Water Rocket Forum

I have been testing MkII of my Tomy timer based side deploy nosecone. Seems to work well on the ground. Will be testing it at altitude this weekend. Here is a video of it in action

[youtube][/youtube]

-todd-
HHWRSA

Looks good! Why not tie a string to your launcher and have it pull out a pin or move a lever to trigger the timer instead of that air flap. It would reduce the drag which in turn will make the rocket go higher.

the timer had quite a bit of torque for its size when wound up so holding it in place needs something solid.

I did look at the recent launch video frame by frame and on the second frame the flap was laying alongside the rocket, so I dont think there is a big aerodynamic cost associated with it.

Having said that I will be going to an electronic launch release at some stage, so I probably wont play with this as its workign well. Lots of other fun things to develop like a two chute deployment system for a drogue and main that Im working on now

thampson wrote:the timer had quite a bit of torque for its size when wound up so holding it in place needs something solid.

I did look at the recent launch video frame by frame and on the second frame the flap was laying alongside the rocket, so I dont think there is a big aerodynamic cost associated with it.

Having said that I will be going to an electronic launch release at some stage, so I probably wont play with this as its workign well. Lots of other fun things to develop like a two chute deployment system for a drogue and main that Im working on now

We used a coat-hanger wire for our timer latch. It was screwed right to the base of the launcher and pulled out as the rocket launched. The idea wasn't so much to save on drag but to reduce the number of moving parts on the rocket. Every moving part is a place to fail or malfunction. It also saves weight if you don't use an air flap.

If you're going to move on to electronic deploy, you can think of ways to trigger without a flap as well. The simplest way is to make a g-switch, or simply put a push button switch on the rocket and hold it in with something on the launcher. You have lots of choices.

Tim,

thanks for the advise. Do you have any pics of the coat hanger assembly ? Im having trouble seeing how it attaches to the timer and keeps it there prior to launch. I agree the less moving parts the less change of something going wrong

-todd-

I think all you need is something to "stop" the timer from unwinding. A coat hanger pushed through a hole in the rocket that "wedged" the timer which would be pulled out when the rocket launches would work.

We've got the same parachute system. And even with the airflaps.
But we dont want the airflaps anymore.. But because our rocket is quite large we dont know a sollution.. Do you have some pictures of the "cloth hanger'' mechanism?

Thnx

Team [D&P] Rockets*

It is a really simple system. Just make a hole in your deployment chamber. that a pin/wire or even popsicle stick will fit through. (make sure that the hole is angled downwards so that the wire can be easily pulled out when the rocket launches. Position the timer so that when the wire or stick is inserted it prevents the timer from unwinding. Simply wind timer, insert stick/pin/wire into the hole and tie string to it and the base of the launcher. When the rocket launches the pin is pulled out and the timer starts running.Simple system, No flaps to create extra weight or drag and timer is activated upon launch. This will also work for electronic timers controlling servo deploys. Just use the stick/pin/wire to hold open a switch. Use a spring to push the switch closed..Another benifit is that most flap controlled timers can be adapted to use this method.

I hope that helps.

Cloud Dancers wrote:It is a really simple system. Just make a hole in your deployment chamber. that a pin/wire or even popsicle stick will fit through. (make sure that the hole is angled downwards so that the wire can be easily pulled out when the rocket launches. Position the timer so that when the wire or stick is inserted it prevents the timer from unwinding. Simply wind timer, insert stick/pin/wire into the hole and tie string to it and the base of the launcher. When the rocket launches the pin is pulled out and the timer starts running.Simple system, No flaps to create extra weight or drag and timer is activated upon launch. This will also work for electronic timers controlling servo deploys. Just use the stick/pin/wire to hold open a switch. Use a spring to push the switch closed..Another benifit is that most flap controlled timers can be adapted to use this method.

I hope that helps.

I was going through some old boxes of electronic junk that I was helping a friend take to the landfill and found an old mechanical thermostat that uses a mercury filled tilt switch and a metal coil for controlling the heater. It gave me an idea for making a launch detector to start an electronic timer. I plan on mounting the switch so that when the thrust phase ends then the drag will cause negative gravity forces on the rocket and the mercury switch will break connection and start a timer.

I had an even better idea for activating the timer. If you use a "guide rod" like pyro rockets use then why not have that rod hold the timer in the wound position. When the rocket leaves the pad the timer is released to unwind. Simply wind and slide on the launcher.

the mercury switch would be great for a gravity deployment system.

Brian wrote:the mercury switch would be great for a gravity deployment system.

I don't think you can make a mercury switch detect apogee because the rocket would go into free-fall and then the mercury would just float around like it was in zero-g. I don't think it would reliably make a connection. A rocket that was designed to tumble back down would not trigger if the rocket flew a parabolic flight. I have been racking my brain to think of a way to get this idea to work but I keep coming up with possible ways each idea would fail.

I'm open for suggestions though!

Tim Chen wrote:

Brian wrote:the mercury switch would be great for a gravity deployment system.

I don't think you can make a mercury switch detect apogee because the rocket would go into free-fall and then the mercury would just float around like it was in zero-g. I don't think it would reliably make a connection. A rocket that was designed to tumble back down would not trigger if the rocket flew a parabolic flight. I have been racking my brain to think of a way to get this idea to work but I keep coming up with possible ways each idea would fail.

I'm open for suggestions though!

Check out this video clip made by Antigravity Research showing how objects behave inside a water rocket. It shows clearly how everything is in free-fall inside the water rocket.

http://www.antigravityresearch.com/cgi- ... hamber.wmv

I think you can see how hard getting a mercury switch to work in such a chaotic environment would be difficult.

Team Seneca wrote:

Tim Chen wrote:

Brian wrote:the mercury switch would be great for a gravity deployment system.

I don't think you can make a mercury switch detect apogee because the rocket would go into free-fall and then the mercury would just float around like it was in zero-g. I don't think it would reliably make a connection. A rocket that was designed to tumble back down would not trigger if the rocket flew a parabolic flight. I have been racking my brain to think of a way to get this idea to work but I keep coming up with possible ways each idea would fail.

I'm open for suggestions though!

Check out this video clip made by Antigravity Research showing how objects behave inside a water rocket. It shows clearly how everything is in free-fall inside the water rocket.

http://www.antigravityresearch.com/cgi- ... hamber.wmv

I think you can see how hard getting a mercury switch to work in such a chaotic environment would be difficult.

Hey Bill,
When we first started putting cameras on our rockets years and years ago, we thought it would be a good experiment to film objects in zero G. We discovered it had already been done, so we decided to do something else because we didn't want to step on anyone's toes. That video brings back memories.