Well, "Space Planes" are being experimented with.  I believe at the moment there is a competition going for creating a re-usable, inexpensive space vehicle.  I don't know if these take off as planes or if they use rockets though.... if you google "Virgin Space Plane" you will likely find some info.

I don't think any jet aircraft can operate over ~70,000 feet. 

At what altitude does the atmosphere end, and space begin, in any case?

Air breathing engines can operate to about 30,000 kilometers. Jet aircraft can thus do the same with great difficulty.

Herald

!@#$%^&*()

 

That should read METERS, not kilometers.

 

Herald

SCRAM jet engines, as i was suggesting to be used area relatively new technolgicly, based on RAM jet engies. These are very good at packing oxygen into the engine when it cannot get in with normaljet engines (I.E. extremly high speeds or altitudes). So this would improve the maximum height ceiling before the space plane owuld need to fire its rocket engine, or use onboard oxygen in combination with it's fuel source.

They call the concept of a military space plane a Space Fighter because it sounds cool. But it is really more of a space bomber. Just as an airplane flies over the relatively slow moving vehicles operating on or in on the media below it (earth or water) and bombs them, the space bomber operates above aircraft operating in the medium of the atmosphere and bombs them, presumably with variants on current AAMs. Because the fall from space would give these missiles tremendous energy, they would be devastatingly effective compared to conventional AAMs, much as bombs tend to be disproportionately effective against land and sea craft. In order to attack the space bomber aircraft and ground targets would have to be equipped with specialized missiles similar to current ASAT weapons.

 

If another nation deployed spacecraft designed to fight the space bomber on equal terms, THAT would be a space fighter.

You say that you dow`t that any aircraft can fly over 30`000ft?

 

What about the SR-71 and the MiG-25? Which can take off and climb to an altitude of 35,000 meters (114,000 ft) in a little over four minutes?? This aircraft was designed to intercept the SR-71.