Gyrojet Predecessors   

Captain Monty Mendenhall

           MBAssociates partners Robert Mainhardt and Arthur Biehl overcame many problems of small arms rocket technology while developing the Gyrojet.  At no time though, did they claim to have been the first to invent small arms rockets.  Neither, however, did Mainhardt or Biehl credit earlier inventors or inventions as their inspiration.  Left unstated by MBA is the fact that small arms rocket technology is over 165 years old.

Voss Musket Rocket
Danish Small Arms Rockets

          The first known example of a small arms rocket was developed in Denmark by the superintendent of the Royal Danish Army Arsenal.  Patented in 1834, it was named after its inventor, the Voss Musket Rocket. 

          The Voss Musket Rocket was a low-tech small arms rocket. It was launched from a standard military musket.  Externally the Voss musket rocket looks very similar to Mainhardt and Biehls Gyrojet rocket.  Internally though, the Voss Musket Rocket lacks the MBA Gyrojet’s sophisticated engineering.

          The earliest Voss rockets were loaded into muskets on top of a normal charge of black powder. When the flintlock musket was fired, the black powder both launched the rocket and ignited its own internal charge of propellant.

          Though there is no data to support this claim, the author feels that it is likely that the original blackpowder launched Voss Musket Rockets achieved the highest velocity of any small arms projectile up to that date. The Voss Musket Rocket was launched at a normal musket’s velocity by the blackpowder charge. Then, after exiting the musket barrel, the Voss Musket Rocket continued to accelerate burning its own internal propellant.


Walter Hunt and his ‘Rocket Ball

          Many US firearms enthusiasts have heard of the ‘Rocket Ball’ that was patented by Walter Hunt in 1848.  The ‘Rocket Ball’ was a hollow bullet that was filled with propellant.  In the center of the’ Rocket Ball’s’ base was a vent hole that allowed the propellant to be ignited by an external primer.  Hunt also invented, and patented in August of 1849, a tubular magazine lever action rifle that used his ‘Rocket Ball’ ammunition.

          Hunt was an inventor, not a manufacturer.  He formed a partnership with George Arrowsmith to manufacture his invention.  It soon became apparent that although it was very it innovative, Walter Hunt’s lever action rifle design was not perfected. 

          One of Arrowsmith’s employees was a skilled gunsmith named Lewis Jennings.  Jennings made several simplifications and improvements to Hunt’s lever rifle design. He patented them on Christmas Day of 1849.  In a move that produced a quick profit for the Hunt, Arrowsmith and Jennings team, the patents for the Hunt Rocket Ball, the original lever rifle and Jenning’s improvements to it, were sold to Courtland Palmer for $100,000.  That was a tremendous sum in the dollars of 1849.

          Palmer was a profit motivated investor, not a manufacturer.  He contracted with the firm of Robbins & Lawrence to produce five thousand lever action repeating rifles of .54 caliber.  The contract was fulfilled in 1851, but sales were slow.

          The Hunt ‘Rocket Ball’ was underpowered and the patented lever action rifle was very sensitive to imperfections in the individual rounds of ‘Rocket Ball’ ammo.  If the ‘Rocket Ball’ was slightly undersized, it would fall so deeply into the chamber that it would not ignite.  When this occurred, the unfired round was difficult to remove.

          Daniel Smith and Horace Wesson (yes, that Smith & Wesson) became partners with Palmer in 1854.  Oliver Winchester (yes, that Winchester) soon became an investor too.  They called their partnership, The Volcanic Arms Company. 

          Horace Smith became disenchanted and departed Volcanic Arms in 1855.  Due primarily to problems with the ‘Rocket Ball’ ammo, Volcanic Arms failed.  Horace Smith and Daniel Wesson soon reunited and began manufacturing revolvers.  Oliver Winchester abandoned the ‘Rocket Ball’ concept but continued to develop the Volcanic lever rifle using a more practical .44 caliber rim fire cartridge.


  Wehrmacht 9mm Rocket 

German Small Arms Rockets

          Cartridge ammunition proved to be very practical. Small arms rocket ammunition was forgotten for many years.  During World War Two though, while Werner von Braun was experimenting with large NAZI V2 rockets, other German Wehrmacht arms researchers designed a self contained 9mm small arms rocket round.  It was similar in many aspects to the later produced MBAssociates Gyrojet.   The German 9mm small arms rocket, like the Gyrojet, which followed it twenty years later, had a machined steel casing that was filled with a hollow cored propellant.  In the center of  the German 9mm rocket’s extended base was a primer.  Concentrically surrounding the primer, were six symmetrical rocket nozzles. 


US Navy 9mm Rocket and 13mm MBA Gyrojet 

US Navy Small Rockets

          Little is known about the performance of the German 9mm rocket ammo.  It must have intrigued the US Navy however.  After World War two ended, the US Navy continued experiments with the German 9mm rocket ammo.  Again, little is known about the US Navy’s experimental .354 inch diameter small arms rocket round.


  13mm MBA Gyrojet 

Mainhardt & Biehl

          The author does not intend to belittle the many achievements of Mainhardt and Biehl.  Though the Gyrojet was not a totally original concept, these two determined, hard working researchers actually brought their small arms rocket and its launcher to the marketplace.  While doing this, they overcame many obstacles that would have stopped many less determined and less innovative inventors.

          Though the Gyrojet small arms rocket was not a resounding financial success for them, without government assistance, Mainhardt and Biehl succeeded where many others have failed.  Their achievements represent the true spirit of American individualism, innovation and perseverance.









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