The Model 133-4.62 Advanced Technology Tactical Transport (ATTT) proof-of-concept demonstrator is a 62% scaled version of an airplane designed to challenging STOL and long range requirements. The ATTT was developed and test flown by Scaled Composites, Inc. under contract to DARPA. The initial flight test program consisted of 51 flights with the original cruciform tail configuration, measuring and refining performance, stability and control, and handling qualities. The results of the fabrication and test program were presented in a comprehensive report to DARPA .
In an effort to improve the aft loading capability of the aircraft and to correct aerodynamic deficiencies discovered during the test program, the ATTT aircraft was modified with a twin-boom tail whose general configuration was similar to that of the Rockwell OV-10 Bronco. This modified configuration is shown in the accompanying photograph. Pratt and Whitney of Canada PT6A-135A turboprop engines were attached to the twin booms in a tractor configuration. A simple fully mechanical flight control system was installed, with full control available from both seats. The Scaled-designed landing gear is actuated using electric motors.
The M-133 demonstrator used a unique flap system to enable its STOL performance. The high lift configuration consists of eight Fowler-type flaps, each of 43% chord. The flap system was designed to allow the initial takeoff roll to be performed with the flaps extended, but at low deflections to minimize takeoff drag. As rotation speed was neared, the flaps were quickly rotated to the maximum lift position via a separate pilot action. The ATTT was a key program for Scaled. It demonstrated our ability to perform a challenging aerodynamic and structural design, and to build, test, and deliver what amounted to two different manned research airplanes, including all design and flight test data, to DARPA for less than 3 million dollars, including all recurring and nonrecurring costs.
The Scaled ATTT (also seen as AT3) was flown in two different configurations. First as Model 133-3-62 with a conventional tail section with cruciform tailplanes. First flight 29 December 1987. Later in the test programme small endplates were added to the horizontal tail. During 1989 it few again as Model 133-4-62 with the twin tail booms. Engines were two 850hp P&WC PT6AS-135A end registration was N133SC.
In original form wingspan was 53.208ft, length 44.854ft and height 14.075ft. Internally the project was referred to as SMUT (Special Mission Utility Transport). It was an approx. 62% scale technology demonstrator for a planned ATTT -Advanced Technology Tactical Transport and some money may have come from DARPA – Defence Advanced Research Projects Agency.
The ATTT is in storage at the Air Force Flight Test Center Museum, at Edwards Air Force Base.
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