Bottle Rocket B

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Re: Bottle Rocket B

Post by space scientist » April 8th, 2011, 7:39 pm

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Littleboy wrote:What exactly is the best material for fins? What we used to use is to heavy now that we made extremely light nose cones and the center of gravity gets too far back. What do you use?
I find that balsa wood is okay for fins although a friend of mine is using Styrofoam for fins. When I alter the center of balance, I prefer to use modeling clay (I got the idea of using it after I had some left over from a science project.) since the mass of the modeling clay can easily be adjusted. in addition, modeling clay is easy to find.
Balsa: breaks sometimes when hits ground/something else in its path (What thickness do you use?)
Styrofoam: Produced too much drag for us thus reducing its height.[/quote]

I know about the balsa wood breaking, but that shouldn't be a problem if the recovery system works. In addition, fins made out of balsa wood can be repaired, but I don't know about the effects of using Styrofoam (although what you said makes sense).
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Re: Bottle Rocket B

Post by Primate » April 8th, 2011, 7:44 pm

I had the same exact trouble with balsa, using 1/8" thickness. I don't think you'd want to go any thicker, so if you're frustrated with it don't bother. Is your rocket not backsliding properly, though? Once we optimized ours the balsa stopped breaking and the index cards stopped bending.

The reason I like Youen's method is because they're so easy to make. I sat down for an hour one day and folded a good thirty fins, and glued them onto sleeves made out of other 2L bottles. Whenever they'd get muddy/torn up, I'd just switch out the fins. Again, though, once we got it backsliding the fins held up perfectly.
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Re: Bottle Rocket B

Post by Littleboy » April 9th, 2011, 4:27 am

mhmm our backslides great
I guess I'll give both of those another shot. I do have an idea of my own that I'd like to test before telling.

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Re: Bottle Rocket B

Post by Cheesy Pie » April 9th, 2011, 8:46 pm

Try a long PVC pipe with a little ball on the end for a nosecone.
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Re: Bottle Rocket B

Post by Primate » April 9th, 2011, 11:29 pm

Cheesy Pie wrote:Try a long PVC pipe with a little ball on the end for a nosecone.
Isn't that really heavy?
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Re: Bottle Rocket B

Post by Rocketeer » April 10th, 2011, 4:40 am

Any ideas out there on how much does the rocket need to weigh? By drastic reduction, my rocket weight is down to ~200 grams now (without the water) but first flight was 7 seconds at 60 psi. Also, what is the launcher like at the competition? So far mine leaks at 60 psi due to the homemade nature of the rubber stopper.

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Re: Bottle Rocket B

Post by space scientist » April 10th, 2011, 5:47 am

Rocketeer wrote:Any ideas out there on how much does the rocket need to weigh? By drastic reduction, my rocket weight is down to ~200 grams now (without the water) but first flight was 7 seconds at 60 psi. Also, what is the launcher like at the competition? So far mine leaks at 60 psi due to the homemade nature of the rubber stopper.
The most common launcher that I have seen was a commercially made launcher that was in the shape of a tripod, and water was poured into the bottle rocket and the pressure was added through the launcher. However, I have seen a launcher that has the water put into the bottle rocket while it was on the launcher. Therefore, I would mark a water line on the bottle rocket in addition to knowing how much water to use (in customary and metric systems).
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Re: Bottle Rocket B

Post by robotman » April 10th, 2011, 1:50 pm

Rocketeer wrote:Any ideas out there on how much does the rocket need to weigh? By drastic reduction, my rocket weight is down to ~200 grams now (without the water) but first flight was 7 seconds at 60 psi. Also, what is the launcher like at the competition? So far mine leaks at 60 psi due to the homemade nature of the rubber stopper.
This is generally the standard launcher Most competitions I have seen use this but your state may be differant
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Re: Bottle Rocket B

Post by Cheesy Pie » April 10th, 2011, 1:57 pm

We put our rocket on the launcher, then a machine pressurized it. When it was pressurized, we pulled a string to launch it.
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Re: Bottle Rocket B

Post by Primate » April 10th, 2011, 2:25 pm

space scientist wrote:The most common launcher that I have seen was a commercially made launcher that was in the shape of a tripod, and water was poured into the bottle rocket and the pressure was added through the launcher. However, I have seen a launcher that has the water put into the bottle rocket while it was on the launcher. Therefore, I would mark a water line on the bottle rocket in addition to knowing how much water to use (in customary and metric systems).
Mark it on both ends of the bottle, just to be safe.

I think this is the launcher you're talking about, made by Pitsco. I've seen this one used at all the competitions I've been at.
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