By Chuck WullenjohnMay 6, 2013
Space cannon blasts into 1960's space race
By Chuck Wullenjohn
Notable hallmarks of the 1960's were precisely engineered rockets for space travel constructed by the Soviet Union and the United States, with the goal being to obtain bragging rights as the first nation to land a manned mission on the moon.
While numerous rocket-powered space missions were conducted by both powers, less well known are the thundering experiments with giant cannon developed to fire scientific payloads into space. One such monster gun was constructed at Yuma Proving Ground and, though it hasn't fired a projectile in decades, it remains today, slumbering in the desert.
Officially called the "High Altitude Research Project," or "HARP," for short, the program was the brainchild of gifted engineer Gerald Bull, a native of Canada. The great dream of his life was to fire supersonic cannon projectiles from the earth directly into outer space.
Ballistically speaking, a space cannon made some sense, for the idea offered several advantages over rockets. When a rocket blasts off, it must carry not only its own weight, but also that of the fuel. Cannon "fuel" is contained and expended within a gun barrel, plus, it offers far more explosive bang for the buck than rocket fuel. Also, cannons are simpler and cheaper to operate.
But disadvantages also exist. The payload must be slender enough to fit into the barrel and must be capable of surviving the huge acceleration force of a cannon blast. Manned missions are out of the question.
In the 1865 science fiction novel "From the Earth to the Moon," Jules Verne told the story of space travelers propelled to the moon by a cannon shot. While he was unaware of the technical impossibilities, it made for an entertaining tale.
Though the bulk of the HARP project's well over 100 artillery firings took place on the island of Barbados, one of the most significant occurred at Yuma Proving Ground. At 118 feet in length, YPG's HARP gun was the largest artillery piece in the world and, in October 1966, it fired a 185 lb. payload 111 miles high, into the lower reaches of space. It was a world altitude record that still stands. A record was also set that day for the greatest amount of powder ever loaded into a gun -- 1225 lbs.
To achieve this success, engineers devised a number of technological innovations, one of which was a new ignition system. Instead of igniting the bottom of a 15-feet long stack of powder bags loaded into the gun's breech, the HARP gun ignited the charge at five separate points so the entire charge would ignite simultaneously. The projectile reached a maximum velocity of 6,800 feet per second upon leaving the barrel. When the gun fired, it produced a huge explosion and plume of fire that gushed hundreds of feet into the sky.
Another innovation were the supersonic shells developed for the gun. Dubbed the "Martlet," they were cylindrical finned projectiles about eight inches wide and over five feet long. Each weighed several hundred pounds. The Martlets were scientific research craft designed to carry payloads of chemical smoke, meteorological balloons or metallic chaff. While in the gun's barrel, the Martlet was surrounded by a wooden casing known as a "sabot" that held it tightly against the gun's bore, then fell away after leaving the tube. Engineer Bull hoped to eventually fire a Martlet into earth orbit.
YPG's famous HARP shot took place long after most employees had left for home; at 11:56 p.m. to be exact. The shell was tracked from three points -- at Yuma Proving Ground, in the nearby town of Wellton and at Arizona Western College. As the Martlet reached maximum altitude, it released chemicals that glowed in the night sky and could be seen with the naked eye. It came down on the proving ground about 30 miles from where it was shot.
Despite the HARP gun's Yuma Proving Ground success, the project was cancelled shortly thereafter. Disappointed, Bull went on to establish his own company to sell artillery wares to nations around the globe -- Britain, Italy, Egypt, Israel, Australia, Angola, South Africa, and to both sides during the Iran-Iraq War of the 1980's. Later, working for Saddam Hussein, he designed a 500-foot long, 2100 ton super cannon that would allow Iraq to fire payloads into orbit.
Some were concerned, even perturbed at the threat this represented. In March 1990, Bull was assassinated at the door of his apartment in Brussels, Belgium. Shot five times with a silencer-equipped 7.65 mm automatic pistol, the assassin was never located. Some say it was an Israeli intelligence operative, but no one knows for sure.
Yuma Proving Ground's HARP gun is the only thing in Arizona that fired a round into space. At the very least, it won the proving ground an asterisk in the international space race history books.