Non veni pacem mittere, sed gladium.
But worth the price.
i recall reading that the fuel efficiency actually improved the higher and faster it flew.
Yep, less drag the higher you go.
I only recently learned that this was the reason the Air Force killed it. Every single time it flew it cost $2 million and it came out of the Air Force's operating budget.
Any time JP-7 was spilled on the tarmac, it would erode the concrete.