Hypersonic Speeds!

Does anything changes or happen on an aircraft when it hits mach 5?

mach 1 is supersonic, and that makes sense but why do they call it hypersonic when you hits mach 5?

sure, its no longer affected by the gravitational pull of the planet in the sense that it does not have a tendency to fall back to earth at that speed. Also the frictional heating of the "air" is almost 2000 degrees plus allowing Hydrogen in the atmosphere to be used for fuel. The term "lift" no longer applies in regards to control surfaces as there is no longer an air body that is dense enough to affect the control of the "craft" plus the windspeed on any exposed control surface (outside of the "shock wave") puts enough pressure to tear it off. You can no longer use "air" as a medium for combustion in your "engine". There probably is about 5 or 6 other things that I did not list. But I hope you understand the complexities of going "hypersonic".

robertfenix
You can no longer use "air" as a medium for combustion in your "engine".

Thats not true, What about scramjets, the can go at least mach 10, and the scoopr up the oxygen (not stored in a tank).

www.aerospaceweb.org...

Why is hydrogen used as fuel in a scramjet engine?
- name withheld

In order to better understand this question, we must first understand some of the fundamental hurdles that must be overcome in operating a supersonic combustion ramjet (scramjet). Scramjets are designed to operate in the hypersonic regime of flight. A vehicle using such an engine typically flies faster than Mach 5, or 5 times the speed of sound since this speed is generally accepted as the beginning of the hypersonic regime. Flight at such speeds is nothing new. After all, Air Force test pilot and current California state senator Pete Knight set an unofficial world speed record on 3 October 1967 when he flew the X-15 research plane upwards of Mach 6.7. At its peak altitude of over 350,000 ft (107,900 m), that speed corresponds to about 4,530 mph (7,300 km/h).

You really should know what you are talking about first before you post saying something I have posted is "un true"

www.aviation-history.com...

Scramjet is an acronym for Supersonic Combustion Ramjet. The scramjet differs from the ramjet in that combustion takes place at supersonic air velocities through the engine. It is mechanically simple, but vastly more complex aerodynamically than a jet engine. Hydrogen is normally the fuel used.

"air" in the normal sense of the word as people typically imply "oxygen" is not really what is happening in a Scramjet. Its really the "friction" of the particles moving at high-supersonic speed over the combustor section that is the medium when mixed with hydrogen to sustain the thrust in a scramjet engine. The actual makeup of the inlet componet really does not matter as long as it includes HYDROGEN driven at high velocity, in fact if you could run the scramject in only a hydrogen rich atmoshpere you could limit the amount of "fuel" you would have to use to sustain hypersonic flight.

Provided of course you first got the "thing" up to hypersonic speed to begin with, by solid rocket or whatever means needed.

www.tfd.chalmers.se...

This is the detailed report from los Alamos Labs/ Sandia Labs about Hypersonic Hydrogen combustion. The only critical component is Hydrogen when they state the compressed "air" they actual use a H2 and C2H4 mixture that mimick the density of atmospheric "air" knowing that Oxygen or "air" is not required to sustain hypersonic combustion. Its actually the compression and density of the input "air" to the required heating and then the interjection of the Hydrogen fuel that causes autoignition. There is no mention about the need for a specific oxidizor, noting that Hydrogen subjected to hypersonic compression will autoignite
[edit on 2-9-2004 by robertfenix]

[edit on 2-9-2004 by robertfenix]

[edit on 2-9-2004 by robertfenix]

This is a good post, sorry this may seem like spam now, but later on...i'm posting so i can find it in my posted threads. I'll explain some pretty cool concepts to you on drag and lift coefficients and how they change in supersonic, subsonic, and transonic flight. Mach 1 is only transonic flight, i can clear that for you now look out for the post

Oh, thanks for explaining, # I ALLREADY KNOW!

Ohhhh, you know how to cut and past from a site, wow, your much smarter then me.

and also is does not autoignite, at those speeds what they do is have a flam in the engine itself wich is behind a wall in the engine so the high speed wind dont put it out.

and you kept stating you dont need "air", yes you do because its the only thing we have here on earth that can go through an engine.

Originally posted by Murcielago
Oh, thanks for explaining, # I ALLREADY KNOW!

Ohhhh, you know how to cut and past from a site, wow, your much smarter then me.

and also is does not autoignite, at those speeds what they do is have a flam in the engine itself wich is behind a wall in the engine so the high speed wind dont put it out.

and you kept stating you dont need "air", yes you do because its the only thing we have here on earth that can go through an engine.

what? copy and paste from a website? I dont know what your talking about. Sigh...ok well you just saved me some time i guess.


Just for the record, the guy with a skunk is right. The hypersonic flight engines. Scramjets use the oxygen already present in the atmosphere.

[edit on 2-9-2004 by Aether]

Nah Aether I was referring to robertfenix