'World's Fastest Plane'
Discussion
http://news.sky.com/home/technology/article/162145...
Interesting news, would love to know more about it.
Interesting news, would love to know more about it.
RobDickinson said:
Scramjet of some sort? Exotiv materials etc.
Is it really a plane? An unmaned thing launched from a rocket ? Sounds more like a missile than a plane.
True. Would be interesting to find out the scale of it. It must be fairly sizable to carry enough fuel as well as the potential for bombs, unless this is merely a scaled down prototype.Is it really a plane? An unmaned thing launched from a rocket ? Sounds more like a missile than a plane.
It's pure science/engineering. An attempt to learn to control (and survive) hypersonic flight.
This is the second one - the first didn't manage to establish controlled flight but gave them enough of an idea as to what was wrong, this one did much better http://www.theregister.co.uk/2012/04/23/darpa_over... (although the article is by Lewis Page which seems to be a dirty word here).
This is the second one - the first didn't manage to establish controlled flight but gave them enough of an idea as to what was wrong, this one did much better http://www.theregister.co.uk/2012/04/23/darpa_over... (although the article is by Lewis Page which seems to be a dirty word here).
Eric Mc said:
How come the Shuttle was capable of controlled flight at Mach 22 - or was it not controlled enough for USAF needs?
I assume that the shuttle only goes at this speed as it enters the upper atmosphere? I couldn't find what altitude the HTV2 was flying at, but drag and frictional heating will be a lot more significant when the air is more dense!Yes, the initial interaction with the upper atmosphere is at 17,500 mph or so and it gradually slows down as the atmopsheric friction bleeds off the speed. However, the Shuttle was still doing Mach 10 to Mach 15 or so in relatively dense parts of the atmosphere.
Back in 1967 the X-15 A2 managed Mach 6.7 at around 102,000 feet but was so badly damaged by the heat generated that it never flew again.
Back in 1967 the X-15 A2 managed Mach 6.7 at around 102,000 feet but was so badly damaged by the heat generated that it never flew again.
maffski said:
http://www.theregister.co.uk/2012/04/23/darpa_over... (although the article is by Lewis Page which seems to be a dirty word here).
Just read the article to see why you needed the bracketed butt cover.... Goodness me- its like it was written by a hyperactive child, do they even have editors on the Register?Odie said:
If they are trying to get this to fly at mach 20.
Whats the current fastest military/commercial aircraft in service? and whats its speed?
SR71, ~Mach 3!Whats the current fastest military/commercial aircraft in service? and whats its speed?
http://en.wikipedia.org/wiki/SR71_Blackbird
There is no manned aircraft in service that can maintain a constant speed exceeding Mach 2.5 at the moment. The fastest ever was, of course, the SR-71/A-11/YF-12 family which could maintain Mach 3.2.
The fastest manned aircraft ever was the X-15 which reached a peak speed in one flight of Mach 6.7 - but almost lost the aeroplane.
The Shuttle could, of course, maintain aerodynamic control at extremely high Mach numbers but in this flight regime it was unpowered and effectively slowing down all the time once it entered the atmosphere.
Maintaining a constant Mach 20 within fairly dense parts of the atmosphere and maintaining aerodynamic authority and stopping the airframe from melting due to atmospheric friction is extremely difficult and may not be achieveable - or even worth doing.
The fastest manned aircraft ever was the X-15 which reached a peak speed in one flight of Mach 6.7 - but almost lost the aeroplane.
The Shuttle could, of course, maintain aerodynamic control at extremely high Mach numbers but in this flight regime it was unpowered and effectively slowing down all the time once it entered the atmosphere.
Maintaining a constant Mach 20 within fairly dense parts of the atmosphere and maintaining aerodynamic authority and stopping the airframe from melting due to atmospheric friction is extremely difficult and may not be achieveable - or even worth doing.
AlfaFoxtrot said:
Odie said:
If they are trying to get this to fly at mach 20.
Whats the current fastest military/commercial aircraft in service? and whats its speed?
SR71, ~Mach 3!Whats the current fastest military/commercial aircraft in service? and whats its speed?
http://en.wikipedia.org/wiki/SR71_Blackbird
Eric Mc said:
AlfaFoxtrot said:
Odie said:
If they are trying to get this to fly at mach 20.
Whats the current fastest military/commercial aircraft in service? and whats its speed?
SR71, ~Mach 3!Whats the current fastest military/commercial aircraft in service? and whats its speed?
http://en.wikipedia.org/wiki/SR71_Blackbird
My question basically leads to why are they making a massive jump from around mach 3 to mach 20? why are they not gradually building up to 20? or are pulsejet/scramjet not capable of slow flight? are they trying to build an aircraft around an engine technology?
Eric Mc said:
Yes, the initial interaction with the upper atmosphere is at 17,500 mph or so and it gradually slows down as the atmopsheric friction bleeds off the speed. However, the Shuttle was still doing Mach 10 to Mach 15 or so in relatively dense parts of the atmosphere.
Back in 1967 the X-15 A2 managed Mach 6.7 at around 102,000 feet but was so badly damaged by the heat generated that it never flew again.
So using this resource (http://astronomy.neatherd.org/meteorites/entry.htm) it shows that the Shuttle slowed down to ~Mach 3 at an altitude of 80,000feet (after encountering the top of the atmosphere at Mach 25 at 400,000 feet). For most of the descent it came in at a 40 degree angle, so that the heat absorbing tiles on the underside could take the heat of re-entry. I'm assuming that there was therefore a much larger surface area which the air was slamming into and over which to dissipate the heat (compared to essentially just the leading edges if you were in conventional level flight). Also, most of the time at the extreme velocities was done in extremely rarefied bits of the atmosphere. To compare with the X15, the Shuttle was doing Mach 7 at about 135,000feet. The density scale height of the Earth's atmosphere is about 8km (i.e if you go up 8km, the density drops to 1/e of its original value), so the Shuttle was forcing its way through air that was almost 4x less dense, in addition to the other (presumed) advantages.Back in 1967 the X-15 A2 managed Mach 6.7 at around 102,000 feet but was so badly damaged by the heat generated that it never flew again.
AlfaFoxtrot said:
Eric Mc said:
Yes, the initial interaction with the upper atmosphere is at 17,500 mph or so and it gradually slows down as the atmopsheric friction bleeds off the speed. However, the Shuttle was still doing Mach 10 to Mach 15 or so in relatively dense parts of the atmosphere.
Back in 1967 the X-15 A2 managed Mach 6.7 at around 102,000 feet but was so badly damaged by the heat generated that it never flew again.
So using this resource (http://astronomy.neatherd.org/meteorites/entry.htm) it shows that the Shuttle slowed down to ~Mach 3 at an altitude of 80,000feet (after encountering the top of the atmosphere at Mach 25 at 400,000 feet). For most of the descent it came in at a 40 degree angle, so that the heat absorbing tiles on the underside could take the heat of re-entry. I'm assuming that there was therefore a much larger surface area which the air was slamming into and over which to dissipate the heat (compared to essentially just the leading edges if you were in conventional level flight). Also, most of the time at the extreme velocities was done in extremely rarefied bits of the atmosphere. To compare with the X15, the Shuttle was doing Mach 7 at about 135,000feet. The density scale height of the Earth's atmosphere is about 8km (i.e if you go up 8km, the density drops to 1/e of its original value), so the Shuttle was forcing its way through air that was almost 4x less dense, in addition to the other (presumed) advantages.Back in 1967 the X-15 A2 managed Mach 6.7 at around 102,000 feet but was so badly damaged by the heat generated that it never flew again.
The principle of blunt bodies is that the flat angle of attack creates a bow shock ahead of the surface of the vehicle and it is the leading edge of the bow shock that takes the maximum heating rather than the vehicle itself. It is only when speeds have dropped off to about Mach 7 or lower that the bow shock starts to fade out and the heating impinges directly onto the surface of the vehice.
The problem for maintaining normal atmospheric flight at extreme Mach numbers is that you cannot make use of blunt body techniques and fly a practical aircraft.
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