Stratosphere only starts at 60,000ft and ends at 200,000ft. I think it was just translated wrong by someone who didn't know better, because an air breathing rocket engine is not a requirement at 60,000ft. The only reason they would mention rockets is if they meant to go higher than that, vid related.
Also a point of interest flying at those altitudes is difficult for two main reasons, jet air intake drops and the control surfaces dont have enough air passing over them to work. The U-2 is a great example because the low speed at 65,000ft meant the pilot had basically no control ability, the engine also barely provided any thrust and the airplane had to mostly glide. Basically the airplane could get up there, but it couldn't exactly evade.
To fix these two problems the vehicle needs to go faster. For example if someone wants to fly and control an aircraft at 65,000 feet altitude they have to fly at around Mach 2. At 75,000ft altitude the speed necessary is Mach 2.8, if someone wants to both fly and control their aircraft. Flying at Mach 3.3 permits an altitude of 85,000ft. To get to 90,000ft and still have some maneuverability, an airplane would have to be hypersonic. To get to 100,000ft with an airbreathing engine, the speeds are so high that the lifting surfaces would have to be reversed and force it DOWNWARD, because it's above escape velocity.
This is why engines like Sabre (vid related) and this new NK-32 are so important, they can close the jet cycle and pump liquid oxygen in, traveling at essentially any altitude they want.
It's becoming clear is that Russia is trying to absorb as much practical experience as possible from the war in Syria.
One thing they're doing is rotating troops in a way to give as many soldiers as possible a chance to fuck up and get quality combat experience. Another thing they've decided is instead of doing things the easy way they are doing everything the hardest possible way they can think of. For example they're launching ship borne mach 2 cruise missiles which aren't meant for low value targets.... and using strategic bombers like Tu-160 on high-stress flight paths to take out a few mud huts.
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