I have an idea where I have put the turboramjet( j-58) in the front of the engine including the six bypass tubes. Behind that engine, I have put a scramjet. I know the scramjet won't get enough o2 for combustion. For that, I have given the scramjet two additional air inlets above and below the engine nacelle which will open up only after Mach 3.5. The main air inlet for the j-58 will close at that speed the engine will shut down and the scramjet will turn on only after that speed is reached. In order to cool the j-58, the two air inlets will let some air pass through around the engine nacelle. Thus, it is an air-cooled turboscramjet engine.
I don't know if it will work. Please excuse me, I am only thirteen and I have no experience in these fields.