Posterboard Fins.

[PDawg]

I was bored at work and cut some fins out of a posterboard. I was surprised how stiff and thin they were. I built up a little rocket and it feels very strong with little flex. What are the downsides compared to Balsa? I can get a lifetime supply of this stuff for free and it cuts and assembles very well. I only fly lighter rockets with C or E engines for the most part.

 

[Sandy H.]

There are a wide variety of materials commonly referred to as posterboard. In my opinion, some are just fine for rocketry use and others are less ideal. If you have some that seems stiff and is consistent and not easily delaminated, it is probably pretty viable for lots of smaller rockets. Depending on exactly what you have, it might also be fine for centering rings. You could also laminate pieces together to make stronger rings if desired. A lifetime supply for free makes it well worth experimenting with.

Good luck!

Sandy.

 

[PDawg]

Launched with a C6-7. Perfect flight, no damage or wear. Pleasantly surprised.

 

[BABAR]

I was bored at work and cut some fins out of a posterboard. I was surprised how stiff and thin they were. I built up a little rocket and it feels very strong with little flex. What are the downsides compared to Balsa? I can get a lifetime supply of this stuff for free and it cuts and assembles very well. I only fly lighter rockets with C or E engines for the most part.

I use cheap thin posterboard to make nose cones for my polygonal (usually square, sometimes triangular) rockets. I have used picture matting board for rockets and fins. It’s probably about as strong as balsa of similar thickness, it’s definitely heavier, but requires less finish work (although papering fins isn’t that hard either, and still weighs less than the matting. The venerable Estes Viking using some sort of cardboard fins, works great.

 

[banjonate]

2-ply 11 point works very well for me. Used it on up to D power so far.

 

[PDawg]

Today was the 3rd flight of my posterboard fin E-12-6 rocket and it was perfect other than getting stuck in a tree. My Puck Futin C6-7 rocket has launched 6 times with posterboard fins and still flies great. I'm thinking anything small, cheap, or likely going to get lost is getting these fins from now on. Pleasantly surprised.

 

[jqavins]

Those fins look really thick for anything I've ever called poster board, but then A) what what Sandy H. said, i.e. that there are lots of things which go by that name, and 2) if it's working for you, that's what matters.

But what is it? Is it extraordinarily thick paper? Very thin foam core? Something else?

 

[PDawg]

Those fins look really thick for anything I've ever called poster board, but then A) what what Sandy H. said, i.e. that there are lots of things which go by that name, and 2) if it's working for you, that's what matters.

But what is it? Is it extraordinarily thick paper? Very thin foam core? Something else?

It's about 1/16th inch thick. It's the same stuff we used for Science Projects in grade school and is sold in colored sheets. It's basically cardboard that is very dense and has a smooth finish on both sides and is available in tons of colors. My E powered rocket had 3 flights and even though it's now in a tree, the fins still look straight and undamaged. I have almost 10 flights on another rocket with these and while a had to reattach a fin twice I've had to do that with Balsa as well.