Deciding on Fin shape or Planform

The Rocketry Forum

Help Support The Rocketry Forum:

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.


Well-Known Member
May 2, 2004
Reaction score
So how do you guys decide on your Planform.

I know Stine provides excellant examples and even some design rules for Clipped Delta planform.

Using either of the two main Sim's available will provide extremely good 'recomended' shapes.

What I would like to know, especialy from the 'minimulists' out there is.
How do you decide on your Planform.

Do you get an idea then SIM it till its right, or just build and add nose weight till its stable.
I guess it depends upon if I'm building for looks or utility. If utility, then I typically use a clipped delta, and I'll often make the semispan equal to the tip length and half the length. Make sense? Basically the plan form is a rectangle made from two squares, one of the squares being cut diagonally in half.

If building for looks, I start off with something that looks nice. Once the initial design is complete I tweak fin size, position & possibly shape. But if it teh tweaking doesn't look right I'll consider adding noseweight, and I often I do.
Everything I build tends to be built for strength. That means no weird fins shapes like forward swept fins.

I prefer triangular fin shapes for a little more extreme stuff because to me at least, the fins seem stiffer than clipped deltas as Stine recommends em. I builld for strength and stay away from fins with big spans or swept back fins.

Any "normal' planform works.

I also have VCP. I guesstimate the weights and I build the rockets to be about 2.5 calibers stable. Then I have no worries about stability. Just check your CG on the first few flights to get a feel for the rockets. I rarely add weight.