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Technical Paper

Failure of Aircraft Structural Joints Under Impulse Loading

Numerical simulations indicate that blast loading on aircraft structural joints can impart loading rates in excess of 10 Mlb/sec (ten million pounds per second, Reference 1). Experimental evidence, on the other hand, suggests that mechanical joint failure loads are highly loading rate dependent; for example, the failure load for a dynamically loaded tension joint can double from its static value. This paper discusses the progress and to-date findings of research on the assessment of strength failure of aircraft structural joints subjected to loading rates expected from an internal explosive detonation, and several associated experimental procedures to generate such dynamic loading. This work is conducted at MDC and at the University of Dayton Research Institute (UDRI) in support of the FAA Aircraft Hardening Program.
Technical Paper

Heat-Powered Environmental Control Systems for Fighter Aircraft

Heat powered ECS concepts using a Rankine or Stirling power cycle to drive a vapor compression refrigeration cycle were evaluated for future fighter aircraft. Arrangements with separated power cycle and refrigeration cycle working fluids were considered, as were arrangements combining these cycles via a common working fluid. Promising heat sources and working fluids for these concepts were identified. Haste heat sources in the propulsion system and airframe were compared with regard to heat capacity, temperature level, and collection system design complexity. A screening process, which distinguished between the requirements imposed by the power cycle and refrigeration cycle, was developed to select promising working fluids. Concepts were evaluated using various system arrangements, heat sources, and working fluids to minimize the ECS-related TOGW penalty.
Technical Paper

Design and Flight Test of One-Man Operability in the F/A-18

The F/A-18 has the capability to perform a greater variety of fighter/attack missions than any other single-place aircraft ever produced. This paper will not address any new discussion of the “one vs. two” crewmember situation, but only present the human factors engineering history that produced the current man-machine interface in the F/A-18. The extensive software capability of the airplane has made changes found desirable during flight test reasonably easy to incorporate into production aircraft. These changes encompass everything from aircraft handling qualities and display formats (heads-down and heads-up) to radar and weapons system operation. Previous aircraft have depended, in varying degrees, on the unique capabilities of the pilot to compensate for inherent crew station/weapon system deficiencies.
Technical Paper

Integrated Design Engineering and CAD/CAM Applications

In October 1986, the trainer version of the AV-8B jump jet, the TAV-8B, made its first flight. The event concluded a significant CAD/CAM milestone in the history of McDonnell Aircraft (MCAIR), since the forward fuselage and canopies were designed and manufactured using CAD/CAM. This major pilot program applied the MCAIR computer graphics system with wire frame and surface technology to the integration of all design and supplied Manufacturing with digital data for CAM applications. The presentation will focus on the Engineering management of the design integration effort, the computer graphics applications with a CAM interface, the savings associated with this large scale pilot program and the lessons learned.
Technical Paper

Near Term Enhancements of the AV-8B Harrier II

The United States Marine Corps (USMC), the Royal Air Force (RAF) and Royal Navy of the United Kingdom have proven the operational benefits provided by fixed wing powered lift aircraft. The USMC demonstrated the powered lift fixed wing V/STOL light attack concept in the United States with the AV-8A. The Marines eventually needed additional range and payload capability due to expanded mission requirements, but could not afford a simultaneous engine and airframe development program. The AV-8B was developed, fielded, and successfully filled all stated Operational Requirements identified at that time. It is time now to plan for and expand the powered lift capabilities further to keep the AV-8B effective as part of the Marine Amphibious Task Force in the face of growing threat capabilities. The cornerstone of this improvement is the Pegasus −408 growth engine.
Technical Paper

The F-15 STOL and Maneuver Technology Demonstrator (S/MTD) Program

McDonnell Aircraft Company (MCAIR) is currently conducting the STOL/Maneuver Technology Demonstrator (S/MTD) Program for the Air Force's Flight Dynamics Laboratory (AFFDL) under Contract F33615-84-C-30I5. This program involves the modification of an F-15B. S/N 71-290, to incorporate the following advanced technologies: Two dimensional, thrust vectoring/thrust reversing exhaust nozzles (2D TV/TR) An integrated flight/proputsion control (IFPC) system Modified rough field landing gear An advanced pilot/vehicle interface (PVI) system which includes an on-board landing guidance display system
Technical Paper

Aerodynamic Design Considerations of Variable Geometry Aircraft

Aircraft designs have been characterized by an increasing utilization of variable geometry features as aircraft capabilities expand into new flight regimes. The trend seems likely to continue as requirements for new aircraft become continually more demanding. The successful application of variable geometry depends on several things: the understanding of the aerodynamic principles involved, efficient structure, and whether an overall worthwhile improvementin performance, maneuverability, or flying qualities is gained; since it certainly will cost more, be less reliable, and more difficult to maintain. The application of some existing and proposed variable geometry schemes to aircraft is discussed. The aerodynamic factors affecting low and high speed performance, maneuverability, and stability and control characteristics indicate some of the desirable and troublesome aspects of these concepts.
Technical Paper

Structural Considerations for Variable Sweep Wings

Pivot point concepts for fighter type aircraft with variable sweep wings are reviewed. Structural and aerodynamic considerations involved in sweep pivot location, a summary of endurance testing of Teflon lined journal bearings, and variation of fatigue life of the aircraft versus wing sweep position are discussed.
Technical Paper

Demonstration of an Electrically Actuated Brake with Torque Feedback

The U.S. Air Force has recognized the need for an alternative to the conventional hydraulic brake system. Hazards associated with fires and the maintenance required for a hydraulically actuated system are the principal drawbacks of hydraulic brake systems. In addition, an alternative brake system will be required to support a “More Electric” aircraft of the future. The solution to these problems was provided by the “Electrically Actuated Brake Technology (ELABRAT)” program, a three year program sponsored by the Flight Dynamics Directorate at Wright Patterson AFB. ELABRAT developed and demonstrated an Electromechanically Actuated (EMA) brake system to replace the existing hydraulically actuated piston housing and associated hydraulic control hardware.
Technical Paper

Development of the McDonnell Douglas MD-90

Douglas developed the MD-90, an IAE V2500-powered derivative of the MD-80, to satisfy a customer need for a more environmentally - friendly 150-seat, short/medium range jet transport. The program was launched in late 1989 with requirements to: significantly reduce community noise and engine emissions improve aircraft fuel efficiency make other technical improvements where cost effective for the customer. The aircraft was certificated in November 1994 and entered airline service in April 1995. The MD-90 meets all of its technical requirements.