Shoot, I just realised I'm quoted in the OP without providing actual data, just vaguely remembering stuff. Give me about an hour, I need to fix that. Setup details are in the spoiler: I started a new game in Sandbox Mode, loaded the Aeris 4A, and replaced its jets with aerospikes. I then launched it, and in the debug menu turned infinite propellant on. I then took these measurements, being careful not to induce aero effects while flying when recording FPS. The biggest flaw I can see