DocEmrick wrote:The F-22 was fitted with some kind of hydrogen powered scramjet prior to it's final development (I believe it was codnamed F-22a or something similar). It was changed to a two seater.
I find that all but impossible to believe. The material and structural changes make this a non-starter.
The two major advantages a scramjet brings are: 1) the ability to combust air that is flowing at supersonic speeds and, 2) following on to that, the ability to achieve much higher flight speeds than a ramjet aircraft can attain. However, with those higher speeds come ridiculous increases in temperature to which that the aircraft's surface is exposed.... like, well over a thousand degrees F. That requires the use of heat-resistant materials, as well as specialized design to allow for the expansion of those materials at those temps. The SR-71 was famous for leaking fluids on the ground because the aircraft was literally designed to expand and seal joints once the aircraft got to speed.
And it's not just a simple matter of putting a scramjet into a ramjet's airframe. The inlet design on a ramjet requires divergence in front of the first compressor stage (to slow the airflow to subsonic speed) and a scramjet requires a convergent nozzle (so the incoming airflow remains at supersonic speed). You need to make so many changes to accommodate that type of propulsion system that you can't really adapt an existing airframe, especially one that is on a shoestring like the Raptor. The USAF Raptor demo team doesn't even have any aircraft dedicated to them; before they can commit to a show, they have to find the closest Raptor base that has an aircraft or two available and borrow them for the duration of the show. The Air Force isn't about to take one of their very limited assets and turn it into a technology demonstrator that may or may not bear any fruit.
Hypersonic (~Mach 5+) aircraft also cruise at much higher altitudes, in part because the thinner atmosphere mitigates some of the heating effects. But once you go above ~60,000 in altitude (Armstong's Line) you are not coming back across it alive without pressurization. Why? The water in your lungs and mouth would literally boil. And that would suck. I'm not sure if tactical jet aircraft pressurize their cockpits (I don't think they do; one bullet or piece of shrapnel through the window and it would be rendered moot), but have you ever seen SR-71 aircrew? They wore frickin' space suits. (And some of them were actually awarded astronaut wings). Again, another major design change to accommodate.
Plus, it should be remembered that the F-22 can hit around Mach 1.7 without using its afterburners. (Actual number is classified, but the Raptor pilots with whom I've spoken don't bat an eye at that suggestion, so take that for what it's worth) So, absent the necessary materials changes needed to sustain the higher speeds a scramjet-powered aircraft can hit, a scramjet is of dubious benefit to a Raptor. And it is simply not feasible to make all those structural and material changes to a Raptor.
There were two X plane variants of the Raptor proposed by Lockheed-Martin; the X-44 Manta (a delta wing, tailless aircraft) and something called the FB-22 that would have been a replacement for the F-15E Strike Eagle. Neither aircraft made it off the drafting table.
Finally, 'F-22A' is the actual name of the aircraft as it has been deployed to the USAF. And currently there are a little over 100 of the beasts that have been delivered to the Air Force - all of them are accounted for, and none of them are two seaters. And none of them have hydrogen powered anythings scooting them around the sky.
In other words, I call shenanigans on your claim.