The events of 9/11 as they unfolded through actual audio.
Possibly the World's Largest Gun
In the world of ordnance system development the need for system and subsystem testing under dynamic conditions is obvious. A number of approaches have been used by various agencies throughout the years. Rocket sleds. Powder guns. Compressed gas guns. Although each approach has its advantages and disadvantages, it is the disadvantages of traditional approaches that led to the creation of the Variable Energy Research Accelerator (VERA). Rocket sleds are often too expensive for small programs to utilize for extensive test series, and in addition to challenging packaging issues, traditional guns present a violent acceleration profile that can damage test hardware. The designer of VERA endeavored to create a cost effective system to deliver useful payloads to useful velocities while subjecting payloads to acceleration forces significantly lower than those associated with typical gun systems. The result of this effort is VERA. VERA is a low cost, low acceleration, compressed charge combustion gun featuring a 40 foot (12.2 m) barrel and a 19 inch (483 mm) bore. VERA was designed to minimize payload acceleration forces, accommodate large and/or oddly shaped projectiles, and allow for in-barrel instrumentation and control of energetic or inert payloads.