NASA - Dryden History - Historic Aircraft - X-1 Contributions
October 9, 2008
- The XS-1 was designed largely in accordance with specifications provided by the National Advisory Committee for Aeronautics.
Among other specific design contributions of the NACA were:
- recommending that the airplane be designed to withstand loads up to 18 times the force of gravity (compared to the 12g load limit of contemporary fighter aircraft), a figure arrived at independently by the AAF and Bell;
- urging that it have very thin wings so it could safely encounter the shock waves of flight through the transonic region just below the speed of sound;
- determining that the horizontal stabilizer should be 2 percent thinner than the wing, thus avoiding simultaneous transonic shock wave effects;
- also urging that the horizontal stabilizer be located above the wing wake to reduce the latter's interference with the tail;
- specifying that the aircraft be equipped with a movable horizontal stabilizer to provide pitch (nose up or down) control when shock waves made the elevators ineffective.
The NACA performed the general planning for the flight research, then collected the flight data and analyzed it for the initial two aircraft and later, for more advanced versions such as the X-1B and X-1E.
- Gathering the flight data entailed both extensive and accurate instrumentation, roughly 500 pounds of sensors, wiring, tubing, and associated switches and relays.
- Relatedly, the early X-1 flights highlighted the importance of airspeed/position-error calibration, ushering in the airspeed or air data specialist as a key discipline for successful transonic and supersonic flight research.
- The XS-1 #2 (tail number 46-063) was flight tested by the NACA to provide design data for later production, high-performance aircraft.
- Throughout, the NACA provided an emphasis on flight safety and careful, incremental steps in the flight research to ensure that the research data were as extensive as possible and of high quality.
- Data from the X-1 flight research validated (and in some cases, revealed the limitations of) transonic wind tunnel data and theoretical analysis developed elsewhere.
- The research techniques used in the X-1 program became the pattern for all subsequent X-craft projects.
- The NACA X-1 procedures and personnel also helped lay the foundation of America's space program in the 1960s.