Topic summary
HTHL
Extracted from the Wikipedia article Takeoff and landing.
Spacecraft (HTHL)
Horizontal takeoff, horizontal landing (HTHL) — is the mode of operation for the first private commercial spaceplane, the two-stage-to-space Scaled Composites Tier One from the Ansari X-PrizeSpaceShipOne/WhiteKnightOne combination. It is also used for the upcoming Tier 1bSpaceShipTwo/WhiteKnightTwo combination. A prominent example of its use was the North American X-15 program. In these examples the space craft are carried to altitude on a "mother ship" before launch. The failed proposals for NASA Space Shuttle replacements, Rockwell X-30 NASP used this mode of operation but were conceived as single stage to orbit.