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Wheel Brakes and Their Application to Aircraft

Description: "The advantages to be gained from braking have not been ignored, and in the search for a suitable method many schemes have been suggested and tried. Some of the methods discussed in this paper include: 1) increasing the height of the landing gear; 2) air brakes of various forms; 3) sprags on tail skid and axle; and 4) wheel brakes. This report focuses on the design of wheel brakes and wheel brake controls" (p. 1).
Date: May 1928
Creator: Dowty, G. H.
Partner: UNT Libraries Government Documents Department

Aerodynamic characteristics of a slot-lip aileron and slotted flap for dive brakes

Description: From Introduction: "As a part of this investigation, a study is being made of test results obtained during the development of devices designed primarily for other purposes, such as high lift or lateral control, but which may also be used for dive control. These results have been reanalyzed and are herein presented in a form that should make them convenient for design purposes."
Date: April 1941
Creator: Rogallo, F. M.
Partner: UNT Libraries Government Documents Department

A Brief Study of the Speed Reduction of Overtaking Airplanes by Means of Air Brakes, Special Report

Description: As an aid to airplane designers interested in providing pursuit airplanes with decelerating devices intended to increase the firing time when overtaking another airplane, formulas are given relating the pertinent distances and speeds in horizontal flight to the drag increase required. Charts are given for a representative parasite-drag coefficient from which the drag increase, the time gained, and the closing distance may be found. The charts are made up for three values of the ratio of the final speed of the pursuing airplane to the speed of the pursued airplane and for several values of the ratio of the speed of the pursued airplane to the initial speed of the pursuing airplane. Charts are also given indicating the drag increases obtainable with double split flaps and with conventional propellers. The use of the charts is illustrated by an example in which it is indicated that either double split flaps or, under certain ideal conditions, reversible propellers should provide the speed reductions required.
Date: May 1942
Creator: Pearson, H. A. & Anderson, R. F.
Partner: UNT Libraries Government Documents Department

The effects of aerodynamic brakes upon the speed characteristics of airplanes

Description: Report presenting a study of the factors influencing the performance of aerodynamic brakes. The increases in drag coefficient that are characteristics of several types of wing and fuselage aerodynamic brakes, which have been tested in wind tunnels or in flight, are summarized in the report.
Date: September 1949
Creator: Stephenson, Jack D.
Partner: UNT Libraries Government Documents Department

A study of the application of data on various types of flap to the design of fighter brakes

Description: Report presenting an approximate method of applying the available data on various types of flaps in the design of fighter brakes together with several examples of its use. The computed effects of flap type, size, location, and deflection as well as the effects of altitude and initial velocities on braking characteristics are also shown in some examples using the method to determine various flap arrangements.
Date: June 1942
Creator: Purser, Paul E.
Partner: UNT Libraries Government Documents Department

The Effects at a Mach Number of 6.86 of Drag Brakes on the Lift, Drag, and Pitching Moment of an Ogive Cylinder

Description: Memorandum presenting results of three-component force tests of a cylindrical body with an ogival nose equipped with panel-type drag brakes each covering approximately 21 percent of the body circumference and located on opposite sides of the body at the rear end. Results regarding the drag brakes in the horizontal plane, drag brakes in the vertical plane, comparison of drag brakes, and minimum drag are provided.
Date: March 19, 1956
Creator: Penland, Jim A. & Fetterman, David E., Jr.
Partner: UNT Libraries Government Documents Department

A New Dynamometer Brake

Description: The mechanism here described belongs to the class of dynamometer brake in which the motive power is transformed into heat in the brake itself. This mechanism was invented by the writer for the purpose of measuring forces in which the two factors, torque and speed, vary within broad limits, the mechanism itself being of simple construction and of still simpler operation.
Date: September 1921
Creator: Segrè, Marco
Partner: UNT Libraries Government Documents Department

A Variable Speed Fan Dynamometer

Description: Fan brakes used as absorption dynamometers in testing internal combustion engines have the disadvantage that a given fan will run only at one speed when the engine is delivering full power. In order to be able to vary the speed at which a given power will be absorbed, English manufacturers have for some time been using a cylindrical housing around the fan with one or two variable openings in the periphery. Here, results are given of tests conducted to determine how great a range of speed can be obtained from such a device.
Date: December 1920
Creator: Wood, Karl D.
Partner: UNT Libraries Government Documents Department

Experiments With Airplane Brakes

Description: This report begins by examining the forces on the brake shoes. For the determination of the load distribution over the shoes it was assumed that the brake linings follow Hooke's law, are neatly fitted and bedded in by wear. The assumption of Hooke's law, that is, the proportionality between compression of the lining and the absorption of force, is fulfilled to a certain extent for the loading, as becomes apparent from the load tests described further on. But there is a material discrepancy at unloading.
Date: September 1931
Creator: Michael, Franz
Partner: UNT Libraries Government Documents Department

Tests of a 0.30 scale semispan model of the Douglas XTB2D-1 airplane wing and fuselage combination in the NACA 19-foot pressure tunnel 1: full-span flap and air-brake investigation

Description: Report presenting testing in the 19-foot pressure tunnel of a scale semispan model of the XTB2D-1 airplane wing and fuselage combination. The purpose of the investigation was to determine the optimum position of the double-slotted flap, the characteristics of the full-span flaps at various deflections in their fully extended position, the effectiveness of deflecting the full-span flaps to small positive angles as a camber changing feature, the stalling characteristics of the wing, and the effectiveness of the flap as a brake when deflected to negative angles.
Date: September 1944
Creator: Ashworth, C. Dixon; Spooner, Stanley H. & Russell, Robert T.
Partner: UNT Libraries Government Documents Department

Frictional behavior of automotive brake materials under wet and dry conditions

Description: The purpose of this effort was to develop an improved understanding of the relationship between the structure and frictional behavior of materials in the disc brake/rotor interface with a view toward improving the performance of automotive disc brakes. The three tasks involved in this Cooperative Research and Development Agreement (CRADA) were as follows: Task 1. Investigation of Brake Pads and Rotors. Characterize surface features of worn brake pads and rotors, with special attention to the transfer film which forms on them during operation. Ford to supply specimens for examination and other supporting information. Task 2. Effects of Atmosphere and Repeated Applications on Brake Material Friction. Conduct pin-on-disk friction tests at ORNL under controlled moisture levels to determine effects of relative humidity on frictional behavior of brake pad and rotor materials. Conduct limited tests on the characteristics of friction under application of repeated contacts. Task 3. Comparison of Dynamometer Tests with Laboratory Friction Tests. Compare ORNL friction data with Ford dynamometer test data to establish the degree to which the simple bench tests can be useful in helping to understand frictional behavior in full-scale brake component tests. This final report summarizes work performed under this CRADA.
Date: December 15, 1996
Creator: Blau, P.J.; Martin, R.L.; Weintraub, M.H.; Jang, Ho & Donlon, W.
Partner: UNT Libraries Government Documents Department

Speed-brake investigation at low speed of a 1/10-scale model of the MX-1554A airplane with a circular jet nozzle

Description: Report discussing an investigation of the effect of curved speed brakes on the drag characteristics and longitudinal stability and control characteristics of a model of the MX-1554A with a circular jet nozzle. The speed brakes were tested at several deflections, gaps, and locations in the landing configuration and clean configuration. Results of a lateral- and directional-stability study due to reduction in the vertical tail area are also provided.
Date: January 7, 1954
Creator: Solomon, Martin
Partner: UNT Libraries Government Documents Department

Heavy and Overweight Vehicle Brake Testing: Five-Axle Combination Tractor-Flatbed Final Report

Description: The Federal Motor Carrier Safety Administration, in coordination with the Federal Highway Administration, sponsored the Heavy and Overweight Vehicle Brake Testing (HOVBT) program in order to provide information about the effect of gross vehicle weight (GVW) on braking performance. Because the Federal Motor Carrier Safety Regulations limit the number of braking system defects that may exist for a vehicle to be allowed to operate on the roadways, the examination of the effect of brake defects on brake performance for increased loads is also relevant. The HOVBT program seeks to provide relevant information to policy makers responsible for establishing load limits, beginning with providing test data for a combination tractor/trailer. This testing was conducted on a five-axle combination vehicle with tractor brakes meeting the Reduced Stopping Distance requirement rulemaking. This report provides a summary of the testing activities, the results of various analyses of the data, and recommendations for future research. Following a complete brake rebuild, instrumentation, and brake burnish, stopping tests were performed from 20 and 40 mph with various brake application pressures (15 psi, 25 psi, 35 psi, 45 psi, 55 psi, and full system pressure). These tests were conducted for various brake conditions at the following GVWs: 60,000, 80,000, 91,000, 97,000, 106,000, and 116,000 lb. The 80,000-lb GVWs included both balanced and unbalanced loads. The condition of the braking system was also varied. To introduce these defects, brakes (none, forward drive axle, or rear trailer axle) were made inoperative. In addition to the stopping tests, performance-based brake tests were conducted for the various loading and brake conditions. Analysis of the stopping test data showed the stopping distance to increase with load (as expected) and also showed that more braking force was generated by the drive axle brakes than the trailer axle brakes. The constant-pressure stopping test data revealed ...
Date: October 1, 2013
Creator: Lascurain, Mary Beth; Capps, Gary J & Franzese, Oscar
Partner: UNT Libraries Government Documents Department

Wind turbine trailing edge aerodynamic brakes

Description: Five trailing-edge devices were investigated to determine their potential as wind-turbine aerodynamic brakes, and for power modulation and load alleviation. Several promising configurations were identified. A new device, called the spoiler-flap, appears to be the best alternative. It is a simple device that is effective at all angles of attack. It is not structurally intrusive, and it has the potential for small actuating loads. It is shown that simultaneous achievement of a low lift/drag ratio and high drag is the determinant of device effectiveness, and that these attributes must persist up to an angle of attack of 45{degree}. It is also argued that aerodynamic brakes must be designed for a wind speed of at least 45 m/s (100 mph).
Date: April 1, 1995
Creator: Migliore, P G; Miller, L S & Quandt, G A
Partner: UNT Libraries Government Documents Department

REPORT on the TRUCK BRAKE LINING WORKSHOP and FLEET OPERATORS' SURVEY

Description: The report summarizes what transpired during brake linings-related workshop held at the Fall 2003 meeting of the Technology and Maintenance Council (TMC) in Charlotte, NC. The title of the workshop was ''Developing a Useful Friction Material Rating System''. It was organized by a team consisting of Peter Blau (Oak Ridge National Laboratory), Jim Britell (National Highway Traffic Safety Administration), and Jim Lawrence (Motor and Equipment Manufacturers Association). The workshop was held under the auspices of TMC Task Force S6 (Chassis), chaired by Joseph Stianche (Sanderson Farms, Inc.). Six invited speakers during the morning session provided varied perspectives on testing and rating aftermarket automotive and truck brake linings. They were: James R. Clark, Chief Engineer, Foundation Brakes and Wheel Equipment, Dana Corporation, Spicer Heavy Axle and Brake Division; Charles W. Greening, Jr, President, Greening Test Labs; Tim Duncan, General Manager, Link Testing Services;Dennis J. McNichol, President, Dennis NationaLease; Jim Fajerski, Business Manager, OE Sales and Applications Engineering, Federal Mogul Corporation; and Peter J. Blau, Senior Materials Development Engineer, Oak Ridge National Laboratory. The afternoon break-out sessions addressed nine questions concerning such issues as: ''Should the federal government regulate aftermarket lining quality?''; ''How many operators use RP 628, and if so, what's good or bad about it?''; and ''Would there be any value to you of a vocation-specific rating system?'' The opinions of each discussion group, consisting of 7-9 participants, were reported and consolidated in summary findings on each question. Some questions produced a greater degree of agreement than others. In general, the industry seems eager for more information that would allow those who are responsible for maintaining truck brakes to make better, more informed choices on aftermarket linings. A written fleet operator survey was also conducted during the TMC meeting. Twenty-one responses were received, spanning fleet sizes between 12 and 170,000 ...
Date: February 3, 2003
Creator: Blau, P.J.
Partner: UNT Libraries Government Documents Department

Thermal transport properties of grey cast irons

Description: Thermal diffusivity and thermal conductivity of grey cast iron have been measured as a function of graphite flake morphology, chemical composition, and position in a finished brake rotor. Cast iron samples used for this investigation were cut from ``step block`` castings designed to produce iron with different graphite flake morphologies resulting from different cooling rates. Samples were also machined from prototype alloys and from production brake rotors representing a variation in foundry practice. Thermal diffusivity was measured at room and elevated temperatures via the flash technique. Heat capacity of selected samples was measured with differential scanning calorimetry, and these results were used to calculate the thermal conductivity. Microstructure of the various cast iron samples was quantified by standard metallography and image analysis, and the chemical compositions were determined by optical emission spectroscopy.
Date: October 1, 1996
Creator: Hecht, R.L.; Dinwiddie, R.B.; Porter, W.D. & Wang, Hsin
Partner: UNT Libraries Government Documents Department

Functional test procedure, Fifth Wheel: SS-R42351, Issue D

Description: This report describes the equipment required for initial assembly/maintenance and inspection/resetting of the Fifth Wheel system. It also gives a step-by-step procedure for initial assembly/maintenance inspection and procedures for resetting the system and Eager-Pac installation. The Fifth Wheel system is associated with a tractor-type vehicle used for materials handling.
Date: July 12, 1994
Partner: UNT Libraries Government Documents Department

Compositions, Functions, and Testing of Friction Brake Materials and Their Additives

Description: The purpose of this report is to present a survey of commercial brake materials and additives, and to indicate their typical properties and functions, especially as regards their use in heavy trucks. Most truck pad and shoe materials described here were designed to wear against cast iron. Brake material test methods are also briefly described. This report does not address issues associated with the fabrication and manufacturing of brake materials. Since there are literally thousands of brake material additives, and their combinations are nearly limitless, it is impractical to list them all here. Rather, an attempt has been made to capture the primary constituents and their functions. An Appendix contains thermo-physical properties of some current and potential brake materials.
Date: October 22, 2001
Creator: Blau, PJ
Partner: UNT Libraries Government Documents Department

A computational study of tandem dual wheel aerodynamics and the effect of fenders and fairings on spray dispersion

Description: With the goal of understanding how to mitigate the safety hazard of splash and spray around heavy vehicles, a computational study of the aerodynamics and spray dispersion about a simplified trailer wheel assembly has been completed. A tandem dual slick (TDS) wheel model that neglects complex geometric features such as brakes, wheel bolts and wheel cutouts but with the same dimensions as an actual trailer wheel assembly was used . A detailed simulation of the wheels alone demonstrated that the flow field is both unsteady and complex, containing a number of vortical structures that interact strongly with spray. Preliminary simulations with fenders and fairings demonstrated that these devices prevent the ballistic transport of drops larger than approximately 0.1 mm, but the fine mist speculated to be responsible for visibility reduction is unaffected. This work suggests that to use computational fluid dynamics (CFD) to design and evaluate spray mitigation strategies the jet or sheet breakup processes can be modeled using an array of injectors of small (< 0.01 mm) water droplets; however the choice of size distribution, injection locations, directions and velocities is largely unknown and requires further study. Possible containment strategies would include using flow structures to 'focus' particles into regions away from passing cars or surface treatments to capture small drops.
Date: January 13, 2006
Creator: Paschkewitz, J S
Partner: UNT Libraries Government Documents Department

Probability of failure of the waste hoist brake system at the Waste Isolation Pilot Plant (WIPP)

Description: In its most recent report on the annual probability of failure of the waste hoist brake system at the Waste Isolation Pilot Plant (WIPP), the annual failure rate is calculated to be 1.3E({minus}7)(1/yr), rounded off from 1.32E({minus}7). A calculation by the Environmental Evaluation Group (EEG) produces a result that is about 4% higher, namely 1.37E({minus}7)(1/yr). The difference is due to a minor error in the US Department of Energy (DOE) calculations in the Westinghouse 1996 report. WIPP`s hoist safety relies on a braking system consisting of a number of components including two crucial valves. The failure rate of the system needs to be recalculated periodically to accommodate new information on component failure, changes in maintenance and inspection schedules, occasional incidents such as a hoist traveling out-of-control, either up or down, and changes in the design of the brake system. This report examines DOE`s last two reports on the redesigned waste hoist system. In its calculations, the DOE has accepted one EEG recommendation and is using more current information about the component failures rates, the Nonelectronic Parts Reliability Data (NPRD). However, the DOE calculations fail to include the data uncertainties which are described in detail in the NPRD reports. The US Nuclear Regulatory Commission recommended that a system evaluation include mean estimates of component failure rates and take into account the potential uncertainties that exist so that an estimate can be made on the confidence level to be ascribed to the quantitative results. EEG has made this suggestion previously and the DOE has indicated why it does not accept the NRC recommendation. Hence, this EEG report illustrates the importance of including data uncertainty using a simple statistical example.
Date: January 1, 1998
Creator: Greenfield, M.A. & Sargent, T.J.
Partner: UNT Libraries Government Documents Department

Evaluation of Corrosion Failure in Tractor-Trailer Brake System

Description: As reported to ORNL, concomitant with the introduction of different deicing and anti-icing compounds, there was an increase in the brake failure rate of tractor-trailer trucks. A forensic evaluation of a failed brake system was performed. Optical and scanning electron microscopic evaluation showed corrosion to be mostly confined to the brake table/lining interface. The corrosion is non-uniform as is to be expected for plain carbon steel in chloride environments. This initial analysis found no evidence for the chlorides of calcium and magnesium, which are the newly introduced deicing and antiicing compounds and are less soluble in water than the identified chlorides of sodium and potassium, in the scale. The result could be as a result of non-exposure of the examined brake table to calcium and magnesium chloride. The mechanisms for the increased failure rate are postulated as being an increased rate of corrosion due to positive shifts in the corrosion potential, and an increased amount of corrosion due to an increased ''time of wetness'' that results from the presence of hygroscopic salts. Laboratory scale evaluation of the corrosion of plain carbon steel in simulated deicing and anti-icing solutions need to be performed to determine corrosion rates and morphological development of corrosion product, to compare laboratory data to in-service data, and to rank economically feasible replacement materials for low carbon steel. In addition, the mechanical behavior of the lining attached to the brake shoe table needs to be assessed. It is opined that an appropriate adjustment of materials could easily allow for a doubling of a brake table/lining lifetime. Suggestions for additional work, to clarify the mechanisms of rust jacking and to develop possible solutions, are described.
Date: October 22, 2002
Creator: Wilson, DF
Partner: UNT Libraries Government Documents Department

Innovative Structural and Joining Concepts for Lightweight Design of Heavy Vehicle Systems

Description: Recent advances in the area of Metal Matrix Composites (MMC's) have brought these materials to a maturity stage where the technology is ready for transition to large-volume production and commercialization. The new materials seem to allow the fabrication of higher quality parts at less than 50 percent of the weight as compared to steel, especially when they are selectively reinforced with carbon, silicon carbide, or aluminum oxide fibers. Most of the developments in the MMC materials have been spurred, mainly by applications that require high structural performance at elevated temperatures, the heavy vehicle industry could also benefit from this emerging technology. Increasing requirements of weight savings and extended durability are the main drivers for potential insertion of MMC technology into the heavy vehicle market. Critical elements of a typical tractor-trailer combination, such as highly loaded sections of the structure, engine components, brakes, suspensions, joints and bearings could be improved through judicious use of MMC materials. Such an outcome would promote the DOE's programmatic objectives of increasing the fuel efficiency of heavy vehicles and reducing their life cycle costs and pollution levels. However, significant technical and economical barriers are likely to hinder or even prevent broad applications of MMC materials in heavy vehicles. The tradeoffs between such expected benefits (lower weights and longer durability) and penalties (higher costs, brittle behavior, and difficult to machine) must be thoroughly investigated both from the performance and cost viewpoints, before the transfer of MMC technology to heavy vehicle systems can be properly assessed and implemented. MMC materials are considered to form one element of the comprehensive, multi-faceted strategy pursued by the High Strength/Weight Reduction (HS/WR) Materials program of the U.S. Department of Energy (DOE) for structural weight savings and quality enhancements in heavy vehicles. The research work planed for the first year of this project ...
Date: August 31, 2005
Creator: Prucz, Jacky C.; Shoukry, Samir N. & William, Gergis W.
Partner: UNT Libraries Government Documents Department

A stable finite difference method for the elastic wave equation on complex geometries with free surfaces

Description: The isotropic elastic wave equation governs the propagation of seismic waves caused by earthquakes and other seismic events. It also governs the propagation of waves in solid material structures and devices, such as gas pipes, wave guides, railroad rails and disc brakes. In the vast majority of wave propagation problems arising in seismology and solid mechanics there are free surfaces. These free surfaces have, in general, complicated shapes and are rarely flat. Another feature, characterizing problems arising in these areas, is the strong heterogeneity of the media, in which the problems are posed. For example, on the characteristic length scales of seismological problems, the geological structures of the earth can be considered piecewise constant, leading to models where the values of the elastic properties are also piecewise constant. Large spatial contrasts are also found in solid mechanics devices composed of different materials welded together. The presence of curved free surfaces, together with the typical strong material heterogeneity, makes the design of stable, efficient and accurate numerical methods for the elastic wave equation challenging. Today, many different classes of numerical methods are used for the simulation of elastic waves. Early on, most of the methods were based on finite difference approximations of space and time derivatives of the equations in second order differential form (displacement formulation), see for example [1, 2]. The main problem with these early discretizations were their inability to approximate free surface boundary conditions in a stable and fully explicit manner, see e.g. [10, 11, 18, 20]. The instabilities of these early methods were especially bad for problems with materials with high ratios between the P-wave (C{sub p}) and S-wave (C{sub s}) velocities. For rectangular domains, a stable and explicit discretization of the free surface boundary conditions is presented in the paper [17] by Nilsson et al. In ...
Date: December 17, 2007
Creator: Appelo, D & Petersson, N A
Partner: UNT Libraries Government Documents Department