Current dimensions: 23.6 inch x 17.75 inch x 11.88 inch tall

It’s been a little while since my last post and quite has happened. The big news is that the preliminary design review (PDR) held on October 30 was a success. I have received feedback from the judges which was mostly positive although there are a few areas of concern that I will attempt to address.

Specifically, there was concern about the material the EcoSphere is made of (blown glass). The manufacture of the EcoSphere does not offer a version in a plastic sphere but I’m currently searching for a suitable an acrylic or polycarbonate seal-able sphere that the contents of the EcoSphere could be relocated to.

Another concern was about establishing a control for the effects of hyper-gravity. This potentially has a very simple solution due to the rotating stage that is being incorporated into the design. With modifications to the rotation controller, it could potentially be sped up to act as a centrifuge. To simulate 2 G’s at the outer wall of the 4 inch sphere, the sphere would have to be rotated at a rate given by the expression:

f=sqrt(a/(4*pi2*r))

where r = 0.05 m, a = 20 m/s^2, pi = 3.14, and f is the rotation rate to be solved for.

The given parameters necessitate a rotation rate of 3.18 revolutions per second or about 190 revolutions per minute. This is might be a bit difficult but I’ll give it a try.

The full PDR feedback is posted below.

In addition to PDR, I’ve been working on figuring out the sizing of the payload and how it will be secured in the plane. The PDR judges suggested possibly using Velcro to secure the payload to the aircraft. I still need to figure out if this would be viable but I would love to save the expense of the aluminum mounting plate.

Additionally, the judges recommended I look for opportunities to condense the payload due to space limitations. One possibility is to use a smaller waterproof tub such as the one below but this one only has 4 latches instead of the 6 latches on the larger tub.