Essentially, the Pioneer is an upgraded Tadiran Mastiff which was re-engined to accommodate a greater payload by request of the US Navy. To accomplish this, the original "Limbach" two-cylinder two-stroke engine was replaced with a Fichtel & Sachs two-cylinder two-stroke. The Limbach motor utilized a 28 inch propeller from Propeller Engineering and Duplicating, Inc. of San Clemente, California. The newer, more powerful Fichtel & Sachs motor was outfitted with a 29 inch propeller (which spins in the opposite direction) from the Sensenich Propeller Manufacturing Company of Lancaster, Pennsylvania.
Launched by rocket assist (shipboard), by catapult, or from a runway, the Pioneer recovers into a net (shipboard) or with arresting gear after flying up to 5 hours with a 75-pound (34 kg) payload. It flies day or night missions with a gimbaled EO/IR sensor, relaying analog video in real time via a C-band line-of-sight (LOS) data link. Since 1991, Pioneer has flown reconnaissance missions during the Persian Gulf, Somalia (UNOSOM II), Bosnia, Kosovo and Iraq conflicts. In 2005, the Navy operated two Pioneer systems (one for training) and the Marines operated two, each with five or more aircraft. It is also operated by Israel and the Republic of Singapore Air Force. In 2007 Pioneer was retired by the US Navy and was replaced by the Shadow UAV.
The "R" is the Department of Defense designation for reconnaissance; "Q" means unmanned aircraft system. The "2" refers to its being the second of a series of purpose-built unmanned reconnaissance aircraft systems.