Limit

The flying engine: top speed: 1050m/s

Pure stock parts in version 0.16 Top speed of 1042 m/s in horizontal flight at approx 17,000m Takeoff sequence is from a different run (just pics to get an idea of the design) Ive managed 1043m/s but didn't get the screenshot unfortunately Ready for takeoff Climbing to optimum altitude Waiting for all the fuel to run out Top speed!

This is the max I dare take this design, total of 37 engines, top speed of 1042 m/s Pic of the craft shortly after running out of fuel Evidence of top seed:

Very nice shuttle! Ive been trying hard to make one that has some sort of resemblance to the real thing.

I think true level flight is both at a pitch angle of +/- 10 degrees and a vertical speed of less than 10m/s (Nao both your craft are falling at more than 100m/s!!)

And even faster still (this time no mech jeb)...top speed: 1040m/s

Made it after quite a few iterations... top speed: 1027m/s

Here's the stripped down and turbo charged version that made it to the south pole in 30 minutes and 25 seconds (was really pushing the descent hard to get it in under 30minutes but I would of lost control of the plane!)

Here's my entry: Managed to reach the north pole in exactly 32 minutes (as soon as I came to a complete stop)