• Expected Speed & Altitude: Mach 4.7, 29,000 ft

• Expected Dynamic Pressure: 175 psi

• Motor propellant fraction: 71%

• Motor mass fraction: 55%

• Flight result: 💥☹️

This rocket was built to Colin Chapman's famous motto: 'simplify, then add lightness'

After my subscale motor test, I moved up in scale and built my first properly serious flight vehicle. I went for the most basic optimizations first, such as eliminating parts like the recovery anchor by including it in the forward closure bond, eliminating the tailcone and expansion cone completely,  and simplifying manufacturing by splitting the forward closure into two parts. These optimizations led me to a motor with a propellant mass fraction of 71%, and a vehicle mass fraction of 55%. According to RASAero II, the rocket was expected to fly Mach 4.7 and 29,000 ft

This rocket had a lot of composites, and I had to be sure I could have good process control over everything. For the nosecone, I developed a 3-part compression mold to yield a stronger, more reliable composite nosecone and, additionally, enable easy ablative molding. The 5 ply layup consisted of sleeve and axial uni, to handle both internal pressure and flight loads from the expected 175 psi max Q (not a typo). I was very consistent with my process and amount of resin used, and the entire vehicle matched the CAD within 30g, which I am very proud of.

Unfortunately, the rocket exploded on ignition due to a gap between the sealed liner and pressure vessel, leading the liner to rupture and burn through the pressure vessel within 50ms of ignition. I will be trying again this year.

A 'quick and dirty' rocket build that I put together over the course of about a week. While it was initially meant to fly, I didn't finish the avionics bay in time, and I decided to static fire instead. I achieved ~ a 65% motor mass fraction, and scoped out a lot of the process that I would use for future composite case builds.