
Reagan’s Impossible Dream: The X-30 National Aerospace Plane - high_frontier
https://thehighfrontier.wordpress.com/2016/01/02/reagans-impossible-dream-the-x-30-national-aerospace-plane/
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Animats
Ben Rich, while he was head of Lockheed's Skunk Works, looked at the proposal,
and decided they would not bid. He'd worked on the SR-71, which was the
highest performance aircraft ever built. His comment: "We used titanium. You
know something stronger?"

Getting rid of the heat was the biggest problem. Rockets which launch
vertically don't spend much time in the atmosphere. Aircraft which accelerate
horizontally do. Hypersonic in-atmosphere travel means having to get rid of
huge amounts of heat with no place to dump it. Running liquid hydrogen fuel
over the vehicle exterior for cooling was considered and rejected for the
SR-71. (Many rocket engines run the cryogenic fuel and oxidizer through
cooling channels in the engine bell before using it as propellant. That's not
a totally unreasonable idea.)

The X-30 was supposed to have a big cabin, which would have to be kept cool.
Only a small part of the SR-71 is kept cool; the pilot is in a space suit.
Even cooling the pilot was hard. Remember, at hypersonic speeds in atmosphere,
there's no place to dump the heat; you have to bring your cold with you.

The only real advantage of this approach over rockets which get out of the
atmosphere as soon as possible is that you don't have to carry oxidizer. That
improves the mass fraction (rockets to orbit are > 90% fuel). Not enough to be
a win, though.

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high_frontier
It's interesting to note though that although Ben Rich explains that they
decided they wouldn't bid, Lockheed WERE one of the airframe contractors in
Phase 2 and it's difficult to imagine that the Skunk Works weren't a part of
that effort especially given the work they did towards the scramjet powered
X-24c in the seventies.

Also, they went on to the X-33 in the mid 90's so clearly felt confident in a
suitable "something stronger" thermal protection system by then

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Gravityloss
"DuPont’s configuration devised under COPPER CANYON had included no landing
gear, orbital manoeuvring system or fuel reserves."

I've long held the opinion that the real lesson to take from NASP is that the
higher the level of decision making, the more detached it is from physics or
business.

Air breathing works for cruise (limited speed and altitude range, long
duration, low thrust requirements).

Rockets work for acceleration (wide speed and altitude range, short duration,
high thrust requirements).

Orbital missions are only about acceleration. Bringing very heavy air
breathing engines to orbit doesn't make sense at all.

The lowest dry mass (=lowest cost) single stage to orbit vehicle designs tend
to be dense propellant pure rockets.

In Finnish there's a saying "ajaa käärmettä pyssyyn": make the snake go into a
gun barrel. An organization trying to achieve a needlessly hard thing because
of political reasons. Closely related to Not Invented Here.

~~~
paulmd
I'll go beyond "dense, propellant pure" rockets - the whole concept of single-
stage vehicles is a pipe dream.

Staging is immensely important because it lowers the "order complexity" of
carrying additional payload. In order to add payload you need to add fuel, and
then you need to add more fuel to carry that fuel, and so on. This is
immensely easier if you don't need to drag the dead weight of your initial
stages along with you.

Single-stage is barely even feasible to orbit. Anything past that is just
flatly science-fiction.

~~~
SEJeff
With today's technology yes. Those that don't dream big however are destined
to be replaced by tomorrow's technology.

~~~
nradov
That's rather naive. This isn't a failure to dream big. Everyone understands
that SSTO will require major advances in propulsion and materials to be really
practical and cost effective.

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sandworm101
If the super-rich are in that much of a hurry to get from london to newyork
that they will pay the ticket prices needed to sustain such an aircraft, I
have a better idea. Build some mercury capsules. Stick them and a solid upper
stage atop a one-engine version of a SpaceX booster. For what, 40K worth of
fuel and upper stage (?) billionaires can now fly solo to NY in minutes,
experiencing all the majesty of vomiting in zero G.

Think of what suborbital, zero-G, would be like in a plane with 100
passengers. Given the forces involved I cannot see suborbital transport ever
replacing first class seats on BA.

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api
A more luxury version of this is what I've long suspected the Virgin Galactic
project to be: suborbital flights around the world. I've long thought it to be
a stealth suborbital spaceplane effort that would add a very expensive but
extremely rapid long range flight option to Virgin's lineup.

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sandworm101
Virgin Galactic is suborbital, but the scheme has nowhere near the velocities
necessary to cover any distance. It's just a rollercoaster. There is little
point in launching a transport from a plane. Getting to 10,000m is nothing
compared to the speed needed for london-NY.

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Balgair
Hm, maybe add in fuel rods in place of the fuel to generate the heat? I mean,
sure, an open and unshielded just sub-critical reactor is going to have
'environmental effects'. But if the point, from the black budget perspective,
is to have an under the radar bomber, the environment is going to shit
anyways. Project Pluto is a good, and completely insane, starting point into
nuclear scramjets.

[https://en.wikipedia.org/wiki/Project_Pluto](https://en.wikipedia.org/wiki/Project_Pluto)

Choice Quote edit:"After delivering all its warheads, the missile could then
spend weeks flying over populated areas at low altitudes, causing tremendous
ground damage with its shock wave. When it finally lost enough power to fly,
and crash-landed, the engine would have a good chance of spewing deadly
radiation for months to come"

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Shivetya
So how does the new SABRE engine factor into this? Originally a lot of
skepticism was there but BAE did invest in it so it might pan out

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quattrofan
Likely this dream will be achieved but perhaps not by the US:

[https://en.wikipedia.org/wiki/HOTOL](https://en.wikipedia.org/wiki/HOTOL)
[http://www.reactionengines.co.uk/](http://www.reactionengines.co.uk/)

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DanielBMarkham
Interesting.

So Wiki says a fully-loaded B-52 can carry 35 tons of bombs.

Everybody knows 1) re-entry after achieving orbital speeds is non-trivial, and
2) doing a stationary drop from orbital heights is possible. There is even
some talk of "skydiving from orbit"

So you take a B-52 out over the ocean. At 50,000 MSL, you extend two rocket
pods, point the nose straight up, and take yourself out of the atmosphere
post-haste. Somewhere around 200-400,000 MSL, you roll over into a standard
orbit configuration.

Burn about half your fuel. Once you get to where you want to go, burn the
other half, reach a dead stop, then parachute into the lower atmosphere, do an
engine re-start, and be on your way.

I'm not saying it wouldn't be a helluva ride, but I'm failing to see the part
where we couldn't have done this 20 or 30 years ago. Perhaps the problem was
that folks tried to imagine some sort of new propulsion system -- and the
numbers just don't work out. Instead of solving SCRAMJET, maybe that money
would have been better spent on truly reusable rockets and high-performance,
plane-rated parachutes?

ADD: This comment was meant to address the problem of sub-orbital flight from
point A to point B, not getting completely to orbit. Both SSTO and suborbital
flight were mentioned in the article. My point was that suborbital flight
doesn't have as many problems as we might think it does.

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jessriedel
"Suborbital" refers to a ballistic trajectory that is "close" to an orbital
trajectory, so that the projectile follows an unpowered arc, but one that is
not wide enough to achieve orbit. The energy required for suborbital
trajectories is still in the same neighborhood as orbital flight.

The reason your proposal doesn't work is that during the portion of the
trajectory outside the atmosphere, you either need to be ballistic (and
therefore suborbital if you're traveling intercontinental) or you need to be
constantly directing a portion of your rockets thrust downward. The latter is
fantastically inefficient, which is why planes operate in the atmosphere
(where they can use air to convert efficient horizontal thrust to lift) and
why suborbital rockets are ballastic for the large majority of their flight.

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mikeash
Suborbital just means you went to space but didn't achieve orbit. There's no
requirement to be "close" to an orbital trajectory. Blue Origin's New Shepard
and Virgin Galactic's SpaceShipOne are classic examples of suborbital
spacecraft, and neither of those came anywhere _near_ orbital speed.

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walkingolof
Great article!

For the latest developments:
[https://en.wikipedia.org/wiki/Skylon_(spacecraft)](https://en.wikipedia.org/wiki/Skylon_\(spacecraft\))

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irremediable
How much of a future do you think the Skylon project has? A couple of friends
in the aerospace industry have told me they think SpaceX will effectively
"win" now that they can land the Falcon. Are they too optimistic about SpaceX?

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creshal
All SpaceX did was building a normal rocket that can land again.

Which, as it turned out, was anything but trivial and took 14 years. Their
main competitors – ULA and Arianespace – already announced they won't be able
to manage similar capabilities this decade; and their plans for the next
decade are still not as sophisticated as SpaceX's approach (they only want to
recover the engines and build a wholly new stage around them).

Skylon is a massively more ambitious undertaking compared to that – if it
works, it'll be the first practical SSTO, the first horizontal takeoff
spaceplane, the first vehicle to use multi-mode engines, the first practical
space plane to use a novel heat shield technology, …

That's an awful lot of challenges to tackle. _If_ it turns out to work, and
_if_ it then turns out to be as re-usable as hoped (something that did never
panned out for the Shuttle, and which SpaceX will only learn over the next
years for their Falcon), _then_ it could beat SpaceX… in a decade or two.

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mikeash
The trouble with Skylon is that all of these things you mention make it more
_ambitious_ , but they don't really make it more _useful_.

The main advantage Skylon would have over the Falcon 9 is the fact that the
Falcon 9 is not fully reusable because they don't and can't recover the second
stage, while the entire Skylon is recovered.

That's significant, of course. The second stage makes up about 25% the cost of
the rocket, so that places a ceiling of about 75% on how much Falcon 9
reusability can save..

But then, starting from where the Falcon 9 is now, building a new rocket that
can also recover the second stage doesn't seem _too_ difficult. It's a big
challenge, to be sure, but relative to Skylon it's not too bad.

Skylon is certainly much more ambitious in terms of how it works, but it
doesn't seem to be very ambitious in terms of what it can do, which is not a
promising combination.

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Thorondor
Skylon does have the advantage of burning atmospheric oxygen at low altitudes,
meaning it would have a significantly higher payload fraction than the Falcon
9.

~~~
mikeash
It's somewhat higher, but not dramatically so. Skylon is projected to be 325
tons loaded with a LEO payload of 15 tons, Falcon 9 Full Thrust a.k.a. Falcon
9 1.2 is 541 tons loaded with a LEO payload of 13-17 tons depending on who you
believe. And that's comparing paper hardware with flying hardware. Spacecraft
tend to get heavier as they go from paper to reality.

Plus, payload fraction is another thing like SSTO, horizontal takeoff, novel
heat shields, and all the rest that are cool but just don't matter except for
how they affect the end result. All that matters in the end is how much you
can launch, and how much it costs.

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gozur88
>And that's comparing paper hardware with flying hardware. Spacecraft tend to
get heavier as they go from paper to reality.

That's the critical point. Skylon is still vaporware, and they've really
assumed the best case in published numbers.

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trhway
btw, the BrahMos 2 Indian-Russian cruise missile coming in 2017 (well, of
course there is always a big "if") is scramjet powered and expected to fly at
Mach 7. [https://en.wikipedia.org/wiki/BrahMos-
II_%28missile%29](https://en.wikipedia.org/wiki/BrahMos-II_%28missile%29)

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ck2
And just think today we can't even get Congress to fund repair crumbling
infrastructure

\- why do today what you can wait for a national crisis tomorrow?

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Shivetya
while the numbers are large when measured in percentages it isn't that bad.
Most of the deficient bridges are locally owned, this means at levels lower
than state level. No one also ever seems to mention that at is peak in the 90s
there were nearly 150,000 bridges found to be deficient and that number is
down to near 60,000.

In other words, the Federal government isn't responsible for most of what is
out there and many state and local governments refuse to fully fund their own
obligations.

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randallsquared
> No one also ever seems to mention that at is peak in the 90s there were
> nearly 150,000 bridges found to be deficient and that number is down to near
> 60,000.

Wow. No kidding that "no one also ever seems to mention"! That puts things in
perspective a bit, doesn't it?

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twoodfin
Believe you me, "crumbling infrastructure" has been a constant talking point
of those who want greater federal spending for decades. Not to say it's all
crying wolf, but if it had been true the whole time it was being complained
about, by now things would be more obviously crumbled.

State governments in particular love federal infrastructure spending, since it
is more or less a direct cash transfer to a) their own budgets, where local
infrastructure spending can crowd out other priorities and b) the politically
potent building and construction trades.

