I think that the main reason of replacing the SSME with J2-X is that the second stage of the spacecraft won't be reusable.
Launching a space shuttle is clear. After jettison of the SRBs the shuttle swithes to a second stage: the external tank, the orbiter and her engines.
But CEV would be different. The first stage will be reusable, because it is a single SRB that could be refubrished. The problem is with the second stage. After the orbit burn, it will jettison from the capsule with the crew and probably will burn into the atmosphere.
So what? Can we think of a way to make the second stage reusable?
The shuttle doesn not 'switch' to second stage after SRBs burn out. The SSMEs burn during the whole flight, from liftoff to ET separation. It's the airstart in CLV (after stage separation) that's problematic to SSME, it would need redesigning for that.
The CEV is reusable, except for the service module. Making the 2nd stage of the CLV recoverable would take a whole lot of TPS and parachutes which are all weight and a recovery force in the Indian Ocean.
Does anyone have any further news about Griffin wanting disposable SRB's to try to reduce costs?
It did the rounds on the rumour mill, but seems to have gone quiet since.
Ross.
Jim,
What makes the a SSME reusable (apart from the fact that the land back)? and what would be " reduced " to allow it to be disposable (lower the cost), even if it could be air started ?
Avron - 20/4/2006 11:18 PMJim,What makes the a SSME reusable (apart from the fact that the land back)? and what would be " reduced " to allow it to be disposable (lower the cost), even if it could be air started ?
I couldn't honestly tell. Just that is built to take repeated loads, to me means extra material