Re: sci space policy targeted by disinformation experts?

A lot of speculation - I recall reading really interesting stuff, that
just falls off the radar screen so to speak for no damned good
reason. Usually when something doesn't work for a sound technical
reason, you can find some arcane journal article explaining why. When
you cannot find that, there is a possibility - if the ideas are sound
otherwise, they've been taken black.

One way to check that out is to track the researchers. Are they
teaching and not doing a damned thing, or are they busy and have moved
from where they were to points West and stopped publishing?

Thats another inferential point to anyone who cares.

Energy is a problem with high speed flight. Aurora nominally burning
hydrogen in air in an external combustion scramjet - and a 10%
structural fraction - producing thrust by intercepting the shock
waves. You eject the fuel into the stream at the stream velocity -
right at the shock wave at the nose - so its stationary in the flow.
By the time it reaches the thrust structure at the rear of the
aircraft, its mixed with an oxidizer - you stablize that with an
expansion shock, and detonate it with a laser or spark or particle
beam - and the shockwave and thrust surface are shaped to interact to
produce thrust.

Mach 6 and drag coefficient gives you an estimate of power. The X-15
had a drag coefficient at hypersonic speeds of Cd = 0.095

Drag force is equal to

F = 1/2 rho V^2 * Cd * A

http://en.wikipedia.org/wiki/Aurora_aircraft

area looks to be in the 30 sq m range

http://en.wikipedia.org/wiki/Scramjet_Programs

http://en.wikipedia.org/wiki/Mach_number

Mach 6 is around 1,800 m/sec, and rho=0.01 kg/m3

So,

F = 1/2 * 0.01 * (3.24e+6) * 0.095 * 30
= 46,170 newtons
= 4,701 kgf
= 10,343 lbf

at around 50 km altitude

Force times distance is energy.
Force times speed is power

So, 46,170 newtons x 1,800 m/sec = 88.106 megawatts

Hydrogen when burned in air releases 143 megajoules per kg. Assuming
1/4 of this energy is usefully applied to the propulsion system,and
3/4 of the energy is wasted in various ways - means 35.75 megajoules
of propulsive energy is available per kg of hydrogen. This gives us a
burn rate of 2.46 kg/sec to maintain that thrust. With a 50% cycle
efficiency - fuel use is cut in half 1.23 kg/sec

This is the likely fuel consumption of hydrogen for the aircraft at
this speed - from first principles.

Going back to our models of Aurora - it likely has a 600 cubic meter
fuel volume. and hydrogen has a density of 70 kg per cubic meter
which obtains 42,000 kg fuel mass. Enough to power the aircraft for
4 hours and 45 minutes at Mach 6 cruise - at thelower efficiency, and
9 hours 30 minutes at the higher efficiency. Enough to fly 3/4 of the
circumference of the Earth at cruise at the lower efficiency, and 1.5x
around the world at the higher efficiency.

One can imagine a number of interesting missions for such an aircraft
if it exists.

..
.

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