Gyrojet for Space


As requested in another thread, here are two pics of a .50-caliber, aluminum case 12.7x36.9mm Gyrojet developed by MBAssociates (MBA) under a NASA contract in the 1960s. The purpose of the rocket was for satellite defense, and the idea was that if a U.S. satellite detected an enemy satellite or warhead about to attack, the U.S. satellite would fire one or more of these rockets to destroy or disable it. During testing (on the ground), the rocket achieved 3,500 feet per second (fps). In theory, it could have flown at 10,000 fps in the vacuum of space with zero aerodynamic drag. Mainhardt (the “M” in MBA) reminded me of the formula F=MA, where F (force) equals M (mass) times A (acceleration). In other words, a very light projectile such as a small aluminum rocket with a phenolic nozzle can do a lot of damage if it’s going fast enough, and 10,000 fps is pretty fast. According to Mainhardt, aluminum was selected as the case material and a phenolic composition for the 4-port nozzle because it was so expensive to lift anything to orbit, and weight needed to be at the minimum possible.

Gyrojets have their own oxidizer in their nitrocellulose propellant, so they function in space (and underwater). Gyrojets have no recoil at launch, and their launchers can be very simple and light, both desireable characteristics for a projectile to be fired from a satellite.

The rockets weighed 102.7 grains (6.65 grams), and the propellant weighed 39 grains. They were ignited by fuses run through one of the nozzle ports.

Also of possible interest, MBA had another NASA contract in 1961 for a feasibility study of a hypervelocity gun that would fire small projectiles at up to 100,000 fps to simulate micrometeorites, which NASA thought would be dangerous to spacecraft. MBA used a 1.3-pound high explosive detonation to compress a magnetic field to very high flux and energy levels, and then as the field expanded (theoretically at the speed of light), it would accelerate particles to a very high velocity. By July 1962, MBA had achieved velocities of 32,800 fps, proving its hypervelocity gun was at least feasible.

I don’t know of any Gyrojet rocket or firearm that was actually carried in space, but if a weapon was to be carried, a Gyrojet would have been the perfect choice. Hope that helps.


All this cool stuff should be in a book somewhere… someday? Soon?


excellent Mel

( I am waiting on your Gyrojet book? )

best regards


Very interesting item, Mel!

Had a little lunch time fun…If the section looks a little like this the weight would be about 102.5 grains empty.

Plug 10,000 fps into the old “1/2 Mass x Velocity sq.” and we get 22,765 ft.lbs. energy if my math is right.

That would “leave a mark” so to say…

I’m still looking for the ammunition Rick’s Cosmic Space Gun from the other post uses.




Your image is very accurate (and neat!), except that the case walls are the same thickness all over, not thicker at the nose. The nozzle ports (holes) are also tapered (small end inside) to act as expansion chambers, which added about 18% to the thrust (this design is in almost all Gyrojets). I have several fired specimens in addition to the unfired one pictured, and all of the nozzles are firmly in place, so whatever glue (epoxy?) MBA used worked well. I don’t know what exact alloy was used for the case.

John and Harrie,

Thanks for asking. The first draft of the complete book, 387 pages, is complete. “MBA Gyrojets and Other Ordnance.” I’ll have at least a review copy or two at SLICS 2010, and might be ready to take orders then. I’ll also be a presenter at the Seminar Thursday night and finally, I’ll have a fairly large Gyrojet display.



Very nive informations - thanks


Hear yea, hear yea

Not to blow smoke up one’s skirt…but…

There is no one I know, have known, or have heard of, that has amassed a more complete collection of a specific subject matter

…examples/rounds/experimentals/prototypes/weapons/documentation/interviews/multi -media…

and has become a more complete authority with thousands of “i’s” dotted and “t’s” crossed than Mel…as it applies to anything “Gyrojets” …or more specifically anything to do with “MBA” and thus synonymous with “Gyrojets”.

Few folks are more detailed oriented than aircraft pilots (those that are alive to talk about it) and none more than a career military pilot who wrapped it up and retired an instructor/educator.

Need I say more ?..the book “might" be worth adding to your library !!!



In James Bond’s film You only live twice (1967), a MBA Gyrojet pistol is featured.



You’re correct. In fact, MBA provided 15 or more Gyrojet firearms and several boxes of rocket ammunition the movie.

The pic is from the Ninja school scene, where “Tanaka” fired both a Gyrojet pistol and a Finjet hidden in a cigarette (actually developed by MBA). I have the gold-plated Mark I Gyrojet pistol that’s on the upper left corner of the table and two of the resin prop carbines made for the action scenes. All of the guns and ammunition shown on the table are real. Chapter 23 of the book is titled “MBA at the Movies,” and most of it is about MBA’s involvement in “You Only Live Twice.”


A tasty collection indeed…I’ll have the one in the kimono ;-)



No problem Tony - TAKE HER -she must be arround 70 years today :-)


Then she must be experienced!


And lots easier to catch. Although there might be some wrasslin’ around involved when caught.