BWAH bwah

Hamilton, Ontario | Let It Go (Without A Bang)

Low Impact Parachute Deployment Separation Device

High-Level Project Summary

The purpose of this challenge was to optimize the way a parachute is released by creating a low impact version that omits the use of pyrotechnics. Our team spent a lot of time coming up with different ideas until we eventually thought about using our greatest natural tool to our advantage: gravity. We developed a mechanical system that involves the use of a rotational blade to cut through the reefing line of a parachute, using a spring motioned by the force of gravity during freefall.

Link to Project "Demo"

https://drive.google.com/file/d/1uYZb13bgBn2OUj-h-186nPkMTYSyKwPi/view?usp=sharing

Link to Final Project

https://drive.google.com/drive/folders/17xCg_EFaZqzr5Zbv3Z_zUjQEdSPwdI2w

Detailed Project Description

Our project heavily involves the force of gravity to motion the blade towards cutting the reefing line. We start off with a cylinder with a diameter of 17.5cm and a height of 26cm. Within this casing, there is a rotational blade that is powered by an external motor. A spring will be attached to this motor, with the blade on the other side of the spring. As the space object, to be released, is taking off, the spring will compress due to air resistance. This will continue to occur until the object reaches a momentary stop in mid air, where the spring will then be at equilibrium. Once the object starts to accelerate downwards, air resistance will act in the opposite direction of the object's motion, therefore the spring will begin to stretch. The spring will stretch more and more as the object freefalls. Overtime, there will be a point where the spring is stretched enough that the blade will reach the other side of the cylinder. As the blade reaches the reefing line, the rotational motion caused by the motor allows for a quick snip of the wiring, thus disconnecting the parachute.

This external motor will be powered by 20W , therefore allowing for a maximum rpm of 6000 (in reference to a datasheet for a particular DC Brushless Motor). This rotational speed is more than enough to be able to slice through wiring without requiring a strong "push-pull" force of the spring.

The spring force will be very weak as it's solely dependent on gravity and air resistance, although it would not be ideal to have a sensitive spring. It is preferred to have a high spring constant (300N/m) so that the displacement would be minimal over time. We can use Hooke's Law to further prove the relation between spring displacement and gravitational force.

The material of the blade would be made of Titanium alloy since this material is able to withstand -128 degrees Celsius. When prototyping the blade on Autodesk Inventor, it was found that it weighed 1.067kg although this material is based off of 3D printing material. The downside towards using titanium is that it would weigh much more than originally intended although we can reduce the sizing to scale, in order to accommodate for this surplus of mass.

Space Agency Data

We found the stages of space flight through NASA's website which demonstrated the separation process of the parachute. The references given in the challenge were also very useful when determining the validity of our project.

Hackathon Journey

Since this was our first hackathon it appeared to be quite intimidating however, the addition of technical workshops allowed insight on aspects we lacked within our project. At first glance, we assumed the issue of a mechanical separation device to be a simple one, release a chute after launch and finish. However, our assumption was wrong, as we continued with our project we found making a low impact separation device to be a greatly difficult concept and simply creating a logical prototype was even more so. Through further research, we found that the deployment of parachutes is a recurring issue within space flight for NASA, SpaceX and other flight companies.