A Combined Approach Better Than SSTO's? in Science & Spaceflight Posted Sunday at 03:27 PM · Edited Sunday at 04:45 PM by RCgothic You can't just compare masses of airliners and rockets. (By the way 737max is roughly 1/4 payload at max takeoff mass). Falcon 9 is the single most popular launch platform worldwide bar none. The F9 upper stage masses approx 112t wet including 16t heaviest payload actually flown. It stages high (80km) and fast (Mach 6) so that in likelihood an aircraft-launched upper stage is going to have to work much harder So a reusable upper stage less than half the mass of F9 upper stage is going to have less than half the payload and tighter margins, even before you include the effort of making it reusable (F9US is not reusable). Tighter margins means the vehicle has to work harder, which makes it less reusable. It's no coincidence that the two new reusable craft on the drawing board - starship/superheavy and New Glenn are both going larger than Falcon9.