During the safety upgrades carried out after the Challenger accident, pneumatically operated latches were added to hold the valves open.Ģ) Would it be efficient if reused for 'asparagus-staged boosters'? There was also a concern that the disconnect valves could slam closed during operation of the SSMEs resulting in destruction of the vehicle. This was straightforward except for accessing the area which was far aft and underneath the orbiter belly. There was a documented EVA procedure for the crew to go out and crank the doors closed manually. This same concern existed for electrical or mechanical failures in the door closing mechanism. Failure of the umbilicals to retract into the orbiter could prevent the doors from closing, which would result in an imperfect heat shield for entry. If the ET was mechanically separated while this happened, it would tumble, and could hit the orbiter. If the fluid disconnect valves on the ET side did not close, the residual prop from the ET would vent out. The concerns with the system as designed were pretty obvious from the description above. Then the pilot flipped switches to release the centerline latches on the doors, close the doors, and latch them closed. Finally pyrotechnics blew the structural interface apart and the Orbiter fired down-firing jets to fly away from the ET. If not, a waiting period began to let the systems blow down through the open valves and a warning was issued to the crew. The system then checked to ensure that all valves were closed. Then triple redundant hydraulic actuators pulled the orbiter side umbilical plates into the Orbiter below the outer mold line.
#Kerbal crossfeed free
Three explosive bolts on each umbilical plate fired to free the interface. First the valves on each side of the fluid connections closed. Each fluid connection had a shutoff valve on both sides of the interface.Īfter the SSMEs shut down, the ET separation sequence began. The outside of the doors was covered with shuttle TPS tiles.Īt launch, obviously the doors were open and all umbilicals mated (the actual mating surface was called the ET umbilical plate). Large electrically operated doors (latched open at launch by electrically operated latches) covered the umbilical openings and also the aft structural connections between the ET and orbiter. There were also numerous electrical and data lines. Five fluid pathways connected through these two umbilicals: 17" liquid oxygen and liquid hydrogen lines, 3" gaseous oxygen and hydrogen repressurization lines, and a smaller hydrogen recirculation line. There were two umbilical areas towards the rear of the shuttle belly. The system as implemented on Shuttle was complicated but caused major problems only once in the program (see below). The buzzwords to use for googling this topic are "ET Umbilical". At a glance, it looks like it's just a notch away from what would be needed for the 'asparagus'.Ĭan someone provide an overview of the crossfeed system - in particular the detachable joint that fed LOX to to the shuttle from the tank? Would it be efficient if reused for 'asparagus-staged boosters'? Or was it plagued with enough problems - or even just too expensive or inefficient for such use?ġ) Can someone provide an overview of the crossfeed system - in particular the detachable joint that fed LOX to to the shuttle from the tank? The idea of ' asparagus staging' is that external boosters of the rocket feed their own fuel into the main engine, or into boosters that would separate later, so that at the moment of separation the craft's remaining tanks are still full, meanwhile, during the launch all engines are engaged - engines of later stages are not carried as dead weight, but contribute to thrust from moment one.Īnd yet, we had a system, where an external, detachable fuel tank would feed massive amounts of LOX bipropellant to engines in a separate stage - the shuttle's fuel tank feeding the SSME.
#Kerbal crossfeed professional
Whenever a fan of Kerbal Space Program mentions the super-efficient 'asparagus staging' in any professional context, the automatic response is 'That won't work.