i need help with my 1.5 liter rocket!

[Teamdbrockets]

I have made a 1,5 liter rocket but he is not stabil in the air.
i use 3 fins.
the first one i lost in the grain field.

so i made an other one and this time he's unstabil!

[RaZias]

Please post a photo, otherwise it will be difficult to understand what is wrong.

[Teamdbrockets]

i go take a picture from it and i wil upload it at 20.00 pm.

Do you speak dutch?
thats eazyer for me...

[RaZias]

i go take a picture from it and i wil upload it at 20.00 pm.

Do you speak dutch?
thats eazyer for me...

I can´t speak dutch, I speak Portuguese, Spanish, French and English.

[rockets-in-brighton]

i go take a picture from it and i wil upload it at 20.00 pm.

Do you speak dutch?
thats eazyer for me...

I can´t speak dutch, I speak Portuguese, Spanish, French and English.

Nobody speaks Dutch except the Dutch, which is why the Dutch speak better English than the English. We will understand you perfectly, but if necessary there is always Google Translate.

[Teamdbrockets]

okay!

[Tim Chen]

I have made a 1,5 liter rocket but he is not stabil in the air.
i use 3 fins.
the first one i lost in the grain field.

so i made an other one and this time he's unstabil!

Were both of the rockets you made unstable or just the second one? The first one is identical in shape to the first one?

The problem could be your nozzle size or that you need more weight in the nosecone area at the top of the rocket.

Yes. Please post a photo of the rocket.

[Teamdbrockets]

a hour its uploaded

[Teamdbrockets]

<a href="http://s22.photobucket.com/albums/b343/ ... rectie.jpg" target="_blank"><img src="http://i22.photobucket.com/albums/b343/ ... rectie.jpg" border="0" alt="Photobucket"></a>

[rockets-in-brighton]

This one is a different design to those shown in your videos. Only guessing because we don't have measurements of key things like CG.

Just going by the shape, unless there's extra weight in the tip of the nose the centre of gravity is likely overlapping the centre of pressure. Usually you need to add some extra body length to get some separation between CG and CP (more like those is the videos)

The fins could be further back, especially with only 3 of them - and they look like they would flap around. Combined with the overall shape, I think there's your problem.

[Teamdbrockets]

okay!
let's try it.

[Teamdbrockets]

i make it longer!
let's try it works...

[U.S. Water Rockets1]

i make it longer!
let's try it works...

So, can you report any success with the modified rocket?

[Teamdbrockets]

Yes!! it works!

i am trying a pvc rocket now but the altitude looks simulair to my standart pet rockets

[Tim Chen]

Yes!! it works!

i am trying a pvc rocket now but the altitude looks simulair to my standart pet rockets

PVC is really heavy, so it doesn't come as a surprise that you can't get it to go much higher. The strength to weight ratio of PVC is too small so you have to put more pressure in it than it is rated for to break even about 1000 feet. It's just too heavy and not strong.

It also explodes when it fails and shatters like glass so it can make a lot of shrapnel. Be careful if you use it.