Results 71 to 80 of about 891,158 (301)
Comparison of predicted engine core noise with proposed FAA helicopter noise certification requirements [PDF]
Calculated engine core noise levels, based on NASA-Lewis prediction procedures, for five representative helicopter engines are compared with measured total helicopter noise levels and proposed FAA helicopter noise certification requirements.
Groesbeck, D. E., Vonglahn, U.
core +1 more source
Wildlife Biology, EarlyView.Resource managers require accurate estimates of large herbivore abundance and demography to maintain ecological integrity. Common methods to count these species, including observations from low altitude helicopter flights, may conflict with other protected area management objectives and struggle to produce precise estimates for more cryptic species. To
Hanem G. Abouelezz, N. Thompson Hobbs
wiley +1 more source
Comparison Between Helicopter and Cable Crane in Logging Operation
Chemical Engineering Transactions, 2017 In Italy, differently from others European Countries (Switzerland) where the use of helicopters is more diffuse, log transportation in slop land is generally performed by cable crane although its use is generally difficult and high time consuming for ...
M. Manzone, P. Balsari
doaj +1 more source
Materials and structural aspects of advanced gas-turbine helicopter engines [PDF]
The key to improved helicopter gas turbine engine performance lies in the development of advanced materials and advanced structural and design concepts. The modification of the low temperature components of helicopter engines (such as the inlet particle ...
Acurio, J., Freche, J. C.
core +1 more source
Annual survival in a dynamic species: pronghorn survival patterns across their northern range
Wildlife Biology, EarlyView.Quantifying variation in demographic patterns, such as survival and recruitment, is critical for understanding population dynamics and informing evidence‐based and adaptive wildlife management. In this study, we leverage an extensive dataset from over 1000 GPS collared pronghorn Antilocapra americana to provide the first large‐scale evaluation of ...
Molly C. McDevitt +5 more
wiley +1 more source
Results of the noise measurement program on a standard and modified OH-6A helicopter [PDF]
A field noise measurement program has been conducted on a standard OH-6A helicopter and one that had been modified by reducing the rotor speed, altering rotor tip shape, and treating the engine exhaust and inlet to reduce the external noise levels.
Henderson, H. R. +2 more
core +1 more source
Ultra-heavy vertical lift system: The Heli-Stat [PDF]
, 1975 A hybrid VTOL airship which is combined with helicopters is evaluated. The static lift of the airship supports approximately the full empty weight of the entire assembly.
Piasecki, F. N.
core +1 more source
Monitoring wildlife using long‐endurance solar‐electric UAVs
Wildlife Biology, EarlyView.This report discusses the effectiveness of using small solar‐electric UAV (uncrewed aerial vehicles) for aerial wildlife monitoring. We review four years of aerial wildlife monitoring missions using a 5.5‐m wingspan, solar‐electric UAV that was equipped with a gimballed IR/RGB camera.
Götz Bramesfeld +3 more
wiley +1 more source
Numerical optimization of helicopter rotor blade design for active twist control
Aviation, 2007 The vibration of a helicopter has several different sources, such as the rotor, engine and transmission system. This creates a number of problems with performance, for example poor manoeuvrability, discomfort of the pilot, low fatigue life of the ...
Andrejs Kovalovs +2 more
doaj +1 more source
Research requirements for development of regenerative engines for helicopters [PDF]
The improved specific fuel consumption of the regenerative engine was compared to a simple-cycle turboshaft engine. The performance improvement and fuel saving are obtained at the expense of increased engine weight, development and production costs, and ...
Semple, R. D.
core +1 more source