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USCM Tech: UD-4L

The UD-4L “Cheyenne” Utility Dropship is a creation of James Cameron’s Aliens, with 2 different dropships playing integral roles in the film’s plot. The first being the dropship unofficially designated “Bug Stomper,” piloted by Ferro and Spunkeyer, which originally brings the marines to the colony on LV-426. After their encounter with the aliens in the hive, Hicks requests immediate evac, but “Bug Stomper” is unable to follow through on this mission when a stowaway xenomorph kills the unsuspecting pilots, causing the ship to crash, along with its plentiful armaments, wasting the APC in the process, damaging the atmospheric processor’s cooling system, and ultimately leaving the survivors stranded with little weaponry.

The second dropship, “Smart ASS” (also an unofficial designation), is piloted remotely then manually by Bishop, in order to escape the site before the processor went critical. Smart Ass was successful in bringing Ripley, Newt, Hicks, and Bishop to safety, but it was on this dropship that the Alien Queen hitched a ride, appearing in the hangar bay in a last ditch effort to avenge her fallen hive. True to the style of almost all of what we see in the world of Aliens, Cameron and Company put painstaking detail into the creation of this vehicle. The Colonial Marines Tech manual outlines a great deal of specifics that were considered in its realization, as well as further defining its purpose within the corps. The UD-4L “Cheyenne” is a versatile dropship and tactical transport employed in a primary role in the US Colonial Marine Corps.

The UD-4 has evolved into the definitive dropship design, influencing the shape of many deriviatives and successors. The Cheyenne’s unique flexibility comes from its ability to lift itself into orbit under its own power from unprepared landing sites with the aid of its vertical take-off (VTOL) capability. In addition to carrying its large payload, the Cheyanne can operate in the close-support gunship frole by deploying weapons pods and hardpoints for rockets and missiles, as well as using its own internal. The UD-4’s lifting-body airframe is built around its 1cubic meter internal payload bay, flanked to the sides and aft by the tri-skid undercarriage. Forward of the payload space is the cockpit and the mounts for the lift engines. Aft of the space is a raised tail assembly which mounts the ramrocket engines and control surfaces. The principle frame is constructed from the superplastic-formed diffusion-bonded metal matrix composites (MMC).

These light, oxidation-resistant MMC structrual members are formed from high-modulus, high-strength gold and chrome doped zirconium oxide reinforces fivers in a titanium aluminide matrix. They form a structural web running the length of the fuselage, encompossing the payload volume. Spars and members attached to the main frame are constructed from titanium aluminide MMC and refractive composities with titanium root fittings to transfer bending moments to the structurcal web. The fuselage skinning comprises tr-layer plates attached to the titanium aluminide frame. The inside layer is a carbon-carbon composite (graphite fibers in a carbon matrix) bonded to a middle layer of single-crystal carbo. This crsytal carbon later will not melt on the re-entry and can effectively conduct excess heat away from the leading-edge surfaces. A thin ceramic outer layer provides thermal and oxidation protection in the high altitude, high speed realm. The payload bay is a l x w x h meter (1cubic meters) volue with a meter wide deck ramp suspended from four dual-hydraulic assemblies.

The deck ramp can confortably carry a fully-crewed M577 APC (with turret stowed) or a HALOS stores pallet, and is able to raise the cargo completely into the payload space from the grond level. Within the bay, detent lataches are automatically activiated, extending to hold cargoes in place when the deck is raised. Aft of the payload bay, a step gantry can be lowered to the port side to allow crew access. Forward of the bay, a small volume accomodates three seats for passengers and additional crew. To either side of the forward payload space, the structural web extends outwards to form the static load points for the undercarriage, the fuel tank volume and the mounths for the secondary weapon bats.

Aft of the payload space is the huge rar skid strut and the fuel tankage for the ram rockets. The UD4 undercarriage is a tri-skid arrangement in which the skids retract flush with the underside of the fuselage. The ramrocket engines are mounted above the main fusealge module, their intakes accepting the airflow across the upper fuselage. The aft fuselage assembly occupies the space between the engines and extends reward to the butterfly control surfaces. This volume contains the Fire Control Hamming Suite towed unit and the oxidant tankes fro ramrocket operation during exoatmospheric flight.

With their associated cryogenic storage equpiment. Just aft of the main engine nozzles are a pair of flush fitted extending airbrake panels which can also be deployed during reentry for transonic and hypersonic stability. The butterfly control surfaces are designed to provide control authority in all axes at all speed regimes. They also supply tail life at low speeds when the dynamic pressure on the underside of the dropship lifting body drops and shifts the static center of the lift forwards. ————– The spacious pressurixed cockpit is accessed from the payload bay and features two crew positions, seated in tandem.

Both crew sit in Matrin-Siekert R2101 zero-zero ejection seats which are cleared for operation at any altitude below 10,000m and speeds below mach 1. In the event of an emergency, explosive cord blow the canopy off and the crew are ejected clear of the shio. The main fuselage also features the mounting points for the main weapons pods and the secondary weapons bay. The main weapons pods are attached to cross-folded pylons just forward of the ramrocket intakes, which in supersonic flight are stowed flush against the fuselage sides and the rear of the secondary bays. At subsonic speeds, the m pylons can be deployed crosswise to expose the ordanance within the pods. The total span of the pods when deployed is m. The pods cannot be deployed at speeds above transonic because of the adverse effects of drag and the torsion caused by dynamic pressure on the pylones.

The secondary bays also fold flush against the sides of the lifting body, and can be swung out to expose all the weapon hardpoints and allow exhaust space for weapons launch. Survivability featues high on the list of UD-4 featues. The airframe has proven crashworthy at low speeds and altitudes. A sandwich of Blar ballistic armor layers protect the cockpit, fuel tanks and tamrocket cowlings from light ground fire or spent missile fragmentation and the ceramic outer skin later has limited ablative properties against pulsed lasers. . Though not designed to slug it out with ground or space defenses, experience has proven the Cheyanne to be exceptionally rugged, capable of withstanding considerable punishment while still remaining airborne. However, it must be noted that even light damage can prevent a dropship from lifting into orbit.

A breach of the fuselage skin will seriously compromise the ship’s highspeed thermal protection, and even a tiny hole can cause oxidation or ‘burn through’ when atmospheric speeds exceeds m5.-. To prevent such accidents, a sensor net is bonded to the inside of the skinning to monitor for breaches, a different hull termpature and ionization. IF a breach is detected, a warnning is flashed to the cockput monitor to notify the crew. The manual goes on to explain Flight and Stealth characteristics of the Cheyenne, as well as its avionic, sensor, and defensive systems. As far as is possible, the fuselage has integrated low observable characteristics including rounded ledding surfaces, shielded compressor intakes, and a butterfly tail. Much of the composite skinning is radar absorbent and from the forward quarter the Cheyenne has a radar cross-section (RCS) of less than 1.3m, while from the front, where the engine intakes are fully visible. RCS increases to around 2.5m. However, despite the attention paid to keeping RCS low, values for the beam and stern aspecs are much greater, in some cases exceeding 50m.

In the infared, the Cheyenne is far easier to detect. Airframe heating is almost impossible to digusing at ranges under 10km, and if the dropship has just completed a transatmospheric ascent or descent the detection radius can be 30km or more in clear skies. Cold air blowers are intalled in the side-bleed nozzles and the nose exhaust to reduce the infrared signature from the lift engines. A variety of laser-absorbent skin coatings probide some defense against lidar and laser-targetting systems by attentuating the reflected strength of the beams. Even against coded beams this can cause range or profiling errors. However, because the coatings tend to be frequency-specific, they only provide coverage against a limited number of systems. The Cheyenne has a crew of two, comprising a Pilot and a Crew Chief/Weapons officer. Flight control is quadruplex digital fly-by-light with automatic self-monitoring and reversion to back-up modes, all handled through the flight computer.

Ther is no manual reversion since the dropship is too unstable to be flown with direct control inputs. Engine thrust and nozzle setting are automatically moved to their optimum positions depending on speed, altitutde, throttle and stick settings. An intelligent autopilot facility allows the automatics to fly all phases of the mission profile, including ingress and egress to the target zone as well as landing and docking cycles. The intrumentation and control layout is basically convential, with a right-hand dispalcement-type control stick and left-hand throttles. About twenty fingertip controls on these handles give hand-on-throttles-and-stick control of sensors, weapons, defense-aids, etc. The avionics system is designed to facilitate maximum cockpit efficiency, the semi-intelligent software registering all flight information as required on the pilot’s wide[angle, heads-up dispay, and the three integrated Lorac multi-function displays.

These displays provide sensor-fusion presentations, map displays, armament status diagrams, checklists, etc. The pilot’s workload is reduced by a direct voice inout system, which may be employed for data entry, the selection of communication channels, and operate modes for the MFDs, as well as weapons selection. Navigation combines and intertial system with ring laser gyros and strapdown accelerometers, backed up by Global Positioning from references satellites where available. Raw sensor information from all sources is collated and processed by the Integrated Flight Tactical Data System (IFTDS), which largely handles flight related data and routes all tactically information through to two major sub-processors, both of which are integrated with the offensive and defensive systems. The first is the Advances Threat and Launch Indication System – ATLIS, which is designed to detect and identifiy threates to the dropship and then direct the defensive countermeasures systems against them.

The second is Target Identification and Acquisition System – TIAS, which processes battlefield target data and provides and interface between the crew and fire control systems. ATLIS is a powerful logic driver designed to evaluate threates from enemy aerospace craft, ant-aircraft artillery, and surface to air missiles, and compile a composite picture of the threat environment around the dropship. The picture is fed to the cokpit displays in the form of tactical displays, warnings, and menus of defensive option to meet any actual or potential threats. The Missile Defense System is a point defense system employed against incoming missiles in their terminal phase, usually within 1500 meters. The AAS-162 lidar acquires a missle then strobes a beam across its nose. This system is capable of dazzling a missile’s optical/infafred seeker, or feeding false range information to its laser fusing system. Nauturally, the MDS is ineffective against radar or jam-homing weapons not equiooed wiith laser fusing. Fire control for the dropship can be accessed by either the pilot or weapons officer, however, most of the weapons workload is handled by the back-seater. When not in combat, the weapons officer usually works “heads down” in the cokpit, monitoring the tactical data output from ATLIS and TIAS.

In practices, the weapons officer has responsibility for all targets in the tactical zone, though the pilot can engage targets immediately in front of the ship, and handles all the pint and shoot attacks, such as with the rockets. The fire control systems can either fire weapons automatically, as soon the target is within an optimum attack parameter, or can provide a firing indication for manual attacks. In the case of some unguided or unintelligent weapons, TIAS will command the fire control system to set the weapon fusing at the moment of launch according to the target type, and adjusts the aimpoint accordingly. The “L” Variant tactical transport carries a wide array of powerful weaponry that can be used in dedicated support of its troop complement. Two main weapons bays fold out on extended pylons to deploy weapon hardpoints capable of carrying 16 x 150 mm unguided rockets, 6 x 70 mm un guided rockets and 4 x 120 mm guided rockets each.

Two secondary bays on the port and starboard side of the fuselage house a further 14 hardpoints for air to air and surface to surface missiles. The dropship also mounts a dedicated 25 mm gatling gun in a powered cupola beneath the nose. The GAU-113B is a six barrel weapon driven by pneumatic motor turned by the engines at 6,000 rounds per minute and geared down to the rear of the gun. Rounds are caseless, and do not carry their own propellent. Instead, the GAU-113 system uses hyperholic liquid fuels, stored and loaded separately, as a binary propellant. When fed into the chamber via spray nozzles, they react simulatneous to explode and propel the shell. Ammunition comprises a mix of armor piercing indendiary, armor pierding discarding sabot and high explosive incediary, and is fed from a 900 round drum beneath the cockpit. In the colonial marines, the UD-4 is emploed as an integrated member of the aerospace/ground tactical team, having the capability to deploy troops and its own dedicated firepower direct from orbit to the operational area. Typical pay-loads into an operation landing zone may include up to four fully euipped infrantry squads or one M577 APC.

The Cheyenne also has the capacity to carry up to 16,000 kg of stores. Typical mission profiles include Assault Transport, CasEvac, Search and Rescue, Forward Supply, Close Air Support and REconnaisance. The UD-4’s flexiblity as a transport nd weapons platform has made it a ubiquitous workhorse within the corps. As explored previously on the channel, in the video Aliens and the Vietnam War, James Cameron and company drew heavy inspiration for the Dropship from 1960s Vietnam Era aircraft, creating a vehicle that combines timeless and futuristic elements. While we’ve only seen the dropship play a part in one film in the series, it’s remained an iconic and instantly recognizable element within the extended universe. The dropship has made appearances ranging from semi-cameos to large parts within the plots over a span of many comic books and novels within the extended universe, showing up as far timeline-wise within post-Alien Resurrection continuity with Alien: Sea of Sorrows.

It’s also featured in a great many video games related to the Alien franchise – a dropship bay commonly being a popular map we’ve seen used in games over the years. Do you think we’ll ever see it appear again in another movie? Would that be something you’d like to see? Comment below and let me know how you feel about the Alien series flying the friendly skies with the Cheyenne once again.

As always, I’d like to Thank you very much for watching. I really appreciate it, and If you enjoyed this video, please make sure to give it a like, and you can also subscribe for all the latest videos from the channel A very, very special thanks goes out to Weyland Yutani Executives EmYaruk, and Lady Anne, part of the Patreon Hive. If you’d like to join the hive and support the channel, check out my Patreon page for exclusive posts and contests. In the meantime you can catch up with Alien Theory over social media- follow @Alien_Theory on Twitter, and @AlienTheoryYT on Facebook and Instagram for more. And until next time, this is Alien Theory, signing off. .

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