The M577 Armored Personnel Carrier[7] (APC) is a type of light armored tactical response vehicle[2] employed by the United States Colonial Marine Corps. It is a lightweight troop transport designed to operate as a multi-role vehicle and capable of being dropped into combat by dropship.[7]

Aside from its principle transport role, the M577 is also equipped with sufficient weaponry to serve in an infantry support role on the ground.[4][8]

Development and Overview[]

The M577 evolved from the Marine 70 battlefield deployment strategy, which called for a low-cost, lightweight APC capable of being transported rapidly into combat aboard the UD-4 "Cheyenne" Dropship. As a result, the M577 is highly mobile and well armed, but lighter and less capable than other APCs currently in service as a result of its need to be dropship-transportable.[7]

Because of the weight restriction (15,000 kg[9]) imposed by the USCM during development, the vehicle's components were designed to be as lightweight as possible. The prototype chassis was based on that of the M570 family of wheeled vehicles, developed for use in a variety of roles throughout the 2160s. The final production chassis is constructed of bonded titanium.[9]


The M577 is based around a four-wheel drive layout employing electric hybrid propulsion; each of the 159 cm diameter wheels is independently driven and houses an internal direct-drive Roto-Dynamic Industries transaxle motor.[1] Power is provided by batteries located at the rear of the vehicle, while a 286 kW Arco Continental R-370 multi-fuel gas turbine is used to generate electricity when the batteries are low.[10] The vehicle has a maximum range of 140 km on a single battery charge but will use the turbine to recharge these cells, increasing the range to 580 km. The micro-turbine can be run on a variety of fuels, including diesel, biofuels, compressed natural gas and liquid petroleum gas.[10] The M577 has a top speed of approximately 150 km/h (93 mph).[2]

Although the vehicle's wheeled configuration does not provide the same level of cross-country performance as tracked vehicles, it is both lighter and more reliable. Each of the wheels can steer independently for increased maneuverability. The tires are armoured against small-arms fire and shrapnel, and their pressure is controlled by a central regulation system, allowing the driver to reduce the vehicle's ground pressure over soft terrain by deflating the tires, whilst still being able to re-inflate them for road travel.[9] Ground clearance is normally only 22 cm, but the vehicle incorporates fully active hydro-pneumatic suspension, allowing for a clean ride even over rough terrain. Should the situation require, the suspension is capable of boosting clearance by up to 30 cm, which, combined with the vehicles large tires, allows the M577 to tackle vertical obstacles up to half a meter in height.[9]


The M577's chassis incorporates a 5 cm foam-packed floor cavity to protect occupants against explosives such as mines or shaped charges. The hull is constructed of light alloys and is latched and bonded (rather than welded) to the chassis in order to prevent fatigue and failure from piezo-electric effects associated with an alloy-titanium interface.[9] The inside of the hull is lined with additional protection in the form of boron carbide ceramic tiles, each of which is coated with a polymer resin to prevent cracks or shattering during normal travel; this resin also provides limited protection against pulsed laser weapons. The tiles are also backed with a thick layer of woven, fire-resistant polymer Venlar armor that limits spalling in the event of hull penetration.[9] The driver's forward windshield is constructed of exceptionally tough quartz armored crystal.[9]

As a result of the stringent weight restriction in the design requirement, the M577's armor is comparatively light — while capable of defeating battlefield shrapnel, small arms munitions and low-velocity armor penetrating rounds such as rifle grenades, its resistance against dedicated anti-tank weaponry is minimal.[9] The slab-sided design also generates a high radar cross-section on the battlefield. Attempts have been made to reduce this, primarily through the incorporation of radar-absorbent materials into the hull skinning, but this has proven only partially successful.[4] Hull paints are laser absorbent to protect against lidar, while the APC incorporates an infrared camouflage feature in which cooling elements are arranged in patches and stripes beneath the skin to break up the vehicle's IR signature.[4]

Crew and passengers[]

The M577 is operated by a crew of two (driver and section commander) and incorporates seating for 12 passengers — eight at the rear of the cabin plus four more along the starboard side, two of which are forward of the main access door.[10] All seating is equipped with harness restraints to ensure occupants are secure during orbital combat drops with the exception of the gunner's seat, which is not occupied during a drop.[10] Other than the primary access via a sliding door on the starboard side, the vehicle has a small driver's hatch on the port side.[9] The interior is relatively spacious, allowing for ample weapons and supply stowage. The Marine 70 requirement specified that the vehicle should be able to carry sufficient ammunition and supplies for up to three days of fighting; while this is possible, in practice the interior of the vehicle becomes cramped.[9] Typically, no more than two days of supplies and ammunition are carried, except on long-range operations where resupply is limited.


The Tactical Operations Center aboard an M577.

The midsection of the APC houses the Tactical Operations Center (TOC), a comprehensive suite of audio and video uplinks that allow the section commander to oversea combat operations without ever setting foot outside the vehicle. From this station, the commander is able to stay in contact with the vehicle's infantry complement, monitor their EKG/EEG readings, view operations in real-time (via the feeds sent from the Marines' M10 helmet cameras) and maintain communications with the outside world to a radius of 100 miles.[9] The commander's chair is affixed to rails in the cabin floor, allowing them to traverse the length of the TOC in moments; during drops, this seat locks back against the rear bulkhead.[11]


The driver's forward view is somewhat limited thanks to the small size of the windshield, although periscope ports provided vision to the sides and forward quarters of the vehicle. Multi-function screens by the driver and commander's positions present a sensor-fusion display of the tactical area around the APC.[9] These sensors can be activated either by the driver or the section commander in the TOC.

The aforementioned TOC (Tactical Operations Console) takes up a significant portion of the cabin inside the M577, but this component is vital to the small-force C3I (Command, Control, Communications and Intelligence) available to the Marines in combat manoeuvres. Consisting of a bank of individual data terminals (one for each Marine), each Marine linked via electronic signal to the APC's TOC provides a constant data feedback loop which consolidates several forms of information for tactical analysis by the commanding officer overseeing the team. The most important signal is the real-time display of a Marine's helmet camera, which allows the commanding officer to make decisions and direct movement without verbal updates via radio. The other data stream fed to the TOC is the computer-assisted visual log of the information collected by the non-contact transducers in the M3 Marine Armor which constantly apprises the commanding officer of the physiological condition of the Marine squad linked to the APC, regardless of audio/visual transmissions. The M3 Armor transducers and the TOC provide a longitudinal comparison graph which can allow an attending qualified medical officer to make an assessment as to the combat condition of an individual Marine. The four primary sensors which provide this crucial MASINT to the TOC are an electrocardiogram (ECG), ballistocardiogram (BCG), electroencephalogram (EEG) and an electrooculogram (EOG).[4]

  • The Electrocardiogram (ECG) is used to check for arrhythmia in the field which may be a sign of panic, fatigue, aggression, stress, poisoning, or other critical condition which may need to be addressed. In its most simple use, it can facilitate at-a-glance combat triage.
  • The Ballistocardiogram (BCG) collates data on the pressure and force of the blood from the heart, which when extrapolated by a medical professional, can inform diagnoses of hypovolemia, dangerous weight loss/starvation, obstructed vascular or venous passages, poisoning, etc.
  • The Electroencephalogram (EEG) provides insight into the mental fortitude and condition of a Marine, which may show drowsiness, chemically altered states, sleep patterns, panic, unconsciousness, or any other aberrant brain pattern which may hinder combat efficiency and focus.
  • The Electrooculogram (EOG) can lend an insight into the status of the Marine's visual acuity, motion and health. The sensor can show if the Marine is in a combat situation through analysis of eye movement with a baseline, or if their vision has been impaired by darkness, smoke, dazzling lasers and other combat hazards. The sensor can also reinforce a diagnosis via comparison or contrast with other sensor feeds, giving a clearer picture of what a Marine is suffering from (i.e an elevated heartbeat might be worrisome, but a REM pattern on both the brainwave scan and eye motion scan might simply lead to the conclusion that the Marine is having a nightmare).

The TOC is also able to, via multiplexed radio signals and computer software, display and manage other critical battlefield data and command decision relays. The section commander can monitor data streams from remote unattended ground sensors, robot sentries, reconnaissance drones and satellite surveillance.

The M577 features a powerful roof-mounted white light and infrared searchlight for the active illumination of targets, supplemented by a sensor cluster that can sweep a 270 degree zone in front of and around the vehicle. This array includes a thermal imager, video optics with magnification from ×4 to ×20, an ultraviolet detector and a motion tracker and has an effective range of approximately 3,000 meters against man-sized targets in open terrain.[4]

The M577 is also fitted with an autopilot system and associated sensors that allow it to automatically load itself into the payload bay of a Cheyenne dropship, ensuring the vehicle is properly positioned and allowing the dropship to extract the APC as quickly as possible in combat situations.[12]


In line with its role as a fast-deploying tactical assault vehicle, the M577 is outfitted with a formidable array of weaponry to support its infantry complement.

Roof turret[]

The vehicle's primary armament is in the form of a roof-mounted turret to the rear that offers a 360-degree field of fire and the ability to engage targets from the protection of a hull-down position.[13] The turret is entirely self-contained (including ammunition and power supply) and mounted on a track that runs down the rear of the APC, allowing it to be depressed to the rear to significantly reduce the vehicle's headroom for dropship transport. Weapons are stabilized within the turret to allow for firing whilst the vehicle is on the move. The turret can be elevated and depressed between +85 and -7 degrees, while additional hydraulic rams allow for it to be tilted up to 15 degrees in all axes, providing additional elevation or maintaining a level firing platform for the weapons.[13]

The turret can be controlled manually, either by the section commander in the TOC or from the gunner's position inside the APC,[6] or it can be set to automatic. In the latter mode, millimeter-wave targeting radars mounted in the turret are able to communicate with the APC's sensor array, allowing the weapons to track and engage targets detected by the vehicle's primary sensor suite; alternatively, the turret can use its own ground-mapping and search functions to acquire targets independently.[4]

Over the course of its deployment and development, several different turret weapons systems were developed for the M577, offering different capabilities depending on mission parameters.

RE700 rotary canon[]


Schematic of the M577's dual RE700 rotary cannon.

A forward cupola mounted on the starboard side of the vehicle contains a pair of synchronized Republic Electric RE700 20mm rotary cannon. These are fed by a 1,700-round multi-feed ammunition dispenser offering a selection of High Explosive Armour Piercing (HEAP) and "Beehive"-type Anti-Personnel Flechette (APF) rounds at the flick of a switch.[4] As with the M577's main turret, the forward cupola is capable of tracking targets automatically, either on its own or by interfacing with the APC's main sensors.

Unusually for a weapon of this caliber, the RE700 uses a binary propellant system (the only other such system in Colonial Marine service is the 25 mm GAU/113 aboard the Cheyenne dropship) — the individual rounds carry no propellant of their own, and are mechanically fed into the guns' revolving chambers before being sprayed with hypergolic binary propellants that ignite and launch the round.[4] This system offers substantial weight, rate-of-fire and reliability advantages over traditional caseless weapon designs, making it ideally suited to its role in providing anti-personnel support in the M577.

One drawback to the weapon is that its mounting position means it can only cover the APC's forward arc, traversing between 60 degrees left and right of axis, and cannot be fired from a hull-down position.[4]

DSGR Smart Missiles[]

In addition to its gun turrets, the M577 is also equipped with two missile launchers loaded with multi-role DSGR Smart Missiles capable of destroying light armor and other high-value targets. The missiles are fitted with a rage of guidance systems, including automatic lock-on-before-launch and lock-on-after-launch capability. They can also be remotely laser-guided from the APC's gunner station.[6] When not in use, the launchers are concealed beneath panels on the vehicle's roof.[6]

Defensive systems[]

Active defenses for the M577 include a smoke/chaff/decoy flare dispenser mounted to the rear of the vehicle, supplied by a multi-cartridge rotary feed. As well as a visual barrier, the particulate smoke employed also serves to disrupt ranging or pulsed lasers. The APC is also fitted with a fire control jammer capable of spoofing millimeter-wave tracking radars, although power available for this system is limited. These defense countermeasures are automatically deployed if activated by the driver or section commander.[4]




Boyars PARS 150 turret from an M577A1 APC.

The initial production version of the M577, the M577A1, mounts two 20 mW Boyars PARS 150 phased plasma cannon in the turret, powered by a 6 mW hydrogen fuel cell sufficient for 3,000 firings before refueling.[5] The fuel cell drives a homopolar fast-discharge generator which stores power until it has sufficient energy to charge the plasma gun's laser — when the laser is fired, it creates an ionized trail in the atmosphere which is charged by the gun's electromagnetic coil to form a solenoidal magnetic tunnel. The ammunition — 5 g cadmium telluride pellets — is fed mechanically into the tunnel, where it is vaporized by the laser beam into a superheated plasma and accelerated by the magnetic coil to velocities in the region of 5,000 m/s.[5] The plasma travels the tunnel until it impacts the target at a focused point, using its considerable kinetic and thermal energy for maximum effect penetration. Because of the power usage, both guns in the turret fire in sequence rather than simultaneously.[5]


On the M577A2 model the plasma gun was replaced with a twin Republic Dynamics M2025 40 mW free-electron lasers in the 2.0-3.0 micron range, effective against both ground and air targets.[5] Beam power is supplied by a 10 mW hydrogen fuel cell driving a homopolar fast-discharge generator. The beam is propagated, without the need for lasants, by the interaction of a particle-accelerated electron beam with a static electric field.[5] The advantage of a free-electron laser in USCM service is its ability to be tuned to wavelengths that minimize beam degradation by local atmosphere. The beam could be fired in two modes — a low power setting (20-50 kW) designed to burn out optical/infrared sensors or blind enemy combatants and pilots, and a high-power "pulse", which causes damage by superheating the target area and is capable of penetrating infantry armor or the skin of a missile or aircraft.[5] The weapon's range was stated to be 3,000 m, but in reality atmospheric interference would often reduced effective range to little over 1,000 m.[5]



M577A3 APC.

Likely due to range and degradation issues with the M2025, the M577's turret was again modified to contain two 20 MeV turboalternator-powered charged particle beam cannon, with this version being designated the M577A3.[5] The installation of the A3's particle accelerator guns was made possible due to the introduction of a Martin-Continental micro magnetohydrodynamic turbine, capable of generating the 20 mW of electrical power required to run the weapons. The turret contains sufficient turbine fuel to power the guns for 50 seconds firing, along with 300 kg of deuterium to provide particle beam mass.[5] The weapon is effective against light armored targets up to 3,000 m, and is still capable of disrupting unshielded electronics at even longer ranges.[5]

Notably, an M577A3 model was deployed to Hadley's Hope aboard the USS Sulaco, although it was subsequently destroyed on site.[11]


M579 APC

M579 AA platform.

The M579 is an anti-aircraft platform based on the M577 in which the retractable roof turret is replaced with a quad mount housing four 20mm rotary canon.[14] Guided by a highly accurate multi-spectrum sensor, the AA turret can track and defeat even hypervelocity threats up to 1,500 m away by filling the sky around them with high explosive and armour-penetrating shells. Although intended for a strictly anti-aircraft role, the rotary canon can be employed (to devastating affect) against infantry on the ground, although such actions during the Linna 349 campaign drew fierce international condemnation.[15] In place of the M577's forward gun cupola, the M579 is also armed with a quad vertical launch bin housing SIM-118 Hornet ground-to-air missiles.[15]

Behind the Scenes[]


Hunslet ATT77

A Hunslet ATT77.[16]

It was initially planned to build the film's APC entirely from scratch, and Ron Cobb developed a design for a wedge-shaped vehicle with four enormous wheels.[17] However, budget limitations meant the bespoke design was scrapped in favor of basing the APC on an existing vehicle; the donor vehicle chosen was a four-wheel drive, four-wheel steering, 635 hp Hunslet Air Towing Tractor, Model ATT77[18] used for towing aircraft, acquired from British Airways at London Heathrow Airport.[19] When it was first delivered it weighed 72 tons — aircraft tractors are deliberately massively ballasted to enhance traction — which was so heavy the vehicle would have fallen through the floor of Acton Lane Power Station, where the Hive scenes were filmed. As a result, the production crew had to remove 44 tons of lead ballast from the tractor.[19] James Cameron modified Cobb's original designs to fit the ATT77's frame before a metalworking firm in the town of Slough (near Pinewood Studios) constructed the vehicle's exterior shell.[20] The transformation was completed in less than two weeks. Top speed for the final vehicle was around 35 miles per hour. A remote-control miniature with a mechanized gun turret was also constructed for some scenes.


The APC on display. Image from The Harry Harris Aliens Collection & Archive.[21]

The full size APC prop was displayed in London's Leicester Square in 1986 before the film opened there.[21]

"APC to the Rescue" sequence[]

For this sequence, Robert Skotak and Peter Russel designed a miniature set, and Faisal Karim constructed it. A special mechanism was devised to create the sparks as the APC scraped against the walls. Roger Dear storyboarded this sequence as well as the APC driving through the alien landscape of LV-426 and grumbling to a halt outside the Atmosphere Processing Station.


The Command Center and the rest of the interior were dressed by Crispian Sallis and Mark Harris. The hand controls for the APC were foot controls from a Vulcan bomber. Standard video equipment was used to create the images of the Marines penetrating the Alien nest, which were displayed on the Command Center's monitors.


  • In the novelization of Aliens, the APC has six wheels instead of four.[22]
  • It is clear in the film (and mentioned in the DVD commentary) that the APC interior set was far larger than could conceivably fit within the actual vehicle. For instance, actors seen standing comfortably straight within the set are seen to be taller than the vehicle when standing outside it.
  • The IAV Stryker used by the main characters in Aliens vs. Predator: Requiem was included as an homage to the M577 in Aliens.[23]


Rides and attractions[]


Behind the scenes[]


  1. 1.0 1.1 Graham J. Langridge. Alien: The Blueprints, p. 39 (2019), Titan Books.
  2. 2.0 2.1 2.2 2.3 2.4 2.5 2.6 2.7 2.8 Graham J. Langridge. Alien: The Blueprints, p. 38 (2019), Titan Books.
  3. 3.0 3.1 3.2 Lee Brimmicombe-Wood. Aliens: Colonial Marines Technical Manual, p. 74 (2012), Titan Books.
  4. 4.00 4.01 4.02 4.03 4.04 4.05 4.06 4.07 4.08 4.09 4.10 Lee Brimmicombe-Wood. Aliens: Colonial Marines Technical Manual, p. 71 (2012), Titan Books.
  5. 5.00 5.01 5.02 5.03 5.04 5.05 5.06 5.07 5.08 5.09 5.10 5.11 5.12 Lee Brimmicombe-Wood. Aliens: Colonial Marines Technical Manual, p. 73 (2012), Titan Books.
  6. 6.0 6.1 6.2 6.3 Graham J. Langridge. Alien: The Blueprints, p. 41 (2019), Titan Books.
  7. 7.0 7.1 7.2 Lee Brimmicombe-Wood. Aliens: Colonial Marines Technical Manual, p. 68 (2012), Titan Books.
  8. Aliens versus Predator 2, Microsoft Windows version, Monolith Productions, 2001.
  9. 9.00 9.01 9.02 9.03 9.04 9.05 9.06 9.07 9.08 9.09 9.10 9.11 Lee Brimmicombe-Wood. Aliens: Colonial Marines Technical Manual, p. 70 (2012), Titan Books.
  10. 10.0 10.1 10.2 10.3 Graham J. Langridge. Alien: The Blueprints, p. 40 (2019), Titan Books.
  11. 11.0 11.1 James Cameron (writer and director). Aliens (1986), 20th Century Fox [DVD].
  12. Graham J. Langridge. Alien: The Blueprints, p. 63 (2019), Titan Books.
  13. 13.0 13.1 Lee Brimmicombe-Wood. Aliens: Colonial Marines Technical Manual, p. 72 (2012), Titan Books.
  14. Lee Brimmicombe-Wood. Aliens: Colonial Marines Technical Manual, p. 83 (2012), Titan Books.
  15. 15.0 15.1 Lee Brimmicombe-Wood. Aliens: Colonial Marines Technical Manual, p. 85 (2012), Titan Books.
  16. "Encyclopedia of cars in pictures - Hunslet ATT77 1986–????". Retrieved on 2014-11-15.
  17. Mark Salisbury. Alien: The Archive, p. 167 (2014), Titan Books.
  18. "The Aliens Legacy - Original APC Aircraft Towing Tractor". Retrieved on 2014-11-15.
  19. 19.0 19.1 Gale Anne Hurd, Sigourney Weaver, Michael Biehn, Bill Paxton, Stan Winston, John RichardsonSuperior Firepower: Making Aliens (2003), 20th Century Fox [DVD].
  20. James Cameron, Gale Anne Hurd, Michael Biehn, Bill Paxton, Stan WinstonAliens audio commentary (2003), 20th Century Fox [DVD].
  21. 21.0 21.1 "The Harry Harris Archive - APC in Leicester Square". Retrieved on 2014-03-21.
  22. Alan Dean Foster. Aliens, p. 87 (2014), Titan Books.
  23. Aliens vs. Predator: Requiem - Alec Gillis and Tom Woodruff, Jr. commentary
  24. "Facebook". Retrieved on 2014-10-24.

External links[]