In the mid-1980s, the American government agency
DARPA, developed a concept for a
tandem wing STOL transport, intended to act as a technology demonstrator and to meet a requirement for a long-range high-speed transport for US special forces, intended to fill the gap between helicopters and larger transport aircraft such as the
C-130 Hercules. In 1986, DARPA placed a contract with
Scaled Composites, a company set up by
Burt Rutan and owned by
Beechcraft to build prototypes for advanced aircraft, for a 62% scale proof-of-concept demonstrator for the concept, called the Advanced Technology Tactical Transport (shortened to ATTT or AT3). The ATTT had high-
aspect ratio tandem wings, joined by long
nacelles which carried the aircraft's
tractor configuration turboprop engines, large fuel tanks, and the main undercarriage units for the aircraft's retractable
tricycle landing gear. As first built, it had a conventional, cruciform tail. A novel arrangement of eight fast acting
fowler flaps was fitted, inboard and outboard of the engines on each of the wings. These would be extended rearwards in a low-drag configuration prior to commencing the take-off run then quickly lowered to increase lift at the point of take-off. The aircraft was of
composite construction, mainly
glassfibre and
carbon fibre. It was powered by two
Pratt & Whitney Canada PT6A-135 turboprops. The ATTT demonstrator made its
maiden flight on December 29, 1987 from
Mojave Airport, base of Scaled Composites. It completed its initial test program of 51 test flights, with a total of 112 flying hours, on November 8, 1988. It was then rebuilt with a revised tail, with a
twin-boom configuration replacing the original single cruciform tail unit, with the fuselage shortened and a rear-loading ramp fitted. The revised layout improved handling, lowering minimum single-engine safety speed (which was previously significantly higher than the stall speed). A further 13 test flights were flown to evaluate the revised layout. The aircraft has been de-registered and is currently in storage at the Air Force Flight Test Center Museum at
Edwards Air Force Base. ==Specifications (Final configuration)==