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Silicones have been utilized in multiple industries in the last 50 years and their applications are still expanding as technology grows. Ice phobic coatings, as an example, have been utilized on lock walls, navigation channels, wind turbines, hydropower intakes, and aircraft. Without protection these applications have a high risk of failure in the functions they perform. For example, ice build up on an aircraft?s aerodynamic surfaces increases drag which reduces lift during flight operations. Utilizing a silicone ice phobic coating significantly reduces the adhesion of ice to aerodynamic surfaces. Compared to other polymeric materials, silicones are known for their broad operating temperature range and lend themselves to excellent performance in a variety of harsh environments. Especially in low temperatures where ice adhesion is a concern, silicones retain their elastomeric physical properties and low modulus.

Abstract A novel use of state estimation methods as initial input for a landing response analysis is proposed in this work. Six degrees of freedom (DOF) non-linear landing response model is conceived by considering longitudinal dynamics of aircraft as a rigid body with heave-and-pitch motions coupled onto a bicycle landing gear † arrangement. The DOF for each landing gear consist of vertical and longitudinal motions of un-sprung mass, considering strut bending flexibility. The measurement data for state estimation is obtained for three landing cases using non-linear flight mechanics model interfaced with pilot-in-loop simulation. State estimation methods such as Upper Diagonal Adaptive Extended Kalman Filter (UD-AEKF) with fuzzy-based adaptive tuning and Un-scented Kalman Filter (UKF) were adapted for landing maneuver problem. On the basis of estimation error metrics, aircraft state from UKF is considered during onset of touchdown.

Abstract From the fact that a propulsor consumes less power for a given thrust if the inlet air is slower, simulations are conducted for a propulsor imposed behind an airfoil as ideal boundary layer ingestion (BLI) propulsor to stand on the benefits of this configuration from the point of view of power and efficiency and to get a closer look on the mutual interaction between them. This interaction is quantified by the impact on three main sets of parameters, namely, power consumption, boundary layer properties, and airfoil performance. The position and size of the propulsor have great influence on the flow around the airfoil. Parametric studies are carried out to understand their influence. BLI propulsor directly affects the power saving and all of the pressure-dependent parameters, including lift and drag. For the present case, power saving reached 14.4% compared to the propeller working in freestream.

Abstract A flight envelope for aircraft performance in the vertical plane illustrates the performance limitations on the aircraft, usually indicating the minimum and maximum airspeeds at a given altitude, the airspeeds for maximum rate of climb and maximum angle of climb at a given altitude, and the maximum altitude or absolute ceiling of the aircraft. This study outlines the procedure for constructing a vertical-plane flight performance aircraft for an aircraft with a fixed-pitch propeller, which involves additional complexities due to the variable propeller efficiency. The propeller performance, engine power, and drag polar models are described, as is the computational procedure. Envelopes for the flight performance in the vertical plane are presented for a particular remotely-piloted aircraft at different take-off weights.

This specification covers honeycomb core made of polyamide paper sheets in a non-hexagonal, flexible cell configuration and supplied in the form of blocks, slices, and ordered shapes.

This specification covers a flexibilized epoxy resin formulation, supplied as a two-component system, requiring an oven cure for attainment of maximum properties.

This specification covers a flexibilized epoxy resin formulation, supplied as a two-component system, requiring an oven cure for attainment of maximum properties.

There are a number of numerical and experimental studies of the aerodynamic performance of wheels that have been published. They show that wheels and wheel-housing flows are responsible for a substantial part of the total aerodynamic drag on passenger vehicles. Previous investigations have also shown that aerodynamic resistance moment acting on rotating wheels, sometimes referred to as ventilation resistance or ventilation torque is a significant contributor to the total aerodynamic resistance of the vehicle; therefore it should not be neglected when designing the wheel-housing area. This work presents a numerical study of the wheel ventilation resistance moment and factors that affect it, using computational fluid dynamics (CFD). It is demonstrated how pressure and shear forces acting on different rotating parts of the wheel affect the ventilation torque. It is also shown how a simple change of rim design can lead to a significant decrease in power consumption of the vehicle.

As a result of the increasing use of fibre reinforced plastic (FRP) components in a modern commercial aircraft, manufacturers are facing new challenges - especially with regards to the realisation of significant build rates. One challenge is the larger variation of the thickness of FRP components compared with metal parts that can normally be manufactured within a very narrow thickness tolerance bandwidth. The larger thickness variation of composite structures has an impact on the shape of the component and especially on the surfaces intended to be joined together with other components. As a result, gaps between the components to be assembled could be encountered. However, from a structural point of view, gaps can only be accepted to a certain extent in order to maintain the structural integrity of the joint. Today's state of the art technologies to close gaps between FRP structures comprise shimming methods using liquid and solid shims.

On-highway tractor-trailer vehicles operate in a complex aerodynamic environment that includes influences of surrounding vehicles. Typical aerodynamic analyses and testing of single vehicles on test track, in wind tunnel or in computational fluid dynamics (CFD) do not account for these real world effects. However, it is possible with simulation and on-road testing to evaluate these aerodynamic interactions. CFD and physical testing of multiple vehicle interactions show that traffic interactions can impact the overall drag of leading and trailing vehicles. This paper will discuss results found in evaluating the effects of separation distances on tractor-trailer aerodynamics in on-road and CFD evaluations using a time-accurate Lattice Boltzmann Method based approach and the ramifications for improving real world prediction versus controlled single vehicle testing.

In this paper, we describe a practically efficient methodology of improving the aerodynamic characteristics of an UAS's wing using a morphing approach. We have replaced a part of the original wings' upper and lower surfaces with a flexible, composite material skin whose shape can be modified, according to the variable airflow conditions, using internally placed actuators. The optimal displacements of the actuators, as functions of the external flow characteristics, are determined using a genetic algorithm based optimizer, coupled with a three - dimensional numerical extension of the classical lifting line model for estimating the modified wing aerodynamic coefficients. We have used the optimization tool to decrease the overall drag coefficient of a military grade UAS' wing equipped with the flexible skin. We have obtained good quality solutions for only a fraction of the computational cost needed when performing viscous flow field calculations.

The performance enhancement of a vertical tail provided by aerodynamic flow control could allow for the size of the tail to be reduced while maintaining similar control authority. Decreasing tail size would create a reduction in weight, drag, and fuel costs of the airplane. The application of synthetic jet actuators on improving the performance of the vertical tail was investigated by conducting experiments on 1/9th and 1/19th scale wind tunnel models (relative to a Boeing 767 tail) at Reynolds numbers of 700,000 and 350,000, respectively. Finite-span synthetic jets were placed slightly upstream of the rudder hinge-line in an attempt to reduce or even eliminate the flow separation that commences over the rudder when it was deflected to high angles. Global force measurements on the 1/9th scale model showed that the flow control is capable of increasing side force by a maximum of 0.11 (19%). The momentum coefficient that created this change was relatively small (Cμ = 0.124%).

This study analyzes the power consumption of a specific Planetary Exploration Vehicle (PEV) subsystem known as Flexible-Wheel (FW) suspension, more specifically the interaction between a FW and the deformable terrain upon which it traverses. To achieve this a systematic and analytical calculation procedure has been developed, which culminates in the definition of three dimensionless properties to capture the FW-soil interaction. Aimed towards the design engineer participating in concept evaluation, and the control engineer conducting initial analyses, this study has found that the resistance coefficient for the interaction between a FW and the deformable terrain can, in general, be several orders of magnitude higher than the rolling resistance of a pneumatic tire operating upon rigid terrain.

An aerodynamic analysis methodology which makes efficient use of ANSA and FLUENT software's in the aerodynamic design of tractor-trailer class heavy commercial road vehicles is presented. The aerodynamic drag coefficient of the truck is used as the main control parameter to evaluate the performance of the methodology. Analysis methodology development activities include determining optimal FLUENT software analysis parameters for the defined problem (RANS based turbulence models, wall boundary layer models, solution schemes) and the necessary ANSA mesh generation parameters (boundary layer number and growth rate, wall surface mesh resolution, total mesh resolution). Proposed methodology is first constructed based on CFD simulations for the zero-degree yaw angle case of the 1/8 sized GCM geometry. The present results are within 1% of the experimental data.

The Continuously Variable Transmission (CVT) is a widely adopted transmission system. The operation of a CVT is simple, but successfully foretelling the longitudinal motion of a vehicle that utilizes this transmission is sophisticated. As a result, different vehicles taking part in BAJA-SAE competitions were developed using various strategies to model the vehicle’s longitudinal dynamics and CVT operation. This article aims to provide a tool for obtaining a quantitative estimate of the longitudinal performance of a CVT equipped vehicle and for the selection of an optimal drive-train gear ratio for such a vehicle. To this end, this article proposes a novel, relatively simple, and reasonably accurate mathematical approach for modeling the longitudinal motion of a vehicle utilizing a CVT, which was developed by a novel integration of existing vehicle dynamics concepts.