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An algorithm is developed and validated for automatic avoidance of restricted airspaces. This method is devised specifically for implementation with an advanced flight control system designed for general aviation application. The algorithm presented here implements two inputs to the aircraft; the bank angle, and the airspeed, while the control system always ensures coordinated maneuvers. Unlike collision avoidance systems, the current method is not designed to serve in an advisory role, but to assume complete control of the aircraft if necessary. It is demonstrated that in order to implement this technique, the aircraft must be assigned an immediate domain whose size would have to depend on the aircraft performance and flight conditions. The strategy is designed such that as the domain surrounding the aircraft approaches that of the restricted airspace, aircraft control would switch gradually away from the pilot and to the controller, which would initiate an evasive maneuver.

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.

An envelope protection scheme is proposed for responding to a microburst. This approach is based on limiting the allowable maximum inertial deceleration of the aircraft when flying at low airspeeds. This technique is shown in simulations to be very effective at preventing stall and resulting in minimal loss of altitude. It is speculated that the same scheme can also protect an aircraft in the event of other forms of windshear encounters, such as making a sudden turn to downwind.

Most composite assemblies and structures generally fail due to weak interlaminar properties and poor performance of their bonded joints that are assembled together with an adhesive layer. Adhesive failure and cohesive failure are among the most commonly observed failure modes in composite bonded joint assemblies. These failure modes occur due to the lack of reinforcement within the adhesive layer in transverse direction. In addition, the laminated composites fail due to the same reason that is the lack of reinforcement through the thickness direction between the laminae. The overall performance of any composite structures and assemblies largely depends on the interlaminar properties and the performance of its bonded joints. Various techniques and processes were developed in recent years to improve mechanical performance of the composite structures and assemblies, one of which includes the use of nanoscale reinforcements in between the laminae and within the adhesive layer.

The fatigue behavior of Hilok fastener joints under constant amplitude loading has been investigated experimentally. The effects of load transfer in an unbalanced joint configuration was characterized in terms of a stress severity factor relative to the open-hole configuration. The experimental data indicates that the clamp-up forces dominate the performance of fastener joints with the open-hole fatigue life being the lower bound at the stress levels investigated. The failure modes were observed to transition from a net-section type failure across the minimum section to a fretting induced failure at some distance from the hole. The experimental data has been used to develop stress severity factors to be used as a measure of the fatigue quality of the fastener joints.