Omnidirectional integrated helicopter air data system based on the stationary multichannel aerometric transducer

In this paper, a problem of measuring the altitude-speed helicopter performance in the range of low and near-zero flight velocities is considered. The structural functional scheme of the omnidirectional helicopter air data system based on the stationary aerometric multichannel transducer (AMT) as well as the jet-convective measuring channels is shown and algorithms for the formation of the system output signals are presented. In order to extend the lower bound of operating speeds, it is proposed that the omnidirectional system be integrated with the aeromechanical measuring computer system that realizes the VIMI method with Luenberger’s observer. Also given is the algorithm support and the accuracy of the integrated system operation is estimated.     

Propulsion of space ships by nuclear explosion

Recent progress in the research on deuterium-tritium (D-T) inertially confined microexplosions encourages one to reconsider the nuclear propulsion of spaceships based on the concept originally proposed in the Orion project. We discuss first the acceleration of medium-sized spaceships by D-T explosions whose output is in the range of 0.1–10 t of TNT. The launching of such a ship into an Earth orbit or beyond by a large nuclear explosion in an underground cavity is sketched out in the second section of the paper, and finally we consider a hypothetical Mars mission based on these concepts. In the conclusion it is argued that propulsion based on the Orion concept only is not the best method for interplanetary travel owing to the very large number of nuclear explosion required. A combination of a super gun and subsequent rocket propulsion using advanced chemical fuels appears to be the best solution for space flights of the near future.From Kosmicheskie Issledovaniya, Vol. 43, No. 1, 2005, pp. 67–75.Original English Text Copyright © 2005 by Linhart, Kravárik.     

Correlations between GPS and USNO Master Clock time

The U.S. Naval Observatory Master Clock is used to steer the Global Positioning System (GPS) time. Time transfer data consisting of the difference between the Master Clock and GPS time has been acquired from all satellites in the GPS constellation covering a time period from 10 October 1995 to 12 December 1995. A Fourier analysis of the data shows a distinct peak in the Fourier spectrum corresponding to approximately a one day period. In order to determine this period more accurately, correlations are computed between successive days of the data, and an average of twenty five correlation functions shows that there exists a correlation equal to 0.52 at delay time 23 h 56 min, which corresponds to twice the average GPS satellite period. This correlation indicates that GPS time, as measured by the U.S. Naval Observatory, is periodic with respect to the Master Clock, with a period of 23 h and 56 min. An autocorrelation of a five day segment of data indicates that these correlations persist for four successive days     

Determination of the threshold acceleration for the gravitropic stimulation of cress roots and hypocotyls.

To determine the range of the threshold acceleration (a-threshold) for the gravitropic stimulation of Lepidium sativum L. roots and hypocotyls, experiments were performed on a centrifuge-clinostat with two-orthogonal axes. The rotation rate of the clinostat was 4 rpm (< or = 1.8 x 10(-4) g), while that of the centrifuge was from 3 to 17 rpm (3 x 10(-3) to 10(-1) g). The gravitropic response was determined: (i) after growth of roots and hypocotyls in their normal vertical position and subsequent gravitropic stimulation for 3 h by accelerations of 4 x 10(-3) to 10(-1) g, and (ii) after continuous stimulation in the lateral direction by centripetal accelerations of 4 x 10(-3) to 10(-1) g. The a-threshold was defined by an extrapolation of the regression line of R = p + rx, where x was either ln a or l/a for 3 h or a continuous stimulation, respectively. The a-threshold estimated after 3 h stimulation was equal to 2.6 x 10(-3) g for roots and 3.1 x 10(-3) g for hypocotyls. The threshold accelerations that were unable to evoke a gravitropic response even with continuous stimulation of cress roots and hypocotyls were approximately 3.1 x 10(-3) g and 3.6 x 10(-3) g, respectively. Increasing the stimulation acceleration up to 4.1 x 10(-3) g led to a statistically confirmed gravitropic response of a definite proportion of both the root and hypocotyl populations. In the experiments where acceleration and stimulation time were variable, the threshold dose (D-threshold) for roots was determined to be about 14 to 22 g x s, depending on the stimulation duration and the range of accelerations. The kinetics of gravitropic response at a near-threshold acceleration (4 x 10(-3) to 1.9 x 10(-2) g) differed from that at 1 g (horizontal stimulation). At low forces, the maximal response dependent on the magnitude of acceleration could not be enhanced by increasing the stimulation time up to at least 210 min.     

Optimization of efficient order service by information unmanned aerial vehicles

We propose a mathematical model and the numerical method for an optimal choice of unmanned aerial vehicles (UAVs) from those being in flight to fulfill a newly received order for monitoring (reconnaissance) of a new region. Examples of using the approach being proposed and main lines of its realization in promising information unmanned aircraft complexes (UAC) are presented.     

Investigation of helicopter maneuverability by the power balance method

The algorithms for calculating available overloads and maneuvers are presented. Nesterov’s loop maneuver is analyzed.     

On application of the theory of face seals with microgrooves to high-speed FV engine rotors

With allowance made for thermoelasticity of working surfaces and inertia forces on the lubricant coat, a hydrodynamic problem is solved for the noncontacting face seals with microgrooves in the high-speed rotors of FV engines. Also shown are the initiation of surface waviness in the zone of lubricant coat fracture and the influence of its amplitude upon the seal characteristics.     

Parametric navigation system synthesis on the basis of a magneto-inertial course transmitter

A technique for the parametric synthesis of the navigation system on the basis of the magneto-inertial course transmitter is proposed; the technique makes it possible to minimize the error scatter in determining the ground speed components, to analyze a nature of the error scatter variation in determining the location coordinates in time, to simulate and further choose regular intervals of using additional data obtained from the radionavigational satellite system.     

Metal creep model with the initial strain discontinuity and functional material constants

It is proposed that curves of metal creep be approximated by the time-relative linear law with the initial creep strain discontinuity; as a result, the solution of initial boundary value rheological problems is considerably simplified and is characterized by the adequate precision with a large service life. The labor intensity of computations is similar to the steady-state creep law. The introduction of functional material constants makes it possible to perform calculations of creep under the action of temperature that is different from the specified one in the basic experiments as well as calculations of nonuniformly heated structure elements.     

Effect of “Noisy” sun conditions on aircrew radiation exposure

In computer codes used to estimate the aircrew radiation exposure from galactic cosmic radiation, a quiet sun model is usually assumed. A revised computer code (PCAIRE ver. 8.0f) is used to calculate the impact of noisy sun conditions on aircrew radiation exposure. The revised code incorporates the effect of solar storm activity, which can perturb the geomagnetic field lines, altering cutoff rigidities and hence the shielding capability of the Earth’s magnetic field. The effect of typical solar storm conditions on aircrew radiation exposure is shown to be minimal justifying the usual assumptions.