mxaxai wrote:moo wrote:aviationaware wrote:Still absolutely incredible every time I see it... I hope their first flight(s) with refurbished first stages due soon work out fine and, most importantly, that they manage to do what NASA never did with the Shuttle, which is getting the refurbishment effort down to a minimum. I guess that's the real key to substantial cost savings.
Unfortunately it doesnt look like its going to be as substantial as Musk and SpaceX first thought - there are is a lot of talk coming out of SpaceX about just how much damage the rockets are taking on the landing, and Musk recently revised the re-use down to just two or three for each first stage. It looks like there is a lot more refurb to do with each stage they recover, and they arent proving to be as reusable as first thought. This might be something fixed in later iterations, but right now its not panning out as planned.
What kind of stresses would lead to that amount of refurb being neccessary? They are not performing reentry maneuvers like the space shuttle used to do. Airplanes flying at high speeds perform landings and take-offs every day without needing rebuilding of, say, the engines or the gear. The most stressfull stages would probably be
a) The takeoff itself and associated forces/vibrations
b) Aerodynamic forces while returning
c) Vibrations and shock during the final burn & touchdown
Are there any parts that undergo significant shape change due to e. g. fuel pressure or aero forces? Anything which uses ablating materials or is expected to lose material some other way? Those are certainly more difficult to design for multiple launches and would need to be checked after each one.
They are seeing a lot more damage and degradation to the engines and engine mounts due to heat and stress during the reentry, which means more refurbishment is necessary. Two of the recovered stages have so far been deemed unflyable, which was not expected.