T-45d power armor

The T-45d Power Armor was the first version of Power Armor to be successfully deployed in battle and is the most basic Power Armor model in Fallout 3.

Originally built by the United States Military, it is currently employed by several factions, including the Brotherhood of Steel and the Brotherhood Outcasts. Each of these groups have their own variant of Power Armor.

History
In 2067, the first T-45d suit was deployed in Alaska during the Anchorage Reclamation. This Power Armor was incredibly effective against Chinese tanks and infantry. Its ability to carry heavy ordinance became key in various localized conflicts, and it allowed soldiers to destroy entire towns without endangering themselves. In 2076, the more advanced T-51b was introduced.

Nearly two centuries later, around a hundred T-45d suits were discovered by the Capital Wasteland Brotherhood of Steel in the ruins of the Pentagon and were extensively used, with modifications and makeshift repairs.

Design
The T-45d lacks the mobility of newer models (such as the T-51b Power Armor); it limits the wearer's agility. The first version deployed on the front lines operated on Small Energy Cells and it burned through them at an alarming rate. Some later versions were either manufactured or retrofitted with built-in microfusion packs.

While it is similar in general shape to the more advanced T-51b Power Armor, it is significantly more primitive, using riveted steel plates instead of composite materials for construction. Various subsystems of the armor are exposed on the outside rather than sealed within. In addition, a specialized body suit is required to be worn in order to use the armor.

Variants
Wearing Power Armor requires the player to receive Power Armor Training by talking to Paladin Gunny in the Citadel, by completing the Anchorage Reclamation simulation (Operation: Anchorage), or have acquired Ashur's Power Armor and left The Pitt (The Pitt (add-on)). In addition, it can be unlocked via console commands in the PC version with.

T-45d Power Armor can be repaired with the T-51b Power Armor, but the reverse cannot be done. It might be a bug or it might be the fact that the T-51b Power Armor is more advanced and uses parts that cannot be substituted with T-45d parts.

Power Armor
Regular Power Armor can be acquired from merchants, although they rarely appear in stock. You also receive a complete suit of Power Armor in 100% condition from Sarah Lyons at the beginning of the game's final quest, Take it Back!. It can also be acquired from some fallen Brotherhood of Steel members. Power Helmets can be found from merchants and fallen Brotherhood of Steel members.

Brotherhood Power Armor
This variant is found on most fallen Brotherhood members and has the same appearance and attributes as regular Power Armor. There are no differences other than the name and that it will not appear in merchant stock (This armour is very rare since most Brotherhood members' inventories are placed with "normal" T-45 Power Armour).

Outcast Power Armor
Outcast Power Armor can be acquired from the corpses of fallen Outcasts and from Fort Independence. However, having Outcast variants in your inventory (equipped or not) when speaking to Protector Casdin will cause him to confiscate the armor unless you have gained the Outcasts' trust. Outcast Power Helmets can be acquired from fallen Outcasts.

Lyons' Pride Power Armor
Lyons' Pride Power Armor is the same as regular Power Armor, except that the Lyons' Pride insignia is on the shoulder instead of the standard Brotherhood insignia. It can be acquired from the corpses of dead Lyons' Pride members or reverse-pickpocketing: Sentinel Lyons, Knight Captain Gallows, Paladin Vargas, Paladin Glade, Paladin Kodiak and Knight Captain Dusk.

Army Power Armor
Army Power Armor & Helmet can only be acquired on the PC version using console commands or modified save files through Hex modding. It has a US army band on each shoulder.

Linden's Outcast Power Armor
A unique Outcast Power Armor obtained as a quest reward for completing the quest Oasis in Leaf Mother Laurel's favor.

Prototype Medic Power Armor
This is a variation of the Army Power Armor and can only be found in the Old Olney sewers. This suit automatically applies Med-X and can alert you about threats in the area.

Ashur's Power Armor
Ashur's Power Armor is a unique version of the Tribal Power Armor and is only found with The Pitt add-on. It is worn by Ashur, leader of The Pitt.

Tribal Power Armor
Tribal Power Armor is only found with The Pitt add-on. It can be aquired by giving 100 Steel Ingots to Everett for the unmarked side quest Mill Worker.

IDs
There are several variants of this armor model; each of these variants have a different Base ID as given in the following table.

Behind the scenes

 * The history of the T-45d was mentioned in the Fallout Bible timeline, while its designation was first mentioned in the Van Buren tech demo by Corporal Armstrong who wears the armor. The armor itself is ubiquitous in the Capital Wasteland, and the Museum of Technology has a log of proposed exhibits for 2078, which includes a suit of T-45d Power Armor.
 * According to the Fallout 3 art book, the Power Armor was designed directly in 3D, skipping the concept art phase.
 * A texture for a Pink Power Armor can be found in the "Fallout - Textures.bsa" file. It has a white heart on its chest.

Quotes

 * "Though that design was intended for the "real" F3 power armor (T-51b), we wanted to have an alternate texture for the armor Armstrong describes, T-45d, which ran off small energy cells. It would only have appeared in the tutorial as a "back in the day" detail." - J.E. Sawyer
 * "I [...] have fifty three hours of field experience in the T-45d Power Armor, citizen. Most of those were during the Anchorage Reclamation.[...]This T-45d eats up small energy cells like Chans at a rice buffet!" - Corporal Armstrong