Best fins for water bottle rocket design?

[Habesha Capt_Joshua]

Hi everyone! So for my Physics class we will be doing a water bottle rocket competition where the rocket that lasts in the air the longest wins. What type of shape should my fins be and how should I set them up so that my rocket can glide and stay in the air the longest, once it has reached its max altitude? Also any things I should be considering when building and designing?

[Myrador]

Your rocket is like a Dart so i would suggest you imitate the "wings" from an ordinary dart?!

[jhendriks87]

keep the weight near the top keep the fins near the bottom and put an areodynamic nosecone on the top lol. It a bottle rocket haha, not much more you can do with it. lol

[Myrador]

maybe put some nosecone on it thats a little heavier than the rest if you keep it straight it should fly longer

[E-Man720]

MOAR..........

[jhendriks87]

Цитата допису E-Man720:

MOAR..........:Khappy:

I agree a bottle rocket with bottle rocket boosters. preferably asparagus staged haha

[Habesha Capt_Joshua]

what type of nose cone do you suggest? Parabola shaped or cone like?

[dwringer]

I would actually be amazed to learn if there is a difference in performance at all between the two shapes at such low velocities on such an oddly-shaped rocket.

[Jamjuice]

Are you allowed to put a parachute in the nosecone?
That would give you the best "time in the air".

[95Bravo95]

Add MOAR bottles.... ;)

http://cdn.ymaservices.com/editorial_service/media/images/000/044/202/original/Water-bottle-rocket.jpg.jpg?1404215259

[Habesha Capt_Joshua]

Цитата допису Jamjuice:

Are you allowed to put a parachute in the nosecone?
That would give you the best "time in the air".

yea but I have no idea how the mechanism will work exactly. Someone from previous year did it with some controlled timing.

[jhendriks87]

http://www.instructables.com/id/How-to-build-a-bottle-rocket-with-a-parachute/?ALLSTEPS

[ExaltedDuck]

What I would do is make fins out of construction paper or something similar. A simple shape like KSP's "Advanced delta winglet" would propbably be easiest to put together or at least easist to explain the next part of the gimmick that might win it for you.

I don't expect there will be any meaningful gliding. You can try to make an airplane-like shape but good luck maintaining a steady glide. What I would make is a simple, traditional fins-on-the-back design that flies straight up and has minimal drag to keep the rocket oriented upward, but then make the fins fold over in a way that imparts spin spin as the rocket comes back down.

This is where that shape comes in to play. It's pentagonal, but also essentially a square and triangle sharing an edge. The pentagon should be a single piece of paper or card stock but the shared edge between the triangular and square parts would be a crease. The fins would be connected to the body only along the triangular portion. That is, the square parts are free to swing along the crease. Travelling upward, air resistance can keep the fins straight but on he way down (assuming it comes down backwards), the crease would swing the other way and impart a spin along the rocket's primary axis. You might need to weight the cap end to encourage a proper descent attitude and you might need to apply a small amount of spring force to help the fins articulate consistently. But with a little testing and tuning, it might blow away the competition.

[SievertChaser]

Combining with a parachute, you could also experiment with a multistage design, modified nozzle width to control thrust and duration, and strap-on boosters that get decoupled under gravity. I can't dig up the relevant article, but you can basically recreate an R-7.

[Barking Sands]

Цитата допису 95Bravo95:

Add MOAR bottles.... ;)

http://cdn.ymaservices.com/editorial_service/media/images/000/044/202/original/Water-bottle-rocket.jpg.jpg?1404215259

The FAA would likely frown on this. :)

I was thinking about using aerofoils in a single-helical trajectory configuration (like maple seeds or common emergency flares) for the descent in lieu of a parachute. Remember that both parachutes and gliders depend on a mass to generate lifting forces and counter gravitational forces.

The lifting surfaces should be designed such that the payload's weight is fairly balanced with the induced drag of the sail/glider. Too large a wing/parachute will cause it too fall faster through the air with less resistance (due to lack of an applied force acting as thrust), and too little will have the same effect.

[=37th= minepagan]

Pah...bottle rockets....REAL MEN USE ROCKETS FILLED WITH EXPLOSIVES AND MADE OUT OF CARDBOARD! SO IT EXPLODES!