Reply To: EmDrive + Focus Fusion = Space Access for all?

[belbear]

Tulse wrote: belbear, in the system you describe the only thing that FF would be doing is providing an alternate power source. As I understand it, the problems with scramjets aren’t in that area, but instead in the engineering of the hypersonic air passage. Perhaps I’m wrong, though — someone else here may be more knowledgeable on this topic.

The problems of designing a scramjet are mainly in how to prevent a “flameout”, i.o.w. the need to maintain fuel combustion in a hypersonic airflow.

A FF powered scramjet does not do chemical combustion at all, so this problem does not pose itself, because it would work by simple heating of incoming air (using either electricity, X-rays or ion beam) And that always work.
Instead of fuel injection it could be using a tungsten heat exchanger, operating at very high temperature (2000°C) to transfer heat from the source to the airflow.

And in aviation and space flight the weight of the fuel to carry is of course also an important issue. For a FF aircraft, the landing weight is essentially identical to the takeoff weight. Although some kind of backup fuel could be used: Kerosene or even water injection could provide an extra low-speed boost during take-off. (afterburner)

There were experiments with water injection in turbojets, and it worked, but in the end it proved more efficient to simply carry the same weight in fuel.
In contrary to fuel, water injection also works reliably at hypersonic speeds. So water injection can give the upper rocket stage that extra final boost before separation.