Hi from Christian

[Ripper]

I became a water rocketeer all the way back in 1999 when i was studying physics in Copenhagen Denmark (that's where i live). Since then, i've quit physics, but i kept on making a number of rockets. I like the open-minded spirit of the wr-community, and i want to achieve, not compete.
I've having a hard time getting suitable sodabottles here in Denmark, where a refund-system governs any fizzy beverage. Thus bottles are either 1.5L heavduty and meant to be refilled, or flimsy and filled with ripples and designed to be compressed after use. The heavyduty bottles will withstand more than 16bars of pressure(!) but pumping those by hand is impossible and the weight penalty is too much. Thus searching for suitable imported bottles is a never-ending quest.

I've however had a number of succesful rockets, although finding a large enough lauchsite is a problem too. I live in the city of Copenhagen and large areas of open space is scarce here...

I've solved this partly by developing a 2-stage recovery system. It's based on a radiocontrol meant for rc-cars or boats. By pushing one button, i can deploy a drogue parachute at apogee. This prevents wind drift during descent by having a rather fast descent rate. Close to the ground, i push another button to deploy a large chute to provide for a soft landing. The large chute can also be deployed alone should the drogue fail. Details and pictures are at the Water Rocket Group at yahoo: Old Mailing List

A couple of videos of my rockets with this recovery system in action can be seen on my channel at YouTube: http://www.youtube.com/user/Ripper2800

Pushing a button, and seeing a chute deploying at your command feels so great! But it requires good timing and nerves of steel to get the chutes out at the right times. The system has been performing admirely during 10+ launches, the only fails has been the main chute getting stuck in the nosecone (poor packing?) as seen on one of my videos, and that a fishing swivel that i use to attach the main chute snapped. Both of these has occured only once - the mechinism worked every time.

Cheers
Christian

[Tim Chen]

I became a water rocketeer all the way back in 1999 when i was studying physics in Copenhagen Denmark (that's where i live). Since then, i've quit physics, but i kept on making a number of rockets. I like the open-minded spirit of the wr-community, and i want to achieve, not compete.
I've having a hard time getting suitable sodabottles here in Denmark, where a refund-system governs any fizzy beverage. Thus bottles are either 1.5L heavduty and meant to be refilled, or flimsy and filled with ripples and designed to be compressed after use. The heavyduty bottles will withstand more than 16bars of pressure(!) but pumping those by hand is impossible and the weight penalty is too much. Thus searching for suitable imported bottles is a never-ending quest.

I've however had a number of succesful rockets, although finding a large enough lauchsite is a problem too. I live in the city of Copenhagen and large areas of open space is scarce here...

I've solved this partly by developing a 2-stage recovery system. It's based on a radiocontrol meant for rc-cars or boats. By pushing one button, i can deploy a drogue parachute at apogee. This prevents wind drift during descent by having a rather fast descent rate. Close to the ground, i push another button to deploy a large chute to provide for a soft landing. The large chute can also be deployed alone should the drogue fail. Details and pictures are at the Water Rocket Group at yahoo: Old Mailing List

A couple of videos of my rockets with this recovery system in action can be seen on my channel at YouTube: http://www.youtube.com/user/Ripper2800

Pushing a button, and seeing a chute deploying at your command feels so great! But it requires good timing and nerves of steel to get the chutes out at the right times. The system has been performing admirely during 10+ launches, the only fails has been the main chute getting stuck in the nosecone (poor packing?) as seen on one of my videos, and that a fishing swivel that i use to attach the main chute snapped. Both of these has occured only once - the mechinism worked every time.

Cheers
Christian

Hi Christian,

You should set up a trade business for bottles because the heavy duty ones you don't like to use are very much sought after by people in other countries which don't use them. There were a couple of water rocket people in the Netherlands who used them for everything and now they can't get them anymore and pretty much quit water rockets because of it. You need to get in contact with them and start trading!

[Ripper]

Hi Christian,

You should set up a trade business for bottles because the heavy duty ones you don't like to use are very much sought after by people in other countries which don't use them. There were a couple of water rocket people in the Netherlands who used them for everything and now they can't get them anymore and pretty much quit water rockets because of it. You need to get in contact with them and start trading!

Lol - don't know if it's even legal...
Anyway, i might have found a glue that's suitable for splicing, and then using heavy-duty bottles becomes another thing, as the weight gets chopped a great deal when removing the top or bottom part. But unless i can get them up to a high pressure, it probably still won't give a high thrust to weight ratio.
I've tested one 1.5L bottle with a bicycle pump. At higher pressures, i needed to have my friend clinging to my back to act as ballast on the downstroke! (i think you can agree that this approach is not practical ) Anyway, we go it to 15.5 bars (225psi). Then the pump died. The cap had started to turn from cocacola-red into white due to the stress, but the bottle itself didn't seem to be in any trouble.
With walls about 1mm thick, this type of bottle weighs about as much as two robinson-coupled 2L bottles. That's less than 40% the volume-to-weight ratio.

Cheers
Christian

[Tim Chen]

Ha ha ha.... I just pictured in my mind you pumping with your friend on your back to get the pressure higher. That's priceless!

I suppose if it was your GIRLfriend, that would be a positive, but if not it doesn't sound like a good method.

[WRA2]

I became a water rocketeer all the way back in 1999 when i was studying physics in Copenhagen Denmark (that's where i live). Since then, i've quit physics, but i kept on making a number of rockets. I like the open-minded spirit of the wr-community, and i want to achieve, not compete.

Welcome to the forum Christian,

Participation in our competitions is not a requirement for membership in the WRA2. We have a large membership base which includes everyone from beginners, Educators, and of course teams competing for the world records. Membership in the WRA2 is also not required to participate in this forum. As the largest community of people actively participating in the hobby of water rocketry we look forward to your contributions.