Guided Bomb Unit-27 (GBU-27)
The Guided Bomb Unit-27 (GBU-27) is a GBU-24 modified for delivery by the F-117 stealth fighter. The operator illuminates a target with a laser designator and then the munition guides to a spot of laser energy reflected from the target. It uses a 2,000-pound penetrating warhead against hard targets. The GBU-27 was used in Operation Desert Storm. According to the Air Force, the GBU-27 hit 70 percent of its targets.

The GBU-27 was designed specifically for use by the F-117's advanced target acquisition/designator system. The GBU-27 uses a BLU-109 improved performance 2,000 pound bomb developed in 1985 under the project name HAVE VOID. The BLU-109 was designed for use against hardened structures and features a high-strength forged steel case and a new delayed-action tail fuze. It carries 550 pounds of high explosives and can penetrate more than six feet of reinforced concrete.
The GBU-27 uses a modified Paveway II guidance control unit which provides "terminal trajectory shaping" for optimum impact angle against various target structures. For example, it will hit an aircraft shelter with a vertical impact, but make a horizontal approach to a bridge support. A Paveway II tail assembly with folding wings completes the bomb.
 

The F-117 can carry two GBU-27s in two weapons bays and is reportedly capable of hitting a one square meter target from an altitude of 25,000 feet.

Specifications
Mission  Close air support, interdiction, offensive counter air, naval anti- surface warfare
Targets  Mobile hard, fixed hard, fixed soft
Service  Air Force
Program status  Operational
First capability  1987
Guidance method  Laser (man-in-the-loop)
Range  Greater than 10 nautical miles
Development cost  Not available - Air Force officials state that development cost was not available because they do not have records covering the development period.
Production cost  $176.715 million
Total acquisition cost  Not available
Acquisition unit cost  Not available
Production unit cost  $55,000
Quantity  3,213
Platform  F-117