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(_Zero-G Devices and Weightlessness Simulators A special report prepared by Siegfried J. Gerathewohl February 196O for the Armed Forces-NAS-NRC Committee on Bioastronautics Panel on Acceleration Publication 781 National Academy of Sciences âNational Research Council Washington, D. C. 1961
.L 1575 .Q4 1961 c.1 Gerathewohl, Siegfried j. Zero-G devices and weightlessness simulators Library of Congress Catalog Card Number 6O-6OO44
PREFACE This report has been prepared under the auspices of the Armed Forces-National Research Council Committee on Bio- Astronautics. Under the approved mission of the Committee's Panel on Acceleration, namely, to review and report upon the research and development problems concerned with the biological effects of mechanical forces, this review of the problem of weight- lessness is the first of a series of such studies designed to cover a number of areas of importance in the acceleration field. The re- views are designed to assist the investigator and the development engineer by placing before him a summary of the present state of knowledge of the area, together with as complete a bibliography as practicable, both prepared by a recognized authority. It is in the hope that this initial review meets an immediate need of the Committee on Bio-Astronautics that it is forwarded by the Chair- man of the Acceleration Panel. JAMES D. HARDY 111
FOREWORD The chief mission of the Panel on Acceleration Stress, NRC- Armed Forces Committee on Bioastronautics, is to evaluate the research problems and development activities associated with the biological effects of mechanical forces which will be encountered during space flight operations. This also includes the area of ground-based research concerned with the production and simula- tion of these forces. In view of the importance of this field of in- vestigation, and because of the complexity and the rising costs of such activities, a review of available facilities and research de- vices was initiated by the Chairman of the Panel. The objective of this survey is to assure maximum usefulness of such devices, optimum cooperation between agencies, and to guarantee that new requirements of the future be incorporated in research proposals on bioastronautics. This report concerns the devices, methods, and techniques which have been used for the investigation of the effects of zero-G and weightlessness by many investigators. A letter was therefore sent out to investigators who were familiar with these devices or had proposed their use for zero-G research (see Appendix 1). Moreover, several proposals have been included concerning the construction of advanced facilities and the utilization of unorthodox methods. While some of them have been analyzed and treated in detail, only a few results were presented in this context. The report, therefore, is not a scientific treatise of the problem of weightlessness and the effect of sub- and zero-gravity upon the organism, but rather a description of research equipment and techniques. The description of the zero-G devices and simulators was prepared in accordance with a 10-point scheme furnished by the Chairman of the Panel. Its objective was to assure a classifica- tion of information which was thought to be necessary for a practi- cal and economical utilization of these devices. These guidelines are given in Appendix 2. The material was arranged in two separate sections. The first one deals with devices which can be used for producing sub- and zero-gravity. They encompass the vertical motion simulators,
by means of which short periods of weightlessness can be pro- duced alternating with periods of relatively high accelerations. By the application of this principle, sub-gravity periods can be produced for several seconds only. Weightless periods up to about one minute and more occur during aerodynamic parabolas in high performance aircraft. The chapter on this subject contains general descriptions of the air- craft and techniques for flying parabolic trajectories and some of the results obtained. These data may also be applicable to other advanced types of aircraft to be used in weightlessness research. In a similar way, some of the advanced missile systems used and available for zero-gravity research were treated in the last chapter of Part I. The objective of this chapter is to famil- iarize the reader with those fundamentals of rocketry which must be known in order to utilize this type of space vehicle for weight- lessness research. While the Saturn vehicle is still in the con- struction and testing stage, it may play an important role in the investigation of the zero-G conditions in an orbiting manned satellite laboratory. The periods of weightlessness produced by the use of rocket vehicles ranges from several minutes to several days, or even weeks if the big boosters are made available. A simple mathematical treatment of the physical parameters involved in sub- and zero-G conditions precedes each of the three chapters. The devices treated so far actually produce sub- and zero-G conditions. In Part II, instruments and techniques for the simula- tion of weightlessness are described. In several instances the effects observed during simulated weightlessness are different from those obtained under actual zero-G conditions. New experi- ments have been done at the USAF School of Aviation Medicine, Brooks Air Force Base, Texas, and at the Naval School of Avia- tion Medicine at Pensacola, Florida, using the immersion method for longer periods of time. Although the data could not be included in this report, techniques and results very closely resemble those obtained through previous experiments. S. J.G. vi
CONTENTS Page PREFACE iii FOREWORD v INTRODUCTION 1 I. DEVICES FOR PRODUCING THE ZERO-G CONDITION A. Vertical Motion Devices 4 The Drop Tower 7 WADC Vertical Deceleration Tower (Drop Tower) 8 The Elevator 12 The Subgravity Tower 15 The Gravitron 18 George C. Marshall Space Flight Center Vertical Linear Accelerator ("Pogo Stick") 22 The Sulinac (Super Linear Accelerator) 25 George C. Marshall Space Flight Center Flight Acceleration Simulator 28 B. Aircraft 35 Convair C-131B 38 Lockheed T-33A 49 Lockheed F-94C, Zero-G Facility 52 KC-135 57 TF-100F Aircraft 60 F-104A "Starfighter" 63 The X-15 Research Aircraft 66 C. Ballistic Missiles 68 U. S. Army JUPITER (SM-78) 78 THOR and THOR-ABLE Combinations 83 ATLAS, AGENA and CENTAUR 88 LITTLE JOE Vehicle 90 SATURN ..,,..,. 94 Vll
Page II. WEIGHTLESSNESS SIMULATORS Null-Gravity Simulator 108 Supplement 1 109 NASA Weightlessness Simulator 1ll WADC Frictionless Device 114 Orbital Air Bearing Simulator 117 The Multi-Axis Test Facility 118 Martin Reaction Control Simulator 122 SUMMARY STATEMENT 126 GENERAL BIBLIOGRAPHY 129 APPENDIX 1 141 APPENDIX 2 ........................ 142 Vlll
