Search Results

This paper discusses the side stick and fly by wire elements of the Airbus Industrie A320. After discussion of the cockpit and the effect on it of the side sticks, the arrangements of the side sticks themselves is discussed, travel, forces and electronic coupling. The control laws form the body of the paper with some emphasis on the new things that become possible with fly by wire that Airbus Industrie has vested in A320. Pitch roll and yaw control are discussed in detail and so to are the protection systems that will contain the flight path within safe limits. Some illustrations of the functioning of the protection system in flight on a test A300 equiped with the A320 control laws will be presented.

Three Model Propulsion Simulators (MPS) were designed and built to evaluate candidate counterrotation Ultra bypass fan model blade designs of nominally 2-ft. (0.61m) tip diameter for an advanced “pusher-type” aircraft engine. These propulsion simulators (nominally 1/5 engine size) are capable of operation over a wide range of subsonic conditions and can deliver up to 750 shaft horsepower per rotor at rotor speeds of 10,000 rpm. The rotor thrust and torque, dynamic blade stresses, and system temperature data are transmitted through an integral telemetry system to facilitate data acquisition. Salient features of the design, instrumentation, and operation of these simulators are described in this paper.

The installation of advanced (M = 0.8) turboprop propulsion systems on transport aircraft represents a challenging task to design engineers. The installation aerodynamics of wing-mounted, single-rotation (SR), tractor turboprop systems have been extensively investigated by NASA Ames using a large powered semi-span wind tunnel model. Two configurations have been studied: a straight under-the-wing (UTW) nacelle and a contoured over-the-wing (OTW) configuration. The installation characteristics of these two configurations are presented in terms of installed drag, wing pressure distributions, and surface oil flows. Through the use of wing leading-edge modifications, the installed drag of the UTW nacelle was reduced to less than isolated nacelle drag at the cruise condition of M = 0.8 with a wing CL of 0.5. At this condition, the favorable interference is attributed to the recovery of a portion of the swirl in the slipstream generated by the single rotation propeller.

Future aircraft requirements dictate the need to integrate all aspects of an engine starting system early in the program. In the past, an engine starter was sized, designed, and selected with minimal consideration of its application to the total aircraft system. Then came expanded aircraft requirements, such as extended motoring, clearing engine stalls, making leak checks, and integrating the starter system with secondary power systems and/or start self-sufficiency. The result: costly extensive revisions of the original design. To avoid this in the future, efforts must be made to consider as many as possible of the above factors early in the initial design phase. This paper presents the many aspects of system design and provides technical approaches which will satisfy specific requirements in a program's preliminary design phases. Pneumatic systems are typical of the various types of starter systems being addressed.

A study was conducted to demonstrate the ability of a low order panel aerodynamic flow code to predict the aircraft-induced propeller plane flow field and the resulting steady state propeller blade loads for a single-rotation, wing-mounted tractor system. Comparisons between predicted and measured flow field surveys and resulting blade loads, including the first five harmonics, were made for the U.S. Navy P-3C land-based patrol turboprop aircraft. The study showed that low order flow codes accurately model the induced flow field.

In addition to designing fighter engines for stall-free idle to maximum power operation and stall recoverability, it is important to give proper emphasis to sub-idle operation for successful starting. This permits the pilot to confidently bring the engine on-line following an inadvertent flameout caused by either the airplane departing the flight envelope or by a fuel interrupt due to a malfunction. Thus reliable and fast airstart capability enhances flight safety especially of single engine airplanes. Flight testing, therefore, is substantially devoted to airstart evaluation. The paper first explains the influence of engine design features on airstarting, particularly the advantages of the low bypass ratio cycle F100-PW-229 (PW229) engine, which is an increased thrust derivative (IPE) of the highly successful F100-PW-220 engine. Enhancing airstarting capability of the PW229 using variable geometry features and digital control flexibility is discussed.

The Diagnostics Tested Facility (DTF) at NASA's John C. Stennis Space Center (SSC) in Mississippi was designed to provide a testbed for development of rocket engine exhaust plume diagnostics instrumentation. A 1200-lb thrust liquid oxygen (LOX)/gaseous hydrogen (GH2) thruster is used as the plume source for experimentation and instrument development. Theoretical comparative studies have been performed with aero-thermodynamic codes to ensure that the DTF thruster (DTFT) has been optimized to produce a plume with pressure and temperature conditions as much like the plume of the Space Shuttle Main Engine (SSME) as possible. Operation of the DTFT is controlled by an icon-driven software program using a series of soft switches. Data acquisition is performed using the same software program. A number of plume diagnostics experiments have utilized the unique capabilities of the DTF.

There is a need for a space launch system that can provide ready, reliable, unencumbered access to space. The need exists for a highly reliable launch system that can operate from numerous available sites, that can provide all azimuth launch capability, that is fully reusable, and that can carry significant payloads into low earth orbit. A vehicle concept was developed to demonstrate the ability of near term aeromechanics and propulsion technology to support such a system. The vehicle was composed of two stages. The system takes off horizontally and both stages return to a horizontal landing. Turbojet, ramjet, and rocket propulsion is used. The sensitivity of the system to thrust, drag, weight, and staging Mach number was examined. The two stage system is able to accommodate a range of performance variations yet still retain significant mission potential.

Using LH2 heat sink capacity for air precooling in turbojets allows to increase specific impulse and in many cases to reduce specific mass (mass-to-sea level thrust ratio). A number of precooled turbojet schemes are considered. Classification of turbojet according to the cooled air amount and depth of cooling is proposed. ATR with extended precooling (Tout=100K) is examined in more detail. For propulsion systems including different types of engines, running simultaneously the concept of LH2 heat sink capacity concentration for turbojet air precooling is proposed.

A main objective of the STOL and Maneuver Technology Demonstrator, (S/MTD) Program was to evaluate the operability and performance of its unique engine/nozzle configuration which can deliver thrust in three different modes; conventional, vectored and through variable vanes which give the option of going from forward to reverse thrust. The two-dimensional nozzle and the modified engine were extensively tested during sea level and altitude testing to satisfy all flight clearance requirements. This paper concentrates on the flight test results of the various modes of vectoring and reversing ending with a compilation of the actual usage of the propulsive controls that could be used by designers of similar advanced propulsion systems.

Aerodynamic effects induced from vectoring an exhaust jet are investigated using a well established thin-layer Reynolds averaged Navier-Stokes code. This multiple block code has been modified to allow for the specification of jet properties at a block face. The applicability of the resulting code for thrust vectoring applications is verified by comparing numerically and experimentally determined pressure coefficient distributions for a jet-wing afterbody configuration with a thrust-vectoring 2-D nozzle. Induced effects on the body and nearby wing from thrust vectoring are graphically illustrated.

This paper presents an overview on an Air Force initiative aimed at increasing the performance and reliability of aircraft batteries. A major thrust of the initiative is the elimination of flight line battery maintenance shops. Cost savings, increased mission capability and battle readiness are the pay-offs that will be realized from this effort. Current maintenance requirements for vented nickel-cadmium (Ni-Cd) batteries used in most U.S. military aircraft are unacceptable. This paper addresses other available technology options, decisions made to date and benefits that will result from this effort to increase the performance and reliability of aircraft batteries.

The paper will review operating experience of the present day composite bladed propellers which have been in service for over 10 years. Topics will include how the composite blade has coped with the commuter environment, how effective is electronic control and how service life is being developed. Prospects for future developments are addressed as the commuter market moves forward to the high speed turboprop and is challenged by the Regional Jet.

A number of theoretical investigations have been conducted in the development of the design and analysis of advanced propeller configurations. Lock and Theodorsen as described by Davidson have been utilized to study counterrotating propeller systems. A different numerical method known as “SSTAGE”, which is an Euler solver for the Unducted Fan (UDF) concept, was used to predict the acoustic near field that compared well with experimental data. The NASPROP-E numerical analysis also consisting of an Euler solver has been used to theoretically study the near acoustic fields for the SR series propfan configurations. A counterrotating propeller test rig (CRPTR) was designed and built to obtain an experimental performance/acoustic data base for various propeller configurations for means of comparison with theoretical predictions.

An elementary analysis has been made of generic wing-body configurations with variable volume allotment in wing and body, for constant total useful volume, including the all-wing configuration. These aircraft were compared on the basis of the Lift-to-Drag (L/D) ratio, for specified flight conditions. In addition the parameter ML/D for constant corrected thrust has been optimized, resulting in certain combinations of altitude and speed for maximum specific range (if corrected TSFC = constant). Finally, the effect of volume allotment on L/D for given engine size was studied. It has been found that in many cases optimum volume allotments indicate that wing-body combinations are to be favored. Only in the case of relatively low Mach numbers and high-altitude flight the flying wing outperforms conventional aircraft, but it will generally require larger engines.

This paper describes the hardware and software that was designed, developed and built by Boeing to support the Major Fatigue Testing of full scale 757 and 767 airframes. These test control systems resulted in significant cost savings over previous programs. These systems are capable of applying pseudo random loading of complex flight load spectrums with up to 72 channels of control and 110 channels of Data Acquisition. The Major Fatigue Tests consisted of the application of two normal lifetimes of flights in a test environment that is performed on the ground with loads applied by closed loop servo hydraulic load control systems.

This paper deals with a thrust generation method which can be applied to nuclear as well as chemical propulsion systems. It takes into consideration both incompressible and compress-ible flow cases, however both of these cases are based on one dimensional flow within an ideal rocket framework. In the case of constant area duct steady state flow the obtained Induced Thrust (IT) formula is: where p1 and p2 are opposing pressure fields and u* is a function of u2, p2 and u1 (u1 and u2 being opposing gas efflux velocities). For the compressible and incompressible flow fields, IT formulas are obtained but they are not as reliable. One feasible application for this launch-propulsion method is the Joined-Ship model. In this model the combustion chamber pressure within one space vehicle acts as the back pressure of the joined space vehicle and vice-versa.

A survey of the CONCORDE supersonic transport aircraft programme has been made, starting from initial studies in the late 1950's and ending with the proposed developed type B version. The survey covers the aspects for which aerospatiale in France was responsible, with only a minimum of reference to BRITISH AEROSPACE items, covered in another paper. Much knowledge can be drawn from the study of the technical development of this unique aircraft and it is hoped that this paper will help pass this knowledge on.

The Comet Rendezvous Asteroid Flyby (CRAF) mission involves seven years of flight from 0.6 to 4.57 Astronomical Units (AU), followed by about 915 days of maneuvering around a comet. Ground testing will characterize the very critical attitude control system thrusters' fuel consumption and performance for all anticipated fuel temperatures over thruster life. The ground test program characterization will support flight condition monitoring. A commercial software application hosted on a commercial microcomputer will control ground test operations and data acquisition using a newly designed thrust stand. The data acquisition and control system uses a graphics-based language and features a visual interface to integrate data acquisition and control.

After seven years of test flying and more than fifteen years of commercial operations Concorde remains unrivalled and unique among civil transport aircraft. Many problems, technical, political and financial have been overcome and the aircraft, flagship of both Air France and British Airways, is now proven, safe and reliable. The aircraft's unmistakable low aspect ratio delta wing, optimized for supersonic cruise, brings with it the penalty of high drag at low speed; a factor impressed on flight crews during initial conversion to type. Concorde's large flight envelope is severely restricted by the need to balance the movement of the aerodynamic centre of pressure by a shift of aircraft Centre of Gravity. The dual-compressor axial flow Rolls-Royce Olympus engines, augmented by afterburning for take-off and transonic acceleration, provide the high jet velocity and high thrust needed for Mach 2 flight.