This paper describes the architecture, capabilities, and design considerations of a common baseline research system, which was developed at the NASA Langley Research Center for use in its three general aviation research aircraft. NASA Langley has acquired a Cessna 206X Stationair, Lancair Columbia 300X, and a Cirrus Design SR22X aircraft to support a variety of NASA flight-research programs, in particular the Small Aircraft Transportation System (SATS) Project, and the Aviation Safety Program. The SATS Program is a partnership involving NASA, the FAA, states, industry, and universities to develop key enabling transportation technologies. A set of general aviation research requirements was developed, and a baseline research system architecture was derived from those requirements. The baseline design requirements include: modular architecture; standard interchangeable components; re-configurable equipment mounting; and, an extensive sensor suite. A combination of commercial off-the-shelf (COTS) and custom-designed systems were selected, purchased or fabricated, and installed. These systems include: separate research power; multi-function flat-panel displays; state sensors; airborne internet; serial data bus; video recording; data acquisition; data-link; Global Positioning System (GPS)/Differential GPS (DGPS); telemetry; and instrumentation. Several open architecture standards were used in the selected research equipment. These open standards include: Ethernet; Controller Area Network (CAN); Intel x86-based computers; and the Common Airborne Instrumentation System (CAIS). The Cirrus Design SR22 and Lancair Columbia 300 aircraft are small, single-engine, four-place, composite-construction aircraft with limited payload and electrical power. These attributes presented significant additional design challenges beyond those as