Bottle Rocket B

[andrewwski]

1/3 indeed was the sweet spot for me with the 1L bottles a few years ago. But that's really something you should optimize yourself for best performance. Not very difficult to get data on.

[Sasher Applesauce]

The current wiki for this event on this web site seems to paraphrase the 2011 rules at the beginning in stating that 1L bottles will be used, and then later on it discusses a so - called "standard design" that uses a 2L bottle.

This is a little confusing. I don't know if we should be experimenting with 1L bottle rockets or 2L bottle rockets. Bottle rocket design considerations are seriously affected by the type of bottle.

i seriously dont know but i think it is 2L because they are more common

[Bubba1960]

People used all kinds of bottles last year. See the image gallery.

[robotman]

The current wiki for this event on this web site seems to paraphrase the 2011 rules at the beginning in stating that 1L bottles will be used, and then later on it discusses a so - called "standard design" that uses a 2L bottle.

This is a little confusing. I don't know if we should be experimenting with 1L bottle rockets or 2L bottle rockets. Bottle rocket design considerations are seriously affected by the type of bottle.

i seriously dont know but i think it is 2L because they are more common

Your pressure vessel must be a 2L (3.a)

[cvmsrocksyoursocks]

so what can we use and not use....

[andrewwski]

Read the rules! That is the only official source for that information - don't get misled by anything else! If you haven't obtained and read the rules, you need to do so before starting work on the event.

[calgoddard]

My post quoted above was dated Agusut 22, 2010, BEFORE the official 2011 rules were published.

The 2011 BOTTLE ROCKET rules require that the "[r]ocket pressure vessels must be made out of a single 2-liter plastic carbonated beverage bottle."

[cvmsrocksyoursocks]

so would I be able to do the following....to poke a few holes into it to make air go inside and keep it floating longer (I won't poke holes into the actual bottle, just the nose cone thing....also where would u say is the best place to put the fins and how many)

[andrewwski]

I don't see anything that prevents you from poking holes into a nose cone or any other part than your pressure vessel (make sure you fit the definition of a blunt nose cone).

But poking holes isn't going to keep it up longer. Doesn't effectively increase your drag. You really want to ensure that your rocket tumbles or falls horizontally. Read up on "backsliders" - you want your CoG (Center of Gravity) to be closer to your CoP (Center of Pressure) - this will cause it to fall more irregularly than going nose-first.

[cvmsrocksyoursocks]

I'd like to try to have it come down the way it goes up and then make sme fins that are kind of like parachutes, except they don't move

[bcsimons]

I was wondering if anyone has really experimented in building this into a glider?

I'm working on a couple right now and havent tested yet, but my main concern is the bottle stalling as it falls on its side. Has anyone figured out if this happens or if there is a way to take care of it?

[bcsimons]

Well I tested my first 2. Didnt go to well one i accidentaly blew the wings off :0 the other i launched and it went about 10 feet up and shot straight out like a missile and kind of glided into the ground 30 feet away. Both only lasted about 3-5 sec. Got a long way to go

[AlphaTauri]

My friend and I tested a couple rockets over the summer...the best we got was about 7 seconds (with a 2-liter Coke bottle, fins/nosecone made of paper and packing tape, and at around 50 PSI according to the gauge on the bike pump). I think it went about 60 feet up on average (key word: think, I'm horrible at estimation), and thankfully, no lawn darts.

[coterotie]

Anyone have any firm idea on what constitutes a change of shape?

I'm not saying this would necessarily work, but say folding flaps that are held flat in place by drag, that then unfold to provide drag on the way down?

[wlsguy]

Anyone have any firm idea on what constitutes a change of shape?

I'm not saying this would necessarily work, but say folding flaps that are held flat in place by drag, that then unfold to provide drag on the way down?

I think that would qualify as both a change in shape and the deployment of a recovery system, both of which are prohibited. A good general guideline would be if it looks different when it comes down than when it went up, it had to change shape.