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We have built our rocket with a one litter bottle, and we have a paper cylinder on top. We have a paper cone, and the parachute and ball are stuffed inside. However, when we launch, it spins. This appears to be caused by the top of the rocket tipping over, which is probably because it is top heavy. Can anyone confirm our suspicions, and help us out a little bit. Will changing our fins help? We currently have 4 triangular fins that are around 5 inches long and 8 inches tall.

Note, we are in NorCal, so it is an outside event.

EDIT FOR CLARIFICATION:

Our rocket is flipping over such that the top(cone) part is on the bottom and underneath the fin portion.

sciolynoob wrote: ↑February 17th, 2020, 8:12 pm We have built our rocket with a one litter bottle, and we have a paper cylinder on top. We have a paper cone, and the parachute and ball are stuffed inside. However, when we launch, it spins. This appears to be caused by the top of the rocket tipping over, which is probably because it is top heavy. Can anyone confirm our suspicions, and help us out a little bit. Will changing our fins help? We currently have 4 triangular fins that are around 5 inches long and 8 inches tall.

Note, we are in NorCal, so it is an outside event.

The reason it's spinning is likely because of your fins (are they angled, even a little bit?)

sciolynoob wrote: ↑February 17th, 2020, 8:12 pm We have built our rocket with a one litter bottle, and we have a paper cylinder on top. We have a paper cone, and the parachute and ball are stuffed inside. However, when we launch, it spins. This appears to be caused by the top of the rocket tipping over, which is probably because it is top heavy. Can anyone confirm our suspicions, and help us out a little bit. Will changing our fins help? We currently have 4 triangular fins that are around 5 inches long and 8 inches tall.

Note, we are in NorCal, so it is an outside event.

Spinning or flipping? If the bottle is spinning, it shouldn’t be too big a problem, but if it’s flipping, the rocket is just off balance or something.

builderguy135 wrote: ↑February 17th, 2020, 8:37 pm

sciolynoob wrote: ↑February 17th, 2020, 8:12 pm We have built our rocket with a one litter bottle, and we have a paper cylinder on top. We have a paper cone, and the parachute and ball are stuffed inside. However, when we launch, it spins. This appears to be caused by the top of the rocket tipping over, which is probably because it is top heavy. Can anyone confirm our suspicions, and help us out a little bit. Will changing our fins help? We currently have 4 triangular fins that are around 5 inches long and 8 inches tall.

Note, we are in NorCal, so it is an outside event.

The reason it's spinning is likely because of your fins (are they angled, even a little bit?)

Our fins are definitely angled! We will try to fix that. However, our rocket is rotating, sorry for the bad phrasing. It rotates such that the top of the rocket is on the bottom.

Hartman wrote: ↑February 17th, 2020, 8:57 pm

sciolynoob wrote: ↑February 17th, 2020, 8:12 pm We have built our rocket with a one litter bottle, and we have a paper cylinder on top. We have a paper cone, and the parachute and ball are stuffed inside. However, when we launch, it spins. This appears to be caused by the top of the rocket tipping over, which is probably because it is top heavy. Can anyone confirm our suspicions, and help us out a little bit. Will changing our fins help? We currently have 4 triangular fins that are around 5 inches long and 8 inches tall.

Note, we are in NorCal, so it is an outside event.

Spinning or flipping? If the bottle is spinning, it shouldn’t be too big a problem, but if it’s flipping, the rocket is just off balance or something.

It is flipping over so the top(cone) is on the bottom.

sciolynoob wrote: ↑February 17th, 2020, 9:02 pm

Hartman wrote: ↑February 17th, 2020, 8:57 pm

sciolynoob wrote: ↑February 17th, 2020, 8:12 pm We have built our rocket with a one litter bottle, and we have a paper cylinder on top. We have a paper cone, and the parachute and ball are stuffed inside. However, when we launch, it spins. This appears to be caused by the top of the rocket tipping over, which is probably because it is top heavy. Can anyone confirm our suspicions, and help us out a little bit. Will changing our fins help? We currently have 4 triangular fins that are around 5 inches long and 8 inches tall.

Note, we are in NorCal, so it is an outside event.

Spinning or flipping? If the bottle is spinning, it shouldn’t be too big a problem, but if it’s flipping, the rocket is just off balance or something.

It is flipping over so the top(cone) is on the bottom.

You need to add weight to the top of the rocket. Look up center of gravity versus center of pressure. It's been talked about this season. Basically you need to move the CG toward the nose cone by adding weight toward the nose or reducing weight by the fins. Think of your rocket like a dart, weight up front, fins (center of pressure) in the back.