RAPTOR

Winner of Discover Magazine Award for Technical Innovation, 2000

The current industry wide method for cutting and repairing concrete pavement is by the use of pneumatic breakers, more commonly referred to as "jackhammers." These noisy and heavy devices pose a severe health hazard to the operator. Foot, wrist, ear, and back injuries are common among jackhammer operators. In response to the gas industries need for a faster, quieter, and user-friendly method for breaking up city streets, the Energy Sciences and Technology Dept. of Brookhaven National Laboratory (BNL Home Page) under the sponsorship of the Gas Technology Institute (formerly the Gas Research Institute), Con Edison of New York, and KeySpan Energy (formerly Brooklyn Union Gas) developed the Rapid Cutter Of Concrete (RAPTOR). RAPTOR RAPTOR is a device which launches gram sized projectiles at velocities up to 1800 m/s, roughly five times the speed of sound in air, onto the pavement surface. The pavement is broken-up by the action of crack propagation between projectile impact points. The projectile remains imbedded within the concrete leaving only a coin size crater at the point of entry.

The above photograph shows RAPTOR mounted horizontally on a test stand. Unlike a jackhammer, which requires a noisy diesel engine driven air compressor, RAPTOR operates on a supply of compressed air and helium from standard gas cylinders (located at the rear wall in the photograph). The projectiles are launched from a barrel which is supplied with high-pressure helium gas produced in a free-piston compressor. On the photograph, the end of the barrel can be seen protruding from the black flange on the left side. The free-piston compressor consists of a compression tube (metallic tube on right side) containing a piston (shown on the stand top plate) that is propelled by moderate pressure air stored in a reservoir. Using this technique, the helium pressure can be increased by a factor of 500 at the end of the piston stroke. This gas gun method of launching projectiles has been used for many years in the study of high-speed aerodynamics. Typically the barrel, compression tube and reservoir are configured linearly end-to-end making for a relatively long device. The RAPTOR design is based on a novel co-axial component configuration resulting in a shorter, much more practical device length. The RAPTOR design requires the replacement of a single rupture disk and projectile between projectile launches.

For field use the device can be equipped with peripheral equipment not shown in the above photograph. Such equipment includes: a projectile storage magazine and automatic projectile loader so that firing rates of up to 10 shots per minute are possible, a silencer to reduce the noise level when fired, safety interlocks to prevent the device from being fired when not oriented in the vertical direction, a steel mesh shroud enclosing the lateral area between the barrel exit and the pavement surface to contain any concrete dust or stray fragments that may be produced (note tests have shown that there is little in the way of flying debris produced by the impact of the projectile).

The device was originally designed to meet the needs of the gas utility industry to make "key hole" openings in city streets so that crews can gain access to underground pipes and cables. The specification required that the device be below 200 pounds and have the capability to break up concrete pavement between four and six inches thick. Other applications for the device are envisioned, such as mining, demolition, and surface decontamination. The free piston gas gun RAPTOR technology has been patented in the U.S., see the complete text of the patent at United States Patent: 6,125,834. For more information on commercialization opportunities please contact BNL's Office of Technology Transfer.

Dr. Ciccarelli was awarded the prestigious Discover Magazine Award for Technical Innovation in the year 2000. Winners in the various categories (RAPTOR was in the transportation category) were featured in the July 2000 issue of Discover Magazine. The award was presented on June 24, 2000 at a ceremony held at Epcot in the Walt Disney World Resort in Florida. RAPTOR was also on display to the public during a two day long Tech Expo. See photographs taken during the Epcot Discover Magazine Award Ceremony and Expo.