Zero-G Devices and Weightlessness Simulators (1961) / Chapter Skim
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DEVICES FOR PRODUCING THE ZERO-G CONDITION
DEVICES FOR PRODUCING THE ZERO-G CONDITION
Pages 4-107
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From page 4... ...
Speaking in terms of kinematics, the acceleration of gravity acting on the body during its free fall cannot be maintained for an appreciable length of time, and therefore the velocity of the falling body soon approaches a constant value. In order to find the general formula which can be applied for determining the parameters pertaining to a body falling within the atmosphere, it is assumed that the total weight of the body is designated by G
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From page 6... ...
Practically, a few seconds of virtual weightlessness have been obtained in free-fall experiments from drop towers. In order to produce longer free-fall periods, itwould be necessary to ascend to higher altitudes and regions of reduced air densities.
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10. Copies of the film mentioned in paragraph 5 above are available from the Department of Research Photography, School of Aerospace Medicine, Brooks Air Force Base, San Antonio, Texas.
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1. The Vertical Deceleration Tower was undergoing proof testing at the Aerospace Medical Laboratory, Wright Air Development Center, Air Research and Development Command, Dayton, Ohio.
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About 2 seconds of virtual weightlessness occur during the drop. Figures 2 and 3 show the structure and location of the test subject.
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WADC Vertical Deceleration Tower 10
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WADC Vertical Deceleration Tower: Location of the Subject 11
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Experiments which do not involve elaborate instrumentation can be arranged, subject to Aerospace Medical Laboratory's priority commitments, by request through Headquarters, WADC. At present, the Chief of the Biophysics Branch, and Mr.
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thus transforming Equation (19) into S|Y.
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The device is available at the Aviation Medicine Research Center in Rome, Italy. A schematic picture is given in Figure 5.
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a. Power device: Consists of four bundles of elastic (rubber)
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Figure 5. Subgravity Tower The maximum distance covered by the subject is about 7.
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8. Cost figures not available.
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1957) Height, velocity and subjectively felt gravity force in an I-tube gravitron, of hypothetical dimensions: height of free fall "b" = 240 meters; height for deceleration-acceleration "a" = 1000 meters.
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Certain principles of other free fall and acceleration devices could be applied and incorporated, however. This pertains specifically to performance testing and scoring, telemetry, photography, and other data collecting techniques.
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•iH _£ O +3 O rt o o o o o > M rt CO -&*
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Marshall Space Flight Center Vertical Linear Accelerator ("Pogo Stick") is located in Building 4487, Guidance and Control Laboratory, George C
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The kinetic energy of the piston has not been exhausted so it continues to move downward, displacing the air beneath it at constant pressure. It is this period of constant pressure that imposes constant deceleration on the piston, thereby producing the desired G loading.
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N Allen, Applied Research Branch, Guidance and Control Laboratory, Marshall Space Flight Center.
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Marshall Space Flight Center, Huntsville, Alabama.
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2. An artist's conception of the proposed device is given in Figure 10.
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4. Theoretical basis of equations as given before.
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George C Marshall Space Flight Center Space Flight Acceleration Simulator 1.
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2. It consists of track captured capsule traveling on circular horizontal track capable of switching into a vertical track and return.
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Typical Acceleration Pattern Two-Stage Booster 3. Figure 17 shows typical acceleration-time history to be duplicated.
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vtLOornr (FT/MO VELOCITY IMI/HR)
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5 Ft. Track Other programs might include physical and biomedical experiments under sustained high G forces by refueling of the sled 33
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As in case of the latter, the characteristics of the ABMA Space Flight Acceleration Simulator does not provide for a smooth transition from linear acceleration into angular acceleration. In order to avoid jolts during the change from linear to angular acceleration and vice versa, another transition than proposed seems to be necessary.
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From page 35... ...
In ballistics, the duration of the trajectory is defined as the time required for the projectile to again reach the level of its initial projection. In our flight pattern, T is the duration of the weightless state.
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From page 36... ...
The velocity reaches its minimum at the peak P of the parabola where the vertical component vanishes. The magnitudes of the speed at beginning and end of the parabolic arc are equal.
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shows that the optimal angle of climb depends upon the ratio of excess thrust and minimum controllability speed. Finally, we want to know what relationship exists between the duration of the weightless state and the peak altitude of the maneuver.
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Convair C-131B 1. The Convair C-131B Aerospace Medical Airborne Laboratory is located at WCTOC, Wright-Patter son Air Force Base, Ohio.
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The duration is approximately proportional to the maximal speed the craft can achieve. The minimal controllable speed has little influence unless it amounts to an appreciable fraction of the maximal speed.
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The height increases approximately with the square of the maximal speed. For minimal speeds of 150 and 250 knots, the curve is shifted up or down, respectively, by approximately 1000 feet.
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The optimal angle increases with increasing maximal speed and approaches 90° for very large speeds. (Official USAF Photo)
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Velocity-Time-Acceleration Nomogram for C-131B Flight Parabolas (Official USAF Photo) Figure 30.
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Reese Effects on visual measures Major Pigg - Captain Pitt Effects on self-propulsion and muscle force Dr. Hertzberg The following experiments were prepared for the Aerospace Medical Convair during the period 1 July 1959 to 1 October 1959: No.
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31-b) Vestibular Canal - Subjects will record rotation sensations as pitch, roll, and G's are recorded (Dzendolet)
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The Propulsion Laboratory (Fluid Behavior During Weightlessness) will use approximately 40% of the flight time and their short negative-zero G maneuver is not compatible with the tests.
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Walking Under Zero-Gravity Conditions The first complete experiment with magnetic shoes, which enable man to walk with an approximately normal gait under weightless conditions, was conducted by J
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Figure 31b. Psychomotor Performance Test During Zero-G in the C-131B.
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(Official USAF Photo) Figure S-1.
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Figure 32. Lockheed T-33A (Official USAF Photo)
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From page 50... ...
T-33 Zero-G SAM Flight Parabola: The maneuver starts at an altitude of about 18,000 feet, reaches almost 21,000 feet at the top of the parabola, and yields about 28 seconds of virtual weightlessness. Since the performance of this aircraft was rather limited, relatively high accelerations before and after the push-over maneuver had to be tolerated.
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From page 51... ...
Thus, and because of safety features described below, only short periods (3-5 seconds) of zero-G were produced, and the remaining condition of subgravity was generally designated as "virtual weightlessness.
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m. at 100%, and as the IAS reached 425 knots a climb of 65° to 70° (Official USAF Photo)
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4. The theoretical basis and the equations representing the physical conditions of the subject were given before.
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. (Official USAF Photo)
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. (Official USAF Photo)
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. (Official USAF Photo)
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The gross weight will have to be limited to about 130, 000 pounds in order to keep within the safety requirements during the parabolas.
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(Official USAF Photo) Figure 41.
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From page 59... ...
Since the first modified KC-135 will be stationed at Wright-Patter son Air Force Base, WADC personnel will monitor the test program. Requests for participation in this program should be directed to Commander, Wright Air Development Center, Dayton, Ohio, ATTN: Mr.
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From page 60... ...
Venting and phase separation of cryogenics, heat transfer of cryogenics, ion propulsion, capillary action tests, centrifugal orientation, mercury condenser, liquid N2 and O2 converters, space vehicle reaction control systems, propulsion systems for human locomotion, energy conversion units, fluid motion effects, and CENTAUR restart tests.
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From page 61... ...
Subject is not usually in the control loop since the TF-100F is not used primarily as a reaction control simulator, but subject can be in control loop if desired.
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From page 62... ...
F-100F Instrument Panel for Zero-G Tests (Official USAF Photo) Figure 44.
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The final testing was completed in July 1959. The data recording systems have undergone extensive development and modification since that time, and the coming years will see continuous use of these aircraft in carrying out the zero-G research program of the School of Aviation Medicine, USAF, Brooks Air Force Base, San Antonio, Texas.
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From page 64... ...
In this context, a special purpose version of the F-104 is described. An H^C^ jet reaction control system has been installed in an F-104 aircraft to investigate roll, pitch, and yaw control parameters during high altitude flights at low aerodynamic pressure.
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From page 65... ...
F-104 Reaction Control Instrumentation TABLE V Characteristics of Flight Trajectory of Various Types of Aircraft to Produce States of Weightlessness of Maximum Duration* nmax ~nmin (Feet)
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Installation of the reaction control system was completed in 1959 and flight tests were completed which yielded information on jet reaction control during normal -gravity and in subgravity.
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This system has a growth potential for recording additional variables, particularly those associated with and typical for zero-G effects. Evaluation of the North American Aviation physiological data package began at the Air Force Flight Test Center in March of 1959.
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From page 68... ...
Perception and correction of vehicle attitude, exercised by the control system, are continuous during the powered flight. Both the attitude of the vehicle and the motion of its center of gravity relative to the required trajectory are adjusted by altering the direction of the thrust of the rocket engines, for instance, by putting jet vanes in the exhaust stream or by gimbaling the rocket thrust chambers.
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From page 69... ...
The energy expended in propelling the vehicle during the powered flight increases with the weight of the vehicle. Because both the kinetic and the potential energies are approximately proportional to the weight of the vehicle at thrust cutoff, it is desirable that this weight be as little as possible in excess of the weight of the nose cone.
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From page 70... ...
. Because this medium trajectory requires the smallest speed V, and therefore minimum kinetic energy at thrust cutoff, it is optimum with respect to propellant requirements.
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, (52) g where Ax is the additional range gained because thrust cutoff occurs at B instead of on the ground at O, and where 0 is the angle between the horizontal and the straight line drawn from B to the 71
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(Air Univ. Qtrly.
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From page 73... ...
Consequently a backward component of gravitational force sets in as soon as the missile leaves the thrustcutoff point B, and its magnitude increases steadily with the time since the missile left B The net effect is to shorten the trajectory, so that impact occurs at some point J, rather than at 1.
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From page 74... ...
Figure 53. Variation of Trajectory Due to Changes in Velocity that of a missile of relatively small mass m in free flight under the gravitational attraction of another particle, the earth, of exceedingly large mass M
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From page 75... ...
As to whether any particular trajectory will be a parabola or an ellipse is found to depend on whether the ratio of the missile's kinetic energy to its potential energy at thrust cutoff is equal to unity or is less than unity. Knowing this, one can then show that the speed V of the missile at cutoff determines the type of path as follows: An ellipse with its farther focus at the earth's center if (53)
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From page 76... ...
S Army JUPITER IRBM nose cone in December 1958, a subgravity period at about 0.
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From page 77... ...
Fourthly, the payloads must be prepared so that they can withstand the long checkout periods on the pad before liftoff, the high accelerations and decelerations during the flight, and the stresses involved in re-entry and recovery. Generally, the nose cone is pressurized and climatized, but the bio-package must be protected against the hazards of space factors and secured in case of equipment failures.
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From page 78... ...
In the worst case we are faced with a test, the only yield of which consists of the experience gained through the preparations of the experiment. However, this and the results already obtained in rockets and satellites justify animal experiments on the biological and medical effects of zero-G as an essential step in achieving manned orbital and space flight.
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From page 79... ...
The nose cone, mounted on top of the instrument compartment, is a continuation of the conical section with a bluff re-entry tip. Operational nose cones were successfully recovered after 1,500-mile flights.
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7. Preparation and execution of the experiment must concur with range safety requirements for ground and flight operations.
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5 watts Electrical source 28 v nose cone batteries 81
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TABLE VIU Physiological Factors and Telemetry of Bio-Flight No. (FM/FM: Carrier Frequency 239.
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During the first half of 1958, a series of ICBM re-entry nose cone tests was performed, using as the launching vehicle a two-stage missile consisting of a THOR IRBM and the Aerojet 1040 liquid-propellant rocket. This program, known as Project Able, was carried out by the Air Force and Space Technology Laboratories, and included Project MIA: i.
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From page 84... ...
(US ABMA) Figure 58.
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The nose cone is built by General Electric Company. They are protected by heat shields of ablation material, some of which have been recovered after re-entry shots over 1,500 miles at 10,000 miles per hour.
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From page 86... ...
4. Physical conditions of specimen similar to those in the JUPITER IRBM, but less space in nose cone.
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From page 87... ...
Six biomedical vans are available at Vandenberg AFB for ground support of this project. A biomedical experiment in Discoverer III, launched from Vandenburg Air Force Base on 4 June 1959 was only partly successful because of failure of the vehicle to gain sufficient velocity.
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From page 88... ...
500 miles is produced by Convair Division of General Dynamics Corporation, San Diego, California, which builds the airframe and integrates the subsystems; General Electric Company, Philadelphia, Pennsylvania, and Syracuse, New York, manufacture the nose cone and the Radio Guidance System; Burroughs Company produces the computer; American Machine and Foundry furnished the power supply accessories; and North American Aviation, Rocketdyne Division, manufactures the propulsion system. The ATLAS, which has been undergoing flight tests since June, 1957, at the Air Force Missile Test Center, Atlantic Missile Range, Cape Canaveral, Florida, begins its flight with all three engines in operation developing about 400, 000 pounds of thrust.
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From page 89... ...
However, test flights will most probably precede the actual assigned missions of the vehicles; and the Saturn will be employed for a moon-miss development test. There exists a certain possibility that biological payloads could be carried on some of the earlier sub-orbital and orbital flights, and that some of them could be recovered after ejection from the upper stages.
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From page 90... ...
3. Motion, acceleration, and velocity characteristics are classified and can be obtained from the NASA Space Task Group, Langley Air Force Base, Virginia.
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From page 91... ...
The capsule temperature was kept between 10° and 20°C in both flights. The NASA capsule can be position stabilized through the use of reaction control jets which operate on compressed gas.
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Figure 63. LITTLE JOE Booster and Capsule Before Mating 92
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LITTLE JOE Research Vehicle Capsule separation (1) Escape tower Marman band release (1)
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From page 94... ...
The two biomedical experiments, using rhesus monkeys, done by scientists from the School of Aerospace Medicine, Brooks Air Force Base, Texas, involved physiological instrumentation, psychological performance, and environmental measurements. The flight profile of the rockets included maximum accelerations of about 10 - 12 g, and weightlessness period of about 3 minutes at plus or minus .
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From page 95... ...
First stage of the SATURN vehicle will be a super-booster with 1,500,000 pounds of thrust, plus upper stages. The superbooster is under development at Marshall Space Flight Center.
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From page 96... ...
Rocketdyne Division of North American Aviation is supplying the basic H-1 engines. The individual H-1 engines used in the propulsion system develop thrust from the propulsive gases created by the combustion of liquid oxygen and RP-1, a hydro-carbon fuel similar to that used in turbo-jet engines.
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From page 97... ...
Flight tests will be made from the Atlantic Missile Range at Cape Canaveral, Florida, where a 245-foot self-propelled service stand is being built to handle the huge rocket. MANNED ORBITAL TRANSPORT (NASA Marshall Space Flight Center)
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From page 98... ...
Lunar Landing Vehicle Directional stability of the entire missile will be maintained by swiveling the four outer engines of the cluster. These engines will be mounted on gimbals -- a part of their assembly -- and moved by struts actuated by the guidance equipment of the space vehicle.
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From page 99... ...
1 i 1,1 i / \ LUNAR LANDING (NASA Marshall Space Flight Center) Figure 65d.
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From page 100... ...
4. The theoretical basis and equations representing the physical conditions for the subject have been given before.
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From page 101... ...
The immediate goal is the development and testing of an advanced, integrated, and reliable cabin and life support system which proves to be adequate under weightless conditions of actual orbital flight.
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From page 102... ...
The accuracy of the digital data is limited by the data frequency, countersampling, frequency of the subcarrier channel, and the accuracy limit of the counter. However, the present systems used for the mass accumulation of scientific information are inadequate for long-range measurements.
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From page 103... ...
In summary, it is believed that signals selection, storage, and burst transmittal (the latter by command or automatically) will be applicable for biotelemetry in SATURN space vehicles.
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From page 104... ...
will further increase the reliability of the H-1. The potential use of the SATURN vehicle for manned space flight does not necessarily increase the reliability of the system.
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From page 105... ...
Flights in the SATURN vehicle will be used to test human tolerances to weightlessness and to select astronauts and space crews.
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From page 106... ...
(U) Final Report - Economical Boost Systems Study, MD 59-147, CONFIDENTIAL report, Missile Division, North American Aviation, Inc.
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From page 107... ...
The apparent weight Wa of a body, being equal to the sum of the forces of gravity and inertia, can be expressed as: wa =Fg +Fi =- Fs- (59) where Fg, Fj, and Fs represent the forces of gravity, inertia, and support, respectively.
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