Problems With My Rocket

Discussions about rockets, construction materials, adhesives, nozzles, nosecones and fin design.
RocketAir
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Problems With My Rocket

Post by RocketAir »

Hello,

My rocket is not flying all it seems to do is swerl around until it runs out of pressure and water. I usually make the pressure 50-60PSI is that enouph? And is my rocket design good? I need help to make my rocket fly, please help.


Pictures:

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RocketAir
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Post by RocketAir »

Rocket Weigth Withought Water: 1 Pound.

Rocket Weigth With Water: 3.2045855 Pounds.

Nozzle Size (In MM.): 11.112522225044449
The Mooseheads
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Post by The Mooseheads »

RocketAir wrote:Rocket Weigth Withought Water: 1 Pound.

Rocket Weigth With Water: 3.2045855 Pounds.

Nozzle Size (In MM.): 11.112522225044449
For that weight rocket the nozzle size is quite small for the pressure you are using. The rocket is not getting enough speed at liftoff to achieve stable flight. You should reduce the weight of the rocket so that it can start moving faster, sooner. If you can't make the rocket itself lighter, you can take some of the water out and that will help. You could also increase the pressure ONLY IF IT SAFE TO DO SO AND YOU ARE NOT TOO CLOSE. You could also open the nozzle wider and get more thrust which also would help.

Good luck!
Rick C.
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tsumrall
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Post by tsumrall »

I would recommend that your fins be very thin. They look thick in the pics. Also find a way to connect them to the rocket so they don't move. Fins must be very stiff and well connected. If they are "fluttering" that equals drag.

Make sure the fins are well aligned. Any angle will make your rocket spin and that's drag. Find some boards or books and stack them so they equal half the diameter of the bottle. Place the stack next to the bottle and glue your fin on. This will be real close alignment.

On the weight: The Mooseheads are correct. You need either more power or less weight. It appears that you have used a lot of Duct Tape. Reduce that as much as possible.

Tim
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M5
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Post by M5 »

tsumrall wrote:I would recommend that your fins be very thin. They look thick in the pics. Also find a way to connect them to the rocket so they don't move. Fins must be very stiff and well connected. If they are "fluttering" that equals drag.

Make sure the fins are well aligned. Any angle will make your rocket spin and that's drag. Find some boards or books and stack them so they equal half the diameter of the bottle. Place the stack next to the bottle and glue your fin on. This will be real close alignment.

On the weight: The Mooseheads are correct. You need either more power or less weight. It appears that you have used a lot of Duct Tape. Reduce that as much as possible.

Tim
What do you recommend to make fins out of so that they are strong and will not flop around? I copied what everybody else does and made mine from parts cut and folded from bottles. Thanks.
RocketAir
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Post by RocketAir »

I made my rocket lighter by making those fins twice as thin, and I did not tape them on, I glued them on. Made me PSI a little greater, launch it and it still does not work.
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Post by The Mooseheads »

RocketAir wrote:I made my rocket lighter by making those fins twice as thin, and I did not tape them on, I glued them on. Made me PSI a little greater, launch it and it still does not work.
With the improvements in the rocket, does it show any better performance at all?

Can you describe what the rocket is doing when you launch it? A detailed description of the flight path it takes or a video of the flight would help us diagnose your trouble.
Rick C.
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U.S. Water Rockets1
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Post by U.S. Water Rockets1 »

RocketAir wrote:Rocket Weigth Withought Water: 1 Pound.

Rocket Weigth With Water: 3.2045855 Pounds.

Nozzle Size (In MM.): 11.112522225044449
Hi RocketAir,

What are you using for your nozzle? In the pictures it looks like a full unrestricted bottle neck. What did you do to reduce it to 11mm diameter?

You could try adding a launch tube inside the rocket or an external launch rod or guide to help hold the rocket straight until it gets moving.

With an 11mm nozzle it might need a guide to help it get going straight while it gains enough speed to achieve stable flight.
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tsumrall
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Post by tsumrall »

What do you recommend to make fins out of so that they are strong and will not flop around? I copied what everybody else does and made mine from parts cut and folded from bottles. Thanks.
Anything that is thin and does not bend much in your hand. Hard plastics like cd's or even cd cases work ok. Basswood is nice but you would have to buy some.

Home Depot had some fiberglass sheet used as replacement stove hood light covers. It was about a 4x10 and very thin and nicely stiff. It was very cheap. I've used it for the past few years for all my fins.

[img]sumrallworks.com/rockets/finwork.png[/img]
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Cloud Dancers
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Post by Cloud Dancers »

RocketAir wrote:I made my rocket lighter by making those fins twice as thin, and I did not tape them on, I glued them on. Made me PSI a little greater, launch it and it still does not work.
RocketAir,

You could make the rocket longer by making a tube out of paper or cardboard and adding it to the front of your rocket. Longer rockets will fly more stably at lower speeds.
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Post by The Mooseheads »

Either he got it working, or else he gave up.

Oh well. We tried. :(
Rick C.
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RocketAir
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Post by RocketAir »

Im still working on it, I have school so it is really hard to get work done on it.
Cloud Dancers
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Post by Cloud Dancers »

Keep us posted on how you make out.
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Tim Chen
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Post by Tim Chen »

RocketAir wrote:Im still working on it, I have school so it is really hard to get work done on it.
Does your rocket fly like the one the other guy posted here that looks like the space shuttle? His rocket twirled around and around and crashed. It's a shame because it looked nice. It was all painted and everything!
Tim Chen
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Post by The Mooseheads »

RocketAir wrote:Im still working on it, I have school so it is really hard to get work done on it.
Okay bud! No problem! I know it's hard to get time for everything we want to do. Let us know how things go!

Best of luck to you!
Rick C.
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