[jwparkerjr]

re: air-breathing rocket engine that could power the Skylon spaceplane.

I'm no rocket scientist, but even to my very limited knowledge of such things it seems an air-breathing anything would be seriously challenged in space.

[ArrogantBustard]

Plenty of air to breathe for the first 100,000 feet. One of the great inefficiencies of traditional staged-rocket to orbit is the need to drag a lot of heavy oxidiser through the atmosphere.

[Vaquero]

if you read the article the engine changes from an air breather to a liquid oxygen breather at higher altitudes.