Page 21 of 41

Re: Bottle Rocket B

Posted: March 22nd, 2011, 7:43 am
by Brucester
The rain seems to make my rocket's high lower than expected and descent faster. But when there's rain, there's usually wind, so the two balance each other out.

Brucester

Re: Bottle Rocket B

Posted: March 22nd, 2011, 9:59 am
by Flavorflav
Primate wrote:Winning time for the NY state competition (division c trial event) was 21.5 seconds.
The wind was a real factor, though. It cut our expected time in half.

Re: Bottle Rocket B

Posted: March 22nd, 2011, 11:15 am
by Brucester
My comment before was a joke, so don't attach random bags of cement :roll: .... Regardless, how are people preparing their rockets? I know for my team, we've been designing nice weather ones, waterproof ones, high-wind ones, and different combinations of those three types. We've been having best results with our nice weather ones, but has anyone come across different results? We just can't get a waterproof one to work like our others.

Thanks,
Brucester

Re: Bottle Rocket B

Posted: March 22nd, 2011, 11:49 am
by rocketman 42
Littleboy wrote:Today I got 25 seconds :D Hopefully I can do the same next week and that was not just a fluke. I think we finally figured it out.
littleboy, the wind at the tournament can really screw things up. for instance, i had a 18 second rocket that got 13 seconds at the competition.

Re: Bottle Rocket B

Posted: March 22nd, 2011, 11:51 am
by rocketman 42
Platypus wrote:My highest time is 17 seconds with a backslider. Is this good enough to win/or get close to winning states?
Platypus, Dont count on it, i have seen some rockets with great times at the invitationals, up to 30 seconds or so.

Re: Bottle Rocket B

Posted: March 23rd, 2011, 1:51 pm
by Brucester
I haven't seen any rockets over 30 seconds at any of the 4 invitationals (Northmont, Magsig, Solon, West-Liberty) I was at. The best ones that I saw were around 25s. On the topic of the wind, it actually can help your rocket. If there's a medium breeze and your rocket's light enough, the breeze will give the rocket way more lift during the backslide causing it to fall slower. We launched a rocket at West-liberty that got 19 seconds in tests, but with VERY harsh winds and lots of rain our time went up to 23 seconds. It's about balancing the rocket correctly to be able to handle the wind. If there is a good balance of surface area on each side of the cg, the wind will simply push the rocket over, but keeping it perpendicular to the ground. If there is too much surface area on the bottom or top, the wind will push that side more because of more lift. This will throw off it's "ballistic trajectory" causing it to most likely rotate into a nosedive or an unstable backslide. My rocket at West-liberty drifted to the left about 100 yards, but it remained perpendicular to the ground throughout the flight and the wind worked as extra lift.

Re: Bottle Rocket B

Posted: March 23rd, 2011, 2:01 pm
by Cheesy Pie
During the tryouts, we launched @ 20 psi (I think), and most people got 2-3 seconds. But mine (which was shaped like a giant bullet) got 3.70 seconds (better than one of our rockets @ regionals)

Re: Bottle Rocket B

Posted: March 23rd, 2011, 2:06 pm
by Brucester
Why would you launch the rockets at 20psi? The rocket will show different characteristics at such a low pressure and it doesn't seem like much of a valid test. I'm just wondering out of curiosity because it would be nice to know a way to test the rockets at a low psi without risking destroying them if they don't work at 75psi.

Brucester

Re: Bottle Rocket B

Posted: March 23rd, 2011, 2:12 pm
by Cheesy Pie
It was the tryouts! We were using manual pressurizers!

Re: Bottle Rocket B

Posted: March 23rd, 2011, 2:28 pm
by Littleboy
Well we just use a bike pump and never had a problem getting to 75 within a minute (except frequent leaks)