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The terra hydroplaning describes a condition occurring in certain circumstances of pneumatic tire operation on wet roads, when the load carried by the tire becomes entirely supported upon a water layer retained within the region of ground contact. The paper discusses the phenomena which are primarily responsible for hydroplaning and includes results from studies of the effects due to individual tire parameter such as tread pattern design, tread material, and the construction and sectional shape of the casing. It is shown that the most important of these tire factors is the geometric design of the tread pattern. Some results relating to the effect of wear of the tread pattern are discussed.

A new 340 cu. in. V-8 engine for use in the Plymouth Barracuda and Dodge Dart automobiles is described. This engine, with increased displacement and power, is approximately the same size and weight as its predecessor, the 273 cu. in. 4-barrel engine. This paper describes the evolution of the 273 to the 340 and the features and modifications making the increased displacement feasible and those changes which were made to utilize the increased displacement to make the 340 a high speed, high output passenger car engine.

This paper covers the detail considerations between the initial decision specifying the use of a spline or serration and the final specified tooth proportions. Spline requirements and the manufacturing processes with their associated limitations are discussed. The selection of the spline parameters are explained with respect to the requirements along with spline testing, drafting standards, inspection, and specified situations. Examples of current industry application and practice are presented.

It is shown that the response of the occiput of a cadaver to sinusoidal vibration input to the frontal bone corresponds closely to that of a simple damped spring-mass system having a natural frequency equal to the first mode frequency of the skull, 0.17 damping factor. The first and third bending mode of the skull occurred near 300 and 900 Hz for both the cadaver preparation with silicon gel filled cranial cavity and the live human head. A second mode was found near 600 Hz in the live human. Head acceleration levels at which opposite pole pressure reached near —1 atm were 170 g and 500–600 g in the human cadaver and live monkey head, respectively, which values are roughly inversely proportional to major intracranial diameters. A method is derived for comparing the impact response of a simple system to a general shaped pulse to that of the cadaver head.

Experimental results, together with calculations and formulas for the ultimate strength of cast iron internal threads, are presented. The calculated thread strength based on the formulas and double shear tests of cast iron samples is compared with direct tension tests on steel bolts engaged to various depths in tapped cast iron specimens. The wide range of strength values in cast iron is recognized. A chart for the necessary length of engagement for various SAE grades of bolts with different strength levels of cast iron summarizes the overall results.

A design guide for bolt engagement in cast iron has been developed. The design engagements are sufficient to insure that if a bolt is overloaded and failure occurs, either at assembly or in service, the bolt will break rather than strip the bolt or cast iron threads. In addition to the design guide, this report presents information concerning: 1. The ratio of gray cast iron shear strength to tensile strength. 2. The ratio of shear strength to tensile strength for SAE Grade 5 and Grade 8 bolts.

The effect of seat back rotation, head restraint position, and collision speed on crash dummy head acceleration, extension and flexion was determined by tests using an acceleration sled and vehicle collisions. The sled tests were run with a rigid seat and an adjustable back at 10, 20, and 30 mph. Vehicle collisions were conducted with production seats with and without head restraint devices at 10, 15, 20, 25, 30, 40, and 50 mph impact speeds. Fifty percentile adult male Sierra dummies were used. The head was able to move freely when accelerated backward. In both sled and vehicle collisions, head restraint devices reduced the measured severity criteria on the crash dummies employed in the tests.

A series of cooperative test programs has resulted in the refinement of a bearing test for evaluating the relative deposit and degradation characteristics of synthetic lubricants under a simulated gas turbine engine environment. Future efforts will be aimed at providing a bearing rig test capability to screen candidate lubricants for advanced high-performance engines at temperatures up to 700 F.

Some of the design concepts used in the Atlas ICBM have been refined and utilized in the high-energy upper stage Centaur vehicle. In addition, development of the Centaur vehicle required significant advances in cryogenic technology Although the Atlas/Centaur vehicle development required many advancements in technology, most of the present operational techniques have much in common with other launch vehicles. A brief description of the configuration and checkout will be given. The unique design features of the Atlas/Centaur launch vehicle will be reviewed, and their impact on handling, checkout, and launch operation will be examined in this paper. The continuous advancements in technology in the Atlas/Centaur Program imposed stringent requirements on the test and data management systems. A Unified Test Plan, while eliminating superfluous testing, ensures a comprehensive analysis of the performance of every element of the system.

Battery performance characteristics for automotive power applications can be described in terms of two parameters, specific power and specific energy. Specific power is related to the speed of vehicles and acceleration. Specific energy is related to range. Using these two variables, data are presented graphically for a number of commercially available battery systems and battery systems in development. Included are lead-acid, nickel-cadmium, silver-zinc, metal-air, organic electrolyte, sodium-sulfur, and fused-salt electrolyte batteries. The performance characteristics are related to automotive driving requirements for speed and range by an overlay on the graph of battery characteristics. This overlay shows that, for a given range, specific energy requirements for driving increase with speed, while the energy available from batteries decrease. The applicability of commercially available battery systems and the status and technical problems of new battery systems are discussed.

Forty-eight lateral impact accidents were studied correlating vehicle damage and occupant injury. Side-swipe accidents produced serious injury only when the occupant's elbow was protruding through a window or when the occupant space of the vehicle was seriously compromised. Intersection impacts and drifting impacts, particularly when the impact was caused by a vehicle approaching from the opposite direction, caused the most serious injuries. Fractures of the acetabulum with intrapelvic protrusion of the hip and fractures of the pubic rami are characteristic of lateral impact accidents. The door was the most common injury-producing structure of the vehicle. Deep wrap-around seat designs and stronger doors, door frames, and chassis structures are necessary to reduce occupant space penetration and to absorb impact energy in lateral impact accidents.

This paper describes the application of laboratory test techniques to the development and improvement of some of the tire properties that affect vehicle dynamic performance. Base line tire properties are established, the range of existing performance is shown, and the significance and validity of the laboratory tests are verified by showing that those changes in tire performance which result in detectable changes in vehicle dynamic performance are quantifiable.

The part that the trend design of a passenger tire plays in its wet tractive ability is the most important single variable as far as the tire is concerned. This is apparent when we consider that the tire has to make contact through the wet film on the road before it can become effective. The tread design enables the tire to do this. Once the tire makes contact with the road, the tread compound and tire construction become important. The external variables that affect wet traction are also considered. These include speed, surface coefficient, load, temperature, and inflation pressure. All of these variables are discussed, with special emphasis placed on the tread design.

This paper is a kind of supplement to Hoerner's book “Fluid Dynamic Drag.” It has a twofold purpose: to update knowledge about the effects of roughness on drag, and to clarify the aerodynamic processes by which it causes drag. The important basic flow process is shown to be one of separated flow at low Reynolds number. From this fundamental situation certain conclusions are drawn regarding transition, scale effect, permissible size of roughness, and the like. Specific requirements for aerodynamically smooth surfaces are presented and Nash's drag magnification factor for discrete roughness is considered. General procedures for estimating the drag increment due to roughness for a complete airplane are discussed. Several charts are included to guide and assist in calculation. The paper concludes with a bibliography of pertinent material beyond that mentioned by Hoerner.

This paper discusses the philosophy that guided the design of a 400 hp steering transmission used in the Marine Corps' new 50,000 lb amphibious personnel carrier. It describes in detail the design of the steer and brake section and the problems posed by utilizing an advanced design hydrostatic steer unit. It covers the design of the gearing, the housing, and the hydraulic control and lube system, and it gives information gathered during nearly a year of testing.

Scientific methodology and engineering techniques were applied to a series of twelve automobile rear-end collision experiments to provide data relating to seat, seat backrest and head-restraint design. Five speeds of impact, six seatback heights and six seatback strength values were studied. The purpose was to evaluate the relative protective merits and the practicality of various seat designs with respect to the many variables common to rear-end collisions. This research data provides a basic reference system of collision performance for seat designs with respect to occupant size, posture and proximity to injury producing structures.

Three methods of tolerancing are described. In widest use is the method of extremes, which produces unnecessarily close limits on the components. For the same over-all limits on the assembly the probability method allows wider limits on the components, but there are some unrealistic assumptions involved. A third method is described which results in tolerances falling between the other two. A case history is discussed comparing the three methods.

Tremendous growth has been projected in air transportation for both passenger and cargo markets. The projected growth is so great in fact that a total system concept approach is necessary not only to solve the problems of today, but to provide solutions which satisfy the demands of tomorrow. In using the systems approach it is necessary to determine the significant parameters in the description of the operations, interrelationships, and environment of the airport/aircraft system. This paper discusses the approach being utilized in evaluating airport/aircraft compatibility which is one element of the total system concept. Both short- and long-range considerations are presented. Market data are presented to illustrate the projected growth trends and numbers of aircraft. Long range planning factors such as requirements for wider and stronger runways are discussed.

This paper presents an analysis of the theory of the hydraulic dynamometer, the specific objective being to derive an expression for the capacity constant K in the well-known equation T = KN2D5 in terms of the relevant parameters. The major conclusion is that K is fundamentally a function of only five factors, all of which are discussed fully. The interrelation among the various factors is explained in detail. Based on certain simplifications, an experimental technique is suggested, from which a rational design of dynamometers becomes possible.

Car collisions from a representative; sample of.urban and rural accidents in Great Britain have been analyzed. sA damage severity index scale has been developed which involves comparing the damage to a case vehicle with damage to a similar make and model vehicle which has been in an experimental impact. Damage severity is then correlated with injury severity for four crash configurations: head on, front corner, side, and rear end. The benefits from lap/diagonal seat belts show an increase in at least 12 mph in equivalent barrier speeds for the same injury level in head-on and front-corner impacts, but in side impacts there is no significant benefit to the occupants remaining in the cars. Penetration of the passenger compartment in side impacts and rollover is shown to be closely related to injury severity. When better experimental data are available, this method should allow different makes and models of cars to be assessed in terms of injury prevention.