Minecraft wiki entry for Flying_machines, associated text: Dimensions: 10x6, 2 high minimum, 5 high with roof.
Notes:
The slime block marked a can get another slime block above it, with top slabs on each side sheltering the passenger/cargo minecarts.
The starred minecart is the "pilot's seat".
Before going either way, first make sure the roof is retracted by clicking the <̅ block, and the cargo is retracted by clicking the >̅ block.
To go either way , click the appropriate < >. To stop, spam-click the matching barred block <̅ >̅ .