Tracking Capsule

For Elijah X we used the MSOE Rapid Prototyping Center to design our first payload. We drew up the design in Solidworks and were able to add in all the walls and windows so that we would not have to make any modifications after it was built. The payload was a cylinder 8 inches in diameter and 4.5 inches tall. The lid had a slot built in for an o-ring and had hooks on top and bottom for the capsule to be connected to the parachute and the science experiment capsule. The dividing walls were built in as well and were designed specifically for each piece of equipment used.

We found that using the MSOE Rapid Prototyping Center to build the capsules would be too costly to use in the future.  Also, making modifications if new equipment was needed would be difficult, so from this point on we went with the method of designing and building our own capsules.

Science Experiment Capsule

There were a couple of materials we considered to make our cylinder. First we considered rolling aluminum into a tubular shape. Unfortunately, when this is done the ends of the aluminum sheet have to be welded together. The aluminum could warp during this process and therefore not give us the perfect circular shape we need for a watertight capsule. Next, we looked into plastics. After some research, we found that we could purchase clear cast acrylic tubing at a wide range of diameters from Midland Plastics, Inc. This material is both lightweight and durable.

Other materials include a high strength adhesive, an o-ring, and 10-32 aluminum screws.

The scientific payload was made out of 1/8 inch clear acrylic.  The body is a 6 inch I.D. tube at 5 ¾ inch tall, and the 6 inch top and 6.484 inch bottom disks were machined out of sheets by a Sharnoa CNC.  The top disk was fastened to the tube by using Weld-On, which is an adhesive that melts the acrylic together. The bottom was made of two 1/8 inch sheets adhered together, with a ¾ inch groove milled out at a radius of 3.117 inch. This is where the 1/8 inch o-ring sits and makes contact with the outside of the tube for a watertight fit. The o-ring was compressed 0.018 inch. This number can be found from any o-ring manufacturer. In addition there were four 1-64 x 3/8 inch screws that penetrated the tube’s wall from the bottom for extra holding. Lastly, there are three anchors that were also adhered to the top with Weld-On. These anchors were ¾ inch tubing cut ½ inch tall and consisted of a 13/64 inch hole drilled through the center.