In-flight simulation investigation of rotorcraft pitch-roll cross coupling

An in-flight simulation experiment investigating the handling qualities effects of the pitch-roll cross-coupling characteristic of single-main-rotor helicopters is described. The experiment was conducted using the NASA/Army CH-47B variable stability helicopter with an explicit-model-following control system. The research is an extension of an earlier ground-based investigation conducted on the NASA Ames Research Center's Vertical Motion Simulator. The model developed for the experiment is for an unaugmented helicopter with cross-coupling implemented using physical rotor parameters. The details of converting the model from the simulation to use in flight are described. A frequency-domain comparison of the model and actual aircraft responses showing the fidelity of the in-flight simulation is described. The evaluation task was representative of nap-of-the-Earth maneuvering flight. The results indicate that task demands are important in determining allowable levels of coupling. In addition, on-axis damping characteristics influence the frequency-dependent characteristics of coupling and affect the handling qualities. Pilot technique, in terms of learned control crossfeeds, can improve performance and lower workload for particular types of coupling. The results obtained in flight corroborated the simulation results

Audit of burns patients in the intensive care setting [poster]

No abstract available

The Role of the Social Worker in Services to Deaf Persons

Non

In situ generation of Mes2Mg as a non-nucleophilic carbon-centred base reagent for the efficient one-pot conversion of ketones to silyl enol ethers

Treatment of commercially available MesMgBr with 1,4-dioxane produces the key Mes2Mg reagent in situ which then mediates the deprotonation of ketones to deliver trimethylsilyl enol ethers, at readily accessible temperatures and without any nucleophilic addition, in an expedient and high yielding one-pot process

How Precise are Estimates of the Natural Rate of Unemployment?

This paper investigates the precision of conventional and unconventional estimates of the natural rate of unemployment (the 'NAIRU'). The main finding is that the NAIRU is imprecisely estimated: a typical 95% confidence interval for the NAIRU in 1990 is 5.1% to 7.7%. This imprecision obtains whether the natural rate is modeled as a constant, as a slowly changing function of time, as an unobserved random walk, or as a function of various labor market fundamentals; it obtains using other series for unemployment and inflation, including additional supply shift variables in the Phillips curve, using monthly or quarterly data, and using various measures for expected inflation. This imprecision suggests caution in using the NAIRU to guide monetary policy.

The Strategy of Human Sea in Communist China

The past decade has witnessed profound changes within Chin which have culminated in the establishment of a new type of government. A new power, and a new way of life embracing Communistic idealogies controls the mainland of China and its vast I resource of manpower. A government diametrically opposed to t Western powers and the fester way of life now reigns supreme from the Imperial City of Peiping