Inertial Forces Acting on a Propeller of Aircraft

Background:Aerospace vehicles use propellers with the different design that possess gyroscopic properties. Recent investigations in the area of gyroscope theory have demonstrated that the gyroscope properties are based on the action of the centrifugal, common inertial, and Coriolis forces of the distributed mass elements of the spinning rotor, as well as the change in the angular momentum.Objective:The combined action of the interrelated inertial forces on the propellers presents the interests for the design of the blades. The objective of the manuscript is the derivation of mathematical models for the inertial torques acting on the spinning propellers that enable computing the stresses of the blades and increasing their reliability.Method:The inertial torques generated by the masses of the rotating blades acting on the propellers are represented by mathematical models in L. Euler’s form.Results:The inertial torques are generated by the several inertial forces of the propeller’s blades and hub and manifested the fluctuation of the variable resistance and precession torques acting around different axes of the propeller. Derived mathematical models for the inertial torques are new and should be used for the computing forces and stresses acting on the propellers of the aircraft.Conclusion:The mathematical models for the torques acting on the propellers consider the several inertial forces of the rotating masses that manifest their gyroscope properties. Derived mathematical models for inertial torques enable for computing the stresses of the aircraft propellers and clearly demonstrate the physical principles and origin of the acting inertial forces.

Hysteresis Nutation Damper for Spin Satellite

Hysteresis dampers are commonly used in Passive magnetic Attitude Control System (PACS). In PACS these rods produce a damping torque and reduce the satellite angular momentum and angular velocity. In this paper, a spin satellite was investigated which utilizes a passive magnetic damper consisting of magnetic hysteresis rods aligned with principal axis or spin axis of satellite and de-tumbling of the satellite, and the pure spin was achieved. An analytical model was presented to analyze hysteresis damper and a numerical simulation was performed to obtain dynamic properties of the spin attitude. In addition, assuming a dynamic imbalance, attitude behavior and damper effect on the spin rate of satellite were analyzed. The behavior of this passive magnetic stabilized satellite was simulated from the initial post separation phase.

Selecting Design Objectives for an Integrated Guidance System of a Commercial Launch Vehicle with Application of GPS Technologies

In this article have been proposed the design objectives for an integrated guidance system of a commercial launch vehicle with application of GPS technologies and has been set a technical problem of the conceptual design of an integrated navigation system for the space launch vehicle qualified to inject small artificial Earth satellites into low and medium circular orbits. The conceptual design of the integrated navigation system based on GPS technology involves determination of its structure, models and algorithms, providing the required accuracy and reliability in injecting payloads with due regard to restrictions on weight and dimensions of the system.

A Computational Study on the Aerodynamic Influence of a Propeller on an MAV by Unstructured Overset Grid Technique and Low Mach Number Preconditioning

The influence of a propeller on the aerodynamic performance of an MAV is investigated using an unstructured overset grid technique. The flow regime of a fixed-wing MAV powered by a propeller contains both incompressible regions due to the low flight speed, as well as compressible flow areas near the propeller-tip region. In order to simulate all speed flow efficiently, a dual-time preconditioning method is employed in the present study. The methodology in this paper is verified as providing a reliable numerical simulation tool for all flow regimes, in the additional presence of moving boundaries, which is treated with an overset grid approach.

An Attempt at Large Eddy Simulation for Combustor Modeling

Large eddy simulation (LES) is a promising method for numerical simulation in combustion systems. A LES attempt in a model combustor has been made, and a few important issues related to grid size, inflow condition, wall boundary conditions, physical sub-models and data sampling are discussed. Some of the numerical results are presented and compared with a comprehensive experimental database, which indicates that LES can provide reasonable predictions for the mean axial velocity and temperature distributions inside the combustion chamber. However, in order to make LES a valuable and cost-effective tool in the development of advanced combustion systems, some fundamental questions remain to be addressed and more validation efforts are required. Moreover significant computing power is required for LES to capture both the high and low frequencies of interest in the present turbulent reacting flow.

Investigating the Design Space for Solar Sail Trajectories in the Earth-Moon System

Solar sailing is an enabling technology for many mission applications. One potential application is the use of a sail as a communications relay for a base at the lunar south pole. A survey of the design space for a solar sail spacecraft that orbits in view of the lunar south pole at all times demonstrates that trajectory options are available for sails with characteristic acceleration values of 1.3 mm/s or higher. Although the current sail technology is presently not at this level, this survey reveals the minimum acceleration values that are required for sail technology to facilitate the lunar south pole application. This information is also useful for potential hybrid solar-sail-low-thrust designs. Other critical metrics for mission design and trajectory selection are also examined, such as body torques that are required to articulate the vehicle orientation, sail pitch angles throughout the orbit, and trajectory characteristics that would impact the design of the lunar base. This analysis and the techniques that support it supply an understanding of the design space for solar sails and their trajectories in the Earth-Moon system.