GarryB Sat Apr 28, 2018 11:22 am
A conventional scramjet engine can operate at very high altitudes... above about 30km there is very little air, but moving at 6 times the speed of sound or faster the amount of oxygen going through the engine is more than enough to burn fuel...
At normal air pressure at normal temperatures you can blow on embers... you are not adding fuel, you are increasing the oxygen available for the fuel to burn... obviously however if you blow too hard you risk blowing any fire out.
In a normal jet engine supersonic air will blow out the flame and the fuel stops burning... in a scramjet no speed of airflow is high enough to blow out the fire... it can burn fuel supersonically...
Of course with this nuclear engine there is no fire and no flame to blow out... likely the speed limit would be the short period of time the air flows through the very hot bits would limit its ability to heat the air blowing out the back of the engine... remember air heated expands... hot expanding air means thrust.
Ironically the temperature this engine is working at even water could be injected to increase thrust... when water is heated to 1,000 degrees or more it turns instantly into a gas... a litre of water would generate a huge volume of gas... so flying through a rain storm would likely increase the engines thrust enormously...
Very interesting really...
A high-altitude hypersonic version of the Burevestnik would require a nuclear engine with a power output literally 10x greater, if not more. Not beyond the pale, but its a huge leap beyond the current tech being trialed.
And it introduces the problem of scale... to make it 10 times more powerful might make it 50 times heavier... which means it is not powerful enough any more so it needs to be even more powerful again etc etc.
The end result will be a very very fast weapon but a lot of work for what it is intended for.
In a few decades it might be the best option to get an aircraft from a runway to orbital speed where other more exotic propulsions take it to other planets, but for now... probably not.