20mm Vulcan
Notes:
The Vulcan, and its upgraded version, the PIVAD, is one of the most
common air defense guns in the world, whether in trailer-mounted versions, fixed
mountings, naval mountings, and vehicular use.
A modified form is a very common aircraft gun.
The Vulcan is a six-barreled rotary cannon that fires at an extremely
rapid rate of fire, projecting a virtual wall of metal at targets.
The Vulcan has
also been used as armament for most US military and US-made military aircraft
since the 1950s; in fact, the Vulcan was first designed for use on the F-104
Shooting Star interceptor. In this
guise, the Vulcan has the designation M61.
The initial design, the M61, was fed by linked ammunition, and sent out
for testing in the then-new F-104.
The M61, which had been plagued by misfeeds and jams up to this point, ejected
it’s expended links overboard through a slot under the fighter.
The test pilot, firing while in a turn at about Mach 2, found that the
expended links were ingested into it’s air intake on the right side and also hit
the wing, which was a carefully-shaped special airfoil, and the links hitting
the wing munged up the aerodynamics.
The test pilot, therefore, got to be the first pilot to find out what
it’s like to eject from an aircraft at Mach 2 speeds.
(He spent months in the hospital, and months more before he was fit
enough for flying status.
The M61A1 did
away with the linked ammunition feed in favor of linkless feed.
This essentially worked miracles, making jams rare and doing away with
any problems caused by spent links being ejected overboard.
In addition, expended cases are retained inside the aircraft to keep them
from doing the same thing the M61’s expended links did.
The M61A1 became the standard aircraft cannon for almost all US and
US-made aircraft for 50-odd years, and it is still in widespread use.
It inspired virtually all rotary cannons and machineguns which were
designed after the Vulcan. The
nominal rate of fire for the M61A1 is 6000 rounds per minute (though not even
the AC-130s that carry the Vulcan have that much ammunition); pilots normally
fire in one-second of half-second burst, firing 100 or 50 rounds at an attack.
Some M61A1s (such as on the Brazilian/Italian AMX and the F-106 Delta
Dart) have their rate of fire throttled to 4000 rounds per minute, and some
attack aircraft (like the A-7 Corsair II) can have a rate of fire selected by
the pilot at either 4000 or 6000 rounds per minute.
The M61A1 can
also be mounted under an aircraft (on the wings or centerline; in practice, the
pods are not mounted on the wing except in those rare instances that a pod is
carried under each wing); this pod is known as the GAU-4.
Early versions of this pod were powered by ram air provided by the
forward motion of the aircraft; however, it was quickly discovered in Vietnam
that the GAU-4 became unreliable when the aircraft carrying it was traveling at
less than 400 kmh. The GAU-4 was
modified into the GAU-4/A, which is powered by electricity from a small
generator inside the pod..
There is a new
version of the M61, the M61A2; this version is made of lighter materials,
including a lot of titanium and even ceramics and composites. In addition, the
designers literally removed any metal that did not directly contribute to the
operation of the gun, and the electrical power unit was able to be made lighter
due to new technology. The M61A2
was originally designed for the F-22 Raptor, but it is now also found on the
F/A-18E/F Super Hornet and F-15EX Eagle II.
Aircraft
equipped with the Vulcan normally use API ammunition.
The US Army
calls the M61A1 the M130; it’s primary use in the Army is on the M167 VADS towed
SPAAG, and the M163 VADS. The M163
is mounted on a modified M113 APC chassis; the M167 is on a towed mount and is
normally towed by a medium truck which also carries more 20mm Vulcan ammunition.
The M167 trailer also carries a 10kW generator to power the M130.
Initially, the generator was powered by a large diesel fuel tank, but the fuel
used was later changed in US Army service to JP8. The generator and the fuel
tank essentially form the gunner’s platform, and the rest of the VADS is on top
of this.
The M130 gun is
also mounted on the Israeli Machbet, a variant of the M163, and the original
Phalanx CIWS naval weapons. It is also mounted on an Army AAA version of the
Phalanx; this mount is still in advanced development, but combat testing in Iraq
and Saudi Arabia have yielded good results against cruise missiles, rockets, and
UAV. Sudan and Yemen use M167
Vulcans mounted on top of BTR-152s, and a modified M167 mount has been seen
mounted in the back of a Toyota Land Cruiser in Yemen in the hands of the
Houthi.
The standard
VADS system, whether an M167 or M163, has a range-only radar and an optical
lead-calculating sight. The M167A2
PIVAD adds a new digital optical sight and a ballistic computer, and is much
more accurate than the VADS system on the M167 VADS.
(These improvements were also made to the M163.)
The M130 gun on the VADS and PIVAD may be programmed by the gunner to
fire in 10, 30, 60, or 100-round bursts, though the nominal rate of fire is 3000
rounds per minute. The size of
bursts is programmed by the gunner.
VADS and PIVAD systems normally use HEI-T rounds (an HEI round with a tracer
base). A use not often mentioned
for the M167 and M163 is it’s ability to depress the gun enough to be used
against ground targets; they can decimate infantry, shred light vehicles, and
even take out some light armored vehicles.
Though the M167,
and in some cases, the M163, are still used worldwide, the VADS and PIVAD
systems were phased out in the US in favor of the M1097 Avenger SAM system and
will also be replaced by the truck-mounted Phalanx CIWS.
The M6 Bradley Linebacker was also to be a replacement for the M163,
though the M6 itself was phased out by the Army after a few years. (I don’t know
what brilliant General or Congressional Committee made that decision, or what
they were thinking when he decided to shelve the Linebacker…)
A third model,
the Basic Vulcan, is an M167 designed for export to poorer countries; it deletes
the radar, digital sight, and power controls for elevation and traverse.
The Basic
Vulcan, VADS, and PIVAD are grouped in the second table below by the gun used
(the M130 Vulcan). Note that the
range of the M130 Vulcan differs from the M61; this is because the M130 uses
longer barrels.
Weapon |
Ammunition |
Crew |
Set Up Time |
Weight |
Price |
M61A1 |
20mm Vulcan |
Depends on
Aircraft |
N/A |
112 kg |
$55421 |
M61A2 |
20mm Vulcan |
Depends on
Aircraft |
N/A |
92 kg |
$60964 |
Basic Vulcan |
20mm Vulcan |
3 |
4 Minutes |
1565 kg |
$32769 |
Vulcan ADA |
20mm Vulcan |
4 |
4 Minutes |
1588 kg |
$43692 |
PIVAD |
20mm Vulcan |
4 |
4 Minutes |
1732 kg |
$53692 |
Weapon |
ROF |
Magazine |
Range |
Round |
Damage |
Penetration |
M61A1 Vulcan |
500 |
Depends on Aircraft Capacity |
420 |
AP |
4 |
2/2/2/1 |
|
500 |
Depends on Aircraft Capacity |
420 |
APDS |
4 |
4/3/3/2 |
500 |
Depends on Aircraft Capacity |
420 |
API |
4 |
3/3/2/1 |
|
|
500 |
Depends on Aircraft Capacity |
300 |
HEI |
C1 B5 |
-4C |
|
500 |
Depends on Aircraft Capacity |
420 |
MPT-SD |
4 |
4/3/3/2 |
|
500 |
Depends on Aircraft Capacity |
300 |
SAPHEI |
C1 B3 |
2/2/2/1 |
M61A1 Vulcan (4000 RPM) |
333 |
Depends on Aircraft Capacity |
420 |
AP |
4 |
2/2/2/1 |
|
333 |
Depends on Aircraft Capacity |
420 |
APDS |
4 |
4/3/3/2 |
|
333 |
Depends on Aircraft Capacity |
420 |
API |
4 |
3/3/2/1 |
|
333 |
Depends on Aircraft Capacity |
300 |
HEI |
C1 B5 |
-4C |
|
333 |
Depends on Aircraft Capacity |
420 |
MPT-SD |
4 |
4/3/3/2 |
|
333 |
Depends on Aircraft Capacity |
300 |
SAPHEI |
C1 B3 |
2/2/2/1 |
M61A2 Vulcan |
550 |
Depends on Aircraft Capacity |
420 |
AP |
4 |
2/2/2/1 |
|
550 |
Depends on Aircraft Capacity |
420 |
APDS |
4 |
4/3/3/2 |
|
550 |
Depends on Aircraft Capacity |
420 |
API |
4 |
3/3/2/1 |
|
550 |
Depends on Aircraft Capacity |
300 |
HEI |
C1 B5 |
-4C |
|
550 |
Depends on Aircraft Capacity |
420 |
MPT-SD |
4 |
4/3/3/2 |
|
550 |
Depends on Aircraft Capacity |
300 |
SAPHEI |
C1 B3 |
2/2/2/1 |
M130 Vulcan |
250 |
300 Chute, 500 Chute |
490 |
AP |
4 |
2/2/2/1 |
|
250 |
300 Chute, 500 Chute |
490 |
APDS |
4 |
4/3/3/2 |
|
250 |
300 Chute, 500 Chute |
490 |
API |
4 |
3/3/2/1 |
|
250 |
300 Chute, 500 Chute |
370 |
HEI |
C1 B5 |
-4C |
|
250 |
300 Chute, 500 Chute |
490 |
MPT-SD |
4 |
4/3/3/2 |
|
250 |
300 Chute, 500 Chute |
370 |
SAPHEI |
C1 B3 |
2/2/2/1 |
25mm M-242 Chain Gun
Notes:
Also known as the Bushmaster, this autocannon is fitted to the M-2 and
M-3 Bradley Fighting Vehicles and the LAV-25, as well as US Navy deck mountings.
It is also employed on MOWAG Piranhas used by the Saudis.
Rounds may be fired on semiautomatic, ROF 2, ROF3, or ROF5.
This weapon fires both US-made and European ammunition.
The mechanism is actuated by a chain drive, hence the name. It is
noteworthy that before Operation Iraqi Freedom, the US Army was heavily
considering replacing the Bradley’s 25mm M-242 with a heavier-caliber
autocannon; however, the 25mm M-242 has outperformed expectations and its
replacement is no longer being considered.
Weapon |
Ammunition |
Crew |
Set Up Time |
Weight |
Price |
M-242 |
25mm KBA |
1 |
NA |
153.5 kg |
$11270 |
ROF |
Magazine |
Range |
Round |
Damage |
Penetration |
|
M-242 ChainGun |
5 |
100B (x2) |
390 |
AA |
C1 B8 |
-4C |
|
5 |
100B (x2) |
520 |
APFSDSDU |
6 |
14/12/10/7 |
|
5 |
100B (x2) |
520 |
API |
6 |
5/4/3/2 |
|
5 |
100B (x2) |
390 |
HE |
C1 B5 |
-3C |
25mm Objective Crew-Served Weapon
Notes:
This weapon was designed to partially replace the Mark 19, ASP, and
M-2HB. The OCSWs rounds, like the
OICWs grenade launcher rounds, can be set to airburst over a target’s heads or
strike the target directly. The
OCSW fires a special 25mm round with a computerized proximity fuse, either HE or
HEDP. The OSCW is fired from a
lightweight tripod developed especially for this weapon, or it may be fired from
a NHT mount. The OCSW uses a
computerized laser sight, a slightly improved version of the IR imaging sight on
the OICW. The OCSW is fed from special cassettes of 22 or 74 rounds.
Twilight 2000
Notes: The Objective Crew-Served Weapon (OCSW) was rushed into service several
years ahead of its target date, however, few were available by the Twilight War.
Merc 2000 Notes:
Budget cuts largely ended deployment of this weapon.
Weapon |
Ammunition |
Crew |
Set Up Time |
Weight |
Price |
OCSW |
25mm OCSW |
1 |
1 Minute |
16.5 kg (With
Tripod) |
$15152 |
Weapon |
ROF |
Magazine |
Range |
Round |
Damage |
Penetration |
OSCW |
5 |
22, 74 |
190 |
HE |
C4 B20 |
-3C |
|
5 |
22, 74 |
190 |
HEDP |
C2 B10 |
23C |
|
5 |
22, 74 |
190 |
HEAB |
C6 B24 |
-3C |
|
5 |
22, 74 |
190 |
HEDP-AB |
C4 B15 |
23C |
30mm ASP
Notes:
The ASP-30 (Automatic, Self-Powered) is a gas-operated version of the
30mm ChainGun designed as an infantry support weapon.
It fits on an NHT or any other mount that is equivalent to an NHT.
It is fed from a 50-round belt.
Recoil is manageable when on a tripod or vehicle mount.
Weapon |
Ammunition |
Crew |
Set Up Time |
Weight |
Price |
ASP |
30mm KCB |
1 |
3 Minutes |
48 kg |
$20179 |
Weapon |
ROF |
Magazine |
Range |
Round |
Damage |
Penetration |
ASP |
5 |
50B |
340 |
APFSDSDU |
7 |
14/12/10/7 |
|
5 |
50B |
340 |
API |
7 |
5/4/3/2 |
|
5 |
50B |
250 |
HE |
C2 B10 |
-3C |
|
5 |
50B |
250 |
HEAT |
C1 B5 |
29C |
|
5 |
50B |
250 |
HEDP |
C2 B10 |
13C |
30mm Bushmaster II
Notes: This
weapon is an upgraded M-242 Chain Gun, and retains 70% commonality of parts with
that weapon. The Bushmaster II can
use the same ammunition as the GAU-8, and can also fire 30mm Rarden and KCB
ammunition. It is used on US Navy
deck mounts, and on the Swedish CV-30, and on some versions of the cancelled
AAAV. It is rumored as an interim
upgrade for the Bradley Fighting Vehicle. And the US Marine AAPV-7A1.
Weapon |
Ammunition |
Crew |
Set Up Time |
Weight |
Price |
Bushmaster II |
30mm KCB, GAU-8,
and Rarden |
1 |
NA |
147.4 kg |
$20180 |
Weapon |
ROF |
Magazine |
Range |
Round |
Damage |
Penetration |
Bushmaster II |
5 |
100B (x2) |
625 |
GAU-8 APIDU |
7 |
17/15/13/8 |
|
5 |
100B (x2) |
390 |
GAU-8 HEI |
C2 B10 |
-3C |
|
5 |
100B (x2) |
520 |
KCB APFSDSDU |
7 |
17/15/13/8 |
|
5 |
100B (x2) |
520 |
KCB API |
7 |
6/5/4/3 |
|
5 |
100B (x2) |
390 |
KCB HE |
C2 B10 |
-3C |
|
5 |
100B (x2) |
390 |
KCB HEAT |
C1 B5 |
29C |
|
5 |
100B (x2) |
390 |
KCB HEDP |
C2 B10 |
13C |
|
5 |
100B (x2) |
625 |
Rarden APDS |
7 |
10/9/7/5 |
|
5 |
100B (x2) |
625 |
Rarden APFSDS |
7 |
14/12/10/7 |
|
5 |
100B (x2) |
520 |
Rarden APSE |
7 |
6/5/4/3 |
|
5 |
100B (x2) |
390 |
Rarden HE |
C2 B10 |
-3C |
30mm GAU-8/A Avenger
Notes: The A-10
Warthog CAS aircraft was literally built around the massive GAU-8/A and it’s
huge ammo drum. Since then, it has
been used on the Goalkeeper CIWS shipboard defense system, better to bring down
low-flying missiles at short-range.
As noted above, the 20mm Bushmaster II can also use the GAU-8/A’s rounds.
Warthogs normally carry only APIDU rounds; the Goalkeeper normally uses
only HEI rounds. GAU-8/A rounds are
about the size of a milk bottle or, for those youngns who don’t remember milk
delivery, a 2-liter Pepsi).
Weapon |
Ammunition |
Crew |
Set Up Time |
Weight |
Price |
GAU-8/A Avenger |
30mm GAU-8 |
1 (3 Loaders on
Ground Crew) |
6 Minutes (To
Reload) |
1.584 tons |
$46,100 |
Weapon |
ROF |
Magazine |
Range |
Round |
Damage |
Penetration |
GAU-8/A Avenger |
35 |
1274 Linkless |
2125 |
APIDU |
8 |
17/15/13/8 |
|
35 |
1274 Linkless |
1326 |
HEI |
C2 B10 |
-2C |
35mm Bushmaster III
Notes:
This is a belt-fed autocannon which is just beginning to be mounted on
AFVs; antiaircraft and naval use is still more common.
The Norwegian variant of the CV-9040, for example, uses the Bushmaster
III. 70% of the parts of this weapon are compatible with the Bushmaster I and
II. It fires ammunition identical
to that of the 35mm Oerlikon autocannon, though some new warhead types were
developed along with the Bushmaster III.
The Bushmaster III has been designed to, after the replacement of the
barrel and some minor parts, to be able to fire 50mm Supershot ammunition,
effectively becoming a 50mm autocannon.
As of yet, this has not been done on an operational basis, but the
concept has been thoroughly tested and is ready for deployment upon request.
Twilight 2000
Notes: This weapon has been mounted some versions of the M-2 and M-3 Bradley.
Weapon |
Ammunition |
Crew |
Set Up Time |
Weight |
Price |
Bushmaster III |
35mm Oerlikon
KDA |
1 |
NA |
181.5 kg |
$35841 |
Weapon |
ROF |
Magazine |
Range |
Round |
Damage |
Penetration |
Bushmaster III |
5 |
100B (x2) |
390 |
AHEAD |
C2 B12 |
17C |
5 |
100B (x2) |
520 |
APCI |
8 |
8/7/6/4 |
|
5 |
100B (x2) |
520 |
APDS |
8 |
12/10/9/6 |
|
5 |
100B (x2) |
520 |
APFSDS |
8 |
17/14/12/8 |
|
|
5 |
100B (x2) |
520 |
APFSDS-T |
8 |
20/17/14/9 |
|
5 |
100B (x2) |
520 |
APFSDSDU |
8 |
21/18/14/10 |
|
5 |
100B (x2) |
520 |
API |
8 |
7/6/5/3 |
|
5 |
100B (x2) |
520 |
FAPDS |
C1 B5 |
15/12/11/7 |
|
5 |
100B (x2) |
390 |
HE/HEI |
C2 B10 |
-2C |
|
5 |
100B (x2) |
390 |
HEAT |
C2 B5 |
35C |
|
5 |
100B (x2) |
390 |
HEDP |
C2 B10 |
17C |
|
5 |
100B (x2) |
390 |
HEIBF |
C1 B12 |
-3C |
|
5 |
100B (x2) |
390 |
HEINF |
C3 B15 |
-4C |
|
5 |
100B (x2) |
520 |
SAPHEI |
C1 B5 |
7/6/5/3 |
75mm ARES XM-274
Notes: Initial
development of this heavy autocannon began in 1973 as part of the US Army’s
HSTV-L and HIMAG programs; the development was sponsored by the US DoD’s
ARRADCOM Large Caliber Weapons Laboratory, and though the design work was done
by ARES personnel, most of the work was done at this facility and ARRADCOM
provided partial funding. The
XM-274 was originally going to be used in both a light armored gun system as
well as in a self-propelled antiaircraft gun system, but the HSTV-L and HIMAG
programs came to naught. However,
in 1981, ARES received renewed interest in the XM-274 from the Army, as possible
armament for its RDF/LT program vehicle, the supposed replacement for the M-551
Sheridan at the time. In
conjunction with AAI, a light armored gun system which could be airdropped was
designed, using a low-profile turret and a special feed system for the gun.
However, this program too eventually came to naught.
ARES and MOWAG got together and produced a test version of the Piranha II
armed with this gun, but no one seemed interested.
Test vehicles with the XM-274 as armament were also made on a LAV-25
chassis, again with no takers. Eventually, the gun was shelved, though ARES
still retains the design in their inventory and is willing to put it into
production if someone is interested.
The XM-274 is a
heavy autocannon firing revolutionary (for the time) case-telescoped ammunition.
In vehicular applications, the gun is fed from a 36-round carousel in the
floor of the vehicle under the low-profile turret, though ARES is willing to
consider and has proposed other feed designs.
The CTA ammunition reduces its volume and its weight, as well as making
feed more reliable. The XM-274’s
design called electrical priming of the rounds and a recoil/hydropneumatic
system for operation. Spent cases
are ejected upwards and outside of the vehicle.
The XM-274 is designed to function optimally firing in short bursts of
1-5 rounds, with a cyclic rate of one round per second.
The barrel is fairly long at L/75.48 (5.661 meters), giving it good
accuracy and power despite the relatively small caliber of its rounds.
At the time of
the cancellation of ARES’s entry in the RDF/LT program, ARES was working on a
90mm version of the XM-274, but the rate of research was slow as ARES
concentrated on the 75mm version, and only two such prototypes were made.
Twilight 2000
Notes: In the Twilight 2000 timeline, this autocannon is mounted on the LAV-75
light armored gun system.
Weapon |
Ammunition |
Crew |
Set Up Time |
Weight |
Price |
XM-274 |
75mm ARES CTA |
1 |
NA |
1144 kg |
$65,410 |
Weapon |
ROF |
Magazine |
Range |
Round |
Damage |
Penetration |
XM-274 |
5 |
36 Carousel |
670 |
APFSDS |
17 |
97/84/71/46 |
|
5 |
36 Carousel |
500 |
HE |
C10 B20 |
4C |
|
5 |
36 Carousel |
500 |
HEAT |
C6 B15 |
68C |
|
5 |
36 Carousel |
500 |
WP |
C2 B15 |
Nil |
90mm ARES "XM-275"
Notes: This grew
out of the XM-274 project in the early 1980s, when the Army expressed a wish for
an ARES/AAI RDF/LT with greater firepower (and they were asking for the same
from RDF/LT prototypes in general. The gun was never mounted on a vehicle or
even in a mockup or turret; however, the basic gun system was built to the same
standards as the XM-274 and AAI drew up plans for a carrier vehicle.
In the end, though, the gun barrel was simply too long and the vehicle
itself unable to be airdropped from the C-130 or the C-141 (it was meant to
equip the 82n's Airborne in addition to light formations).
The two working prototypes reportedly still exist, but are mothballed.
The ARES 90mm
gun would have required a bigger vehicle with a bigger turret to make room for
the gun and it's ammunition. It too
is fed by a 36-round carousel on the floor of the vehicle.
The barrel of the ARES 90mm is not as long relative to its caliber, being
56.61 calibers long. Optimal fire
is still a burst of 1-5 rounds, though ARES recommended 3-round bursts to
conserve ammunition and because the rounds themselves are capable of more damage
potential than the 75mm ARES rounds.
Operation is identical to the XM-274.
"XM-275" is the
Twilight 2000 designation, or more likely, "M-275."
Weapon |
Ammunition |
Crew |
Set Up Time |
Weight |
Price |
XM-274 |
90mm ARES CTA |
1 |
NA |
1373 kg |
$86,443 |
Weapon |
ROF |
Magazine |
Range |
Round |
Damage |
Penetration |
XM-274 |
5 |
36 Carousel |
430 |
APFSDSDU |
20 |
152/132/112/73 |
|
5 |
36 Carousel |
320 |
HE |
C16 B30 |
7C |
|
5 |
36 Carousel |
320 |
HEAT |
C11 B20 |
101C |
|
5 |
36 Carousel |
320 |
WP |
C2 B20 |
Nil |
|
5 |
36 Carousel |
160 |
Flechette |
D 30x65; 2d6 Each |
1-Nil |
|
5 |
36 Carousel |
320 |
HESH |
C11 B20 |
121C |