I found the awesome Mk-33 spaceplane mod by Angel-125 to be a little too awesome - it made my Near Future Launch Vehicles rockets much less useful. So I wrote a ModuleManager patch that increases the science threshhold to unlock it, and spreads out the parts into several "stages".
Optimised for games with lots of mods and players who like to squeeze every bit of science out of every planet they visit - the unlock requirements are quite high for the full aircraft, about 6500 for everything compared to the default 1000-science single unlock. However, a a basic Mk-33 can be built for about 4000.
Dependencies:
Raw stats are from the beginning of time until now. Each follower and download entry represents one hour of data. Uneventful hours are omitted.