Hi chicopee

Go to the following site to read all about it.

http://www.nasa.gov/missions/research/x43-main.html

Ed

edbgtr-nasa's site is hard to read but apparently in the article the jet gets its oxygen from the rarified atmosphere of 110,000' altitude.  w/ that info, I gathered that such jet would not be able to work in space regardless how fast it travelled even if speeds of one quarter of the speed of light could be reached.

The scramjet is an air-breathing engine as we website indicates in the very first sentence.  

What does this have to do with 1/4 light speed and space?

TTFN

IRstuff- even in space there are traces of gas including oxygen molecules- since speed appears to be the criteria to make this type of jet work in rarified atmosphere, at 1/4 of the speed of light you would think that you could capture enough oxygen to support combustion in space which is probably absurd.  So this type of engine in space would no longer be considered a jet but a rocket since the vehicle would need to carry the oxidizer. That's the point I am trying to make in reference to the speed of light.

A commonly accepted density for interstellar hydrogen is around 1 atom/cm^3.  

Even assuming a 100 ft^2 scoop, the amount of hydrogen encountered in 1 second at 1/4 lightspeed comes out to ~7*10^15.  

Oxygen density is supposedly around 300 atoms O/10^6 H, so the amount of oxygen encountered is ~3*10^12 atoms/second.

TTFN

Now, to take a tottering step forward, dropping all pretence at accuracy, Avogadro's constant is  about 10^24, so you are going to run into 10^-11 grams of oxygen per second, to fuel your jet, which'll combine with 10^-12 g of H. So you'll develop a power of about 10^-7 W at 100% efficiency.

I'll leave it to someone else to work out how much power it'll take to push through the excess hydrogen.



 

  

Cheers

Greg Locock

chicopee, you're right saying that this craft would not be able to work. But it wasn't intended for this purpose. Still, an air-breathing Mach 10 engine remains a technological marvel.

I'll pass the aerodynamic drag of the vehicle in space, my aerodynamics lectures aren't enough