Japan's Supersonic Aircraft

russ_watters

Quote by FredGarvin

Actually it is an acoustic occurrance that is due to changes in the speed of sound at varying altitudes. The speed of sound usually drops with altitude. There is a location where the speed starts to increase again with continuing altitude. If you look at a plot of speed of sound vs altitude, the section would look like a sideways "V". If a soundwave experiences a change in medium that results in the speed of sound changing, the sound waves refract (bend) towards the area of the lower speed (Snell's Law). To make a long story short, the sound waves get bounced up and down, but never refract to the ground. They are channeled like they are in a duct, hence the name. The only thing is that now the sound will be able to travel very long distances.

It's just a guess on my part. It is probably way off the mark.

http://www.du.edu/~jcalvert/waves/barisal.htm

Sounds reasonable to me. It looks like the temperature (and therefore speed of sound) decreases up to about 10km, holds steady, then starts increasing again at 20km: http://perso.wanadoo.fr/ballonsolaire/en-theorie2.htm

Oh - here's the speed of sound itself vs alt: http://www.aerospaceweb.org/question...re/q0112.shtml

Danger

Quote by russ_watters

you could use retractable rocket combustion chambers inside the scramjet

You've gotta give them points for imagination. It looks good on the surface (to an amateur), but I'm guessing that you've got Fred's brain scratching itself.

Seems to me that it would be easier to put retractible engines elsewhere on the plane.

Astronuc

CONCORDE'S SUCCESSOR

With Dreams of Super-Sonic Jets Dancing in Their Heads

Five years after the crash of a Concorde in Paris, French and Japanese researchers are planning the next generation of super-sonic civilian jets. But without a huge leap forward in technology, their plans may never take flight.

http://service.spiegel.de/cache/inte...363823,00.html

FredGarvin

And in fact, the Concorde's successor is supposed to set new standards in these areas. The Japanese have announced that they have an engine that will be powerful enough to propel the new jet through the skies at a speed five times the speed of sound.

This sounds like another load of BS that a business person is spouting without knowing the technicalities of what they are saying. Let's just for a moment say that they had engines that could reach those speeds which are of the air breathing family and they can carry enough fuel to do go the distances they need. The one thing at M4+ that anyone MUST deal with is thermal managment. The thermal loads on the aircraft systems are phenomenal. I don't mean a little hurdle to overcome, I mean HUGE problems. I'd like to know how they intend to keep the fuel in the tanks from vaporizing. I'd like to know what fuel they plan on using because JET-A ain't gonna cut it. I'd like to know how they plan on keeping all of the people cooled to the point that is comfortable...

FredGarvin

Quote by russ_watters

Sounds reasonable to me. It looks like the temperature (and therefore speed of sound) decreases up to about 10km, holds steady, then starts increasing again at 20km: http://perso.wanadoo.fr/ballonsolaire/en-theorie2.htm

Oh - here's the speed of sound itself vs alt: http://www.aerospaceweb.org/question...re/q0112.shtml

The thing that causes the effect at other altitudes is a temperature inversion which do happen quite frequently.

Cliff_J

Guess: Maybe the 1% just refers to a 20db reduction in noise put in laymans terms?

(manufacturer to journalist)
M: THIS ENGINE IS WHISPER QUIET AT ONLY 135dBA.
J: WHAT?
M: QUIET!
J: WHAT?
M: YEAH.
J: ???? (scribling notes)

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Astronuc Admin	CONCORDE'S SUCCESSOR With Dreams of Super-Sonic Jets Dancing in Their Heads Five years after the crash of a Concorde in Paris, French and Japanese researchers are planning the next generation of super-sonic civilian jets. But without a huge leap forward in technology, their plans may never take flight. http://service.spiegel.de/cache/inte...363823,00.html

Cliff_J Recognitions: Science Advisor	Guess: Maybe the 1% just refers to a 20db reduction in noise put in laymans terms? (manufacturer to journalist) M: THIS ENGINE IS WHISPER QUIET AT ONLY 135dBA. J: WHAT? M: QUIET! J: WHAT? M: YEAH. J: ???? (scribling notes)