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Vulcan Centaur as Illustrated on April 13, 2015
ULA Announces Vulcan
At the 31st Space Symposium on April 13, 2015 , United Launch Alliance (ULA) announced that its Next Generation Launch System (NGLS) would be named "Vulcan", after the Roman god of fire. The company also revealed plans for a step-by-step Vulcan development process that would keep some existing EELV elements in service for years.
During the first step, a new booster stage will replace the existing Atlas 5 Common Core Booster (CCB). The new 5.4 meter diameter booster will be powered, as previously announced, by two Blue Origin BE-4 LOX/LNG engines. It will lift existing Centaur stages and existing four or five meter diameter payload fairings. As many as four solid rocket boosters (SRBs) can be added to augment the four meter rocket, while up six SRBs can boost the five meter rocket. The solids will also be offered for competitive bidding, but are expected to be similar to the existing Aerojet Atlas 5 solids.
With six SRBs and a Centaur within a 5.4 meter fairing, Vulcan would lift more payload than Atlas 5-551, but less than Delta 4 Heavy.
During the second step, the Centaur second stage will be replaced by a heavier and more powerful stage named Advanced Cryogenic Evolved Stage (ACES). ACES will carry three times more LH2/LOX propellant than Centaur and will produce more thrust than Centaur. ACES will also feature an "Integrated Vehicle Fluids" system that will use existing propellant boil-off gases for thrusting, pressurization, and electricity generation, eliminating or reducing hydrazine and helium systems and batteries. Another competition will be held to determine which engine or engines will power ACES. Contenders include RL10, Blue Origin's BE-3U, and an XCOR engine. With six SRBs and ACES, Vulcan will be able to outlift the existing Delta 4 Heavy.
A tri-core "Vulcan Heavy" topped by an ACES could conceivably lift an impressive 22.6 tonnes to geosynchronous transfer orbit - 1.6 times more than Delta 4 Heavy - but development of such a heavy-lifter is unlikely.
ULA will consider recovery of the BE-4 engines, using a heat shield, a parachute, and helicopter air recovery.
ULA's existing Delta 4 Medium will be phased out beginning in 2018, as Vulcan with
Centaur begins to fly. Delta 4 Heavy will be phased out later, likely when ACES
begins to fly in 2023. When Delta 4 Heavy stops flying, one launch pad on each coast
will be retired. Retiring Delta 4 will free up 5 meter tank tooling for Vulcan.
ULA/Blue Origin to Develop Powerful New Engine (September 17, 2014)
BE-4 Model at Press Conference
On September 17, 2014, United Launch Alliance and Blue Origin, a privately held company
owned by Amazon.com founder Jeff Bezos, announced that they were teaming to jointly fund
development of Blue Origin's new BE-4 rocket engine. The development effort would last
four years, with full-scale testing in 2016 and first flight in 2019. The new engine would
be available for use by both companies.
The phrase "Next Generation Launch System" (NGLS) has been linked with ULA's BE-4 powered design. The company was expected to reveal details of NGLS during 2015.
NGLS is likely to be designed to use existing launch pads, upper stages, and payload fairings to the greatest extent possible. Since LNG is less dense than kerosene, one possibility is that ULA will use Delta 4 Common Booster Core 5.1 meter diameter tanks for the BE-4 powered first stage. This would allow the first stage to be the same height as the Atlas 5 Common Core Booster first stage, which is about 4.2 meters shorter than the Delta 4 CBC. Since two BE-4 engines would produce a bit more thrust than a single RD-180 engine at liftoff, the NGLS first stage would likely weigh an equivalant amount more than the Atlas 5 first stage.
At liftoff, the NGLS first stage thrust could be augmented in some vehicle variants by solid rocket motors (SRBs) similar to those that power Atlas 5. At 1.55 x 17.7 meters and weighing more than 46 tonnes loaded, the composite case, single-segment Atlas 5 motors produce 172 tonnes of thrust at liftoff. ULA may want to increase the number of SRBs beyond the maximum of five used by Atlas 5 to provide a variant capable of replacing Delta 4 Heavy. This NGLS Heavy would require a new, or upgraded, upper stage, but once developed would be able to perform EELV Heavy missions using a single-core vehicle.
For NGLS, ULA is likely to initially continue use of the Atlas 5 Centaur, the descendant of the world's first liquid hydrogen/oxygen upper stage. Centaur uses stainless steel balloon tanks, with the lower LOX and upper LH2 tanks separated by a common elliptical bulkhead. The Atlas 5 Centaur is transitioning from its original restartable Pratt & Whitney RL10A-4-2 engine to an updated Aerojet Rocketdyne RL10C-1 engine. Both use a fixed carbon-carbon composite nozzle extension. RL10C-1 produces 10.383 tonnes of thrust at about 450 seconds ISP, compared to RL10A-4-2 thrust of 10.12 tonnes of thrust at 450.5 seconds ISP.
ULA will likely want to replace the RL10C-1 engines at some point in the future with a new, more efficient 15 tonne thrust class engine.
Thin-skinned Centaur cannot easily support the 5.4 meter diameter payload fairing, so the existing Atlas 5 setup that uses a Contraves 5.4-meter diameter composite fairing to enclose Centaur and transfer the payload fairing mass to the first stage will likely be used. This approach was originally used for the Centaur stages on Titan 3E and Titan 4. The fairing itself was derived from Ariane 5 designs.
ULA currently launches Atlas 5 from Cape Canaveral Space Launch Complex (SLC) 41 and Vandenberg AFB SLC 3 East. It also launches Delta 4 from Cape Canaveral SLC 37B and Vandenberg AFB SLC 6. At the Cape, Atlas V is assembled in a new 85.4 meter tall Vertical Integration Facility (VIF) and transported 550 meters on a mobile launch platform to the pad no more than 24 hours before liftoff. The Vandenberg pad uses a conventional mobile service tower, rather than a "clean pad".
The company will want to consolidate these costly launch support facilities for NGLS. If a single-core NGLS can be designed to perform a range of missions from EELV Medium to EELV Heavy, it should be possible to retire Delta 4, allowing the company to abandon SLC 6 and SLC 37B. NGLS could then fly from updated SLC 41 and SLC 3 East. In this scenario, NGLS will also replace Atlas 5, allowing ULA to end use of Russian-made engines.
September-October 2015 Developments
During September 2015, ULA announced that it had rejected a $2 billion take-over bid by Aerojet-Rocketdyne. The company also announced that it would expand co-production capacity for Blue Origin's BE-4 engine. Finally, ULA announced that it had selected Orbital ATK to produce solid motors for both Vulcan and for Atlas 5 beginning before the end of 2018.
The new GEM-63 (63 inch diameter) motors would generally replicate the dimensions and performance of the existing Aerojet Rocketdyne AJ-60A motors used by Atlas. GEM-63XL motors, stretched about 1.52 meters compared to the GEM-63 motors, will power Vulcan. The stretched motors would likely carry 5-10% more propellant and provide about 5-10% more thrust compared to GEM-63.
The announcement further reduces Aerojet Rocketdyne's ULA work. Vulcan will end use of RD-180, RS-68A, and AJ-60A, leaving only the RL-10 upper stage motor. The upper stage motor will likely be competed when the stage is upgraded.
During October, ULA announced that Vulcan would fly from the two existing Atlas 5 launch sites, SLC 41 at Cape Canaveral, Florida and SLC 3E at Vandeberg AFB, California. Both pads would be modified to handle Vulcan, but the modifications would not interrupt Atlas operations, which would continue flying for several years into the 2020s. Modifications would include the installation of liquified natural gas equipment. The Vulcan maiden flight was expected to occur during 2019. The existing Delta 4 pads would remain in service until the ACES stage was developed for Vulcan, perhaps as soon as 2023, several years after the new rocket initially began flying with Centaur. The final Delta 4 Medium flight would take place in 2019, but Delta Heavy would keep flying until the Vulcan/ACES heavy version had proved itself in flight.
ULA was planning for one of two possible Vulcan
first stage designs. A 2 x BE-4 powered version would be at least 5.08 meters (200
inches) in diameter. Some hints suggested that the diameter could grow to as much
as 5.4 meters, the same as the payload fairing. A 2 x AR-1 version would be 3.81
meters (150 inches) in diameter, the same as the Atlas 5 CCB. ULA's primary plan
remained BE-4, with AR-1 as a backup. The final engine decision was expected to be
made before 2016.
April-May 2017 Updates
First BE-4 Rolls Out at Blue Origin during March, 2017
During mid-April, 2017, ULA President and CEO Tony Bruno confirmed that Vulcan would use 5.4 meter diameter tanks. The new tanks, fatter than even the Delta 4 tanks, would be fabricated by friction stir welding four orthogrid panels together. Use of the orthogrid design, replacing the previous isogrid, will play a role in reducing production time by half.
Earlier in the same month, Bruno had confirmed that a final propulsion decision between BE-4 and AR-1 would be made by the end of 2017. At the time, BE-4 was expected to begin full-scale testing within a few weeks. The results of that testing would inform ULA's decision.
Blue Origin had rolled-out its first BE-4 engine during March, 2017. The engine was delivered to the company's Texas test site for full-scale testing.
During May, 2017, Blue Origin suffered a BE-4 "power pack" failure at the company's West Texas test site. The failure appeared to set back development efforts for several months since the expected full-scale BE-4 engine test did not take place "within a few weeks" after its delivery as originally announced.
BE-4 Hot Fire Success
On October 18, 2017, after months of delay following a May 2017 power pack test failure, Blue Origin performed an initial successful hot fire test of its full-scale BE-4 engine. The engine was fired at 50% thrust for about three seconds at the company's West Texas test facility.
On October 10, 2017, ULA CEO Tory Bruno announced, in a Space News opinion piece, that ULA had decided to modify Vulcan’s Centaur stage to meet heavy lift requirements provided in the October 5, 2017 U.S. Air Force EELV Launch Services Agreement RFP. The specification listed payload masses for nine reference orbits. Bruno stated that the change would add about six months to the original program schedule.
Original plans had called for the existing "Centaur 3" stage currently flown atop Atlas 5 to serve as the second stage for an initial Vulcan Centaur variant.
Later, in a question and answer session on Reddit, Bruno revealed that the upgraded stage would be named "Centaur 5" and that it would be 5.4 meters diameter, a substantial increase from the current 3.048 meters. He also noted that while Centaur 5 would bring the heavy lift capabilty forward sooner, the previously-planned ACES stage would still be needed to provide long duration and in-orbit reusability. He said that ACES and Centaur 5 would use the same tooling. He also said that ULA had not yet selected an ACES engine, suggesting that Centaur 5 would still be powered by RL10 engines.
Although ULA had not revealed details of Centuar 5 by month's end, it was clear that the stage would have to carry substantially more propellant than the existing Centaur 3 stage. Such a stage would almost certainly need two or more RL10 engines.
Vehicle Components, Cont'd (Atlas 5 Fairings Shown, Vulcan Details TBD)
====================================================================================== ====================================================================================== Date Vehicle ID Payload Mass Site* Orbit Orbit kg (kmxkmxdeg) Type** ---------------------------------------------------------------------------------------- NN/NN/NN NGLs NNNNN NNNNN NNNN CC41 NNNxNNNNNxNN.NN AAA ---------------------------------------------------------------------------------------- *Site Code: CC = Cape Canaveral, FL, USA CC37B = Space Launch Complex 37B: Delta 4 CC41 = Space Launch Complex 41: Atlas 5 VA = Vandenberg AFB, CA, USA VA3E = Space Launch Complex 3E: Atlas 5 VA6 = Space Launch Complex 6: Delta 4 **Orbit Code: References
Atlas Launch Systems Mission Planners Guide, Atlas V
Addendum, January 1999
Last Update: November 05, 2017