> Could anybody here comment on the differences between spacex's engine, and the engines on the space shuttle? The Space Shuttle's engines were extremely compl

> Could anybody here comment on the differences between spacex's engine, and the engines on the space shuttle? The Space Shuttle's engines were extremely complex beasts that begat the most advanced alloys at the time – very much bleeding edge, with the tightest tolerances possible, to squeeze out performance that wasn't thought possible before, using highly aggressive propellants (hydrogen embrittlement was a huge problem). As a result, they only had a tenth of their planned life expectancy (average of 5-6 instead of 55 flights), and needed an 80% refurbishment between every flight to replace cracked turbine blades etc. pp. Falcon 9's Merlin engines, meanwhile, are best described as "boring": They're firmly a 60s design made cheaper than dirt thanks to modern manufacturing technology, and highly reliable thanks to a simple design and safe fuels (kerosene). SpaceX already demonstrated on the ground that Merlins can perform multiple missions without needing refurbishment. Or, in car analogies: The Space Shuttle is a Jaguar, Falcon 9 is a Ford. While you can, on the paper, drive a Jaguar twice without seeing a workshop, nobody managed it yet. > I was under the impression that SpaceX was trying to make the first re-usable rocket stage, but I've recently found out that that isn't true. The space shuttle already holds that title. Kinda, sorta, in theory: While the orbiters did refly a lot of times, the engines (the most expensive part of the Shuttle) barely did, only in the "Ship of Theseus" sense. Same for boosters (fishing steel tubes out of the ocean and hammering out the kinks was a pure work creation measure), and the huge external tanks were made anew each time. > I'm also kindof curious why they decided to go with a vertical-landing-design, instead of putting some wings on it and having it glide home like the shuttle did. Is that a weight-concern? Precision and weight: Wings are dead weight for a vertically launched rocket, and increase drag (especially supersonic) further than folded-up landing legs do. Hoverslam point landings need very little added mass on the rocket, and you expose a far smaller surface to re-entry heating etc.