A Look Back at the 1974 AHS/NASA Ames Specialists' Meeting and the Rotor Loads Comparison

International audienceThe paper looks back on the 1974 Specialists' Meeting on Rotorcraft Dynamics and the paper on Loads Comparison, and reflects broadly on the ensuing 40 years of aeromechanics R&D and the changes that have taken place. How the 1974 Specialists' Meeting came about and the process of how the Loads Comparison effort was initiated and organized is described, involving as it did, a cooperative effort of disparate industry analysts and government researchers. How these events influenced emerging Army rotorcraft R&D in the Ames environment, and the birth of the AHS San Francisco Bay Area chapter are recalled. To bridge the 40-year span of loads prediction, then and now, new results from today's evolved codes are compared with the original 1974 results. Modern results from RCAS, UMARC, along with CFD/CSD results from the HELIOS/RCAS and GT-Hybrid/DYMORE are presented. Suggestions are offered to address rotorcraft aeromechanics R&D in the future. * Preface The theme of the Fifth Decennial AHS Aeromechanics Specialists' Conference is " Current Challenges and Future Directions in Rotorcraft Aeromechanics. " As we aim toward these challenges and plan future research it is appropriate to look back on the origins of this unique series of five meetings and conferences. Although the technical environment was quite different and the rotorcraft world was of another era, today's challenges trace back to that time. Thus we may draw insight from past approaches and results therefrom and planners of today's research may perhaps benefit from understanding past approaches and lessons learned in the intervening four decades

Rotorcraft aeroelastic stability

Theoretical and experimental developments in the aeroelastic and aeromechanical stability of helicopters and tilt-rotor aircraft are addressed. Included are the underlying nonlinear structural mechanics of slender rotating beams, necessary for accurate modeling of elastic cantilever rotor blades, and the development of dynamic inflow, an unsteady aerodynamic theory for low-frequency aeroelastic stability applications. Analytical treatment of isolated rotor stability in hover and forward flight, coupled rotor-fuselage stability in hover and forward flight, and analysis of tilt-rotor dynamic stability are considered. Results of parametric investigations of system behavior are presented, and correlation between theoretical results and experimental data from small and large scale wind tunnel and flight testing are discussed

Survey of Army/NASA rotorcraft aeroelastic stability research

Theoretical and experimental developments in the aeroelastic and aeromechanical stability of helicopters and tilt-rotor aircraft are addressed. Included are the underlying nonlinear structural mechanics of slender rotating beams, necessary for accurate modeling of elastic cantilever rotor blades, and the development of dynamic inflow, an unsteady aerodynamic theory for low frequency aeroelastic stability applications. Analytical treatment of isolated rotor stability in hover and forward flight, coupled rotor-fuselage stability are considered. Results of parametric investigations of system behavior are presented, and correlations between theoretical results and experimental data from small- and large-scale wind tunnel and flight testing are discussed

Figures of Merit Remembrances of Those Who Built an Army-NASA Collaboration and a New Age of Rotary-Wing Technology 1965-1985

The authors of this book are the Figures of Meritthe scientists, engineers, technicians, secretaries, test pilots, managers, visionaries, and leaders who built a unique interagency collaboration under the Army-NASA Joint Agreement at Ames Research Center and ushered in a new age of rotary-wing technology. The U.S. Army Aeronautical Research Laboratory (AARL) was formed in 1965 to strengthen the Armys capabilities in aviation R&D, and the Army-NASA collaboration at Ames was intended to benefit both agencies by sharing personnel and facilities for research in areas of common interest in low-speed aviation

Genome-wide linkage screen for testicular germ cell tumour susceptibility loci

A family history of disease is a strong risk factor for testicular germ cell tumour (TGCT). In order to identify the location of putative TGCT susceptibility gene(s) we conducted a linkage search in 237 pedigrees with two or more cases of TGCT. One hundred and seventy-nine pedigrees were evaluated genome-wide with an average inter-marker distance of 10 cM. An additional 58 pedigrees were used to more intensively investigate several genomic regions of interest. Genetic linkage analysis was performed with the ALLEGRO software using two model-based parametric analyses and a non-parametric analysis. Six genomic regions on chromosomes 2p23, 3p12, 3q26, 12p13-q21, 18q21-q23 and Xq27 showed heterogeneity LOD (HLOD) scores of greater than 1, with a maximum HLOD of 1.94 at 3q26. Genome-wide simulation studies indicate that the observed number of HLOD peaks greater than one does not differ significantly from that expected by chance. A TGCT locus at Xq27 has been previously reported. Of the 237 pedigrees examined in this study, 66 were previously unstudied at Xq27, no evidence for linkage to this region was observed in this new pedigree set. Overall, the results indicate that no single major locus can account for the majority of the familial aggregation of TGCT, and suggests that multiple susceptibility loci with weak effects contribute to the diseas