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Atlas V 401
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The Atlas V 401 Launch Vehicle is a part of the flight proven Atlas V 400/500 family that is being operated by United Launch Alliance. Atlas V rockets are flown since 2002 and have a near-perfect success rate (one flight was a partial failure, however the mission was catalogued as a success). The Vehicle is operated from Launch Complex 41 at the Cape Canaveral Air Force Station, Florida and Launch Complex 3-E at Vandenberg Air Force Base, California. The vehicle is assembled in Decatur, Alabama; Harlingen, Texas; San Diego, California; and at United Launch Alliance's headquarters near Denver, Colorado.
Atlas V 401 is the smallest of the Atlas V Launcher Family featuring no Solid Rocket Boosters and a 4.2-meter Payload Fairing. The 401 configuration has two stages, a Common Core Booster and a Centaur Upper Stage. Centaur can make multiple burns to deliver payloads to a variety of orbits including Low Earth Orbit, Geostationary Transfer Orbit and Geostationary Orbit, Every Atlas V version has a three digit ID-Number: First Digit: Payload Fairing diameter: 4XX - 4m Diameter; 5XX - 5.4m Diameter Second Digit: Number of Solid Rocket Boosters (0-5) Third Digit: Number of RL-10A Engines on Centaur (1 or 2) |
Photo: NASA Kennedy
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Atlas V 401 Specifications
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| Type | Common Core Booster | |
| Inert Mass | 21,054kg | |
| Diameter | 3.81m | |
| Length | 32.46m | |
| Propellant | Rocket Propellant-1 (Kerosene) | |
| Oxidizer | Liquid Oxygen | |
| Fuel&Oxidizer Mass | 284,089kg | |
| Guidance | From Centaur | |
| Propulsion | RD-180 Engine (2 Chambers) | |
| Type | Staged Combustion | |
| Thrust at Sea Level | 3,827kN | |
| Isp SL | 311s | |
| Thrust (Vacuum) | 4,152kN (933,369 lbf) | |
| Isp Vac | 338s | |
| Egnine Length | 3.56m | |
| Engine Diameter | 3.15m | |
| Engine Dry Weight | 5,480kg | |
| Chamber Pressure | 266.8bar | |
| Nozzle Ratio | 36.87 | |
| Thrust to Weight | 78.22 | |
| Area Ratio | 36.4 | |
| Ox. To Fuel Ratio | 2.72 | |
| Attitude Control | Gimbaled Engine (8 Degrees) | |
| Throttle Capability | 50-100% | |
| Burn Time | 253 sec | |
| Tank Pressurization | Helium | |
| Avionics | Flight Control, Flight Termination | |
| Telemetry, Rate Gyros, Power | ||
| Stage Separation | 8 Retro Rockets |
Photo: NASA
Interstage Adapter
| Section 1 | Cylindrical Section | |
| Diameter | 3.05m | |
| Length | 2.52m | |
| Section 2 | Conical Section | |
| Diameter | 3.81m | |
| Length | 1.61m | |
| Mass | 947kg | |
| Structure | Composite (Graphite Epoxy) | |
| Aluminum Ring Frames |
Aft Stub Adapter
| Diameter | 3.05m | |
| Length | 0.65m | |
| Mass | 181.7kg | |
| Structure | Aluminum Monocoque | |
| Separation | Frangible Joint Assembly | |
| Separation System |
Centaur Upper Stage
| Type | Centaur | |
| Diameter | 3.05m | |
| Length | 12.68m | |
| Inert Mass | 2,243kg | |
| Propellant | Liquid Hydrogen | |
| Oxidizer | Liquid Oxygen | |
| Fuel&Oxidizer Mass | 20,830kg | |
| Guidance | Inertial | |
| Propulsion | 1 RL 10A-4-2 | |
| Thrust | 99.2kN | |
| Isp Vac | 451s | |
| Engine Length | 3.53m | |
| Engine Diameter | 1.53m | |
| Engine Dry Weight | 167kg | |
| Chamber Pressure | 39bar | |
| Thrust to Weight | 61 | |
| Area Ratio | 84 | |
| Burn Time | Variable | |
| Engine Start | Restartable | |
| Attitude control | 4 27-N Thrusters | |
| 8 40-N Thrusters | ||
| Propellant | Hydrazine |
Photo: Pratt&Whitney Rocketdyne
Payload Fairing
| Fairing | Aluminum Skin Stringer | |
| Frame Clampshell | ||
| Boattall | Aluminum Skin Stringer | |
| Frame Clampshell | ||
| Separation | Pyro Bolts | |
| Spring Jettison Actuators |
| Type | LPF | |
| Diameter | 4.2m | |
| Length | 12.0m | |
| Mass | 2,127kg |
| Type | EPF | |
| Diameter | 4.2m | |
| Length | 12.9m | |
| Mass | 2,305kg |
| Type | XEPF | |
| Diameter | 4.2m | |
| Length | 13.8m | |
| Mass | 2,487kg |
Photo: NASA Kennedy
Launch Vehicle Description
Atlas V 401 stands 58.3 meters tall and has a main diameter of 3.81 meters. With a liftoff mass of 334,500 Kilograms, it is the light-weight of the Atlas V Fleet as the 401 version does not feature any Solid Rocket Boosters. The Launcher uses the conventional Atlas V design with a Common Core Booster and a Centaur Upper Stage on top of it. Atlas V 401 features a 4.2-meter payload Fairing under which it can carry payloads of up to 10,470 Kilograms to Low Earth Orbit. Geostationary Transfer Orbit Capability is 4,750 Kilograms.
Common Core Booster
The first Stage of the Atlas V 401 is an Atlas Common Core Booster that is 32.46 meters long and has a diameter of 3.81 meters. With an inert mass of 21,054 Kilograms, the Common Core booster can hold up to 284,089 Kilograms of Rocket Propellant-1 and Liquid Oxygen that are consumed by the single RD-180 Main Engine of the vehicle. RD-180 is being manufactured by NPO Energomash. It is a two-chamber staged combustion engine that provides 3,827 Kilonewtons of liftoff thrust and 4,152 Kilonewtons of vacuum thrust. RD-180 maintains a high-pressure staged combustion cycle employing an Oxygen-rich preburner. It runs with an oxidizer to fuel ratio of 2.72. The drawback of an oxygen-rich combustion is that high pressure, high temperature gaseous oxygen must be transported throughout the engine. The nominal chamber pressure is 267 bar. RD-180 is capable of being throttled from 50% to 100% of rated performance. The engine is based on the RD-170 engine that features four combustion chambers. First Stage control is accomplished by gimbaling the RD-180 nozzles by up to 8 degrees. Engine gimbaling is achieved via the vehicles hydraulics system. The first stage propellants are held inside aluminum isogrid tanks; tank pressurization is accomplished with high-pressure Helium that is stored in Helium Bottles on the Common Core Booster. Tank pressurization is computer-controlled. The Common Core Booster is equipped with a Flight Termination System that can be used to destroy the vehicle in the event of any major malfunction. Also, the CCB is outfitted with redundant Rate Gyros to acquire navigation data. Internal Batteries provide power during powered ascent and an independent telemetry system is utilized for data downlink. First stage separation is initiated by pyrotechnics and the core stage ignites eight retro rockets to drop away from the launcher.
Photo: NASA Kennedy
Interstage Adapter
The first and second stage of the Atlas V launch vehicle are connected by a Interstage Adapter (400-ISA) that is used to join the two stages of the vehicle that feature different diameters. It consists of a cylindrical section that is 3.05 meters in diameter and 2.52 meters in length as well as a conical section with a maximum diameter of 3.81 meters and a length of 1.61 meters. The composite structure is equipped with Aluminum Ring Frames (forward and aft) and weighs 947 Kilograms.
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Centaur Upper Stage
The Upper Stage of the Atlas V 401 is a single-engine Centaur Stage. Centaur is 3.05 meters in diameter and 12.68 meters in length with an inert mass of 2,243 Kilograms. Centaur is a cryogenic rocket stage using Liquid Hydrogen and Liquid Oxygen as propellants. A total of 20,830 Kilograms of propellants can be filled into the vehicle's pressure stabilized stainless steel tanks. The LOX and LH2 Tanks are separated by a common ellipsoidal bulkhead. Centaur is powered by a RL-10A-4-2 engine that is manufactured by Pratt & Whitney Rocketdyne and provides 99.2 Kilonewtons of thrust. The engine uses an expander cycle and operates at a chamber pressure of 39 bar. It is 3.53 meters in length, 1.53 meters in diameter and features a Nozzle Extension. RL-10 has a certified burn time of up to 740 seconds and can make multiple engine starts. It has a dry weight of 166 Kilograms and an expansion ratio of 84:1 achieving a thrust to weight ratio of 61:1. RL-10 can be gimbaled with a electromechanical system to provide vehicle control during powered flight. During Coast Phases, the vehicle's orientation is controlled by Centaur's Reaction Control System. Eight lateral 40-Newton Thrusters and four 27-Newton Thrusters are used for attitude control. The System uses Hydrazine propellant. The Centaur Upper Stage houses the Atlas V Flight and Guidance Computers that are capable of autonomously performing the mission controlling all aspects of the flight. The fault-tolerant inertial navigation unit is located on the Centaur forward equipment module.
In the aft section of the Centaur Upper stage is an ASA - Aft Stub Adapter that is 3.05 meters in diameter and 0.65 meter in length. ASA has a mass of 181.7 Kilograms and consists of a Aluminum Monocoque. It is separated by a Frangible Joint Assembly Separation System.
In the aft section of the Centaur Upper stage is an ASA - Aft Stub Adapter that is 3.05 meters in diameter and 0.65 meter in length. ASA has a mass of 181.7 Kilograms and consists of a Aluminum Monocoque. It is separated by a Frangible Joint Assembly Separation System.
Photo: NASA Kennedy
Payload Adapter
Payload Adapters interface with the vehicle and the payload and are the only attachment point of the payload on the Launcher. They provide equipment needed for spacecraft separation and connections for communications between the Upper Stage and the Payload. The separation system can be based on either the traditional pyrotechnical-initiated bolt cutters/separation nuts or Low-Shock Marmon Type Clamp Band Separation System. For Atlas V, a Launch Vehicle Adapter interfaces with the SIP (Standard Interface Plane) of the Launcher and connects to the Standard Payload Adapter or custom-made adapters. Four off-the-shelf adapters are available to accommodate various payloads. Also, custom made fairings can be fitted atop the Launch Vehicle Adapters to accommodate a variety off different payload requirements.
Payload Fairing
The Payload Fairing is positioned on top of the stacked vehicle and its integrated Payload. It protects the spacecraft against aerodynamic, thermal and acoustic environments that the vehicle experiences during atmospheric flight. When the launcher has left the atmosphere, the fairing is jettisoned by pyrotechnical initiated systems. Separating the fairing as early as possible increases launcher performance. The Atlas V 401 Rocket features fairings with a diameter of 4.2 meters. Three different fairing lengths are available: 12.0, 12.9 and 13.8 meters. Major sections of these payload fairings are the boattail, the cylindrical section, and the nose cone that is topped by a spherical cap. Both fairing and boattail sections consists of Aluminum Skin Stringers and Frame Clampshells. The fairing is separated by pyro bolts and spring jettison actuators that push the two halves away from each other. Payload Fairings are outfitted with acoustic panels, access doors and RF windows. Optional fairing hardware includes thermal shields and ECS doors. Also, the Payload Fairing is connected to a purge air system to ensure a controlled environment
Photo: NASA Kennedy
Atlas V 401 Configuration
