Tests of the 5" HVAR Projectile with Fin and Ring Tails

This report covers tests of a 2-inch diameter model of the 5" HVAR Projectile, conducted at the Hydrodynamics Laboratory of the California Institute of Technology. This work was authorized by a letter dated January 31, 1944 from Dr. E. H. Colpitts, Chief of Section 6.1, Office of Scientific Research and Development. The purpose of the tests was to determine the performance of the projectile with the standard 4-fin tail, and to investigate possible changes in the proportion of the fins in order to better the performance or make a more compact design. This report also includes an extensive investigation of the performance of various fin and ring tails applied to this projectile, as well as to similar projectiles of different lengths. It is hoped that the data contained herein may be of use in the design of a variety of bullet-shaped projectiles having either ring or fin tails. The Water Tunnel tests apply only to the projectile moving at subsonic speeds, i.e., during the acceleration period. The attached appendix gives definitions of the terms used throughout the text, as well as other pertinent data

MK 13-1 Torpedo with Various Noses

This report covers model tests of the MK 13-1 Torpedo without shroud ring tail, conducted at the Hydraulic Machinery Laboratory of the California Institute of Technology. These tests were made at the request of Dr. E . H. Colpitts, Chief of Section 6.1, National Defense Research Committee, in a letter dated October 8, 1943, and were for the purpose of determining the performance of the torpedo with seven different types of nose design

Tests of Four Models of the 5" SSR Rotating Rocket

This report covers tests made on a 2-inch diameter model of the 5" spin-stabilized rocket. The tests were conducted at the Hydrodynamics Laboratory of the California Institute of Technology, and were authorized by a letter of January 31, 1944 from Dr E. H. Colpitts, Chief of Section 6.1, National Defense Research Committee. The purpose of the tests was to determine the performance of the rocket with various nose shapes and variations in body dimensions. Four different models were tested, the same afterbody being used in all cases. The attached appendix gives definitions of the terms used in this report, as well as other pertinent data. This report deals only with the static stability of the projectile without rotation. Since it is not possible to operate the water tunnel at velocities equivalent to supersonic velocities in air, the data herein are applicable to the projectile in the first stages of flight only

Service-learning outcomes at a faith-based institution of higher education.

This quantitative dissertation examines outcomes of a required service-learning program at a faith-based institution. Two hundred and ten students completed a pre/post survey administered to a sophomore level class about background, educational processes, and twelve attitude and knowledge subscales related to service-learning. All subscales met standard reliability standards. Two dependent variables were used to measure critical thinking and students\u27 perceptions of learning. While students entered the class with strong positive attitudes and knowledge on most subscales, four subscales Civic Attitudes, Civic Behavior, Civic Action, and Social Justice showed significant positive changes, and two subscales Motivation for Service and Personal Enrichment were approaching significance. A regression model analysis indicated that significant predictors of Learning Perceptions were: Social Justice Pretest, Learning about the Community Pretest, Learning about the Community Change, and Reflection through Discussion Outside of Class Posttest which accounted for approximately 46% of the variance in the dependent variable. Four independent variables significantly predicted Critical Thinking: Civic Behaviors Pretest, Civic Action change, Interpersonal Skills pretest, and Interpersonal Skills change score which accounted for approximately 21% of the variance in this variable. The literature indicates that students\u27 participation in reflection is paramount to the learning process. However, that was not evident in this study. More research is needed to better understand how reflective experiences affect service-learning outcomes. Findings also indicate that students come to the service-learning experience at different levels and readiness to learn, which has implications for the design of service-learning programs

Upholstered household furniture in the United States: A survey of current ownership and purchasing plans

This report presents highlights of the results of a telephone survey of U.S. households concerning their ownership, purchasing plans, and preferences regarding upholstered household furniture. The survey was conducted in October and November 1989, by the Survey Research Unit of the Social Science Research Center of the Mississippi Agricultural and Forestry Experiment Station. The SUl\u27Vey also included Canadian households, and subsequent reports will present results for Canada as well as statistical analyses of specific results for both countries. The sUl\u27vey was intended to help identify market potential for various items of upholstered household furniture, and the results are therefore not dependent on short-term economic conditions. The economic recession in the United States since the 1989 survey does not affect the validity of results; market potential becomes sup· pressed demand in an economic downturn

MK25 Torpedo Exhaust Gas Investigation

This report covers tests made on models of the Mk 25 Torpedo to determine the effect of gas discharged in the vicinity of a power-driven propeller. It also covers, briefly, tests made on a double exhaust pipe and a single exhaust pipe, both with the vertical rudder set at 10° port but without propeller. All of the above was authorized by Dr E. H. Colpitts, Chief of Section 6.1, NDRC, in a letter dated May 4, 1944. This report is the fourth supplement to the report, Section No. 6.1-sr207-1275. Memorandum Reports dated June 22, 1944, July 15, 1944, and September 29, 1944 have been issued giving preliminary results on the tests reported herein. Tests were made on models having a scale ratio of 11:21. However, all dimensions and data refer to the prototype unless otherwise noted. Gas discharges are expressed in per cent. These figures have been calculated with reference to the amount of gas discharged from the prototype when running at 40.5 knots. Allowances for temperature and composition of the exhaust gases have been made by calculating the exit velocity when the torpedo is running at 40.5 knots and 15 feet submergence, computing the ratio of this velocity to that of the torpedo, and then calculating the amount of air required by the model to obtain this velocity ratio when operating at the equivalent submergence. This criterion requires that a different rate of air flow be taken as the 100% amount for each torpedo velocity investigated. However, as in the prototype the mass rate of gas flow in the model is constant for any given water velocity, independent of the changes in the tunnel pressure (i.e. submergence). With this torpedo operating at the normal speed of 40.5 knots and a submergence of 15 feet, the cavitation parameter is calculated to be 0.67. The appendix to this report gives definitions of terms and other pertinent data

Water Tunnel Tests of the 7.2 Chemical Rocket

This report covers tests of a 2" diameter model of the 7.2" Chemical Rocket to determine its performance and possible means of increasing stability and reducing dispersion. The rocket was tested with the two original tails, the ring tail designated herein as No. 61 and the ring tail with extended fins designated No. 62. Three other tail designs were tested designated No. 63, No. 67, and No. 68. Of these, No. 67 was the only one that produced results superior to the No. 61 and No. 62 designs. This No. 67 Tail has extended fins similar to Tail No. 62 and projects beyond the nozzle about one diameter. Details of these tails are given in Figure 12. Tail No. 62 gave a restoring moment 50% greater than Tail No. 61, and Tail No. 67 gave a restoring moment 45% greater than Tail No. 62, both values being for 5° yaw. It is believed that Tail No. 67 represents about the best that can be done in redesigning the tail, as it produced a fairly high moment, a very large center-of-pressure eccentricity, and only one of the five tails tested has a lower drag coefficient. In this connection it should be noted that all the tails tested gave, without exception, adequate stability to the projectile to insure satisfactory flight after burning is completed. Therefore, the only benefit to be obtained from an increase in the stability above that produced by the original ring tail (No. 61) must come from whatever reduction it might effect in the dispersion occurring during the burning of the propellent. Calculation of the period of oscillation of the projectile in flight, and the equivalent wave length, makes possible a comparison of projectile performance from the standpoint of dynamic stability It can be shown that, for rockets with long burning times, the shorter the wave length for a given projectile, the less will be the dispersion. Using this measure of dispersion, Tail No. 67 would be expected to produce 1S% less dispersion than Tail No. 62, and Tail No. 62, i8% less than Tail No 61. This investigation leads to the conclusion that the No. 61, No. 62, and No. 67 Tails will give a high degree of static stability and it is improbable that much more can be accomplished by a redesign of the tail. It is also a fact that the dynamic stability of the projectile cannot be materially improved if its present physical dimensions are to be retained. The conclusion must, therefore, be reached that the most effective means of lowering the dispersion of this rocket is by reducing the malalignment of the jet with the axis of the projectile and eliminating as far as possible asymmetry in the tail assembly

Water Tunnel Tests of the Hydrobomb

This report covers Water Tunnel tests of a 2" diameter model of the hydrobomb, conducted at the Hydraulic Machinery Laboratory at the California Institute of Technology. This work was authorized by Dr. E. H. Colpitts, Chief of Section 6.1, NDRC, as a part of Project OD-99. The purpose of the tests was to determine the drag, cross force, moment, and center-of-pressure eccentricity for various settings of the vertical and horizontal rudders, and also the extent to which these rudders are effective in controlling the torpedo. Runs were also made to determine the cavitation effects produced under the specified operating conditions, namely, a velocity of 70 miles per hour and a submergence of 15 feet. Photographs were taken showing a wide range of cavitation effects. The report includes curves giving the performance characteristics as well as flow line drawings made by observing the model in the Polarized Light Flume. Appendix A gives definitions of the terms used in this report as well as a brief discussion of the required conditions for stability in a projectile