Maximum horizontal distance competition

[Avnish]

I have recently enrolled myself in a water rocket competition scheduled to be held on 21 March! 2014.

This is my first time I am taking part in a water rocket event. The rules state that
1). The water rockets must travel the maximum horizontal distance. 1 out of 2 tries will be considered and the farthest will win.

2). The rockets must have a soft and crushable cone.

3). Pressure will be 70psi

4). Bottle size 1.5l

I've built a cable tie launcher tube based launcher seeing from the internet. But I have no idea about the nosecone( ivory sheet cones?). Also, how much amount of water should I use.

And angled at 45°? (idk)

Looking forward to your help guys

[Water Rocket Expert]

Hello here from Maryland, where it never seems to stop being cold.

First off, you said you build a cable-tie launcher, correct? Have you test fired a bottle to make sure it worked right. Sometimes adjustments are needed in the height of the cable-ties and sometimes the Scrhader or Presta valves are leaking at the glue.

Second, I would use part of a foam foot ball for the nose cone. They are pretty common and cheap so cutting it up isn't going to be that much of a waste. Or you could try some kind of foam from a box but the foot ball is the better option.

I have a question. Is this competition like a big one or something because they need to purchase a good altimeter. That would do better for competitions. Ballistic isn't that cool.

Team S.P.W.R.

[bugwubber]

I have recently enrolled myself in a water rocket competition scheduled to be held on 21 March! 2014.

This is my first time I am taking part in a water rocket event. The rules state that
1). The water rockets must travel the maximum horizontal distance. 1 out of 2 tries will be considered and the farthest will win.

2). The rockets must have a soft and crushable cone.

3). Pressure will be 70psi

4). Bottle size 1.5l

I've built a cable tie launcher tube based launcher seeing from the internet. But I have no idea about the nosecone( ivory sheet cones?). Also, how much amount of water should I use.

And angled at 45°? (idk)

Looking forward to your help guys

Hello, welcome to the forum!

If they don't define soft other than to say "crushable" anything up to another empty bottle would qualify as long as you cut the neck off. Two 1.5l bottles attached bottom to bottom, make a really good body.

The trick for distance is to test. Mass will be your friend so a tennisball or two for weight. You'll want to balance it so it flys more like an airplane so it will slide along the ground when it hits. I think 45 degrees is probably too steep for maximum distance. You will need to try a multiple launches in the 30-45 range to see what works best for your rocket.

If you can test at a football field that would really help you log distances.

Good luck!

[Avnish]

@water rocket expert - yes I've tried the launcher with some bottles and it works completely alright

@bugwubber - joining two bottles seems a nice idea. That will make the centre of gravity higher, right? And that's a good thing I suppose?

But how do join them base to base? It's so full of contours.

[bugwubber]

@water rocket expert - yes I've tried the launcher with some bottles and it works completely alright

@bugwubber - joining two bottles seems a nice idea. That will make the centre of gravity higher, right? And that's a good thing I suppose?

But how do join them base to base? It's so full of contours.

Depends on the bottles.

Some will interlock with the pentaclaws turned slightly.

Some work better with the lobes matched up.

If they are wobbly in either position, you can cut the top bottle and glue in place.

If you lightly sand the bottles, low temp hot melt glue works pretty good. PL Premium is my preferred glue.

CAM00871.jpg (2.82 MiB) Viewed 43 times

Small bottles on the far right do not interlock well so they are taped with packing tape lobe on lobe.
Just add water rocket has interlocking lobes that were glued.
The pink thing has interlocking lobes held in place with duck tape. 3 vertical stips, then wrapped.
Two bottles to the left of it, illustrate how it is placed.
And finally on the left is a rocket I cut and glued together.

[bugwubber]

You can cover up the seam with the middle cut out of a 2liter bottle if you want to smooth the transition. (And you do)

[Water Rocket Expert]

Bugwubber is right. Try fitting the bottles together at the base. They will usually fit perfectly together and with low temp glue (high temp melts the plastic) they will form a good body. Use duct tape to reinforce the two bottles. And in the picture it looks as if bugwubber has stuff his nose cone with those white swabs (can't think of the real name, drawing a blank). That would work well to if you intend to reuse the rocket.

[bugwubber]

Bugwubber is right. Try fitting the bottles together at the base. They will usually fit perfectly together and with low temp glue (high temp melts the plastic) they will form a good body. Use duct tape to reinforce the two bottles. And in the picture it looks as if bugwubber has stuff his nose cone with those white swabs (can't think of the real name, drawing a blank). That would work well to if you intend to reuse the rocket.

Pingpong ball aquanaughts

[Water Rocket Expert]

Oh I thought those were cotton swabs! Now a closer look reveals those plastic relics!

[bugwubber]

Shh, don't tell them, they were only chosen to go for a ride because they held the tennis ball ballast in place.

[U.S. Water Rockets1]

I have recently enrolled myself in a water rocket competition scheduled to be held on 21 March! 2014.

This is my first time I am taking part in a water rocket event. The rules state that
1). The water rockets must travel the maximum horizontal distance. 1 out of 2 tries will be considered and the farthest will win.

2). The rockets must have a soft and crushable cone.

3). Pressure will be 70psi

4). Bottle size 1.5l

I've built a cable tie launcher tube based launcher seeing from the internet. But I have no idea about the nosecone( ivory sheet cones?). Also, how much amount of water should I use.

And angled at 45°? (idk)

Looking forward to your help guys

Actually, the best angle for a distance launch is between 50 and 55 degrees. The rocket actually does not fly in a perfect parabola which would be the ideal case where there was no air friction, so given that the flight path is modified by the air resistance and the weight change of the rocket as the water exits, you need to alter the trajectory slightly higher to gain altitude and this will extend the reach of the rocket. Good luck in the competition!

[Avnish]

That was very helpful. Thanks!

But guys in not sure about the angle?
And one more thing, the rule book says you can use additive in fuels. Any suggestions?

[Water Rocket Expert]

I don't have much experience in horizontal myself, but USWR said between 50 and 55 was good for distance.

A good additive to you rockets water would be a small bit of dish soap, enough to make a good amount of bubbles. The bubbles mix with the air and water and make a slurry mix so the water is expelled slower.

Sometimes food coloring is just pretty.


Have fun tomorrow and let us know how it goes! Any images or video would be great!

[bugwubber]

That was very helpful. Thanks!

But guys in not sure about the angle?
And one more thing, the rule book says you can use additive in fuels. Any suggestions?

I think you will have more to gain focusing your testing on the aerodynamics, mass optimization and angle than worrying about additives.

[Avnish]

It's hell busy here. And unfortunately, I won't get much time for testing. 1.5 hours at max. Way too congested here :sigh: