[NonZeroSum]

How would one use a scramjet for orbit transfer, which occurs in space? Why would one?

This is a solution looking for a problem.

[CasearianDaoist]

transfer form earth to orbit not to a trasfer orbit. The solution is that it requires much less fuel and can be done from an airstrip. The notion is to cheap, routine and at will flight to orbit.

[jpsb]

How would one use a scramjet for orbit transfer, which occurs in space?

As I am sure you know, one could not use any kind jet in space for any purpose, since all jets require air flowing into their engines.

It looks like the "plan" is to build a craft that can use turbo fan or whatever jets to get moving fast enough (3,000 mph) to switch over to scram jets to get to the edge of space and then switch over to rocket engines to get into space. Seems like a reasonable idea, if they can get the scram jets working. A civilian version would skip the going into space part and operate at a very high speed and a very high altitude.

There are a number of folks researching scram jet engines. I didn't know they needed hydrogen for fuel, that kinda surprises me.