2 replies to this topic

[barr]

I've recently become interested in rocketry and have tried making a few BP rockets and they've gone well, in that they move but i can't seem to get them to go straight.

I've tried adding heavier support sticks and fins but the rocket still falls over and shoots around the ground.

The rockets I have made are: 50mm long, 15mmID

Any help is appreciated.

Thanks

[pritch]

I've recently become interested in rocketry and have tried making a few BP rockets and they've gone well, in that they move but i can't seem to get them to go straight.

I've tried adding heavier support sticks and fins but the rocket still falls over and shoots around the ground.

The rockets I have made are: 50mm long, 15mmID

Any help is appreciated.

Thanks

Do you stick to the general rule of stick = rocket length * 6 ? I once tried slightly shorter than this and the rocket went up around 8 feet then turned 90 degrees and flew horizontal.

[Phoenix]

If you can rest the rocket horizontally on your finger, at the nozzle end, and it either balances or tips stick downards, then the stick isn't likely to be your poblem. If you are using a short, heavy stick, it would be better to use a longer, lighter one. This will achieve the same turning force (moment) when balanced as above, but will give better aerodynamic stabilisation when the rocket is moving.

An underpowered rocket will often tip over in flight too. If it doesn't accelerate to a high speed quickly upon launch, it will lack aerodynamic stabilisation and be prone to arc excessively, even if the stick is long enough. If the rocket doesn't take off fast, then you may need to use a smaller payload or bigger motor, or lengthen the core.