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Why is SpaceX making the same mistakes 70 years later?
by minikites 6y ago
Why is SpaceX making the same mistakes 70 years later?
- naikrovek 6y agoI don't recall NASA ever doing a rocket landing so I'm not sure which mistakes you are seeing repeated.
- bacon_waffle 6y agoI was surprised to learn recently that NASA did do some rocket landings in the 90s: https://en.wikipedia.org/wiki/McDonnell_Douglas_DC-X https://en.wikipedia.org/wiki/McDonnell_Douglas_DC-X
- naikrovek 6y agoOk, so which mistakes is SpaceX making that NASA also made?
- sudosysgen 6y agoNASA and the USSR did many powered rocket landings, actually. NASA even had a program for reusable first stages via powered landings that was scrapped because automatic guidance wasn't feasible yet.
- naikrovek 6y agoOk, so which mistakes is SpaceX making that NASA also made?
- sudosysgen 6y agoFailing to restart an engine in a retrograde trajectory. A difficult task that both the Soviets and NASA (and Arianespace and the Chinese) had issues with, but worked out. It's very difficult because of the turbulent airflow in an engine bell pointed against the airspeed vector. Despite this, many rocket engines can do it reliably.
- naikrovek 6y ago> Failing to restart an engine in a retrograde trajectory That's not a failure, that's the effect of some upstream failure. What failure are they repeating? Pumps sized too small? Improper torquing? You talk like you know the details, so share them.
- sudosysgen 6y agoThere are a lot of reasons for which an engine would fail to start in such a scenario. They all boil down to the turbulent airflow and high pressure in the nozzle inhibiting the ignition process. How exactly you decide to fix it depends on many things. It's impossible to tell. But they are all downstream of the same failure, which is overcoming the high pressure and turbulent flow.
- minikites 6y agoNASA did rocket landings on another planet with 1970s technology: https://en.wikipedia.org/wiki/Viking_program#Entry,_Descent_and_Landing_(EDL) https://en.wikipedia.org/wiki/Viking_program#Entry,_Descent_... >At an altitude of about 1.5 kilometers (5,000 feet), the lander activated its three retro-engines and was released from the parachute. The lander then immediately used retrorockets to slow and control its descent, with a soft landing on the surface of Mars.
- naikrovek 6y agoOk, so which mistakes is SpaceX making that NASA also made?
- snet0 6y agoThe same outcome does not require the same cause.