forces for the G-switches if they were roughly the same or whether they varied widely.

Centrifuge for testing G-switch activation force	Centrifuge in operation

Flight Details