Hypersonic Transport Idea

[KJ_Lesnick]

I was wondering how hard it would actually be for a hypersonic transport to be built with technology available in the 1980's, 1990's and modern day.  I was thinking about this while I was driving around yesterday (I was visiting some family).

- Since the 1960's high temperature, light-weight TPS were developed by McDonnell Douglas which eliminated the need for using the fuel tanks as a heat-sink, and elaborate air-conditioning systems.  They also allowed fairly sharp noses all the way up to Mach 12 at least.  Paul Csysz one time said 14,000 mph which is about Mach 19-22 depending on altitude and air-temperature.  These were lighter and stronger than the tiles used on the space-shuttle.  The only area that needed piped cooling was the nose.
- We've been able to get higher and higher mach numbers out of engines with pretty high pressure ratios due to advances in engine cooling, metallurgy, ceramics, and fabrication techniques
- Hydrogen and Methane Expander engines can produce seriously huge amounts of thrust which allow high T/W ratios, and thus good acceleration.  They also yield remarkably high exhaust velocities suitable for high-speeds even without a particularly high pressure-ratio.  LH2 being burned produces just water vapor which is environmentally friendly and such.
- The altitudes that hypersonics fly at, and the shockwave angles produced at high speeds generally don't produce serious sonic boom issues...

The things I can see that would get in the way would be

- I don't know what time these metal TPS systems became declassified, let alone made public knowledge, so for hypothetical purposes I know it can be done today, but not sure about 1980's 1990's and such.
- The time it takes for the fuselage to cool off, but I'm not sure how quickly these TPS systems Dr. Csysz talks about can dispel heat, it might be able to dispel them pretty fast.  I do remember seeing a YF-12 during testing with NASA that actually used a water-spray for some reason... I don't know why, but you could spray coolant on the skin to help speed up the process
- Most airplanes optimized for hypersonic speeds have very high takeoff and landing velocities.  If you have a lot of thrust this can be manageable I suppose for takeoff, but for landing you could be in some serious trouble especially as most wave-rider designs with their engines low on the fuselage might not be conducive for thrust-reversing (Though I'm not sure of that)
- It would probably be difficult to get an infrastructure set up for providing LH2 or even LCH4 in large enough amounts for a fleet of airliners in the 1980 and 1990 era.  Now it (LH2) could probably be done especially with everybody obsessed with being "green" although LH2 is clear to the best of my knowledge.
- While these engines would produce superbly high exhaust velocities which are great for high speeds, they would make horrendous amounts of noise and would be difficult to keep reasonably low, especially with everybody so obsessed about airplane noise -- Yet you have idiots with the loudest most gigantic stereo systems in their cars, blasting rap music as loud as the system will go, which make the whole street seem to vibrate and makes you wonder how many of these people will be deaf by the time they're 40...


KJ Lesnick

[kitnut617]

In the last British Secret Projects volume, Hypersonics etc. there's quite a bit of info which might help you out.  I will have to read the book again as it didn't all soak in the first time though      I'm a bit like a computer ----- you have to punch the information in   

[pyro-manic]

BSP4 certainly has a lot of very interesting stuff in it on this topic, with high-speed designs going back to the 50s and 60s. I think that if the funding was available, it could certainly be done.

[KJ_Lesnick]

I have that book somewhere...  I don't know where it is *rolls eyes*

[jcf]

While an interesting blue-sky notion, from the practical side there would not have been a viable business case
to develop and produce such a beast, military or civil.
However it is a good subject for a Gerry Anderson universe  build, another big high-tech airliner for
the Thunderbirds to rescue.

[KJ_Lesnick]

JonCarrFarrelly,

I do realize that this particular concept is not realistic economically.  I'm mostly talking about simply how hard it would be to do from a technical standpoint...