T-45 Power Armor

T-45 power armor is a power armor model in Van Buren, Fallout 3, Fallout: New Vegas, Fallout 4, and Fallout 76.

Background
 The T-45 powered combat infantry armor was the first design pressed into service in the Sino-American War, with its first deployments taking place on the Alaskan Front to counter the Chinese offensive. The speed at which it had to be deployed, less than two years after the development of power armor began, resulted in the creation of a stop-gap model utilizing existing technologies and manufacturing techniques. This temporary solution would eventually become the mainstay of American power armor units, especially as subsequent upgrades reduced the impact of the mobility problems that plagued the early production runs. The most important was the implementation of back-mounted fusion packs, rather than relying on the limited supply of small energy cells, consumed by the armor at an alarming rate.

The T-45 model D (its most popular variant) is designed for a single operator and is patterned closely after the human silhouette. It consists of three layers. The first is a black body suit worn by the operator for comfort, insulation, and protection from injuries that may be sustained during the armor's operation. The second layer of the armor is part of the power armor proper. Commonly referred to as recon armor when used on its own, it is a full body suit made of thick, processed fabric with integrated metal plating that serves as a platform for attaching the armor and on-board hardware. The recon armor is, in effect, the underlying chassis of the T-45d power armor model. Its attachment points and power cell plug at the nape of the neck are essential for the operation of the full T-45d power armor, as the third layer consists of the armor, the fusion power cell, as well as the hydraulics and servomotors that allow the operator to carry heavy ordnance into combat and bear the weight of the armor. The helmet completes the third layer and includes an air filtration system, a bullet-proof vision slit, an electric lamp, and external ports that allow the operator to listen to his surroundings and double as attachments points for extensions. The standard upgrade is a drop-down ocular.

The ability to operate crew-served weapons and heavy ordnance alone is one of the key advantages offered by the T-45d power armor. Although the T-45d (and indeed, no power armor to date) had no built-in weapons, the operator could use any kind of weapon that could be fired by an infantryman. Protection came in second. The use of steel plating offered a considerable advantage against most small arms and used existing technologies and materials, allowing the U.S. to quickly manufacture and deploy T-45d suits. However, the armor had its limits and as the war with China dragged on, it became insufficient in both the ability to deploy firepower and protect the operator. However, as the T-51 power armor model did not arrive until 2076, the T-45d became the workhorse of the American military and a test-bed for related technologies.Fallout Bible 0: "2055 The West Tek Research Facility starts working on a new virus to kill the New Plague. Their viral research and close ties to the federal government eventually lead to them being chosen for the Pan-Immunity Virion Project twenty years later as well as Power Infantry Armor and laser research. 2065 August Increasing need for mobility in the United States mechanized cavalry leads the military to focus the efforts on creating a man-based tank - essentially, a two-legged walking armored unit: Power Armor. 2065-2067 Power Armor research grows and several prototypes are developed, many of which prove to be unworkable in the field. These prototypes pave the way for future advances in military, construction, and fusion technology. 2066 Summer ''Adding further insult to the Chinese-American relations, the first crude fusion cell is unveiled, one of the results of the Power Armor project. Devices designed for the fusion cell begin to be manufactured. Incorporating fusion power into the general US infrastructure begins, but the process is too slow to supply power to the regions that need it. Nearly eleven years later, few sections of the United States were supplied with fusion power.'' 2067 ''The first suit of Power Armor is deployed in Alaska. While lacking the full mobility of future versions, this Power Armor is incredibly effective against Chinese tanks and infantry. Its ability to carry heavy ordinance becomes key in various localized conflicts, and it has the power to destroy entire towns without endangering the wearer. China rushes to create its own versions, but they are many years behind the United States.'' 2074	Contrary to their claims of seeking only to retake Alaska from the Reds, American Power Armor units, infantry, and mechanized divisions are deployed to China, but they become bogged down on the mainland, putting a further drain on American resources and supply lines. 2076 June ''Power Armor prototype completed, resulting in the Power Armor players find in Fallout 1. This is the pinnacle of Power Armor technology before the Great War. Many of these units are sent to China, and they begin to carve a swath through the Chinese forces. The Chinese resources are strained to the breaking point, and the supply lines from the nations China has annexed begin to break down.'' 2077 January 22 ''The first domestic use of Power Armor within the United States for crowd and quarantine control. Units originally serving in China and the Anchorage Front Line find themselves fighting Americans at home. Food riots increase, and many civilians are killed. Several soldiers defect from the military both in Canada and the United States. They are captured, and are sent to military prisons.'' 2198 ''Enclave works on various new technologies, including Power Armor variations. None of these are much of an improvement over the conventional old school Power Armor, and some are actually worse.'' 2215 ''Under Presidential Order, Enclave scientists begin to work on an upgraded version of Power Armor. Many prototypes are developed and tested.'' 2220 October ''Enclave scientists develop a reliable version of the Mark II Power Armor. The prototype results (and accidents... and explosions... and deaths) are classified by order of the President Richardson for the sake of morale."''

Following the Great War, the T-45d power armor became a rare sight and a powerful asset for anyone who can procure such a suit. The principal operator of the armor is the Brotherhood of Steel and its children chapters, with the largest known numbers being utilized by the rogue Lyons' Brotherhood of Steel and the loyalist Outcasts. In general, off-duty troops and trainees prefer to wear the armor without the armored layer, allowing them to quickly deploy when needed, but without the encumbrance of full power armor.

T-45a model


An early version of the standardized T-45d, the T-45a model is similar in design to its successors. In-game, it offers less performance and protection than later models. In Fallout 4, the T-45a model is seen rusted and deteriorating, dissimilar to the later T-45 models with gray metal chassis and increased protection in-game.

T-45d basic model


The workhorse of the Brotherhood of Steel, the standard T-45d offers good performance and has been often modified by its owners for personal use. The most basic modification is alteration of the sigils on the armor's pauldrons:
 * Army power armor
 * Lyons' Pride power armor
 * Brotherhood T-45d power armor

MP-47/A prototype medic power armor


An upgrade of the standard T-45d power armor model, using the revised T-47 model (A variant). Although the external shell remains the same as in T-45d models, the MP upgrade was designed to reduce the volume of training necessary to operate power armor effectively, through the use of an onboard computer with a verbal feedback system.

More importantly, the MP upgrade included an automated delivery system for various medical substances (Stimpaks and other injectables), and was planned to offer enhanced command level data collection system for field officers, and a self-destruct system that would kill deserters wearing the armor through lethal injection. Unfortunately, the only extant prototype was made before the defense contract was extended for the company that developed the upgrade, and is only capable of injecting Med-X.

In game terms, the suit will use Med-X from the player's own inventory whenever their health drops beneath 33% or a limb's condition falls below 25%. The injection cannot cause addiction.

Outcast model


Modified by the Brotherhood Outcasts to improve recognition at range, this T-45d power armor boasts a dark black livery with red accents and Outcast emblems on the pauldrons. It is worn with a matching Outcast recon armor, though the Outcasts tend to wear the armor regardless of their duty status.
 * Linden's Outcast power armor is an unique variant optimized for heavy weapon use.

Tribal power armor


An unique, informal variant of the standard T-45d, as a result of the god-like status of Ishmael Ashur of The Pitt. Without access to proper workshops and raw materials, Ashur had to maintain his T-45d power armor in working order with whatever was at hand. The end result is an unique, copper-colored suit with yellow accents, and a patchwork of fixes and replacement parts, the most noticeable of which include the sleeve and glove of the raider iconoclast armor in lieu of a proper left arm, a brahmin skull instead of the left pauldron. Copies of the armor were created basing on salvaged T-45d suits by Ashur's faithful, in the image of their ruler. 
 * Ashur's power armor

NCR salvaged power armor


A post-War variant of the standard T-45d, created out of suits salvaged from fallen Brotherhood of Steel Paladins by the New California Republic Army during the Brotherhood War. Although damage to the armored shell has been repaired, Army technicians have stripped out the joint servomotors and replaced the back-mounted fusion cell with a custom-made unit. Troops outfitted with the armor are slow and clumsy, but they are capable of taking a lot of punishment and remain in combat. To limit friendly-fire incidents, the armor's pauldrons were removed and identification markings (the Bear and Star on the chest and red stripes on the arms) painted on the armor.

Sierra power armor


 An unique variant of the standard T-45d power armor fielded by the New California Republic Army, the Sierra power armor is exceedingly rare and to date only a single soldier, Colonel Royez, is known to have used one. Instead of the base dark grey color of the T-45d, the Sierra power armor has an unique livery: Purple with golden accents on the edges, with additional neon green and red highlights on arbitrary points of the armor. A taxidermied bear's head has also replaced the left pauldron, held in place by a pair of bronze clips bearing the Republic's star.

The Sierra power armor has been upgraded with additional onboard medical systems, helping regenerate the injuries of the user, and a back-mounted power pack superior to the production-run power cells the standard T-45d uses. 

Behind the scenes

 * The designation of the armor was first given in the Van Buren tech demo by Corporal Armstrong who wears the armor, but the connection between it and the Fallout 3 power armor wasn't made until Fallout: New Vegas.
 * The Art of Fallout 3 states that the armor was created as a 3D model from scratch, in order to capture the mood of the game being developed.