Charlie Laser Pears Oddroc?

Saw this category and was wondering if my rocket fits in here?

Charlie Laser Pears is a water rocket. Reaction mass water goes in the bottom and ballast water goes in the top. There's a video camera and altimeter in the middle payload bay. There is no parachute.

The recovery system is what I call Non Ballistic Return. The aim isn't to backglide, but to just fall sideways in a high drag profile. In order to do this, the ballast water added to the top container is automatically flung out as the rocket tips over at apogee. This makes the rocket just slightly tail heavy and the rocket falls sideways at under 30ft per sec even with a video camera on board.

You can see this recovery system in action really well in this video of my other rocket called Just Add Water

https://www.youtube.com/watch?v=C-pMQbfMlk4


And regarding the name- Originally the rocket was named Laissez Le Bon Temp Volent which explains the garter belt, but my kid's class was given the chance to rename it.
Charlie Laser Pears is what they came up with.

Thanks,

Bugwubber
Team SPEW

[YOUTUBE]c1PGpdAOGIU[/YOUTUBE]

Alt on second flight was 232ft.

Wow that thing is fast!

Cool!
Your ballast idea intriguing, although I wonder if the forward drag from that open "nose cone" may bump your CP further ahead than the CG shift from the dumped balance water.
Love the "drag race" multiple launcher system.

Thanks! I put a pingpong ball half cap on that rocket and only got 10 more feet on the altimeter. The water didnt have enough energy to move the pingpong cap out of the way so it lawn darted on that flight. It also goes wild if I launch without the water ballast.

Longer rockets haven't needed the water ballast.

Altimeter showed a peak of 199ft/sec (135mph) on the second flight in that video. It acheived that in .25 seconds.

bugwubber said:

Thanks! I put a pingpong ball half cap on that rocket and only got 10 more feet on the altimeter. The water didnt have enough energy to move the pingpong cap out of the way so it lawn darted on that flight. It also goes wild if I launch without the water ballast.

Longer rockets haven't needed the water ballast.

Click to expand...

On the video looked like a big ballast chamber with a small amount of water. Can you make a smaller chamber directly at the nose cone tip holding the same amount of water, maybe with a slightly smaller aperture?

BABAR said:

On the video looked like a big ballast chamber with a small amount of water. Can you make a smaller chamber directly at the nose cone tip holding the same amount of water, maybe with a slightly smaller aperture?

Click to expand...

I'll have to look into that. Charlie Laser Pears has 12oz chamber on top. The hole is 22mm. Could probably reduce that by half. I do have another rocket with a small water chamber at the top called The Water Buffalo. I think it is having trouble keeping water in during ascent. A smaller opening might help that.

BABAR said:

On the video looked like a big ballast chamber with a small amount of water. Can you make a smaller chamber directly at the nose cone tip holding the same amount of water, maybe with a slightly smaller aperture?

Click to expand...

So I tried a smaller aperture in the nose of the ballast chamber. I also added small holes on the side of the ballast chamber to allow free flow of air. Total success. My descent rate was 29fps which is under the 33fps limit set by the WRA. More importantly, it landed on pavement on one launch and suffered no damage. My new height is 252 ft. Thanks for the suggestion!

bugwubber said:

So I tried a smaller aperture in the nose of the ballast chamber. I also added small holes on the side of the ballast chamber to allow free flow of air. Total success. My descent rate was 29fps which is under the 33fps limit set by the WRA. More importantly, it landed on pavement on one launch and suffered no damage. My new height is 252 ft. Thanks for the suggestion!

Click to expand...

As long as we are on a roll, how about a true conical nose cone with no shoulder, just rests on top of the ballast chamber, with a lose piece of string to keep it attached to the rocket at apogee. This may greatly reduce the drag from your current hole in the ballast chamber. Needs enough of an overlap or lip with the chamber that air flow keeps it in place on boost (check out Estes Pop Fly if you have doubts!). At apogee this literally "falls off" and let's your ballast water out. As mentioned, just have a loose piece of string from the inside of the cone to the inside of the ballast chamber so it stays with the rocket body for the next launch. You could probably cut the plastic from a water battle and roll the cone.

BABAR said:

As long as we are on a roll, how about a true conical nose cone with no shoulder, just rests on top of the ballast chamber, with a lose piece of string to keep it attached to the rocket at apogee. This may greatly reduce the drag from your current hole in the ballast chamber. Needs enough of an overlap or lip with the chamber that air flow keeps it in place on boost (check out Estes Pop Fly if you have doubts!). At apogee this literally "falls off" and let's your ballast water out. As mentioned, just have a loose piece of string from the inside of the cone to the inside of the ballast chamber so it stays with the rocket body for the next launch. You could probably cut the plastic from a water battle and roll the cone.

Click to expand...

Well, here's where things get tricky. As it turns out, objects tend to fall together until a force (such as wind drag or in the case of pyro rockets, an ejection charge) pushes them apart. I need the ballast bottle open just as there is no wind drag and the rocket is essentially weightless.

With that, a weak spring pops into mind. So I got busy and have a cap that I am ready to test. It acts kinda like a bobblehead. Sitting still the spring (made from a zip tie) can push the cap up a bit, but under acceleration, it will lock in place. Only testing will tell how it performs during deceleration. While weightless at apogee, the spring should be strong enough to push the cap completely off the ballast bottle.

I don't think I was clear in my last post that I was testing the smaller aperture ballast bottle on a different rocket. You can see it in action here although by this point, we had dislodged the JBWeld Plastic cap that I had made to reduce the aperature.

[YOUTUBE]C5Xhui18eM4[/YOUTUBE]

So the main difference between these two rockets, this one was powered by a 1 liter bottle instead of 2 and has a 30mm nozzle instead of the typical 21mm.

For testing the spring loaded cap, I've switched back to CLP .

Thanks,

Bugwubber

bugwubber said:

Well, here's where things get tricky. As it turns out, objects tend to fall together until a force (such as wind drag or in the case of pyro rockets, an ejection charge) pushes them apart. I need the ballast bottle open just as there is no wind drag and the rocket is essentially weightless.

With that, a weak spring pops into mind. So I got busy and have a cap that I am ready to test. It acts kinda like a bobblehead. Sitting still the spring (made from a zip tie) can push the cap up a bit, but under acceleration, it will lock in place. Only testing will tell how it performs during deceleration. While weightless at apogee, the spring should be strong enough to push the cap completely off the ballast bottle.

I don't think I was clear in my last post that I was testing the smaller aperture ballast bottle on a different rocket. You can see it in action here although by this point, we had dislodged the JBWeld Plastic cap that I had made to reduce the aperature.

[YOUTUBE]C5Xhui18eM4[/YOUTUBE]

So the main difference between these two rockets, this one was powered by a 1 liter bottle instead of 2 and has a 30mm nozzle instead of the typical 21mm.

For testing the spring loaded cap, I've switched back to CLP.
Thanks,

Bugwubber

Click to expand...

Well, ended up with a lawn dart when the cap failed to let the ballast water out. Got some awesome video though. Did a demonstration launch for 4th and 5th grade at my kid's school after launching their rockets.

You can see two other rockets in flight. The first is obvious but the second went much higher and is seen just before the end of the video. The video is slowed down so you can see things better.

[YOUTUBE]E1UUKC4otwU[/YOUTUBE]

Methinks I'll have to try one of these. I'd like to see a summary of the parts you used. Bottle size, fin materials, etc