A capsule pipeline transports material or cargo in capsules propelled by fluid flowing through a pipeline. There are two general types of capsule pipelines: hydraulic capsule pipelines (HCP), which use liquid (usually water) to suspend and propel the capsules, and pneumatic capsule pipelines (PCP), which use gas (usually air) to propel the capsules. In contrast to the long history of PCP, the HCP is a new technology first considered by the British Authority for military use during World War II. The phenomenon that at high liquid velocities the capsule velocity exceeds the liquid velocity has also been reported by many investigators. Optimum operation of HCP (especially CLP) requires that the velocity to be slightly below the lift-off velocity. At such a velocity, the contact friction between the capsule and the pipe is minimum, and the capsule is moving through the pipe in a stable nose-up position.