Yes, the figure in http://www.ulalaunch.com/site/docs/products/Cutaways/DeltaIVHeavy_Cutaway.pdf indicates that the strap-on cores are mirror images, at least as far as the external attachment points go.
Quote from: ChileVerde on 06/02/2012 04:34 pmYes, the figure in http://www.ulalaunch.com/site/docs/products/Cutaways/DeltaIVHeavy_Cutaway.pdf indicates that the strap-on cores are mirror images, at least as far as the external attachment points go. Same goes for the tail service mast umbilicals. Which means the internal plumbing is different, which is the big impact.
Well, that's interesting. I wonder whether it would be worthwhile to design a symmetrical strap-on that could be used on either side. Probably not, unless the flight rate of D4H increases considerably.
Same goes for the tail service mast umbilicals. Which means the internal plumbing is different, which is the big impact.
Is it right to think some of the move to CBC commonality is driven by a USAF desire for flexibility in the order in which payloads are launched? It must be frustrating when they have a payload that's ready to fly, and a booster that's ready to fly, but the booster was built for a different payload. (That would happen if the original payload for that booster were delayed, for example.)In that case, the Heavy configuration is a whole different beast. Those three CBCs are going to be built to fly together, with no thought of swapping one of them in if a medium payload is ready to fly sooner than the heavy payload.
ATK recently demonstrated a thrust-vectoring GEM-60.http://www.parabolicarc.com/2012/06/01/atk-ula-conduct-ground-test-of-delta-iv-solid-rocket-motor/Is there some reason for this within the Delta IV program? Is the RS-68A thrust vector control in any way less capable than that of RS-68?
702k lbs/f of thrust. That's impressive for a hydrolox engine. Never thought they would be able to get it up that high.
http://www.aerospace.org/wp-content/uploads/docs/Aerospace_AR-2011.pdfAerospace Corporation FY2011 Annual ReportDELTA IV HEAVY UPGRADE PROGRAMThe design certification review for the NRO-funded Heavy Upgrade (HUG) program was conducted in May 2011, culminating a five-year design and development cycle to increase heavy-lift mass-to-orbit performance to meet NRO mission-unique requirements. Flight performance has been increased to 14,500 lbm to geosynchronous orbit and 47,000 lbm to low Earth orbit from the East Coast. The performance improvements were gained through a combination of RS-68 engine performance enhancements, vehicle design modifications, and operational changes. In addition, reliability improvements funded through the Air Force Assured-Access-to-Space program were on-ramped to the RS-68A; most notably, the alternate gas generator igniter--which will reduce foreign object debris in the engine -- and new material bearings to prevent stress corrosion cracking. The RS-68A was certified to three power levels -- minimum power level, full power level, and enhanced power level -- to meet flight performance objectives, improve engine acceptance yields, and preserve the ability to use the RS-68A as a drop-in replacement for the RS-68, the current Delta IV first-stage engine.As a follow-on effort to gain additional confidence in the engine’s durability, the NRO has funded a four-times life-test program. To accommodate the higher dynamic loads and environments, all component qualification margins were reconciled against the new environments and were requalified as necessary. Several hardware items remain to be qualified. Contingency plans have been established for the hardware with the most significant risk, to ensure that qualified hardware is available to support the NROL-15 launch in summer 2012.AEROSPACE SOLVES DELTA IV ENGINE COMBUSTION INSTABILITY PROBLEM> BACKGROUND During development testing in 2008, the Delta IV RS-68A main booster engine demonstrated significant pressure oscillations in the main combustion chamber, leading to unacceptable performance and structural margins.> AEROSPACE ACTIONS Aerospace determined the cause of the problem and recommended a design change that could be implemented and tested in a timely manner. Working with the propulsion community, the design change was refined further. Aerospace lead the testing and certification effort for the design change.> VALUE ADDED Aerospace’s efforts, acknowledged by customer and contractor leaders, allowed the program to avoid costly anomaly resolution efforts and focus on original certification objectives.
This turned up while looking for RS-68A stuff. Interesting chronological information concerning the NRO's Heavy Upgrade program -- it is mentioned in a couple of other RS-68A-related documents. Also, this is the first I've seen that makes it plain the non-black USAF had separate requirements that were melded into the RS-68A development.
http://lunarnetworks.blogspot.com/2009/08/ula-proposed-on-orbit-re-fueling.htmlMonday, August 10, 2009ULA proposed on-orbit re-fueling architecture Graham WarwickAviation Week...a series of upgrades planned or proposed for Atlas V and Delta IV following the U.S. Air Force’s decision to keep EELVs in service to 2030.Phase 1 involves standardization of the Delta IV fleet with the uprated Pratt & Whitney Rocketdyne (PWR) RS-68A rocket engine. The RS-68A, with improved main injector and turbopump, producing 6% more thrust and 5-10-sec. higher specific impulse, is under development to upgrade the Delta IV Heavy for an initial launch capability in 2011. A common booster core outfitted with the RS-68A will be used for the Delta IV Medium and Medium-Plus beginning in 2014, reducing booster cost and improving launch manifest flexibility, says James Sponnick, vice president for Delta programs.
Quote from: FinalFrontier on 06/02/2012 03:00 pm702k lbs/f of thrust. That's impressive for a hydrolox engine. Never thought they would be able to get it up that high. That's one impressive little engine if you think about it. The recent Zenit launch 1.6 million pounds of thrust.If you could mount two RS-68A's on one core you would be just under the thrust of a Zenit, and three would make a real power core!
http://www.unitedlaunchalliance.com/site/docs/publications/HumanRatingAtlasVandDeltaIV.pdfAtlas and Delta Capabilities to Launch Crew to Low Earth OrbitJeff A. Patton1 and Jonathon D. BarrUnited Launch Alliance, Littleton, ColoradoAIAA 2009-6729September 20094. Production Hardware DeliveryA surprising critical path item is production engine fabrication and delivery. The current build cycle for RS-68s is four years from contract complete, to engine delivery, with additional time needed for vehicle assembly in the factory, and pad checkout and processing. This creates challenges with new block changes of the engine occur, such as the switch from RS-68 to RS-68A, or the anticipated change from an RS-68A to an RS-68A+ that adds startup H2 release mitigation. Interestingly, the engines required to support certification for the first flight of the RS-68A in 2012 are already on order with minimal risk associated with RS-68A.
http://www.pw.utc.com/media_center/press_releases/2008/09_sep/9-25-2008_9212990.aspLOS ANGELES, Sept. 25, 2008 -- Pratt & Whitney Rocketdyne, a United Technologies Corp. (NYSE: UTX) company, has begun a series of hot-fire tests on the new RS-68A rocket engine, designed to power heavier payloads than currently possible on the Delta IV Heavy launch vehicle.
http://www.pw.utc.com/media_center/press_releases/2010/02_feb/2-10-2010_8312959.aspCANOGA PARK, Calif., Feb. 10, 2010 -- Pratt & Whitney Rocketdyne has completed the initial step in certifying the RS-68A rocket engine by successfully hot-fire testing the first certification engine.
http://www.pw.utc.com/media_center/press_releases/2010/11_nov/11-22-2010_10812865.aspCANOGA PARK, Calif., Nov. 22, 2010 -- Pratt & Whitney Rocketdyne successfully completed a series of hot-fire tests on the second and final RS-68A certification test engine..."The second RS-68A certification engine E30102 was successfully hot-fire tested for more than 2,900 seconds over a series of 12 tests...
http://www.pw.utc.com/media_center/press_releases/2011/03_mar/3-8-2011_9012146.aspCANOGA PARK, Calif., March 8, 2011 -- Pratt & Whitney Rocketdyne successfully completed a series of Hardware Acceptance Reviews on the first RS-68A production rocket engine...Engine 30003, the first of three RS-68A production engines to undergo a Hardware Acceptance Review, has been shipped to Decatur, Ala., for integration onto a United Launch Alliance Delta IV Heavy launch vehicle.
http://www.pw.utc.com/media_center/press_releases/2011/04_apr/4-26-2011_00000.aspCANOGA PARK, Calif., April 26, 2011 -- Pratt & Whitney Rocketdyne successfully completed the Design Certification Review for the upgraded RS-68A engine configuration, demonstrating the world’s most powerful hydrogen-fueled engine has met all requirements to power heavy-lift vehicles into space... The Engine System Design Certification Review, conducted on March 31 and April 1 by the customer and Pratt & Whitney Rocketdyne, evaluated the RS-68A engine configuration against detailed requirements and specifications. It was the culmination of a series of reviews that assessed the engine at the component, subsystem and system level, and confirmed compliance with requirements through analysis, test and hardware inspections of development engine 14001 and certification engines 30001 and 30002.
http://www.spacenews.com/launch/120615-delta-engine-variant-cost-cutting.html"New Delta 4 Engine Variant is Part of ULA Cost Cutting Strategy"
With the Delta 4, rocket hardware currently must be committed to a specific mission 17 months before the launch, limiting the Air Force flexibility to swap out payloads if one is delayed. The goal of the Fleet Standardization Program is to reduce that time period to six months, similar to that of the Atlas 5...
“Fleet Standardization is currently in the Final Design phase, with a Critical Design Review coming up in October with fleet cut-in and first launch planned in mid 2015,”
the Air Force cited a number of factors that would help keep launches on schedule and thereby keep inventories down. Among them are the Atlas “white tail” and Delta Fleet Standardization initiatives — the latter entailing the common RS-68 engine — which the service said would “increase flexibility in booster assignment, which further reduces the likelihood of launch delays.”