NASA Research Research Articles

Discussion

Abstract Mr. W. B. Horne (NASA, Hampton, Virginia)—Results in the two papers are in agreement with NASA research results. The papers treated the subjects of tread material, tire construction, road surface texture, and tread design very thoroughly. But one essential ingredient to the problem has been left out of the paper discussions, and that is, the effect of water depth. The importance of the water depth effect, and the need to inform both public and government authorities about the importance of removing worn tires from automobiles for the safety of all, is discussed and illustrated very fully by Leland. An example of what happens when the water depth is 0.4 in. is shown in Figure 1. It can be seen that the water penetrates the tire imprint much more rapidly than in shallow water. The effect of road surface texture on braking friction coefficient is illustrated by the data shown in Figure 2. A smooth tread aircraft tire was successfully braked on five different road surfaces ranging in texture from a large aggregate asphalt surface to wet ice. These surfaces are classified as damp in wetness. The surfaces at the time of testing were wet to the touch but did not have any puddles or standing water. Under this condition, damp smooth concrete (smooth as a table top) gave friction values as low as wet ice. This drastic friction loss decreased as the road surface texture increased. It will be noted that the smooth aggregate asphalt data did not fall off in speed as was shown by Maycock in his paper in Figure 15. In Figure 3 the water depth on the smooth concrete and large aggregate asphalt surface was increased from a damp condition to a flooded condition (0.1–0.2 in.). The character of the friction changes of these surfaces due to change in water depth is remarkable. For example, the smooth concrete increased slightly in value. This is an apparent increase, however, because the deeper water produces a fluid drag term which adds to the tire-surface braking force and gives a higher friction coefficient. This is an academic point, however, since the smooth concrete surface is producing viscous hydroplaning even at low speeds. On the other hand, the asphalt surface which alleviated the viscous hydroplaning effect under damp conditions does not prevent dynamic hydroplaning from occurring to the tire when this surface is flooded to a depth of 0.1 to 0.2 in. To summarize, any surface must be evaluated under a range of water depths before its wet friction qualities can be properly evaluated. Smooth tread tires or badly worn patterned tires have demonstrated poor friction capabilities on most wet or flooded surfaces. For this reason, both aircraft and automobile tires should be removed and replaced before wear produces a smooth tread condition.

Evaluation of the Integral by the Discrete Ordinary Method

Journal of Mathematics and PhysicsVolume 46, Issue 1-4 p. 107-110 Article Evaluation of the Integral by the Discrete Ordinary Method† A. Ben Huang, A. Ben Huang School of Aerospace Engineering, Georgia Institute of Technology Atlanta, GeorgiaSearch for more papers by this author A. Ben Huang, A. Ben Huang School of Aerospace Engineering, Georgia Institute of Technology Atlanta, GeorgiaSearch for more papers by this author First published: April 1967 https://doi.org/10.1002/sapm1967461107Citations: 1 †Research supported by NASA Research Grant NsG-657. AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat Citing Literature Volume46, Issue1-4April 1967Pages 107-110 RelatedInformation

Summary of NASA research on jet transport control problems in severeturbulence.

Wind tunnel, simulator and flight test results to evaluate cockpit accelerations, handling qualities and stability and control of jet transports in severe turbulence

NASA and Cancer Research

NASA and Cancer Research

NASA and Cancer Research

NASA and Cancer Research

Magnetic Damping of the Angular Motions of Earth Satellites

1 Kerrebrock, J. L. and Meghreblian, R. V., An Analysis of Vortex Tubes for Combined Gas-Phase Fission Heating and Separation of the Fissionable Material, ORNL CF-57-11-3, revision 1, April 11, 1958. 2 Kerrebrock, J. L. and LaFyatis, P. G., Analytical Study of Some Aspects of Vortex Tubes for Gas-Phase Fission ORNL CF-587-4, July 1958. 3 Kerrebrock, J. L. and Keyes, J. J., Jr., A Preliminary Experimental Study of Vortex Tubes for Gas-Phase Fission ORNL-2660, February 1959. 4 Keyes, J. J., Jr. and Dial, R. E., An Experimental Study of Vortex for Application to Gas-Phase Fission Heating, O'RNL-2837, April 1960. 5 Keyes, J. J., Jr., Heat Transfer and Fluid Mechanics Institute, Stanford Univ. Press, 1960, pp. 31-46. 6 Ragsdale, R. G., NASA Research on the Hydrodynamics of the Gaseous Vortex Reactor, NASA-TN-D-288, June 1960. 7 Einstein, H. A. and Li, H., Heat Transfer and Fluid Mechanics Institute, Stanford Univ. Press, 1951, pp. 33-43. 8 Jet Propulsion Laboratory Research Summary no. 36-3, vol. 1, part 2, June 1960. 9 Pengelley, C. D., Flow in a Viscous Vortex, J. of Appl. Fhys., vol. 28, no. 1, January 1957, p. 86. 10 Schoenherr, K. E., Trans, of the Soc. of Aaval Architects and Marine Engineers. Vol. 40, 1932, pp. 279-313.