Meet the SR-72

In article ,
says...
http://www.dailymail.co.uk/news/arti...ntry-hour.html

Something like the SR-72 may already be flying.


Yeah, and monkeys might fly out your butt, too, but it's pretty damned
unlikely.

Agreed. Those "mysterious flying objects" could be anything. Back in
the day, some of them were the F-117 which is decidedly subsonic,
despite the speculation at the time that a supersonic SR-71 follow-on
was in the works. So one could say that the SR-72 has been "in the
works" a long, long, *long* time based on sightings of UFOs that are
occasionally reported in the media. Popular Mechanics is likely one of
Mookie's favorite magazines for things like this.

Certainly the X-15 achieved the same velocities as those proposed
for the SR-72 back in the 1960s! We have plenty of data on that!
The X-15 achieved Mach 6.7 - higher than the proposed Mach 6.0
we're discussing here!


And you're such a technical ignoramus that you don't see the
difference between X-15 and the SR-72 proposal.

Clearly he doesn't understand the difference between a vehicle designed
primarily for short duration acceleration and one designed for cruise.

Now, while the SR-72 as designed is too small for people, and is
indeed a UAV, a larger airframe of similar shape easily carries
people while hydrogen fuels give the vehicle significant range
at Mach 6 with modest propellant fractions, while also providing
significant cooling capacity.


Ah, Magic MookieMath that assumes nothing changes as you scale things.
It's his usual game and it's still a massively ignorant belief.

But he never learns...

Scaling laws: Mookie breaks them as often as Cincinnati commuters break
the speed limit on I-275. The speedometer in my car only goes up to 85
mph, so sometimes it's hard to tell exactly how fast traffic is flowing.
;-)

Jeff
--
"the perennial claim that hypersonic airbreathing propulsion would
magically make space launch cheaper is nonsense -- LOX is much cheaper
than advanced airbreathing engines, and so are the tanks to put it in
and the extra thrust to carry it." - Henry Spencer

In article ,
says...
I guess Fred has never heard that the X-15 routinely flew
above Mach 6 and we know precisely what we need to know to
build a Hypersonic Transport plane of the type I've described.


I guess Mookie thinks that comparing apples and aardvarks constitutes
'engineering'. It doesn't.

snip Magic MookieMath


Come on Fred, they're exactly alike, except for the propulsion system,
time at maximum speed, materials, cooling systems, and etc.

As one of our top technical leads at work tells everyone (when they're
falling into the same trap), "Things that are different just aren't the
same".

Jeff
--
"the perennial claim that hypersonic airbreathing propulsion would
magically make space launch cheaper is nonsense -- LOX is much cheaper
than advanced airbreathing engines, and so are the tanks to put it in
and the extra thrust to carry it." - Henry Spencer

On Sunday, February 15, 2015 at 5:19:46 PM UTC+13, Fred J. McCall wrote:
William Mook wrote:

On Sunday, February 8, 2015 at 5:42:45 AM UTC-5, Fred J. McCall wrote:
William Mook wrote:

On Sunday, February 8, 2015 at 3:07:03 AM UTC-5, Fred J. McCall wrote:
William Mook wrote:

On Saturday, February 7, 2015 at 8:23:14 PM UTC-5, Fred J. McCall wrote:
William Mook wrote:


Imagine flying to any point on Earth in less than 90 minutes!

Well you can in the SR-72!


Well, no, you can't.

Yes you can. 90 minutes at 2 km per second is 10,800 km - the distance of long range jets today.


Stupid.

Calling names doesn't change facts.


Whinging about calling names doesn't change facts, either. And the
facts are against you.


You demonstrate the problem with MookieMath.

Math is math no matter who does it.


Yes, it is, but math misapplied is a Mookie trait.


You ignore the
small FACTS that the bloody thing doesn't exist

Scramjets don't exist in your world?

That's crazy talk.


Yes, it is, so why did you make it up to pretend I said it?

Mookie, in case it hasn't penetrated to you, the SR-72 (what you're
going on about) does not exist and will not for a generation. As for
scramjets, please point to an operational scramjet vehicle. One will
do.


and if it ever does
come to exist it won't carry people,

Scramjets can't carry people in your world?

More crazy talk.


More ****e made up by Mookie to pretend someone else said it?

Crazy talk, indeed.

The SR-72, which is what you're on about, will be UNMANNED, as in NO
ROOM ON BOARD FOR PEOPLE.


so it doesn't matter how fast it
might be or how far it might fly,

We can calculate the performance of a Mach 6 aircraft based on published data. We can tell what the aircraft will cost and what sort of return those who build it privately might expect to earn.


So it's going to take so long for Lockheed to build one why, again, if
it's as easy as you claim?


Your statements have no basis in reality. They're just crazy talk.


You mean YOUR statements have no basis in reality, don't you? I've
never made the crazy statements that you persist in making up.

you still can't fly anywhere in it.

Circular reasoning. It can't exist because it doesn't exist therefore it can't exist. Your committing a logical fallacy that you can't seem to understand.


Illiterate lying bloviation, since I said none of what you claim
above.


Not to mention that since it hasn't been designed there is no way you
can talk about what range it might have.

So, in your world hypersonic wind tunnels and scramjet research doesn't exist. More crazy talk. Read a few journal articles then you will see that you hydrogen powered scramjets attain 7350 seconds Isp at Mach 6 and that airframes with L/D of 7.14 are possible at Mach 6. This is all you need to plug into the Brequet Range equation to determine less than 10% take off weight need be hydrogen fuel for a Mach 6 scramjet.


So in your world you have to make things up to pretend others have
said because you're such a lying illiterate **** that you can do
nothing else.

Perhaps you should read a few more papers. Or understand the ones you
do read. Either of those would help.

snip remaining random Mookspew


I guess Fred has never heard that the X-15 routinely flew above Mach 6 and we know precisely what we need to know to build a Hypersonic Transport plane of the type I've described.


I guess Mookie thinks that comparing apples and aardvarks constitutes
'engineering'. It doesn't.

snip Magic MookieMath

--
"Ordinarily he is insane. But he has lucid moments when he is
only stupid."
-- Heinrich Heine

Let's see, the SR-72 is an airplane that travels at Mach 6, and the X-15 is an airplane that travels at Mach 6 --- hmm.. do you think anything learned from the X-15 programme might be useful to the SR-72?

Nah!

lol.

Fact is, the engineering data from the X-15 programme contains vital information anyone needs to design a Mach 6 aircraft. Fred would have us ignore that for no good reason.

The ablative skin and time of flight at Mach 6.7 tells us the rate at which heat flows into the aircraft. The L/D achieved by the X-15 tells us the L/D achievable by a Mach 6.7 aircraft.

Renenber, the statement I am responding to is the one that said that heat flux was a show stopper for a manned aircraft. This is nonsense! We can calculate precisely the cooling capacity of slush hydrogen fuel evaporated at a rate needed to supply a hydrogen scramjet at Mach 6. It turns out that it has sufficient cooling capacity to maintain room temperature not only inside a cabin, but also across the skin of an aircraft. This is an important detail since overheating the airframe causes distortions, weakness, and even splitting of the aircraft skin.

Hydrogen powered scramjets attain 7350 seconds Isp at Mach 6 and airframes with L/D of 7.14 are possible at Mach 6 as the X-15 proves.

This is all you need to plug into the Brequet Range equation to determine less than 10% take off weight need be hydrogen fuel for a Mach 6 scramjet.

Starting with slush hydrogen at -260C and warming it to gaseous hydrogen at +22C provides sufficient cooling power to not only keep the cabin at room temperature, but also keep the aircraft skin at room temperature since the rate of evaporation needed to supply the necessary thrust at these speeds provides the necessary cooling.

Since the heat rates scale as the square of velocity, and power scales as the square of velocity, over the pressures possible with modern scramjet speeds of Mach 6 to Mach 9 are easily maintained using slush hydrogen as a fuel. This is a speed of 2 km/sec to 3 km/sec.

On Monday, February 16, 2015 at 4:28:43 AM UTC+13, Jeff Findley wrote:
In article ,
says...
I guess Fred has never heard that the X-15 routinely flew
above Mach 6 and we know precisely what we need to know to
build a Hypersonic Transport plane of the type I've described.


I guess Mookie thinks that comparing apples and aardvarks constitutes
'engineering'. It doesn't.

snip Magic MookieMath


Come on Fred, they're exactly alike, except for the propulsion system,
time at maximum speed, materials, cooling systems, and etc.

The technical differences are not as important as the overall similarities.

The SR-72 flies at Mach 6.

The X-15 did a large number of flights at Mach 6 and up to Mach 6.7

Now, the atmsopheric physics are the same certainly.

Most telling is the method of cooling used on the X-15, placing an ablative film around the surface. A close analysis of the technical details reveals the rate of heating of the X-15 surface at various speeds.

We know the L/D achieved for the X-15. There's no reason to think we'll do worse with modern designs.

We know the Isp of a hydrogen fueled scramjet from technical literature in the journals.

From this we can estimate the propellant fraction needed to achieve various ranges using the Brequet Range equation.

We can also see that slush hydrogen at -260C warmed to +22C at a rate sufficient to maintain thrust at these speeds - will keep the aircraft cool, by transpiration cooling.

Using the hydrogen in lieu of the ablative film.

Do this and its easy to see that you can keep the airframe and the cabin at room temperature from Mach 6 through Mach 9 (2 km/sec to 3 km/sec).


As one of our top technical leads at work tells everyone (when they're
falling into the same trap), "Things that are different just aren't the
same".

Things that are the same are the same however. The X-15 tells us a lot about what's needed to fly at Mach 6 to Mach 9.


Jeff
--
"the perennial claim that hypersonic airbreathing propulsion would
magically make space launch cheaper is nonsense -- LOX is much cheaper
than advanced airbreathing engines, and so are the tanks to put it in
and the extra thrust to carry it." - Henry Spencer

On Monday, February 16, 2015 at 4:24:42 AM UTC+13, Jeff Findley wrote:
In article ,
says...
http://www.dailymail.co.uk/news/arti...ntry-hour.html

Something like the SR-72 may already be flying.


Yeah, and monkeys might fly out your butt, too, but it's pretty damned
unlikely.

Agreed. Those "mysterious flying objects" could be anything. Back in
the day, some of them were the F-117 which is decidedly subsonic,
despite the speculation at the time that a supersonic SR-71 follow-on
was in the works. So one could say that the SR-72 has been "in the
works" a long, long, *long* time based on sightings of UFOs that are
occasionally reported in the media. Popular Mechanics is likely one of
Mookie's favorite magazines for things like this.

Certainly the X-15 achieved the same velocities as those proposed
for the SR-72 back in the 1960s! We have plenty of data on that!
The X-15 achieved Mach 6.7 - higher than the proposed Mach 6.0
we're discussing here!


And you're such a technical ignoramus that you don't see the
difference between X-15 and the SR-72 proposal.

Clearly he doesn't understand the difference between a vehicle designed
primarily for short duration acceleration and one designed for cruise.

Nonsense, you don't understand the value of the information obtained in a test aircraft and how it may be used to design a cruise aircraft. Slush hydrogen at -260C warmed to +22C maintains airframe and cabin temperatures at room temperature through a broad range of speeds, since heating rate and thrust required scales at the square of velocity and the power level possible with a hydrogen scramjet permits speeds from Mach 6 to Mach 9 (2 km/sec to 3 km/sec)


Now, while the SR-72 as designed is too small for people, and is
indeed a UAV, a larger airframe of similar shape easily carries
people while hydrogen fuels give the vehicle significant range
at Mach 6 with modest propellant fractions, while also providing
significant cooling capacity.


Ah, Magic MookieMath that assumes nothing changes as you scale things.
It's his usual game and it's still a massively ignorant belief.

But he never learns...

Scaling laws: Mookie breaks them as often as Cincinnati commuters break
the speed limit on I-275. The speedometer in my car only goes up to 85
mph, so sometimes it's hard to tell exactly how fast traffic is flowing.
;-)

Scaling laws are well defined in aerospace, that's why people use wind tunnels. The X-15 produced a lot of information. A close analysis of that information supports all I say. Waving your hands and yammering about 'laws' that you fail to explain or describe - is bull****.


Jeff
--
"the perennial claim that hypersonic airbreathing propulsion would
magically make space launch cheaper is nonsense -- LOX is much cheaper
than advanced airbreathing engines, and so are the tanks to put it in
and the extra thrust to carry it." - Henry Spencer

On Monday, February 16, 2015 at 4:24:42 AM UTC+13, Jeff Findley wrote:
In article ,
says...
http://www.dailymail.co.uk/news/arti...ntry-hour.html

Something like the SR-72 may already be flying.


Yeah, and monkeys might fly out your butt, too, but it's pretty damned
unlikely.

https://www.youtube.com/watch?v=lPruGs4IyK4


Agreed. Those "mysterious flying objects" could be anything.

https://www.youtube.com/watch?v=daAcBu9xBi4

Back in
the day, some of them were the F-117 which is decidedly subsonic,
despite the speculation at the time that a supersonic SR-71 follow-on
was in the works. So one could say that the SR-72 has been "in the
works" a long, long, *long* time based on sightings of UFOs that are
occasionally reported in the media. Popular Mechanics is likely one of
Mookie's favorite magazines for things like this.



Certainly the X-15 achieved the same velocities as those proposed
for the SR-72 back in the 1960s! We have plenty of data on that!
The X-15 achieved Mach 6.7 - higher than the proposed Mach 6.0
we're discussing here!


And you're such a technical ignoramus that you don't see the
difference between X-15 and the SR-72 proposal.

Clearly he doesn't understand the difference between a vehicle designed
primarily for short duration acceleration and one designed for cruise.

Now, while the SR-72 as designed is too small for people, and is
indeed a UAV, a larger airframe of similar shape easily carries
people while hydrogen fuels give the vehicle significant range
at Mach 6 with modest propellant fractions, while also providing
significant cooling capacity.


Ah, Magic MookieMath that assumes nothing changes as you scale things.
It's his usual game and it's still a massively ignorant belief.

But he never learns...

Scaling laws: Mookie breaks them as often as Cincinnati commuters break
the speed limit on I-275. The speedometer in my car only goes up to 85
mph, so sometimes it's hard to tell exactly how fast traffic is flowing.
;-)

Jeff
--
"the perennial claim that hypersonic airbreathing propulsion would
magically make space launch cheaper is nonsense -- LOX is much cheaper
than advanced airbreathing engines, and so are the tanks to put it in
and the extra thrust to carry it." - Henry Spencer

On 2/14/2015 7:41 PM, William Mook wrote:


My absence of response is not the same as implicit assent. But I'm sure
most of those who read this newsgroup (what all seven of us now?) are or
should be aware of that.

Some further comments:

1. See not only Ben Rich's wonderfully co-authored book "Skunk Works"
but also Kelly Johnson's "Kelly: More that my share of it all" for an
insightful look into the trial and tribulations of designing and flying
high performance aircraft. From those who had a proven/indisputable
track record in this area. Esp. their thoughts on the use of hydrogen as
a fuel in high performance aircraft.

2. Hydrogen slurry?

3. Hydrogen burning scramjet?

4. It's far easier to design electronics to handle the environment
proposed than a human life support system.

5. Skin reaction of the SR72 to high heat? Er. Don't you mean something
that has actually flown that we know the skin composition of. Like the
X-15? Even so, what is the relevance of that to the SR72 until we know
what the skin of the SR72 is made of? Choices in 2015 are a bit
different than they were in the 1950s.

The more Mr. Mook writes on the subject the further we seem to get away
from the SR72 design as proposed by Lockheed. To the point where I
believe the premise is a non-sequitur.

That's all I have to say.

Dave

In article ,
says...

JF Mezei wrote:

On 15-02-20 13:12, Fred J. McCall wrote:

plane" to 'something learned from the X-15 program is valuable in
building a Mach 6 aircraft".

Isn't it far more likely to see New York Sydney in 90 minutes achieved
via sub-orbital that reaches above atmosphere and accelerates via pure
rockets instead of jet engines ? The big issue with such is re-entry at
high Mach, and need for heat shields.


And that's the real issue. IN THEORY, combined cycle engines are a
'win' insofar as efficiency goes. Once you add in additional weight,
drag, complexity, etc, it's always proven to be better (with current
real world engineering) to just use rockets...

Unless an organization has requirements beyond fuel efficiency,
passenger comfort, and etc. The military will always pursue supersonic
cruise, but for reasons that have nothing to do with civilian
requirements. From time to time, the military will make references to
how this technology could be used for civilian transport (on earth or to
LEO), but in the case of hypersonic air breathing vehicles, this is
clearly disingenuous and intended only to gain public and political
support research that is purely for military purposes.

Jeff
--
"the perennial claim that hypersonic airbreathing propulsion would
magically make space launch cheaper is nonsense -- LOX is much cheaper
than advanced airbreathing engines, and so are the tanks to put it in
and the extra thrust to carry it." - Henry Spencer

On Friday, February 20, 2015 at 1:12:46 PM UTC-5, Fred J. McCall wrote:
William Mook wrote:

On Sunday, February 15, 2015 at 5:19:46 PM UTC+13, Fred J. McCall wrote:
William Mook wrote:

On Sunday, February 8, 2015 at 5:42:45 AM UTC-5, Fred J. McCall wrote:
William Mook wrote:

On Sunday, February 8, 2015 at 3:07:03 AM UTC-5, Fred J. McCall wrote:
William Mook wrote:

On Saturday, February 7, 2015 at 8:23:14 PM UTC-5, Fred J. McCall wrote:
William Mook wrote:


Imagine flying to any point on Earth in less than 90 minutes!

Well you can in the SR-72!


Well, no, you can't.

Yes you can. 90 minutes at 2 km per second is 10,800 km - the distance of long range jets today.


Stupid.

Calling names doesn't change facts.


Whinging about calling names doesn't change facts, either. And the
facts are against you.


You demonstrate the problem with MookieMath.

Math is math no matter who does it.


Yes, it is, but math misapplied is a Mookie trait.


You ignore the
small FACTS that the bloody thing doesn't exist

Scramjets don't exist in your world?

That's crazy talk.


Yes, it is, so why did you make it up to pretend I said it?

Mookie, in case it hasn't penetrated to you, the SR-72 (what you're
going on about) does not exist and will not for a generation. As for
scramjets, please point to an operational scramjet vehicle. One will
do.


and if it ever does
come to exist it won't carry people,

Scramjets can't carry people in your world?

More crazy talk.


More ****e made up by Mookie to pretend someone else said it?

Crazy talk, indeed.

The SR-72, which is what you're on about, will be UNMANNED, as in NO
ROOM ON BOARD FOR PEOPLE.


so it doesn't matter how fast it
might be or how far it might fly,

We can calculate the performance of a Mach 6 aircraft based on published data. We can tell what the aircraft will cost and what sort of return those who build it privately might expect to earn.


So it's going to take so long for Lockheed to build one why, again, if
it's as easy as you claim?


Your statements have no basis in reality. They're just crazy talk..


You mean YOUR statements have no basis in reality, don't you? I've
never made the crazy statements that you persist in making up.

you still can't fly anywhere in it.

Circular reasoning. It can't exist because it doesn't exist therefore it can't exist. Your committing a logical fallacy that you can't seem to understand.


Illiterate lying bloviation, since I said none of what you claim
above.


Not to mention that since it hasn't been designed there is no way you
can talk about what range it might have.

So, in your world hypersonic wind tunnels and scramjet research doesn't exist. More crazy talk. Read a few journal articles then you will see that you hydrogen powered scramjets attain 7350 seconds Isp at Mach 6 and that airframes with L/D of 7.14 are possible at Mach 6. This is all you need to plug into the Brequet Range equation to determine less than 10% take off weight need be hydrogen fuel for a Mach 6 scramjet.


So in your world you have to make things up to pretend others have
said because you're such a lying illiterate **** that you can do
nothing else.

Perhaps you should read a few more papers. Or understand the ones you
do read. Either of those would help.

snip remaining random Mookspew


I guess Fred has never heard that the X-15 routinely flew above Mach 6 and we know precisely what we need to know to build a Hypersonic Transport plane of the type I've described.


I guess Mookie thinks that comparing apples and aardvarks constitutes
'engineering'. It doesn't.

snip Magic MookieMath


Let's see, the SR-72 is an airplane that travels at Mach 6, and the X-15 is an airplane that travels at Mach 6 --- hmm.. do you think anything learned from the X-15 programme might be useful to the SR-72?

Nah!

lol.


Note that Mookie has now changed his story from

"the X-15 having taught us "precisely what we need to know to build a Hypersonic Transport plane" to

'something learned from the X-15 program is valuable in building a Mach 6 aircraft".

Those are two very different
propositions,

A Hypersonic Transport Plane is a long distance aircraft that travels between Mach 6 and Mach 8. The X-15 is a short range research craft that travels between Mach 6 and Mach 8.

So, how is building a Hypersonic Transport Plane NOT building an aircraft that travels as fast as the X-15?

Apart from range and staying power, its the same thing!

Specifically how is the X-15 experience NOT helpful in understanding the critical factors of drag, heat rate, lift to drag, that must be known and understood in order to build a Hypersonic Transport Plane?

The answer is, the X-15 is ESSENTIAL to understanding how to build a HST.

So, why promote the artificial division of HST and X-15?

Is the X-15's lack of an airbreathing engine or it's short range or even it's highly limited staying power at speed, all quite different and all required of the HST enough to enforce the highly artificial division and enforced ignorance of the NECESSARY fundamentals of high speed flight? Only among the propagandists of the criminal US military who seeks to restrict from general discussion and public discourse any real appreciation of what is required to create a commercial HST. Because general knowledge of this range of speeds is critical not only to the success of the HST, but to efficient space launch and ballistic transport and re-entry as well.


but not only is Mookie not bright enough

Who do you believe? Someone who explains precisely what's going on and why? OR someone who merely calls names and casts aspersions and never explains in any sensible way their views?


to realize
that,

Realize what? That the X-15 was an X plane and an HST is a transport plane? What you propose is idiocy. To look at the differences between the X-15 and HST and even ballistic transport, and ignore just WHY the X-15 was so important to US mastery of space travel buries significant information. Anyone who wants to build an airframe, be it HST or ballistic transport, that flies in or through these speeds is well served to understand the results of the X-15 programme.

Anyone who loudly calls names and focuses on inconsequential differences to hide these important factors all high speed vehicles have in common, seeks to mystify reduce and restrict access to space.

he thinks everyone else is not bright enough to realize it,
either.

I am and always have been speaking to those who are reading this who are bright enough to understand me. You on the other hand are speaking to those who aren't quite sure and are persuaded by name calling and other tricks of a propagandist.

snip Mookwriggling

--
"Ignorance is preferable to error, and he is less remote from the
truth who believes nothing than he who believes what is wrong."
-- Thomas Jefferson

You misquote Jefferson too. Jefferson wouldn't like you and what you're doing to his country.

On Friday, February 20, 2015 at 3:12:12 PM UTC-5, JF Mezei wrote:
On 15-02-20 13:12, Fred J. McCall wrote:

plane" to 'something learned from the X-15 program is valuable in
building a Mach 6 aircraft".

Isn't it far more likely to see New York Sydney in 90 minutes achieved
via sub-orbital that reaches above atmosphere and accelerates via pure
rockets instead of jet engines ? The big issue with such is re-entry at
high Mach, and need for heat shields.

If you look at how to build a sub-orbital booster, even a pure rocket based booster, and fly it efficiently from zero altitude to sub-orbit and back, you will find that the knowledge developed by the X-15 experiments is critical to understanding how to do that. A lot happens between Mach 6 and Mach 8 and air density is high enough to make it a significant aspect to any airframe design be it X-15, HST, or space launch vehicle. The coating developed for the X-15 to allow it to sustain hypersonic flight were adapted for space launch vehicles for example and are used today throughout the world.

http://www.astronautix.com/graphics/x/x15ablat.jpg
http://corrosion.ksc.nasa.gov/92-2150.htm
http://sciencelearn.org.nz/Contexts/...t-space-launch

Would a commercial ballistic transport be coated with a thermal ablative layer after each flight? (the way transport planes during an ice storm are deiced by spraying chemical on the wings?) Or would you have some sort of built in capacity to do that? (the way some planes of deicing equipment?)

Now I hasten to say deicing a plane is quite different than keeping an airframe cool through ablative heat transport. However, I'm speaking here of operational considerations that impact cost and complexity. A spray on ablative coating that's added as passengers and cargo are shifted and the vehicle refueled, vs evaporating a portion of the cryogenic propellant through the skin of the craft to maintain moderate airframe temperatures at this speed, an extension of an efficient cryogenic propellant storage anyway.

http://mtm-inc.com/reduce_project_ri...ermal_shields/

The point is, you do have to deal with this thermal pulse as you pass through these speeds, and any commercial ship, be it ballistic or hypersonic, must deal with it, and the X-15 experience, properly understood, is critical to successful design.

Now, there are two valid solutions here. One is ballistic transport which is quite distinct from the other solution hypersonic transport.

I showed that the rate of skin heating in the speeds between Mach 6 and Mach 8 was such that liquid hydrogen needed to maintain those speeds at 90,000 ft or so, air density, was sufficient to keep the airframe at room temperature.

That is, to produce the thrust needed to propel the vehicle at these speeds requires a certain amount of fuel. If that fuel happens to by hydrogen, in liquid form, you are using fuel at such a rate that its evaporation draws enough heat to keep the airframe at room temperature while maintaining thrust at a level to maintain speed.

The X-15 gives us all the parameters we need to solve the Brequet Range Equation using hydrogen. When we do that we can see that we can attain global range with a 30% propellant fraction.

So, if we have 1 ton of structure and 1 ton of payload, we requires 857 kg of hydrogen to attain 30% propellant fraction;

0.857 / 2.857 = 0.30

We get this by

(1 + 1) / (1 - 0.30) = 2.857

Now when we add 5.5x the hydrogen weight as oxygen to this to get an efficient hydrogen oxygen booster - we have

0.857 * 5.5 = 4.7135

metric tons of LOX. So we end up with a booster that is

1 ton structure
1 ton payload
5.5705 ton propellant.

for a propellant fraction of 73.58%

With an exhaust speed of 4.5 km/sec we can see that the transformation of our long range HST becomes a long range ballistic transport.

4.5 * LN(1/(1-0.7358)) = 6 km/sec

vonBraun in his book "Across the Space Frontier" wrote that his third stage would be developed first as a competitive high speed transport between cities in North America. The second stage would extend the range of the vehicle to intercontinental distances, with recovery and reuse of the second stage, used as a booster. The third stage would give the ship orbital capabilities. A fourth stage would give it the ability to travel to mars, or orbit the moon. A fifth stage would give it the ability to land on the moon.

http://www.wired.com/wp-content/uplo...Stagelarge.jpg

The Apollo Direct Ascent program followed this approach.

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

In many respects, the political and economic decisions made during Apollo isolated space travel from aviation and made ballistic missiles as arcane, unreliable, and useless as dirigibles. Which is too damned bad. In an ideal world, Lindbergh, Goddard, vonBraun and others would work together in a cooperative venture, absent two world wars, to create a commercial space faring capability that was a natural extension of commercial aviation.

With a LOX/LH2 propellant combination, advanced composite structure, mems based 'smart structures' with advanced cryogenic cooling, and thermal shield, a 7% structure fraction, and advanced mems based propulsion, achieving 4.2 km/sec exhaust speeds at launch rising to 4.6 km/sec at altitude, with an averaged value of 4.35 km/sec. We have a launcher made of 7 identical elements - each with inflatable fold away wings that operate as subsonic speeds.

The Space Shuttle External Tank with an aerospike engine at its base, is a prototype for the type of vehicle we seek - a modern day version of vonBraun's vision.

Let's look at a Boeing 737 as a successful commercial prototype.

http://www.b737.org.uk/techspecsdetailed.htm

35 metric tons and 185 passengers ought to be our design goal.

To orbit 35 metric tons of payload requires that it be boosted to a speed of 9.3 km/sec - when you add in air drag and gravity losses. Dividing by 3 obtains 3.1 km/sec per stage. So you can see with a 4.35 km/sec exhaust speed, we have a propellant fraction of;

u = 1 - 1/exp(3.1/4.35) = 50.97% ~ 51%

This leaves a payload fraction of

1 - .51 - .07 = 0.42 ~ 42%

So, for a 35 ton payload this implies

35/0.42 = 83.3

ton stage weight.

So, a SSTO that takes off and lands vertically gives a range of 3,000 km.

Now, using 83.3 tons as the starting weight we can compute how big the second stage is;

83.3/0.42 = 198.3

This boosts the ship up to 6.2 km/sec - and gives it intercontinental range.. The second stage lands downrange, is partially refueled and 'bounced back' to the launch center minutes after launch.

The third stage, is

198.3 / 0.42 = 472.1

This is the take off weight of an Earth orbiting spaceship carrying 32 tons, the same payload as a Boeing 737.

Let's keep going, adding 3.1 km/sec each time. Adding 3.1 km/sec to 7.9 km/sec attains 11.0 km/sec - Earth Escape Velocity. This lets us contemplate going to Mars or going to the moon.

472.1 / 0.42 = 1,124.1 metric tons.

take of weight.

Adding another 3.1 km/sec - gives the ship the ability to land on the moon by rocket action, or travel to Mars, and aerobrake there to a landing. The take off weigh ton Earth is;

1,124.1 / 0.42 = 2,276.5 metric tons.

The Saturn V was 2,970.0 metric tons at take off. Of course it used hydrogen and oxygen in its upper stages, and LOX/Kerosene in its first stage, which increases its take off weight. It also used hypergolic propellants on the moon for reliability, radically reducing operational efficiency there.

Of course, if we find water on the moon, and India's Chandrasakar spacecraft has done just that, we can use solar or nuclear power to break it down into hydrogen and oxygen, and refuel our spaceship on the moon, and dispense with this last stage and end up with a smaller ship than Saturn V that is more capable.

We can also note that each stage is approximately twice the size of the stage its lifting. That is, our 83.3 ton stage grows as follows;

35.0
83.3 1x 42.5 t propellant
198.3 2x 53.5 t propellant
472.1 4x 63.6 t propellant

1,124.1
2,276.5

This suggests that by building a 7 element system each of which carries 63.6 metric tons of propellant, in an identical airframe, we could build a very low cost and very capable system.

35.0 t - payload
63.6 t - propellant
6.9 t - structure

So, we have a 528.5 t take of weight, and burn 254.4 t of propellant in the first stage to achieve 2.86 km/sec terminal velocity. The four elements fall away and leave three elements. Two of the three propel the craft forward. After dropping the four empties, the three elements and payload mass 246.5 t and burn through 127.2 t of propellant adding 3.16 km/sec to the speed of the spacecraft. A total of 6.02 km/sec. The two empty elements drop away, and the third element continues. Its stage weight after dropping the two empty stages is 105.5 metric tons, and after burning 63.6 metric tons attains a speed of 10.02 km/sec after adding 4.01 km/sec to its speed. Of course with air drag and gravity losses, we have attained no more than 8.7 km/sec.

Now, notice the life of this VTOL vehicle starts out as an intermediate range transport. It can fly from Cleveland to Boston in five minutes, refuel and reload, and fly back! This would be a sensation! It also gains experience in handling passengers, cargoes, crews, operations, logistics, everything need for the 'bounce back' maneuver called for in longer range flights.

To go from a regional carrier to a national carrier, add ONE element, that lands regionally, and bounces back after landing. Meanwhile, the longer range ship flies from NYC to LAX in 7 minutes. The booster rocket drops down in St. Louis, is refueled, and returns to NYC before the LAX ship returns to NYC. Meanwhile the LAX booster drops into Santa Fe to refuel and bounce back to LAX before the longer range ship returns to LAX.

In this way, you could have hourly travel between the cities - 24 flights a day, of 183 people each - leaving on the hour every hour - arriving at your destination on the quarter hour. 1.6 million people per year - per ship (and two boosters)

Add TWO outboard boosters, of similar size to give the ship an intercontinental range! To fly to Europe or Asia from America and back, 12 flights per day.

Add six outboard boosters to give the ship orbital capacity.

63.6 t of propellant is 8.4% the propellant weight of the Space Shuttle External Tank. So, this sizes our system. Its 43.7% the size of the External Tank.

SLWT

Length: 153.8 ft (46.9 m)
Diameter: 27.6 ft (8.4 m)
Empty Weight: 58,500 lb (26,500 kg) 3.5%
Gross Liftoff Weight: 1,680,000 lb (760,000 kg)

Our B737 Ballistic Competitor Article is 20.5 m long and 3.7 m in diameter and weights 6,900 kg empty. The length of the B737 fueselage is 27.6 m and the diameter is 3.7 m.

Of course a sphere 6.5 m in diameter sphere containing liquid hydrogen, atop which a 4.5 m diameter sphere containing liquid oxygen, all built into a cone, with an aerospike engine at the base, with a toroidal cabin above the engine, with 182 seats facing outward, might be an interesting design. Around this cone are placed six 20.5 long ET like tanks 3.7 m in diameter, each with its own aerospike engine set.

This is the sort of vehicle described in some of Arthur Clarke's works, such as the Tales from Whitehart, and was the subject of some early BIS papers..

With modern drone technology, and MEMS based rocketry, we might consider doing this on a smaller scale, delivering packages ballistically. Regionally at first, and then nationally, and internationally, and then to orbit.

If the logistics and staging were worked out, it could be quite competitive with air breathing systems, that traveled at Mach 6 to 8, or used air breathing components instead of propellant tanks.