Author Topic: Future use of RS-68A on Delta IV  (Read 40047 times)

Offline Jim

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Re: Future use of RS-68A on Delta IV
« Reply #20 on: 06/02/2012 04:50 pm »

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.


Same goes for the tail service mast umbilicals.   Which means the internal plumbing is different, which is the big impact.
« Last Edit: 06/02/2012 04:53 pm by Jim »

Offline ChileVerde

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Re: Future use of RS-68A on Delta IV
« Reply #21 on: 06/02/2012 08:36 pm »

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.


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.
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Offline Jim

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Re: Future use of RS-68A on Delta IV
« Reply #22 on: 06/02/2012 08:53 pm »
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.

Can't, the TSM's on the pad are to one side since the vehicle is trucked to the pad horizontally and then rotated to vertical.  Any TSM not on the "back side" would interfere with this operation. 

Atlas would have avoided this issue by craning the booster onto MLP.  The MLP had two TSM's on one side of the flame trench and one on the other side.  The boosters were all the same except for additional attach hardware which could be added to any core.

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Re: Future use of RS-68A on Delta IV
« Reply #23 on: 06/02/2012 09:58 pm »
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.
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Offline TrueGrit

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Re: Future use of RS-68A on Delta IV
« Reply #24 on: 06/02/2012 10:06 pm »
Same goes for the tail service mast umbilicals.   Which means the internal plumbing is different, which is the big impact.

Actually the internal plumbing if you will is identical.  What is different is that the structural attach parts between the Core and the Strap-On are mirrored.  In particular the structural attach points for a Heavy are completely different from a Medium with SRMs.  More easily ilustrated by looking for the lack of mid-hydrogen tank SRM attach points on a Heavy, and lack of upper Strap-On attach points on a Medium.  But the plumbing is identical and secondary support structure is identical.  As for how much impact this makes...  Delta was designed like a airplane with each Strap-On a mirror image wing...  Douglas was after all an airplane company thruout its history up until a few years ago when Boeing, another aircraft company, bought them out...
« Last Edit: 06/03/2012 12:00 am by TrueGrit »

Offline TrueGrit

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Re: Future use of RS-68A on Delta IV
« Reply #25 on: 06/02/2012 10:12 pm »
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.

You can't just seperate the Heavy boosters on the pad...  It requires the stack to be taken back to the HIF to be seperated.  If a Medium vehilce jumps ahead it is easier to roll the Heavy off the pad, and replace it with a Medium booster.  Not go thru the effort to seperate the already matted Heavy.  So for the situation you pointed out there is no benifit of makign the Heavy and Medium interchangable...  At least in terms of Launch Site flow.  So yes the Heavy vehicle is a different beast...  In many ways.
« Last Edit: 06/02/2012 11:59 pm by TrueGrit »

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Re: Future use of RS-68A on Delta IV
« Reply #26 on: 06/03/2012 10:48 pm »
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?
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Offline Jim

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Re: Future use of RS-68A on Delta IV
« Reply #27 on: 06/03/2012 11:28 pm »
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?

All Delta IVs solids have thrust vectoring (except when there are 4, then only 2).  The use of turbopump exhaust for roll control is not strong enough to over come motor misalignments.

Offline Prober

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Re: Future use of RS-68A on Delta IV
« Reply #28 on: 06/04/2012 12:58 pm »
702k lbs/f of thrust.  :o

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!
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Offline ChileVerde

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Re: Future use of RS-68A on Delta IV
« Reply #29 on: 06/10/2012 06:52 pm »
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.


Quote
http://www.aerospace.org/wp-content/uploads/docs/Aerospace_AR-2011.pdf

Aerospace Corporation FY2011 Annual Report

DELTA IV HEAVY UPGRADE PROGRAM

The 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.

Edit: Typographical fixes
« Last Edit: 06/15/2012 06:51 pm by ChileVerde »
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Offline Jim

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Re: Future use of RS-68A on Delta IV
« Reply #30 on: 06/10/2012 08:03 pm »

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.


Still can't state that.  Some times NRO requirements are still funded by the Air Force it is also meets some Air Force needs.

Offline ChileVerde

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Re: Future use of RS-68A on Delta IV
« Reply #31 on: 06/12/2012 05:15 pm »


Well, at long last a hint of when the fleet-wide RS-68A standardization might occur.  Unfortunately the information is almost three years old, but it's all that has come to light so far.

Quote
http://lunarnetworks.blogspot.com/2009/08/ula-proposed-on-orbit-re-fueling.html

Monday, August 10, 2009

ULA proposed on-orbit re-fueling architecture
Graham Warwick
Aviation 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.
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Offline Prober

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Re: Future use of RS-68A on Delta IV
« Reply #32 on: 06/13/2012 02:15 am »
702k lbs/f of thrust.  :o

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!


expanding on this thinking.......can't a low cost, light heat shield be placed between two engines mounted?   Only need to survive what 2.xx minutes?
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Offline Norm38

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Re: Future use of RS-68A on Delta IV
« Reply #33 on: 06/13/2012 03:38 am »
Are any detailed specs on the RS-68a available?  I haven't been able to find anything but press releases, and nothing mentions the weight. Is it heavier or lighter than the current version?

Offline ChileVerde

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Re: Future use of RS-68A on Delta IV
« Reply #34 on: 06/15/2012 06:19 pm »
Here's an interesting bit of information about the RS-68A production cycle. 

Quote
http://www.unitedlaunchalliance.com/site/docs/publications/HumanRatingAtlasVandDeltaIV.pdf

Atlas and Delta Capabilities to Launch Crew to Low Earth Orbit
Jeff A. Patton1 and Jonathon D. Barr
United Launch Alliance, Littleton, Colorado
AIAA 2009-6729
September 2009

4. Production Hardware Delivery

A 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.

Since the first production engine, 30003, shipped in early March 2011, a four year interval between contract signing and shipment means that the NROL-15 engines were under contract in March 2007.  If the Spaceflight Now launch schedule indication that NROL-15 has slipped from December 2011 to June 28 2012 is right, the original intent seems to have been to take nine or ten months to put the D4H together and integrate the payload.  Finally, if the RAND report of 2006 indicating a launch date of 2010 for NROL-15 was correct, the four-year build cycle implies that engines 30003, 30004 and 30005 were put under contract not long after the beginning of the RS-68A development program in 2006 and possibly concurrently with it. Presumably the "minimal risk associated with RS-68A" gave them the confidence to do that.

Just to have an idea of the timeline, I extracted the following from the PWR press release archive.

Quote
http://www.pw.utc.com/media_center/press_releases/2008/09_sep/9-25-2008_9212990.asp

LOS 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.

Quote
http://www.pw.utc.com/media_center/press_releases/2010/02_feb/2-10-2010_8312959.asp

CANOGA 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.

Quote
http://www.pw.utc.com/media_center/press_releases/2010/11_nov/11-22-2010_10812865.asp

CANOGA 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...

Quote
http://www.pw.utc.com/media_center/press_releases/2011/03_mar/3-8-2011_9012146.asp

CANOGA 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.

Quote
http://www.pw.utc.com/media_center/press_releases/2011/04_apr/4-26-2011_00000.asp

CANOGA 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.
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Offline neilh

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Re: Future use of RS-68A on Delta IV
« Reply #35 on: 06/16/2012 04:48 pm »
http://www.spacenews.com/launch/120615-delta-engine-variant-cost-cutting.html

"New Delta 4 Engine Variant is Part of ULA Cost Cutting Strategy"
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Offline ChileVerde

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Re: Future use of RS-68A on Delta IV
« Reply #36 on: 06/16/2012 05:15 pm »
http://www.spacenews.com/launch/120615-delta-engine-variant-cost-cutting.html

"New Delta 4 Engine Variant is Part of ULA Cost Cutting Strategy"

Hey, thanks!  So, fleet-wide introduction ca. 2015.
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Offline baldusi

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Re: Future use of RS-68A on Delta IV
« Reply #37 on: 06/16/2012 05:41 pm »
http://www.spacenews.com/launch/120615-delta-engine-variant-cost-cutting.html

"New Delta 4 Engine Variant is Part of ULA Cost Cutting Strategy"
This pair of quotes seems important:
Quote
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...
Quote
“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,”

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Re: Future use of RS-68A on Delta IV
« Reply #38 on: 06/16/2012 08:40 pm »
Yes, and the confirmation:
Quote
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.”
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Offline Jim

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Re: Future use of RS-68A on Delta IV
« Reply #39 on: 06/17/2012 12:47 pm »
And who says ULA is not doing anything to reduce costs?

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