4 fins or 3 fins

[Anthony]

Wich kind of fin setup should I go for for a small A or B powered rocket designed for vertical flight? 3 fins, 4 fins? And where should they be placed?

[Stephen H]

mine when i had it, was a 3 fins right at the bottem. if you go back in the rocket form i posted a link to a nasa sight and it pridected the height of your rocket and you could choose motors and design them and things

Stephen

[Anthony]

D'oh, I said vertical...

I meant horizontal hehe. Sorry...

So, does it stay the same?

[larry cottrill]

Wich kind of fin setup should I go for for a small A or B powered rocket designed for vertical flight? 3 fins, 4 fins? And where should they be placed?

Either 3 or 4 fins will work fine. As for placement, the requirement for aerodynamic stability is that the center of mass of the rocket as a whole should be well ahead of the center of drag. That's what the fins provide -- the forcing of the drag center well to the rear of the vehicle.

The reason the fins tend to be fairly large on small rockets is that the center of mass is usually farther to the rear than on 'full scale' rockets, because the entire fuel and motor weight is in the tail. You can add a small lead slug or bit of modeling clay into the very tip of the nose cone, to bring the balance point up into the middle of your rocket, allowing smaller fins to be used at the tail end. Of course, this adds a little dead weight that you may not want.

L Cottrill

[Anthony]

I don't think I want this weight, unless it's really necessary.

I never dealt with fin problems before, cause I used them as a stand for the rocket. However, now I want it to fly as straight as possible, and I feel they can make all the diffrence.

Thanks for your help, I will consider this for sure!