How much faster can scramjets be made to fly?

Question

Recently, NASA conducted the test on scramjets. The jet tested flew at a speed of Mach 10, ie, 10 times the speed of sound.

Can scramjet be made to fly much faster, or is that the maximum limit it can fly at?

Answer 1

Yes, supersonic combustion ramjets can fly faster still, albeit with careful redesign and optimization. The real practical limit is around Mach 25, as at that speed, you have reached the orbital velocity and leave the atmosphere. Outside of the atmosphere, there is no air, so a scramjet cannot work anymore.
Thus scramjet could be used as the first stage of a horizontal takeoff space shuttle (which will just need a small rocket once up there to circularize the orbit) or as a transatmospheric high velocity transport that could reach any point on the planet in less than one hour (orbital velocity takes one once around the planet in 90 minutes, so anything further than 45 minutes at maximum speed could be reached faster by flying in the opposite direction).
Flying any faster (than Mach 25) would be pointless as getting more energy makes the craft go higher and slower (due to celestial mechanics).
Scramjet could theoretically be made to go faster than Mach 25, but that would be very delicate from a technology point of view, and totally useless for the condition existing on this planet; actually getting faster would be counter productive.

Answer 2

I believe that they can get faster. The problem of course is the power to fly faster rises exponentially with speed due to increased drag from air resistance.
There comes a point when the weight of fuel required to fly faster is larger than the ability of the aircraft to carry it.
I think the highest speed will be 13-24 Mach. This speed would get you anywhere in the world in about an 30 mins Not even enough time for an in flight snack.

Answer 3

I have read that theoretically a scramjet plane can be made to literally fly into orbit, or around mach 22-24.

Answer 4

After about mach 12 it becomes more efficient and cheaper to use a rocket engine. They might be capable of going faster but why bother if you can do it in another way.