William Orvis, LUNAR#309
After building the MicroMaxx Rack rocket couple of years ago, I decided to go in the other direction. C engine rack rockets are pretty standard and D engine racks have also been done, so, it seems like it is time for an E-engine rack rocket. E12-0 engines had just come available and are just the just the ticket for a rack.
Figure 1. The Rack Rocket Fleet: MicroMaxx, 18mm (C-motor), and Maxx (E-motor).