Control Surfaces:

Most of the research consisted of finding the perfect fin shape. After much consideration, a parallelogram was chosen. These are a few of the reasons:

The most efficient area of the fin is located at the tip where the air current is the smoothest. The closer we get to the body of the rocket, the more turbulent the current, due to the air flowing over the nose cone. Therefore we want a fin with the largest tip possible, making the elliptical, triangular and other highly tapered fins ineffective.

The dimensions of the fin (like the height) are related to the diameter of the body tube. If the fin root cord and the semi span (height and width) are both twice the diameter of the body tube, the design should be stable.These are the calculations: (where w = the height and width of the fin)

w = diameter of tube x 2

w = 18mm x 2

w = 36mm

Therefore the height and width of the fins are 36mm or approximately 1.5" and are in the shape of a parallelogram.

Warning: Make sure you adapt all calculations to your project restrictions and the materials available.

The number of fins to make a rocket stable is usually three or four. More than four and there is excess weight, any less than three and the rocket isn’t stable. We chose to use three as it provides a balance between both extremes.

Warning: When launching your rocket, make sure the engine (in this case: solid fuel) is correctly positioned inside the rocket's tube. If not, the center of gravity is off, and maximum altitude won't be achieved.