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Hypervelocity instrumentation aids ICBM nose cone design
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CURRENT TOPICS
Hypervelocity Instrumentation Aids ICBM Nose Cone Design.-H>.pervelocity instrumentation has been developed by Avco Research and Advanced Development Division, Ll’ilmington, Mass., to measure shock waves, flow patterns, and other events occurring at high Mach numbers in shock tubes and on ballistic ranges. This work is being carried out in connection with the Titan and Minuteman ICBM nose cones which AVCO is developing. AVCO scientists state that hypervelocity instrumentation may be used to study transient phenomena with assbciated velocities equivalent to those encountered in space travel. To date AVCO has developed a Kerr Cell photographic shutter, a high-intensity light source, a special high-speed Shadowgraph System, and a Catadioptric Light Screen and Amplifier in the field of hypervelocity instruments. One type of installation is the shadowgraph system used on the AVCO ballistic range. Here the basic shadowgraph system employs a spark-gap point-light source, a collimating lens, a catadioptric light screen, an objective lens, and a photographic plate. A projectile is fired between the two lenses in the collimated light beam. When the projectile is at the center of the optical field it passes through a very sensitive device called a Catadioptric Light Screen used for detecting the presence of the projectile. A photomultiplier in the light screen sends a signal through a video amplifier to a trigger unit which triggers a pulse generator. The pulse generator pro-
[J. F. I.
vides a high-voltage pulse which makes the action of the light source and Kerr (‘ell mutuall). synchronized with the position of the projectile. The whole action takes place with a “jitter” of less than 0.1 microsecond. Using shadowgraph systems AVCO scientists have been able to “freeze” projectiles in flight and study their drag, attitude, and associated flow patterns. Surface detail has also been studied by the addition of an nuxiliar>light source for front lighting of the Information gained using projectile. these techniques has proven vital in the design of ICBM nose cone shapes. Exposure times in the range of lo-+ and 10e7 second are required to prevent image blur in .\VCO’s work with scaled-down, high-velocity nose cone projectiles. Key to the system is the synchronized pulse generator-light source-Kerr Cell combination. The 2-in. aperture Kerr Cell Shutter is connected directly across the load resistor on the transmission line and, because of this, does not require an impedance matching network. Kerr Cells and Kerr Cell systems such as employed in shadowgraphs and schlieren systems using AVCO’s new11 developed hypervelocity instruments are ideal for measuring disturbances in detonation phenomena and flow patterns around projectiles. These systems have also been used to measure spark ignition in fuels, terminal ballistics, response of photosensitive devices, flow patterns in high-intensit,. plasma generators and rocket motor and projectile emergence exhausts, from gun muzzles.
CURRENT TOPICS
Hypervelocity Instrumentation Aids ICBM Nose Cone Design.-H>.pervelocity instrumentation has been developed by Avco Research and Advanced Development Division, Ll’ilmington, Mass., to measure shock waves, flow patterns, and other events occurring at high Mach numbers in shock tubes and on ballistic ranges. This work is being carried out in connection with the Titan and Minuteman ICBM nose cones which AVCO is developing. AVCO scientists state that hypervelocity instrumentation may be used to study transient phenomena with assbciated velocities equivalent to those encountered in space travel. To date AVCO has developed a Kerr Cell photographic shutter, a high-intensity light source, a special high-speed Shadowgraph System, and a Catadioptric Light Screen and Amplifier in the field of hypervelocity instruments. One type of installation is the shadowgraph system used on the AVCO ballistic range. Here the basic shadowgraph system employs a spark-gap point-light source, a collimating lens, a catadioptric light screen, an objective lens, and a photographic plate. A projectile is fired between the two lenses in the collimated light beam. When the projectile is at the center of the optical field it passes through a very sensitive device called a Catadioptric Light Screen used for detecting the presence of the projectile. A photomultiplier in the light screen sends a signal through a video amplifier to a trigger unit which triggers a pulse generator. The pulse generator pro-
[J. F. I.
vides a high-voltage pulse which makes the action of the light source and Kerr (‘ell mutuall). synchronized with the position of the projectile. The whole action takes place with a “jitter” of less than 0.1 microsecond. Using shadowgraph systems AVCO scientists have been able to “freeze” projectiles in flight and study their drag, attitude, and associated flow patterns. Surface detail has also been studied by the addition of an nuxiliar>light source for front lighting of the Information gained using projectile. these techniques has proven vital in the design of ICBM nose cone shapes. Exposure times in the range of lo-+ and 10e7 second are required to prevent image blur in .\VCO’s work with scaled-down, high-velocity nose cone projectiles. Key to the system is the synchronized pulse generator-light source-Kerr Cell combination. The 2-in. aperture Kerr Cell Shutter is connected directly across the load resistor on the transmission line and, because of this, does not require an impedance matching network. Kerr Cells and Kerr Cell systems such as employed in shadowgraphs and schlieren systems using AVCO’s new11 developed hypervelocity instruments are ideal for measuring disturbances in detonation phenomena and flow patterns around projectiles. These systems have also been used to measure spark ignition in fuels, terminal ballistics, response of photosensitive devices, flow patterns in high-intensit,. plasma generators and rocket motor and projectile emergence exhausts, from gun muzzles.