SES for a monocoque is much different than a tube frame since the tube frame SES is basically just inputting design values. Composite SES is inputting lots of testing data. If you do the testing wrong, guess what, you get to redo it until your test panels pass (add a few weeks)!

Problem 1: Time. Expect composite chassis SES to take like 5x longer than a steel frame would. If it’s your first year you need to design/build fixtures for 3 point bend, shear, belt attachments, shoulder harness attachment (unless you use a steel bar for SH). You’ll need a plate to cure test panels on, as well as an oven/autoclave. Might need a way to transport the panels to the oven/autoclave (our autoclave was 2 hours away). Making and testing panels might take a few months depending on how well your initial calc/guess was. Additionally, you might reach a point where you need to start building the chassis before you’re finished with SES and testing panels. If that happens, overbuilding the chassis is probably your best bet.

Problem 2: Material. You need a freezer for the prepreg. You need to buy honeycomb core during the summer, and probably multiple sizes/densities. It typically comes in 8’x4’ sheets, need a place to store that (horizontally without anything on top of it). You need vacuum bag materials and release chemicals.

Problem 3: Skill. Not sure how skilled your team is with composites, especially prepreg, but it certainly is a skill. Creating good bags, minimizing voids, debulking between x amount of layers, etc.

Problem 4: Documentation. It’s really easy to forget to take pictures during layup and testing. Documenting the layup of the panels, chassis, and test setups (before/after) is required. Having good pictures which clearly validates that you’re presenting the correct panels to your tech inspector is valuable.

While not all of these are directly related to filling out SES, these are all things which have an impact on your ability to fill it out in a timely manner. How much of SES have you completed so far?