Discussion
It's actually very hard to hide a very high Mach No. atmospheric test - simply because an object moving at that speed covers a huge amount of sky in a very short space of time.
Also, keeping an object flying at these speeds within the atmosphere, maintaining its airframe temperature within survivable limits and being able to manouever the craft at those speeds is still incredibly difficult.
The Space Shuttle - plus a handful of other winged re-entry vehicles, have been able to do this in the past - but their exposure to high mach numbers has been relatively brief on each mission and the speeds are not maintained at these high levels in the relatively denser air below 100,000 feet.
Also, keeping an object flying at these speeds within the atmosphere, maintaining its airframe temperature within survivable limits and being able to manouever the craft at those speeds is still incredibly difficult.
The Space Shuttle - plus a handful of other winged re-entry vehicles, have been able to do this in the past - but their exposure to high mach numbers has been relatively brief on each mission and the speeds are not maintained at these high levels in the relatively denser air below 100,000 feet.
There have been a number of test vehicles which have tried hypersonic Mach speeds. The X-15 is probably the most famous. That got up to Mach 6.7 and ran into serious heat damage issues. In fact, it never flew again. We've also had the unmanned X-43 programme which I think has managed over Mach 7. The Chinese and the Russians have also had a go at similar unmanned vehicles.
When you get up to Mach numbers over 10 I think you are better off going into ballistic flight outside the atmosphere. The disadvantage is that it is is (in theory) easier to change direction and course when in aerodynamic flight within the atmophere - which makes the path of the vehicle unpredictable and harder to intercept.
When you get up to Mach numbers over 10 I think you are better off going into ballistic flight outside the atmosphere. The disadvantage is that it is is (in theory) easier to change direction and course when in aerodynamic flight within the atmophere - which makes the path of the vehicle unpredictable and harder to intercept.
Mave said:
The shuttle used to re_enter at M22 IIRC... I wonder what happened to the facilities they used for testing back then?
The excellent Scott Manley did a great video on this not that long ago: https://www.youtube.com/watch?v=v0Z_4VyuzcAEric Mc said:
There have been a number of test vehicles which have tried hypersonic Mach speeds. The X-15 is probably the most famous. That got up to Mach 6.7 and ran into serious heat damage issues. In fact, it never flew again. We've also had the unmanned X-43 programme which I think has managed over Mach 7. The Chinese and the Russians have also had a go at similar unmanned vehicles.
When you get up to Mach numbers over 10 I think you are better off going into ballistic flight outside the atmosphere. The disadvantage is that it is is (in theory) easier to change direction and course when in aerodynamic flight within the atmophere - which makes the path of the vehicle unpredictable and harder to intercept.
Isn't that the whole point of boost glide? High mach ballistic flight outside the atmosphere, then drop to the upper atmosphere, course change, then back out of the atmosphere again. So no sustained M18 heating When you get up to Mach numbers over 10 I think you are better off going into ballistic flight outside the atmosphere. The disadvantage is that it is is (in theory) easier to change direction and course when in aerodynamic flight within the atmophere - which makes the path of the vehicle unpredictable and harder to intercept.
The SR71 could not sustain above M3.2 and that was at 80,000 or sometimes higher. These limitations were not just due to engine capabilities ( 427 degrees maximum compressor intake temp) but also structural factors.
I cannot imagine how high you would need to go to fly at mach 18 and I can't see what you could possibly achieve that can't already be done in other ( cheaper) ways.
I cannot imagine how high you would need to go to fly at mach 18 and I can't see what you could possibly achieve that can't already be done in other ( cheaper) ways.
Mave said:
Isn't that the whole point of boost glide? High mach ballistic flight outside the atmosphere, then drop to the upper atmosphere, course change, then back out of the atmosphere again. So no sustained M18 heating
Yes, but you lose the advantage of aerodynamic manoeuvrability within the atmosphere. High Mach numbers WITHIN the atmosphere is the holy grail - and proving very hard to crack,Eric Mc said:
Mave said:
Isn't that the whole point of boost glide? High mach ballistic flight outside the atmosphere, then drop to the upper atmosphere, course change, then back out of the atmosphere again. So no sustained M18 heating
Yes, but you lose the advantage of aerodynamic manoeuvrability within the atmosphere. High Mach numbers WITHIN the atmosphere is the holy grail - and proving very hard to crack,
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