Bottle Rocket B

[Primate]

MVStangs, what materials are you using to make your backslider and what's your shape?

We're using a long paper nose cone on top of the bottle. We also put clay on the top of the bottle to pull back the COG. It works pretty well, but we've heard of way better times. For fins, we have this plastic material that is light but not that heavy. We put them on there in such a way that the rocket spirals up and goes up farther. It helps, but does anyone else have better ideas?

For a backslider design, the weight of the rocket doesn't matter as much as where the center of balance is unless the rocket is really heavy. Today, a bottle rocket that I built with the center of balance halfway in between the center of pressure and center of lateral area got a time of 6.63 seconds while going in an arc that was caused by a somewhat strong wind.

To get it to backslide, probably not. However, I've found that, for backsliders, the weight of the nose cone is usually enough to put the rocket over its optimal weight, so you don't want to add any additional weight if possible. And obviously, a lighter rocket will fall much more slowly.

[Tramsarran]

what types of times r u getting? I go to IL state compitiotion tomorrow so there's not much I can change to my rocket so I'm praying I get a good time and a medal. Good Luck to everyone!!

Good luck! I got pushed into Tier 2 because the person who built the rocket used Super Glue and it had visible interfered with the strength of the plastic. Got 39 place and the rocket stayed for a little under 3 seconds. The best times that I had witnessed was about 20 seconds from a perfect backsliding rocket that seemed to float as it came down; it was amazing. A time of about 10-15 seconds is really good from what I saw as many rockets nosedived and dug 2-3inch holes into the ground. Whenever you're not at a event you might wanna watch the Bottle Rockets launch it was the most exciting event next to Sumobots in my opinion.

[fishman100]

Are balsa wood fins better than plastic fins?

Balsa seems to break easily, but depending on the thickness, it can help your rocket.

What did you use?

[Tramsarran]

I built one out of some posterboard foam that was quite sturdy and would not crease but I didn't bring my rocket to the competition as another teammate built two other rockets. He also forgot the labels so I asked another group to borrow their labels after they launched their rocket and fortunately they gave it to me.
Yeah, balsa wood sounds like a good idea.

It really depends on what type of plastic you use and what type of rocket you are building. If you use really flimsy plastic the fins might be useless. If you use sturdy plastic that will hold its shape but not lower the COG too much it should work fine.

[thewinner]

I use some sort of corrugated plastic (you know, that material you use in signs). It works really well and is very strong.

[Littleboy]

All that really matters in fins is that they are light, rigid, and don't have much drag.
What times are you all getting?
We tested a couple new ones yesterday. 35 mph winds with 50 mph gusts. They first one went up about 100 feet only because of the wind and then drifted a few hundred yards. And still was only 12 seconds . It was still good and backslided nicely. The other one we launched at exactly when a huge gust came so it went right to the ground. We will fly both again when we get the chance.

[Cheesy Pie]

Make a weather-flexible rocket.

[fishman100]

How would one do that?

[Cheesy Pie]

Like, it won't get affected negatively by wind or rain. Or at least not much. You can't expect a good score if you launch any rocket into a tornado. And I can't explain because I know to do this because we built a rocket incompatible with wind that failed due to wind.

[MVStangs]

I just made a rocket that weighs about 153 grams with everything on it. I know that lighter rockets are good, but how light is too light, meaning how light would it have to be to not go up enough to get a good time?