Unguided bomb

Bomb casings for unguided bombs are typically aerodynamic in shape, often with fins at the tail section, which reduce drag and increase stability after release, both of which serve to improve accuracy and consistency of trajectory.

Unguided bombs typically use a contact fuze for detonation upon impact, or some milliseconds after if a penetration effect is required.

The retarded bomb uses a mechanical method of creating increased aerodynamic drag, such as a parachute, ballute, or drag-inducing petals.

These deploy after the ordnance is released, slowing its fall and abbreviating its forward trajectory, giving the aircraft time to get clear of the blast zone when bombing from low altitudes or with nuclear ordnance.

[1] Generally the high-drag tail replaces the low-drag so that the same bomb can be configured for either mode of attack during weapons preparation.

An unguided 500 lb (230 kg) Mark 82 bomb with no retarder
An F-111 dropping Mark 82 bombs with ballute -type retardation systems (Mk82AIR / BSU49B)
Mk. 82 bomb with a Snake Eye tail retarding device – this photograph shows an unfuzed, museum display Mk 82 with its usual combat paint scheme. For display purposes, the optional high-drag Snake Eye tailfin set used for low-altitude release is shown.