The original 1960s gyrojet firearms.

Gyrojet Firearms
Tech Level: 9
Micro Missile Launcher
Tech Level: 12
Smart Micro Missile Launcher
Tech Level: 13
Rifle Mount Micro Missile Launcher
Tech Level: 13

The soldiers of the future are likely going to face a battlefield full of foes with ever more sophisticated armor. Not just standard fighting vehicles, but soldiers wearing advanced ballistic protection as well as small, heavily-armored UFVs (Unmanned Fighting Vehicles,) all designed to withstand conventional small arms.

A number of future technologies will be able to meet this challenge, but many of them, such as coil gun firearms and man-portable plasma guns, will both be very expensive to develop and may not be available for many decades yet. However, one already-developed technology points the way to developing armor-defeating man-portable weapons that would be both much cheaper and much more near-term: the gyrojet.

Tech Level: 9

The gyrojet line of firearms was developed and sold commercially in the 1960s by the company MB Associates of San Ramon, California. In essence, they were guns that fired bullets propelled by rocket motors as opposed to a chambered explosive charge.

These rocket rounds were, in essence, bullet-sized missiles; the guns--which came in rifle, pistol, carbine, and sub-machinegun configurations--were primarily launching platforms. A pull of the trigger ignited the projectile’s rocket fuel, and the bullet roared out of the barrel, gaining speed as it went. Its velocity was relatively low coming out of the muzzle, but quickly increased to over 1200 feet per second at a range of 30 feet, delivering half again as much impact energy as .45 ACP round. This is in sharp contrast to conventional rounds, whose velocity peaks within the barrel of a weapon.

Stabilizing the projectile in flight was accomplished with multiple specially-angled exhaust ports, which spun the rocket bullet as it sped toward its target. The rounds came in 13mm and 12 mm calibers. The technology was of interest to the military, who also looked into using the gyrojet as a basis for a grenade launcher. The technology was in fact used in emergency survival flares by the US Air Force for many years.

Gyrojets were also much quieter than conventional firearms. Except for the whoosh of the rocket firing, the gyrojet was silent. Some models were capable of firing trans-sonic rounds; however, the sonic boom associated with them occurs well away from the weapon, lessening the chance of giving away the user’s exact position. The exhaust is also smokeless. However, on cold, humid days, the rocket exhaust could form a contrail which could give away the firer’s position. However, under the same weather conditions, the waste gases of a convention firearm would create a cloud of condensation as well which could be just as telling.

Because gyrojet projectiles had low velocity out of the barrel, they were fairly ineffective at close ranges. In fact, the projectile could literally be stopped with nothing more than a naked finger stuck into the barrel, where it would harmlessly expend all its fuel as long as it was blocked. This lack of up-close stopping power as well as the much greater expense of gyrojet bullets were considered the major stumbling blocks to the weapon finding widespread acceptance.

The original gyrojets suffered from other mishaps, such as occasional reports of poor accuracy, slow loading, and the rocket bullets misfiring. However, it was believed these defects could have been readily corrected with continued development of the technology.

Gyrojets were used in a limited capacity in Vietnam. Fictional advanced versions were also seen in some Larry Niven short stories, the old Star Frontier tabletop RPG, and the Traveller RPG universe.

Tech Level: 12

The gyrojet was perhaps ahead of its time. When it debuted there was little it could do that conventional firearms couldn’t do cheaper and more reliably. That, however, may be changing.

Ballistic armor is becoming much more widespread, and much more sophisticated, than in decades past. The ideal the armor designers are working towards is to gear the armors to withstand anything conventional firearms can throw at them.

Micro Missile firearms are the most near-term and economic counter to this projected development. They can be thought of as an updating of the gyrojet concept, but also as the extreme miniaturization of current anti-tank and anti-vehicle missile technology. Both would be correct. They can deliver much more kinetic energy at range than conventional arms of the same caliber, and have a much better chance of defeating armors graded against conventional firearms.

The term "launcher" is used here because even though pistol/rifle/carbine configurations will still likely be the most commonly used, in science fiction we occasionally see unconventional applications of this tech such as shoulder-mounted or forearm-mounted launching pods. The latter two are especially popular in depictions of futuristic powered combat armor, such as Iron Man.

Next-generation rocket guns will share a number of characteristics with their forebears. Relative low velocity upon leaving the barrel along with a tremendous increase in projectile speed and energy along its flight path, somewhat quiet operation, and light relative weight.

The new rocket bullets can take advantage of a great deal of advances in both missile technology and miniaturization over the past decades. The rounds can be made out of more durable composite materials, allowing for lighter weight, hotter and longer burning fuel, and ultimately much greater acceleration and impact energy. At medium and long ranges their force of impact and penetration capabilities will exceed those of conventional firearms of the same caliber.

Since a micro missile’s ‘killer app’ would be armor penetration, the ammunition may come in a wide variety of specialized armor-piercing configurations like those found in anti-tank rockets. Sufficiently advanced and powerful micro missiles could even become a real threat to more traditional armored fighting vehicles like light tanks and APCs.

The main disadvantage of these weapons would be ammunition cost. The launcher/gun is relatively light and cheap, but the cost of the individual rocket bullets with all the advances mentioned would be quite steep compared to conventional rounds. However, such costs could be wound down to reasonable levels if the ammunition was built in quantity.

Also, as with gyrojets, they would be relatively ineffective at close ranges due to their low velocity out of the barrel.

Tech Level: 13
Say hello to Iron Man's little rocket-powered friends. Image copyright Paramount/Marvel.

As these firearms incorporate a great deal of current missile technology in miniature, it would seem inevitable that target acquisition and tracking capabilities would be the next major step in their evolution. More than likely these weapons will be able to switch between guided and unguided modes as needed by the user.

Here, the gun itself becomes more than just a simple launching platform; it would also houses the sensors and microprocessors that acquire the initial target lock. Target locking may be done manually by the user, as would usually be the case with carefully-aimed shots. Or they may be acquired automatically by the gun, picking out at the moment the trigger is squeezed the most likely target on the projectile’s initial flight path. This latter mode would be subject to false acquisition in some circumstances, making the unguided option preferable in some circumstances.

Types of sensors used to home in on a target would include infrared, radar, lasers, or visual. Active sensors like radar may pose a problem for soldiers depending on stealth (micro missiles, like gyrojets, would be relatively quiet if their projectiles remain subsonic) as such a system could alert an opponent looking for such a signature. The gun may ‘pass off’ the target lock to the rocket bullets allow the projectiles to track the target on their own, or the weapon may need to send out a continuous signal to "paint" the target for the bullets to home in on. The latter may be usable only in certain specific circumstances, such as a sniper trying to hit a very specific target.

Each projectile would have its own microprocessor to help adjust its flight, as well as track the target as needed. At the Tech Level (13) these weapons are thought to come into use, electronic components for both sensors and microprocessors would be small enough to be integrated into the rounds with no significant increase in mass or bulk.

Helping the round twist and turn in order to follow the target can be done in several ways. The nozzles at the rear of the bullet may be made moveable, while tiny ‘pop-up’ fins may also be deployed upon leaving the barrel.

Tech Level: 13

These are advanced gyrojets that could be attached to the underbarrel of a standard rifle or assault gun, the way grenade launchers are today. Because of the inherent cost of the ammunition, especially if it’s a ‘smart’ version, micro missile systems seem unlikely to replace standard firearms as a mainstay infantry weapon. However, making an underbarrel version would allow the soldier the best of both worlds, so to speak; a conventional firearm for everyday use, and a high-powered gyrojet to use against heavily-armored targets.

Grenades used in conjunction with rifles are usually intended for anti-personnel area-effect/area denial roles, while micro missiles are designed to be a direct-fire solution to heavily armored targets. As the technology for both matures, they may begin to merge roles. One single launcher may be developed to handle both types of ammunition, with the soldier just simply switching between different clips as needed by the situation. The Traveller RPG had a system similar to this, using what the game called a RAM (Rocket-Assisted Multipurpose) grenade launcher. A soldier could use micro-missile-like rocket ‘grenades’ against armored vehicles or powered armored soldiers, and then switch to more conventional grenade types to use against regular infantry.

These rifle-mount launchers may use either normal or smart micro missiles, depending on the needs of the mission.


Article added 6/4/09