Category Archives: Water Rockets

Servo controlled launcher

First thing to find out was a RC servo is strong enough to pull the launcher release. Did some succesful dry tests up to 60psi as these were indoor tests I didn’t go above 60psi for safety reasons.

As I want the servo to be controlled by a microcontroller so a camera could also be servo controlled I needed to find out if the servo would work over a long cable. At 100 meters with the cable still on the reel there was to much loss for the power to be carried at that length. With the power on a shorter cable and just the signal on the 100 meters the servo worked but there was a lot of jitter.

Since I would not be needing anywhere near that length I repeated the test at 10 meters. Power loss was still a problem but there was no problem with the signal. So I have a additional power source at the launcher for the servo.

I have a microcontroller controlling the servo and also a second servo which will pan the high speed camera up at a predefined speed at launch.

Video processing

I use VirtualDub for processing my videos. I noticed it has this feature where you can export the video clip to a series of photos and import a series of photos to a video clip. Which gave me the idea I could do some of my own processing.

Now since I’m terrible at keeping the camera steady and also tracking the rocket. I though it would be a good idea if I could video the rocket more zoomed out then afterwards zoom in on the video clip once transfered to the computer. Also now you can buy HD video camera it makes it even more worthwhile With VirtualDub producing a series of photos I thought this would be possible.

Since I didn’t want to  individually open up each photo in a photo package and crop and then save. I thought a little program to automatically open the photo I would then click on the rocket and the program would then crop and save the photo and then open the next one.

I’ve successfully wrote such a program but it was still a bit boring clicking on the rocket for each frame. Now since the photos in question are usually of a dark object against a light background I thought I might have a chance of writing the program to actually find the rocket itself.

A few more days of programming and a few unexpected problems I’ve met with success. At least for the one bit of footage I’ve got and while only the sky and rocket is in few. I’ve managed to exclude the ground to a certain extant by making a few assumptions. Trees and Churches on the horizon do cause problems still.

I need to get some more footage to try it on and then I’ll be able to post the results. A HD camera would be handy as well. Christmas is coming 🙂

It’s also given me an idea for another project.

What went wrong with premature stager launch.

My stager is a gardena type connector with the spring removed and arranged so the spring pushs it open. It’s held closed by the pressure of the first stage inflating a bicycle inner tube against the inside of a pvc pipe connected to the ring of the connector.

On removing the pipe I found unsurprisingly the inner tube had got wet from the first launch. The water acted as a lubricant between the inner tube and smooth PVC pipe. I need to add a ridge to the inside of the PVC pipe which I was going to do originally but skipped it since it had such a good grip without (dry of course).

Launch Day 5

Planned launches

  • Tango Ia with green nozzle 60psi
  • Tango IV to test stager and parachute if above succesful

Pumped Tango Ia with the green nozzle up to 60 psi to test the nozzle would hold the pressure. Then launched which was difficult since the restricted nozzle launcher needs a lot of force to release.

Tango IV is a combination of Tango III with modifed Tango II as a second stage. Each stage is 700ml and was filled with 300ml of water each. Pressure was 60psi.

The nosecone departed to early so the launch didn’t test the deployment device. I was pumping the rocket up for a second flight when at about 60psi the first  stage released the second stage. The nose cone stayed on until the deployment device pushed it off. But since it was a premature launch without the first stage it hadn’t got very high and was about 2 meters before impact with the ground. So the parachute didn’t get a chance to open. The deployment device was wrecked.

I’ll be moving on to my next range of rockets with a higher volume before trying the parachute deployment device again.

Launch Day 4

Planned Launches

  • Tango Ia from stager with restricted black 9mm nozzle at pressure 35psi with 250ml of water
  • Tango II at 35psi with 300ml of water to test chute
  • Tango III at 35psi 1st stage 250ml, 2nd stage 300ml water
  • Tango Ia with restricted 9mm green nozzle at 50 psi with 250ml water.

I was pressed for time due to only having a bit of free time at the end of day and there isn’t much daylight this time of year. So I went and forgot to take anything to measure the water out so I think I under filled the rockets which might of been the cause of some failures.

First launch was to test that stager released the second stage when the first stage loses pressure. It was also to test that the second stage would pull out the parachute of the first stage. So the rocket was pressurised and then released the pressure from the first stage. This does pose a problem for launch aborts.

Second launch was to test parachute deployment of final stage. I think due to underfilling the rocket there was not enough flight to for the deployment.

Launch 3 was to test the stager in a actual launch.

Future parachute deployment tests will be done at higher pressures with enough water to give a chance for the parachute to deploy.

Chute deployment 2

Since it didn’t work to well on the first attempt I thought a bit of a redesign was in order. The core device is the same, the difference is that it has a seperate parachute compartment ahead of it and the nose cone is pushed of by a rod connected to the device.

Ground test went well.

Filming Checklist

  • Set video camera to record at 8x Zoom
  • Turn vivitar
  • Set vivitar to video
  • Set vivitar to 4x Zoom
  • Turn on Casio check video setting
  • Set to 3x zoom
  • Turn on ActionCam
  • Start recording on video Cam, Actioncam,Vivitar,Casio
  • Point at launcher wait for focus
  • Check framing on Casio
  • Record for a few seconds
  • Try to find rocket and follow.

Flight Camera

I bought this with the intention to fly it on the rockets to get inflight video footage. I bought this one as it was small, light, cheap and also it has the choice by a slide switch that it can take either video or photos. So when I add a flight computer I can take higher resolution photos than the video clips which are 720*480. Although I have since read on the internet that the sensor might only be 640*480 I’ll have to take a close look a the photos it takes.

As bought.

The insides after I’ve soldered some wires to the switch so it can be controlled by a flight computer or just easier to start it recording when it in the rocket.

Put back together with the wires glue so not to strain the solder joint.

Now I need to be able to bring a rocket back down softly so I can fly it.

Launch Day 3

Planned Launches

  • Tango II full bore at a 35psi with 300ml of water
  • Tango Ia full bore at a range of pressures starting at 40psi with 250ml of water
  • Tango Ia with restricted 9mm nozzle at a range of pressures starting at 30psi with 250ml of water

Decide to try a few launches late in the day and since I had little light left I only took a video off the TangoII launch. Which was to test the parachute deployment.

The deployment device appeared to work, but the parachute didn’t eject properly and catch the air.

Did a succesful launch of the Tango Ia at 40 psi full bore nozzle.

Attempted a launch of Tango Ia at 35psi with the restricted 9mm nozzle but it didn’t release. Then tried at 45psi and launched successfully. So at least the glue on the nozzle holds up at 45psi.