Waverider

From Memory Alpha, the free Star Trek reference

The waverider is an atmospheric shuttlecraft in service aboard Federation Nova-class starships. Unlike other auxiliary craft, the waverider is not stowed in a shuttlebay. Instead, is docked to the ventral side of the primary hull, just forward of the ship's primary navigational deflector. (VOY: "Equinox", "Endgame")

[edit] Background

Although it has never been seen in action, the waverider can be readily identified in the MSD of a Nova-class vessel. The craft's aerodynamic shape suggests that this craft is designed solely for operating within a planet's atmosphere, and as a result probably lacks both impulse and warp engines. It is conceivable that a vessel would require such a craft when it is necessary to land on the surface of a planet whose atmospheric conditions make it far too hazardous to use transporters or traditional shuttlecraft. (Star Trek: The Magazine)

A hypersonic re-entry vehicle known as a "Waverider Shuttle" has actually been conceived and developed, using the "Waverider Theory". [1]