There's a reason why we refer to our Chief Mechanical Engineer Adam Reif as "Close Tolerance Reif," or CTR. Pumpkin customers benefit from Adam's obsession with turning out a quality product at a good price. The U.S. Naval Academy's Bob Bruninga sent us a thank-you email yesterday, as USNA was completing the assembly of their PSAT2, which utilizes a COTS Pumpkin 1U structure:
After a three year design, leading to today and after finally (for the first time) snapping the top panel on our 1.5U CubeSat and having everything fit perfectly, I just had to stop in celebration and come over and send this Email.
It just fits. Everything in the 1.5U frame just fit together perfectly. Especially since we have a 1.2kg central ballast (for longer orbit) and total 1.5U mass of 2.8 kg.
The one mod I made was a small 0.1” notch at each of the corners of the side fame so that when it has slid down over the top of our full stack and the 1.2kg central mass (which is the precise dimensions of the walls so it can be screwed to the walls), that I can then use a small screwdriver at each corner post to get the side frame “started” when I go to remove it.
Without those slots, the fit of the side sleeve to the bottom is so perfect that there is nothing to get in there and pry it loose. Attached is stack photo.
Bob Bruninga, PE
US Naval Academy
Bob relates that PSAT2 is "Built by students for self training in radio art and only using Alumni GIFT funds." More info is available at http://aprs.org/psat2.html
Image courtesy of United States Naval Academy