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A feasibility study was recently completed on a hopping transporter concept for locomotion on the moon. Termed a Lunar Pogo because it would operate similarly to a conventional pogo stick, this vehicle would accelerate up an inclined leg, pick up the leg, and then enter ballistic flight over the moon's surface. Upon recontacting the lunar surface, the Lunar Pogo would decelerate down the leg. Propulsion would be provided by expansion of gas against a piston. Operation would be partially conservative because much of the energy expended by the gas during takeoff would be recovered by compressing the gas during landing. Two models of the ballistics and propulsion have been set up to estimate performance. The simplified first-order model illuminates the thermodynamics of ideal operation. The second-order model, which includes realistic effects such as sliding, provides a better approximation to actual performance. In a one-man Lunar Pogo, an astronaut would typically make 15-m (50-ft) leaps at an average speed of 5-8 km (3-5 miles) per hour.

Millimeter wavelength radars are used to study plasma effects associated with ionized flow fields of projectiles launched at hypersonic speeds into a free-flight ballistic range. Two CW Doppler radars, at frequencies of 35 and 70 Gc/s, measure the nose-on backscattering radar cross sections during flight. The design and performance of the two radars are described in detail. A signal simulator provides absolute calibration. The purpose is to measure changes that occur in the radar cross sections of hypersonic projectiles caused by highly ionized flow fields. Under certain conditions the nose-on backscattering radar cross section of a blunt-nosed metal projectile decreases drastically when a thin, shock-produced layer of ionized gas covers the projectile. A theoretical analysis of this effect is given. Comparisons between theoretical predictions and experimental data show good correlation.

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The subject of this talk is “Physical limitations in electron ballistics”. It is pleasant to have a chance to talk about such physical limitations, because there is so little we can do about them. And, although these limitations are apt to be discouraging, a knowledge of them is very valuable, for it keeps us from spending time trying, like the inventors of perpetual motion machines, to do the impossible.

Recent activity with regard to development of a pulsed laser, remote crosswind measurement system is described. Work was concentrated on system improvements and testing. The improvements included the ability to directly measure the average received intensity, a method of aligning the two laser beams so that they are colinear; normalization to compensate for turbulence strength and laser coherence, and accurate automatic gain calibration. Testing included a comparison of the pulsed crosswind system with in situ measurements and cw measurements of the time delayed statistics.

This report summarizes Ballistic shock test results on 1 inch and 3/4 inch homogeneous armor 'H' plates welded with austenitic electrodes and tested at Aberdeen Proving Ground.

The tests reported here were conducted to determine the effects produced on the ballistics of a liquid monopropellant round by advancing the point of venting of the primer within the propellant column. The tests were conducted with two case configurations in which the L/D ratios of the propellant columns were approximately 3.4 and 5.0. As the point of venting was advanced, muzzle velocity increased in rounds with the L/D ratio of 5.0, but decreased in those with the L/D ratio of 3.4. The amount of unburned propellant remaining in the case after firing increased in both case configurations. In both configurations, the pressure curves were transformed from curves with two distinct pressure peaks, through stages approximating plateau configurations, to curves with one well defined pressure maximum.

Closed-breech interior-ballistic equations were modified for predicting the performance of reactionless launchers. Test firings were made using two reactionless launchers of the Davis Gun type. Direct and high-low launchers were considered. The test firing data was compared with the curves obtained from an analog computer. Using the differences noted, certain factors of the original equations programmed into the computer were varied in order to bring the computer curves into close agreement with actual test results. These factors included heat loss coefficient, initial charge burnt, and in the case of the high-low gun the effective mean impetus of the propellant during the ballistic cycle. It was concluded that the knowledge gained with the computer can be used to optimize the performance of reactionless systems.

A new single-stage, high-pressure, stainless steel, light-gas gun 30 ft long with a 1 3/8-in. bore has been designed and built at DOFL. This gun has driven a 6-gm mass at velocities above 5000 fps. With alterations made to heat the driver section, it is expected to give velocities of over 8000 fps and make possible impact shock pressures of more than 1-megabar. A comparison of the measured and computed projectile velocities at room temperature as well as higher temperatures is included.

A feasibility study of a smoke or vapor stream system to function in the nose cone of a fin-stabilized round was conducted. The conventional base-located system could not be used because (a) the round contained a discarding sabot mechanism, and (b) the vibration, jolt, and dust following the discharge of the large vehicle-mounted gun would cause the gunner to momentarily lose sight of the missile. Hence, a persistent trail observable by daylight was needed. Titanium tetrachloride was tried because, on exposure to air, it forms dense white clouds of titanium hydroxide. However, the corrosive properties of this material made it difficult to package. Since calculations indicated that nose temperatures exceeding 300 deg C would be attained during projectile flight, a new approach using a heat sensitive initiator was formulated. Diazodinitrophenol (DDNP), which ignites after 0.25 second of flight (200 deg C) was pressed into the nose cone tip assembly. A conically shaped red smoke composition was inserted directly behind the DDNP. Two holes drilled near the apex of the cone body allowed the generated smoke to escape. This approach worked satisfactorily in static tests. In ballistic tests, however, the smoke composition was ejected as a puff of red smoke with no streaming.

Variable-resistance strain gages were used to study the operating characteristics of a light-gas gun. Gages were cemented on the outer surface of the gun at several locations, in order to determine chamber pressure, piston velocity, and pressures in the central breech. The high-pressure transition section deformed plastically in most rounds, and a method is suggested for estimating maximum pressures from strain-time records. Results are given for various helium pressures and powder charges.

The work of design and fabrication of three Laser Telemeter Units having 18 channels of IRIG telemetry and using a PPM GaAs Laser is described. After a general discussion of the principles of telemetry and of the signal-to- noise enhancement properties of FM, PPM, and PCM systems, a detailed discussion of the electrical and of the mechanical design is presented.

Techniques were developed to launch ultralightweight models (i.e., densities on the order of 1 lb/3 cu. ft.) from a two-stage light-gas gun. To date, spheres and cones have been launched with some success. The purpose of the development was to determine whether useful aerodynamic data (e.g., sphere drag) could be obtained in a short aeroballistic range at pressures on the order of 0.01 mm Hg. A number of spheres were launched in support of this effort, some at pressures as low as 0.03 mm Hg. There is good agreement between these measurements of sphere drag coefficient and those produced in low-density wind tunnels. The application of this technique to a longer range having a lower pressure capability, say, 0.001 mm Hg, would permit measurements to be made in the near-free-molecule flow regime.

Various aspects of the perforation of thin targets by high speed fragments were investigated. A fragment projector yielding compact steel fragments having a velocity of 3.17 km/sec and a mass of .0234 g was generally used for experimental studies. Design features of this projector are presented with methods of attaining higher velocities. The volume and shape of craters produced in lead at 60 degrees obliquity by fragments having a velocity of 4 km/ sec are compared with the characteristics of craters produced at impact velocities of 3 km/sec and 5 km/sec.

SPARK photography, in which the illumination is provided by an electric spark of such short duration that a moving object appears stationary, has many applications in the investigation of high-speed phenomena. The record obtained is not an image, no lens being used, but is simply the silhouette of objects between the light source and the photographic plate. Two distinct problems are presented in the photography of moving objects. One of these is the timing of the spark so that the desired epoch of the phenomenon under investigation may be photographed, and the other has to do with the duration of the spark. All the photographs described in this article were taken on plates not larger than 8 by 10 inches. A projectile moving at a speed of 2700 feet per second would be in front of such a plate, and therefore in a position to be photographed, for only 0.0003 second. If the projectile is to be photographed within an inch of a predetermined position, the time of occurrence of the spark must be correlated with the position of the projectile to within 0.00006 second.