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The severe temperatures encountered in aircraft at speeds above Mach 3 have created a need for highly efficient use of the fuel supply on board the aircraft as a heat sink for the cooling system. Since the fuel temperature limitations and heat rejection characteristics of the present fixed displacement fuel pumps represent inefficiencies in the system, the use of higher efficiency variable displacement piston type fuel pumps is analyzed. The design of such a pump is shown to be practical and within the present state of the art. It is shown that the effect of the change on the fuel control system is moderate and requires no new or untried techniques.

A new approach is proposed to introduce a change in the physical model of the vorticity on the surface of airfoils which will provide a technique for determining the drag of an infinite span wing throughout the angle of attack range. This approach could provide a method for developing and/or selecting airfoils with lower drag at higher angles of attack to obtain better aircraft maneuver and climb capabilities and can be used to extrapolate small scale wind tunnel tests results accurately to higher Reynolds numbers. In addition, further studies could provide insight into the development of boundary layer control techniques for reducing wing drag.

The installation of a new store in an aircraft introduces changes to its structural dynamics characteristics. Such new configuration can present undesirable instabilities in flight. One of the most dangerous instabilities that the aircraft may experience is flutter. It is a disastrous interaction among inertial, elastic and aerodynamic forces present in the modified aircraft configuration. Therefore, this phenomenon must be prevented. In the study of flutter, the knowledge of parameters such as natural frequencies, damping and shapes of some vibration modes of the aircraft-store/suspension assembly is of crucial importance. These parameters can be obtained from ground vibration tests. This work presents a set of ground vibration test results of a new store intended to be installed in a fighter aircraft. The results are the natural frequencies, damping and mode shapes and are used to evaluate a three-degree-of-freedom model that will represent the mechanical system.

This paper describes a concept related to fault-tolerant design for a redundant motor control system. The design comprises components driven by an electric motor, a motor controller, and a power source, referred to as the More Electric Aero Engine (or MEE). The MEE dramatically improves the engine efficiency and reduces fuel burn and CO2 emissions. However, the MEE system must demonstrate that it can ensure engine safety and reliability before it can take the place of conventional systems. The proposed unique redundant system presented in this paper incorporates Active-Active control and multi-winding motors. Engine fuel flow is controlled by the motor speed control of the MEE electric fuel pump, which uses this redundant system. This concept provides a solution for helping to ensure engine safety and reliability, since it enables a complete one-fail operational engine fuel system for the MEE. Another key technology for the MEE system involves a power generating solution.

Nautilus S.p.A. and the Polytechnic of Turin, in cooperation with Blue Engineering, have developed a very versatile product, the ELETTRA Twin Flyers [6] (ETF), which consists in a very innovative remotely-piloted airship equipped with high precision sensors and communication devices. This multipurpose platform is particularly suitable for border and maritime surveillance missions and for telecommunication, both in military and civil area. To assess the actual maneuver capabilities of the airship [14], a prototype of reduced size and complexity has been assembled [16]. Before the flight tests a further assessment on the flight simulator is needed, because the first version of the software is tuned on the full scale prototype. Steady state performance and static stability of the demonstrator have been evaluated with CFD analysis.

The typical aeronautical engineering approach to low Reynolds number flight studies has been to start with known high Reynolds number aerodynamic paradigms and attempt to match them by scaling to observations of birds and insects. On the other hand, the typical biological approach to natural flight aerodynamics has been to try to fit the observations of birds and insects into the typical known aerodynamic paradigms. Neither of these approaches has met with much success, and although we know more about the potential processes of natural flight, we have not been able to describe them using the framework of conventional aerodynamics. The investigation of low Reynolds number aerodynamic flows at the University of Dayton has led to a proposed new method of characterizing and describing the aerodynamics of natural flight. Lift in natural flight is theorized to be based in the spanwise flow along the curvature of a flapping wing.

Accident statistics indicate that postcrash fire is one of the most serious threats to human life in aircraft crashes. It is also a serious threat in automotive crashes. Several methods are available to reduce this hazard. The simplest and most effective method is through control of the fuel spillage. Aircraft crash testing has shown that fuel systems incorporating tough, flexible fuel tanks that are smooth in contour, free from rigid attachments, and mated with flexible fluid lines are capable of preventing fuel spillage during crashes involving decelerative loading above the human survival range.

A multielment hoc-film sensor has been developed with closely-spaced elements (2.5mm) in the streamwise direction. Constant temperature anemometers are arranged to monitor only the time varying component of the hot-film element output voltage. In addition to boundary-layer transition detection, the output of these multielement sensors can reveal the locations of boundary-layer separation and reattachment by a 180° phase difference in the 0-200 Hz frequency bandwidth between sensor elements on each side of either the separation or reattachment point. This phase difference phenomenon requires no apriori calibration of the hot-film elements and has been demonstrated on both laminar and turbulent boundary layers. The present paper describes the features of multielement hot-film sensor arrays and discusses results from their application to a number of low-speed and transonic airfoil tests.

IN TODAYS' TECHNOLOGICAL WORK, the evaluation of electrical connectors for the electronic industry are many times based on antiquated specifications and unrealistic performance requirements. It is the intent of this paper to explain a new method of connector evaluation. This method is based on the determination of theoretical design, permanent set, cyclic and normal force characteristics which are evaluated as to their significance as independent entities and their interrelationships. This data can be supplemented by normal force - contact resistance - separation force correlations. Proper interpretation of this data can lead to realistic specifications and performance requirements. The data can also be used for the purpose of trouble shooting as well as an important guide for further design programs.

NEITHER severe military maneuvers, such as power dives and inverted flight, nor icing conditions will affect appreciably the operation of the aircraft carburetor described in his paper, Mr. Kittler asserts. To back his claim, he points to over 1½ years experience with several hundred of these carburetors since the start of their development in 1935. After a discussion of the problems of icing, maneuverability, and metering, the author details the construction and operation of the type of carburetor finally developed. This carburetor is unlike commonly known types, he explains, in that the fuel level is controlled by a double-diaphragm mechanism instead of by the conventional float mechanism. In place of the fixed venturi and butterfly throttle construction is a variable-venturi mechanism which forms both the throttles and the venturi. Metering is governed, Mr.

A nonlinear transient coupled flap-lag-torsion aeroelastic response and stability analysis of articulated counterrotating Ultra High Bypass fans is presented. Hinged or elastic blade retention systems with arbitrarily oriented axes are allowed. Additional features include pitch control flexibility, arbitrary pretwist, presweep, and precone of the blade root and spanwise distribution of large blade sweep, droop and pretwist angles. The symbolic derivation of the equations of motion avoids explicit algebraic expansions of the velocity and acceleration vectors. The numerical implementation of the symbolic equations, combined with the state variable form of the equations, makes it easy to change geometric features, add new flexible elements, and extend the analysis to the coupled rotor/fuselage case without additional effort. A 15-th order finite-state two dimensional cascade aerodynamic model has been used.

This paper outlines a process to assess the aerodynamic performance of different vehicle exterior surfaces. The initial section of the paper summarizes the details of white-light scanning process that maps entire vehicle to points in Cartesian co-ordinate system which is followed by the conversion of scanned points to theme surface. The concept of point-cloud modeling is employed to generate a smooth theme surface from scanned points. Theme surfaces thus developed are stitched to under-body/under-hood (UB/UH) parts of the base vehicle and the numerical simulations were carried out to understand the aerodynamic efficiency of the surfaces generated. Specifics of surface/volume mesh generated, boundary conditions imposed and numerical scheme employed are discussed in detail. Flow field over vehicle exterior is thoroughly analyzed. A comparison study highlighting the effect of front grilles in unblocked condition along with air-dam on flow field has been provided.

The concept of using the air cushion ground effect principle to aid an aircraft's take-off and landing is relatively new. This allows the airplane to hover and accelerate to flying speed at a definite height, i. e., free of the ground. This study was initiated to determine whether such a procedure is feasible for the take-off of an airplane, and in so doing, to examine some dominating parameters. This study is limited in scope: the take-off consists of a constant height acceleration to flying speed, then a pull-up to clear an obstacle; a low aspect ratio wing is assumed, furthermore, all thrust is obtained from the lifting fan during take-off. In addition, stability considerations were neglected, augmentation is assumed unaffected by forward speed, the lift fans are operated at constant power and at only one pressure ratio, and the total ram drag was used.

High altitude, high speed flight will push vehicles into regions wherein the density of the surrounding medium is so low that vehicle aerodynamics cannot be described on the basis of the continuum equations of fluid motion. Typical flight trajectories and the characteristic flow regions they traverse are illustrated, and the prediction techniques based on molecular flow physics are outlined. Some analytical, experimental, and flight test results which clearly illustrate the importance of low density effects on the flight performance of vehicles -- particularly lift, drag, and moment -- are discussed. The data presented bring out some fundamental physical principles of molecular interactions in the definitions of aerodynamic behavior, and some of the underlying physical mechanisms are discussed. Molecule-to-molecule interaction is only one of the processes which determine flow field characteristics.

The problem of wing shape modification under loads in order to enhance the aircraft performance and control is continuously improving by researchers. This requirement is in contrast to the airworthiness regulations that constraint stiffness and stress of the structure in order to maintain structural integrity under operative flight conditions. The lifting surface modification is more stringent in those cases, such as UAV configurations, where the installed power is limited but the variety of operative scenario is wider than in conventional aircraft. A possible solution for adaptive wing configuration can be found in the VENTURAS Project idea. The VENTURAS Project is a funded project with the aim of improve the wind turbine efficiency by means of introducing a twisting capability for the blade sections according to the best situation in any wind condition. The blade structure is composed by two parts: 1) internal supporting element, 2) external deformable envelope.

This paper describes a project to build a practical flying car called Starcar 4. The vehicle actually is more like a flying motorcycle, since it uses three wheels on the road. It has a single seat and weighs a little less than 1200 lbs, so it could be certified as a primary class airplane. The vehicle is practical in the sense that it is about as light and simple as its mission allows. A single engine is used to propel the vehicle on the road and in the air. When not in use, the wings hang on the sides, and the driver plugs them into the fuselage when he wants to fly. Most functions serve in both road and sky modes. The driver can do an aerodynamic wheelie on the ground, and he will shift into fourth gear when he reaches cruise altitude.

In order to establish a propellant depletion system for propulsion shutdown on the Atlas space launch vehicle, design criteria have been closely examined to meet the unique environmental requirements in this particular application. A survey of the different types of liquid level sensing systems in common usage has indicated that the magnetostrictive sensor combines the best qualifications available, and also possesses a high degree of ruggedness and resistance to shock. This paper describes the Atlas space launch vehicle fuel depletion system currently under development and test at General Dynamics/Astronautics. The objective of this program is to produce a system exhibiting the highest possible reliability and performance.

Airflow hazards such as turbulence, vortices, or low-level wind shear can pose a threat to landing aircraft and are especially dangerous to helicopters. Because pilots usually cannot see airflow, they may be unaware of the extent of the hazard. We have developed a prototype airflow hazard visual display for use in helicopter cockpits to alleviate this problem. We report on the results of a preliminary usability study of our airflow hazard visualization system in helicopter-shipboard operations.

A formulation for the induced drag of a wing in subsonic or transonic flow is derived from entropy considerations. This approach shows how wave drag and induced drag are related. The new formulation is cast in a form similar to that used in the classic induced drag derivation thus allowing a theoretical comparison of the two approaches. If there are no shock waves in the flow the two formulations agree theoretically only in the case of an elliptic wing loading, although calculations indicate that the quantitative difference may be relatively small. If shock waves are present they can increase or decrease the induced drag leading to the idea of a reduction in the sum of induced and wave drag by a judicious tailoring of the flow over the wing.