Parachute design

As an essential part of the CanSat project, making the parachute has been a hard task though it should have been quite easy. However, this may be caused by poor experience on the field (I´m responsible of its design and construction).

When starting the design our parachute is going to have, we decided to make either a semispherical or a semielliptical one. For safety reasons (we think that it is more stable) we have decided to make it as a half of an orange, even though it would be easier to build the other type in fabric terms.

The material we are using to make it is a common kite fabric, which gives it the strength to handle the forces it may suffer.

We encountered a new problem: the stability of our project. We decided to solve it by putting a small hole on the top of the canopy. This has given us a bit of a headache, because the coefficient varies with this adjustment

When we solved that problem, we started the actual design. It has been done sewing some little triangle-shaped stripes, and cutting the hole in the middle of it. The “bag” is going to be composed out of eight of these semi-triangular pieces.

In order to establish the drag coefficient with the little hole, we will drop a lot of times the parachute without the hole and calculate the Cd. Then we will throw another one with the hole, and calculate its Cd, to put it in the definitive parachute.

Due to the different weather conditions we have in Spain from Andenes, we have to make a parachute designed for the climate there. So we are going to make several parachutes to determinate the definitive one. The point of building that enormous quantity of parachutes is to make the best one for that fits the Northern area of Europe.

Starting with the real parachute design, we first started trying to calculate the surface area needed in orther to calculate how the canopy should behave. While thinking this, we used the simple formula which says:

Weight = ½x ρ x Cd x S

Ρ: air density.

Cd: drag coefficient.

S: surface area

From that point, we evolve on the structure by saying that:

V^2 = (2mg)/(SxCdxp)

Then is when we calculate the surface area, and so the ratio of our parachute, and the ratio of the hole at the top of it.

S= 548 cm 

Rp= 0.095 cm

Rh= 0.02 cm

On the other hand we had to calculate the dimensions for the gores of our chute, to cover that problem we decided to take a model already made, and scale it. 

Of course, as I said these are not ours, they are only a prototype which we are going to adjust for our parachute. The only thing in common is the number of gores: eight.