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Global warming concerns have prompted actions to restrict carbon dioxide emissions by a rapidly growing number of nations throughout the world. The aviation community can expect emission limits in the near future, and should become pro-active in this arena. Rapid advances are being made in the automobile industry to research and develop more efficient vehicles. The very successful introduction of gasoline-electric hybrid automobiles has spawned intense research and development of advanced batteries, ultra-capacitors, electric motors and controls. Opportunities for adapting automobile technologies to small general aviation airplanes should be exploited. Over the past few years, several groups have successfully flown experimental airplanes powered by ground-rechargeable batteries.

Global warming concerns are stimulating accelerated research and development of alternative fuels and propulsion systems for automobiles. The potential application of these emerging technologies to airplanes is reviewed. Preliminary designs of zero greenhouse gas emission airplanes using hydrogen fuel and either internal combustion or fuel cell-electric motor propulsion are presented for a wide body jet transport, medium jet transport, business jet, and single engine propeller airplane. The hydrogen fueled internal combustion engine airplanes offer the easiest path to zero emissions, but the greater efficiency of the fuel cell airplanes allows designs requiring substantially less fuel. The single engine propeller airplane is the easiest to modify for hydrogen fuel, because of the relatively high mass and volume of the engine being replaced. Technology improvements needed to make zero emission airplanes viable are suggested.

Thick airfoils are commonly used for wind turbine and propeller blade inboard sections, and for struts on aircraft. These airfoils are sometimes truncated for manufacturing convenience, or to save weight. The purpose of this investigation was to study the effects of systematic truncation on airfoil performance. In order to investigate these effects two basic airfoil shapes representative of wind turbine designs were tested: the NACA 23024 and the NACA 643-621. The trailing edges of the models were truncated in steps up to the maximum thickness point. Aerodynamic forces and pitching moments were measured for angles of attack from -10° to 90° for each truncated model. Wind tunnel tests were conducted in the Wichita State University 2.13m × 3.05m (7′ × 10′) Walter Beech Memorial Wind Tunnel, using constant chord reflection plane models.

A program has been undertaken to develop new airfoil sections suitable for general aviation aircraft, utilizing theoretical and experimental advanced technology developed in recent years primarily for subsonic jet transport and military aircraft. The airfoil development program is one component of the Advanced Technology Light Twin (ATLIT) program sponsored by NASA Langley Research Center. Two-dimensional tests of a new airfoil at NASA and Wichita State University have demonstrated high cruising performance over a fairly wide C1 range, and a C1max value of 3.69 with Fowler flap and no leading-edge devices. Experimental and theoretical development of additional configurations is under way.