The old new Gatling: M134 Minigun, M61 Vulcan, GAU-8/A Avenger and others.
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description
Way
back, in 1862, someone dr. Gatling of USA patented a manually operated, multi-barreled
mechanical "machine gun", one of the most successful of such designs.
Being gradually updated, this weapon, in many versions, served with number of
armies around the world as an infantry support or a light artillery weapon.
Usually chambered for the contemporary general issue rifle cartridge, the XIX
century Gatling guns usually have 6 to 10 barrels, mounted around the single axis.
Some naval Gatlings, thought, have had calibers up to 1 inch (25mm), and some
derivatives, like the Hotchkiss, were up to 53mm in caliber. When crank at the back of the gun was rotated, the "bundle" of
barrels rotated too. Each barrel had its own bolt, which completed full reloading
circle per one turn of the barrels bundle. This resulted in the rate of fire as
high as 200+ rounds per minute - quite an achievement in the era of the
single-shot and even magazine fed rifles. While first successful
"true" machine guns appeared by 1890, some Gatling guns seen use until
World War 1, especially with the navies.
As the automatically operated machine
guns became more and more mature, Gatling guns were gradually forgotten, until the
late 1940s. At that time, the speed of combat aircrafts became so high, so even
most fast-firing conventional machine guns became too slow to achieve desirable
number of hits during the very brief encounters. This spawned the
famous "Project Vulcan", that was intended to develop a super-rapid
firing weapon for US Air Forces. Project was handled by the General Electric Co.
First tests were conducted with the late 19th century Gatlings, fitted with
electrical drive instead of manually operated crank; this immediately resulted in the rate of fire
of about 4 000 rounds per minute, which was very impressive (it must be noted,
that such tests were first conducted in early 1890s, but lead to no practical
results at that time - there were no need in the rate of fire of up to 3 000
RpM). Further development
resulted in some experimental, electrically driven, .60 caliber machine guns
with 6 barrels, and, in 1956, the 6-barreled 20mm T171 gun was officially
adopted as the M61 aircraft gun. This gun could fire at the rate of 4
to 6 thousands rounds per minute. This achievement is possible due to the fact
that gun has multiple barrels, and the rate of fire per one barrel is about 1
000 rounds per minute or even less, allowing them to not to overheat. M61 became
the main aircraft gun for US AF, and also was used on M161 and M163 Vulcan
ground anti-aircraft
gun mounts. The navies also turned back to Gatlings with the Vulcan-Phalanx CIWS
(Close-In Weapon System).
When
USA entered the Indo-China troubles during early 1960s, they soon found that they need to arm their
helicopters, to provide additional firepower against enemy infantry. These
applications also required a lot of firepower delivered in the short periods of
time, so General Electric designers simply scaled the M61 gun down, for
7.62x51mm NATO ammunition. The resulting weapon, known as the M134 Minigun,
could fire up to 4 000 rounds per minute, and soon found its way to the various
helicopter mounts. It was mounted on chin turrets and in wing pods on AH-1G
"Cobra" attack helicopters, on door, pylon and pod mounts on UH-1
"Huey" transport helicopters, and on many other helicopters and aircrafts,
including famous "Gunship" airplanes like A/C-47 and A/C-119.
Usually, AH-1G "Cobra" carried one or two Miniguns in its chin
turret, with the 2 or 4 thousands rounds of ammunition. The UH-1 could carry one or
two (or even more) Miniguns on various mountings, with as much as 12 000 rounds
of ammo available for "immediate delivery to enemy".
With the introduction of the 5.56mm ammo into the military service, Americans attempted
to scale the the Minigun further down, resulting in the weapon, known as XM-214
Microgun. This little beast had 6 5.56mm barrels, was electrically driven and
could fire up to 10 000 rounds. But the 5.56mm was way too weak for
air-to-ground or ground-to-air (anti-aircraft) applications - the key niches of
the modern Gatling systems. For the infantry, the Microgun had almost no use,
being to heavy, complicated and with too much rate of fire and recoil (recoil
force was up to 110 kg / 240 lbs at the full rate of fire). Infantry simply does
not needed an extremely rate of fire to deal with the enemy infantry, and for AA
use (where such high RoF makes sense), the 5.56mm (.223mm) and 7.62mm (.308)
ammo is way too weak.
Others
than noted, US also developed a number of other Gatling-type designs chambered
in .50BMG, 20mm,
25mm, and even 30mm (like the famous GAU-8/A "monster gun", shown at
left, mounted on the A10 Warthog attack planes). It also must be noted
that the USA was not the only country to exploit Gatling ideas. USSR (and latter
Russia) built several aircraft and AA guns and machine guns. For helicopter use,
they made a 4-barreled machine guns in 7.62mm and 12.7mm, and for aircrafts -
23mm and 30mm 6-barreled guns. Some 6-barreled 30mm Gatling type guns also used
by Soviet and Russian navy for shipborne AA installations, sometimes coupled
with short-range AA missiles.
Modern Gatling guns - pros and cons.
Key advantage of the modern, externally powered Gatling type guns, is the
extremely high rate of fire, usually 4 to 6 thousands of rounds per minute
(RPM), sometimes up to 10-12 thousands RPM. This rate of fire is necessary to
deal with the fast-moving targets, when the engagement time is very short. Such
targets are mostly aircrafts, or ground targets, fired at from aircrafts. The
downside of multi-barreled systems is they relative complexity, heavy weight,
and requirements for external power (electrical, pressured air or hydraulics).
There are few self-powered (gas-operated) Gatling type guns, but they still are
much bulkier and heavier, than the conventional single-barreled guns. Another
drawback of the Gatling-type guns, which is essential for aerial combat, is that
the gun requires some time to get on to the full speed (rate of fire) after the
trigger is pressed. For the M61 Vulcan cannon, for example, the "speed
up" time is about 0.4 second or so.
Modern Gatling guns: some basic data
model
Country
caliber
number
of barrels
Rate of
fire, rounds per minute
weight, the gun itself
power
source
length
peak
recoil force
(estimated)
XM214 Microgun
USA
5.56
mm NATO
6
up
to 10 000
15 kg
electrical
0.69
m
110 kg (240 lbs)
M134 Minigun
USA
7.62
mm NATO
6
4
000
- 6 000
18.8 kg
electrical
0.8
m
120 kg (270 lbs)
GShG-7.62
Russia
7.62x54
mm R
4
6
000
19 kg
gas
operated
??
120 kg
(270 lbs)
YakB-12.7
Russia
12.7x108
mm
4
4
000 - 5 000
45 kg
gas
operated
??
520 kg
(1140 lbs)
GAU-19/A
USA
12.7x99mm
3
1
300
64 kg
electrical
1.37
m
120 kg (270 lbs)
M61 Vulcan
USA
20 mm
6
up to
6 000
114
kg
electrical or hydraulics
1.83
m
???
GSh-6-23M
Russia
23
mm
6
10
000
73 kg
gas
operated
??
???
GAU-12/U
USA
25
mm
5
4
200
120 kg
pneumatics
??
???
GSh-6-30
Russia
30
mm
6
6
000
149 kg
gas
operated
??
???
GAU-8/A
USA
30 mm
7
1
800 or 4 200
281
kg
hydraulics
2.9 m
>
4
ton
Hollywood Miniguns: Predator vs. common sense.
In the year 1987 the movie "Predator" (starring A.
Schwarznegger) hit the screens. One of the most impressive scenes was the one
where the US Commandos, led by "Dutch" (Schwarznegger), attempted to
fight back the alien Predator. One of Commandos was armed with the distinctive
weapon, a 6-barreled rotary Minigun, fed from backpack ammo box. This gave the
impression that the Miniguns can be used for infantry support. It must be noted,
that in this movie a special, blank firing version of the Minigun was sued. The
electric motor was powered via cable, hidden in the actor's pants, and the actor
had to carry bulletproof vest and protective mask to avoid injuries from the
fast and violently ejecting empty cases. Had this gun being fired using real
ammunition, the actor would ended lying on his back, being forced off the legs
by the violent recoil. The "backpack" ammo capacity, also, could be
worth only several seconds of fire. lets calculate: 2 000 rounds of 5.56mm ammo
will weight about 25 kg (55 lbs); 2 000 rounds of 7.62mm will weight about 2
times more, making such load almost impossible to carry on foots. yet this load
of ammo will worth only 20 or so seconds of fire. Add some powerful batteries to
power electrical drive of about 4KWt (4+ horse-power), and the bulk of the gun
itself, and you'll see that even the strongest man won't be able to carry this
load, less to fire it with any chance to hit, due to extremely powerful recoil.
Want to know more? here's the further reading about Gatling
guns, Vulcan cannons and Miniguns!