Provide guidance on how balance machine vector data is captured and reported. Provide an understanding of how to transform balance machine vector data to alternate locations. Provide guidance on how vector imbalances may be used to evaluate and diagnose balance process performance.
Provide a fundamental understanding of reason for completing a bode plot on the balance machine. Discuss potential causes of a resonance within the balance process. Discuss the basis for the WN^2 requirement and how it pertains to the bode plot. Provide guidelines for the usage and interpretation of the bode plot.
The goal of this new Aerospace Information Report is to supplement the content of AS6327™ and provide a reference document for the new Aerospace Standard. This new Aerospace Information Report will serve as a practical resource that offers guidance to the machine operator and Process Engineer for isolating the source(s) of non-repeatability in measured unbalance data. The content will include: • Machine Capability to achieve the specified unbalance tolerances and repeat within those tolerances • Tooling Capability to repeat within the specified unbalance tolerances • Rotor characteristics that may preclude repeating within the required unbalance tolerances.
The scope of these standards will relate to single-axis moment scales only. Topics covered include dimensional characteristics of single-axis moment scale interfaces, general tooling requirements, scale and tooling accuracy, and display instrument accuracy requirements. Additionally, general guidelines for qualification of equipment and tooling are included, as are general requirements for single-axis blade distribution software.
RECENT significant improvements in gas turbine components have yielded unusually high jet engine efficiency under partial thrust operation, the author reports, and he reviews the relationship between cycle temperature and overall jet engine efficiency, in the light of these developments. He considers the general factors influencing the use of turbine-jet engines and turbines geared to propellers, and indicates the effects of these factors upon the performance characteristics of airplanes.
The first American designed and built turboprop powered commercial aircraft, the Lockheed Electra, will go into airline use in 1958 with the Allison ‘power package’. This consists of the 3750 horsepower 501-D13 turboprop engine and the Aeroproducts ‘606’ turbo-propeller. The changes from the military T56-A-l engine are reviewed and the propeller features, such as the hollow steel ribbed blades and self-contained hydraulic system and regulator, described in some detail. It is disclosed for the first time that the propeller and engine reduction gear and other units as initially delivered will handle a higher rated power section, the -Dl5. In addition the -D13 power sections can be brought up to later ratings at fixed cost during overhaul when the new model goes into production. Control and safety features of the power package insure normal functioning of both engine and propeller in case of complete electrical system failure.
INVESTIGATIONS of the lubrication of both reciprocating and turbojet aircraft engines are reported here. For reciprocating engines, the major goal has been to do away with the necessity of applying large quantities of preheated air to start the engines. This is being done through the development of appropriate equipment and improvement of starting techniques. The problem has not been so severe for turbojet engines. In fact, oils of low pour point plus the adoption of the closed-circuit oil system are expected to eliminate any need for heating the lubrication systems of jet engines.
SOME of the aerodynamic and mechanical problems of jet engines designed for supersonic flight speeds are discussed in this paper. The aerodynamic problems considered include the required range of operation of the compressor, the thermal efficiency of the cycle, the inlet-engine airflow match, and jet nozzle design. Structural difficulties due to high operating pressures and temperatures and the bearing and lube problems arising from high temperatures are also presented.
AN ANALYSIS has been made of the performance of basic, reheat, regenerative, and regenerative-plus-reheat turboprop engines for flight speeds of 200-600 mph, altitudes of 0-50,000 ft, and turbine inlet temperatures of 2000-2500 R, and a range of compressor pressure ratios of 6-42. The effects of flight and engine design conditions on fuel consumption, power per unit engine frontal area, power per pound of engine weight, and airplane range are compared for several types of turboprop engine.
This paper was presented at the SAE National Aeronautic Meeting, New York, April 12, 1956. STALL of axial-flow-type compressors limits the flexibility of operation of 1- and 2-spool aircraft turbojet engines. Complete compressor stall or surge is a problem with regard to engine acceleration as well as low-and high-Mach-number flight at high altitudes. Deterioration of compressor performance due to low Reynolds numbers at extreme altitudes aggravates the stall problem. Inlet-flow distortions increase the severity of this problem, particularly for supersonic flight. Rotating stall at low values of equivalent rotative speed is a serious source of blade vibrational failure. This latter problem is also aggravated by inlet-flow distortions.
A SERIES of charts for predicting the performance of the continuous-flow jet engine and its individual components is presented here. Efficiencies of components as well as the momentum pressure loss in the combustion chamber (assuming constant cross-sectional area) are taken into consideration. Performance of a typical jet engine under various operating conditions is calculated by means of the charts and graphed to show the effect of each operating condition on performance when all other conditions are held constant. A set of large, usable charts similar to the figures in this paper may be obtained upon request to the Cleveland Laboratories, National Advisory Committee for Aeronautics.
FROM Karavodine's inefficient tube in 1908 through American developments after the recovery of German V-1 bombs, Mr. Edelman sketches the history of pulsating jet engines. Work in the United States has centered on instrumentation, tube geometry, fuel injectors, air inlet valves, fuel properties, and performance estimation. Realized performance is still low in comparison with predictions of best possible performance; but the author suggests use of the pulsating jet for helicopters having jets at the blade tips, for gliders, for starting turbines of aircraft gas turbine powerplants, and for auxiliary power with conventional aircraft.
THE optimum mode of control for an aircraft engine is dependent on both the configuration of the engine and its application. Each engine application requires several detail modes of control, one for each definable regime of operation of the engine. Discussions of control requirements can be simplified by classifying these regimes by objectives: physical limiting, thrust, and transient control. The turbojet engine is the basis for the discussion in this paper. Acceptable modes of control can often be selected by inspection of the engine and its application. Selection of an “optimum” control mode requires investigation of the operation of the engine and weapons system at every stage of its use. The selection of a “mode” of control requires a compromise between performance and other design factors. The need for simplicity and accuracy must be balanced against the stability requirements. The availability and flexibility of control components may limit the modes of control considered.
A STUDY of various stopping methods indicated, it is explained, that reverse thrust would have to be developed for jet engines if jet transports are to have satisfactory operational flexibility. Requirements for reverse thrust are, therefore, discussed in this paper. Primary reverser-design objectives are inherent safety and reliability, stopping comparable to present-day equipment, lack of effect on engine operation, and need for ground-run control only. The author shows that a jet transport using reverse thrust has a stopping distance on smooth ice consistent with a dry-runway brakes-alone stop. The effects of reverser malfunctions on air-plane flying characteristics are compared to the effects of reversible-propeller malfunctions.
THE bypass or ducted-fan turbojet engine is a highly controversial aircraft powerplant. It is hoped that this presentation of its operating principles will lead to a more rational understanding of the pros and cons of the issue. Discussion is explicitly limited to transport aircraft applications at speeds in the neighborhood of 500 mph. Noise, duct losses, boundary-layer intake, and structural considerations are all shown to be important. It appears that a comprehensive design development of bypass or ducted-fan engines in connection with aircraft aerodynamics and structure poses a serious problem in the field of high-subsonic-speed transport aircraft.