United Launch Alliance First RS-68A Hot-Fire Engine Test a Success

[Chris Bergin]

ULA PAO Mike (who's very good) will be sending a photo in about an hour.

United Launch Alliance First RS-68A Hot-Fire Engine Test a Success

Denver, Colo., (Sept. 25, 2008) - United Launch Alliance today announced
the successful first hot-firing of the new Pratt & Whitney Rocketdyne
RS-68A engine that will be used to power a future upgraded version of
the Delta IV Heavy Lift launch vehicle.  The hot-fire test was conducted
3:16 p.m. CDT, at NASA's John C. Stennis Space Center, Miss., today.
Stennis is the home of America's largest rocket engine test facility.
The RS-68A engine, an upgraded version of the current RS-68 liquid
hydrogen-liquid oxygen engine used on Delta IV, will allow the Delta IV
Heavy vehicle to boost heavier payloads into orbit. Currently, the RS-68
engine can deliver more than 660,000 pounds of sea level thrust and the
upgraded RS-68A will increase this to more than 700,000 pounds.  The
RS-68A also improves on the specific impulse, or fuel efficiency, of the
RS-68.  The Delta IV Heavy is comprised of three Delta IV core boosters.
With the new RS-68A engines, the Delta IV Heavy's thrust will increase
by more than 100,000 pounds.
The hot-fire test lasted the full planned duration of approximately 40
seconds and the test team will spend the next several days evaluating
data to characterize engine performance and to clear the engine for
future tests.  This initial test was on the first of three engines that
will be used during an extensive engine test program.  The test program
will continue during the next twelve months, leading to certification of
the new engine in mid-2010 and initial launch capability of the upgraded
Delta IV Heavy in early 2011.
"We congratulate Pratt & Whitney Rocketdyne and the entire RS-68A engine
team for this successful first step in making the most powerful liquid
hydrogen-liquid oxygen engine in the world even more capable," said Jim
Sponnick, ULA Vice President, Delta Product Line.  "The RS-68A upgrade
is a critical element in upgrading the Delta IV Heavy allowing ULA to
meet evolving needs of our government customers with even greater
reliability and performance than achieved in the past, while keeping
mission success our top priority." 
ULA program management, engineering, test and mission support functions
are headquartered in Denver, Colo.  Manufacturing, assembly and
integration operations are located in Decatur, Ala., Harlingen, Tex.,
San Diego, Calif., and Denver, Colo.  Launch operations are located at
Cape Canaveral Air Force Station, Fla., and Vandenberg Air Force Base,
Calif.
For more information on the ULA joint venture, visit the ULA Web site at
www.ulalaunch.com,

[Chris Bergin]

NASA's Stennis Space Center, Miss. - The successful first
40-second hot-fire test of the new Pratt & Whitney Rocketdyne RS-68A
engine that will be used to power a future upgraded version of the
United Launch Alliance Delta IV Heavy Lift launch vehicle was conducted
at 3:16 p.m. CDT, here today.
The RS-68A engine, an upgraded version of the current RS-68
liquid hydrogen-liquid oxygen engine used on Delta IV is the most
powerful engine of its kind in the world.  The upgraded RS-68A will
allow the Delta IV Heavy vehicle to boost heavier payloads into orbit.
Currently, the RS-68 engine can deliver more than 660,000 pounds of sea
level thrust and the upgraded RS-68A will increase this to more than
700,000 pounds.  (Photo courtesy of Pratt & Whitney Rocketdyne)

[Antares]

Godspeed that the data analysis is more fruitful than that of the first RS-68 tests back in 98.

[kraisee]

Great stuff from PWR!

Seems like it was only yesterday that the project was in PDR!   They've been flying through the effort so far.

Actually, there's a question:   Could someone provide the correct dates for the SRR, PDR and CDR for this development program?

Ross.

[Nick L.]

Oh, very, very cool!

Congrats and here's hoping for a nice trouble-free certification!

[Stephan]

The RS-68A also improves on the specific impulse, or fuel efficiency, of the RS-68.

What will be the ISP of the RS-68A ?

[pm1823]

Expected ISP 365/415 sec or better.

Reconnaissance Office (NRO) to partner with the service on the RS-68 engine work, which is
already in progress. The NRO plans to develop an upgraded RS-68A variant for a mission. From
that variant, NASA would join with the Air Force to develop a common RS-68B version for use on
both the Ares V and the Delta IV, featuring upgrades required by NASA for operability and
changes planned by the Air Force for their Assured Access To Space program to improve
robustness. Planned modifications to the current RS-68 are:
1. Increased power level to 108 percent from the current 102 percent.
2. Main injector changes to improve Isp to at least 414.2 seconds from the current 407.7.
3. New bearing material to decrease stress corrosion susceptibility.
4. Redesigned turbopump pump inlets to incorporate tip vortex suppression.
5. Redesigned fuel turbopump second stage blisk to decrease susceptibility to cracks.
6. Redesigned gas generator igniter that eliminates squib foreign object debns concern.
7. Higher reliability oxidizer turbopump bearing chill sensor.
8. Higher reliability hot gas sensdr.
9. Redesigned oxidizer turbopump to reduce pre-start and operational helium usage.
10. Modified engine start sequence/configuration
to reduce free hydrogen on the pad
during engine start.
11. Redesigned ablative nozzle to accommodate the longer-duration Ares V mission
profile.
The increased power level and main injector modifications are included in an engine
upgrade program that PWR is implementing under a contract with United Launch Alliance for the
RS-68A variant. Changes 3 through 8 are currently conducted under the Air Force Assured
Access to Space Program. NASA will work with the Air Force to combine the AATS upgrades with
changes 9-11 above, required for Ares V, to produce a common RS-68 B engine variant.

[kraisee]

Look at the Ares-V data for the performance expectations for this evolution.

Those are the numbers NASA has been told to expect from this engine.   The only real difference is one will include the necessary human-rating hardware, the other won't.

Ross.

[HIPAR]

Look at the Ares-V data for the performance expectations for this evolution.

Those are the numbers NASA has been told to expect from this engine.   The only real difference is one will include the necessary human-rating hardware, the other won't.

Ross.

What might that human-rating modification be?  If it improves the reliability of the engine, why wouldn't that equipment be cost effective as 'added insurance' towards preventing the loss of billion dollar defense oriented payloads?

---  CHAS

[kevin-rf]

What might that human-rating modification be?  If it improves the reliability of the engine, why wouldn't that equipment be cost effective as 'added insurance' towards preventing the loss of billion dollar defense oriented payloads?

---  CHAS

Human rating means it may not fail in a way that will result in a LOC, it may still fail and any failure on a Delta IV is a LOM.

[siatwork]

LOC can only be mitigated via a launch escape system.  For that an engine needs health monitoring instrumentation such as sensors, LES activation logic.  Nothing to do with engine reliability/production quality.  DOD/NRO/Science don't want to skimp on that either.  Both EELVs engines were just fine for the OSP program under O'Keefe as long as engine health monitoring system was implemented.  Then came ESAS... and made up a ruse to exclude them for launching crews, while pushing "human rated" "safe" Ares-1 solids which embarassingly can't now meet ESAS own human rating reqs (due to TO).

[kraisee]

What might that human-rating modification be?  If it improves the reliability of the engine, why wouldn't that equipment be cost effective as 'added insurance' towards preventing the loss of billion dollar defense oriented payloads?

Chas,
PWR/MSFC looked at RS-68 "as is" and determined that there were over 200 things which needed changing on the engine to meet human-rating standards.   If it were to be flown without those changes, that would require a "waiver" for each of those 200+ things.   Every one of those issues will have to be addressed before any human will ever use that engine.   Each waiver will either have to be fixed, or that specific waiver will have to be justified, rationalized and accepted.

The issues will range from lots of very simple fixes which can be implemented quickly and cheaply to a handful of complicated ones requiring extensive & costly development work.   But almost all of the issues fit into four main categories:-

1) Additional redundancy on some parts; I'm talking backups for many of the smaller valves, actuators and other parts.   This provides additional capability to continue to fly even if certain things fail.   Designed to prevent both LOM & LOC situations.

2) Additional Sensor Package and Health Monitoring Computers.   This allows more extensive examination of the engine while in flight allowing for the detection of problems very early and provides the necessary data to the Launch Abort System to get out of Dodge a little bit quicker - ideally before the engine ever goes critical - i.e. "boom".   Designed to prevent LOC in LOM situations.

Current unmanned engines make the assumption that almost any significant engine failure is going to automatically result in the payload being inserted into the Ocean, and there is nothing which can be done to even try to save the payload if it happens.   So health monitoring and extensive sensor packages are fairly minimal on cargo-only flights.   This has to change for human flights.

3) Software re-write.   The current software used in the RS-68 is commercial-grade and is fairly minimal in capability.   NASA will require the equivalent of mil-spec software, *really* extensive testing and multiple backups for in-flight engine controllers.   These do not exist currently.   Designed to prevent both LOM and LOC events.

4) Finally, more testing.   A lot more testing will be required for NASA to get confidence.   The testing which has been done so far is good, if not excellent, and the handful of flown engines are even better.   But NASA will want to know this engine inside and out.   They will want to also know precisely where its limits are - and no RS-68 has so far ever been pushed to its absolute limits.   They're run a bunch up to their maximum required tollerances and even beyond, but none has so far ever been pushed to its destruct point.   I'd guess that NASA will probably want to *know* precisely where that point is for a human-rated engine - and that is going to be quite a spectacular test to witness, IMHO.   Designed to prevent both LOM and LOC events.


A Human Rating package could be developed for the existing RS-68 first, with the intention to move it over to the new RS-68A.

There are more changes which can be done to improve the engine as well, which aren't specifically Human Rating requirements - and most of those are already being implemented in the RS-68A development work at the core of this thread.   These include changes to reduce the "flame-ball" on engine ignition, and a change to tighten up the bearing tolerances so the engine can use less Helium during start-up too.   And there are internal changes to improve performance also.   But while those are all desirable, none of those are explicitly "required" for human-rating to succeed.

Ross.

[Jim]

1) Additional redundancy on some parts; I'm talking backups for many of the smaller valves, actuators and other parts.   This provides additional capability to continue to fly even if certain things fail.   Designed to prevent both LOM & LOC situations.

2) Additional Sensor Package and Health Monitoring Computers.   This allows more extensive examination of the engine while in flight allowing for the detection of problems very early and provides the necessary data to the Launch Abort System to get out of Dodge a little bit quicker - ideally before the engine ever goes critical - i.e. "boom".   Designed to prevent LOC in LOM situations.

Current unmanned engines make the assumption that almost any significant engine failure is going to automatically result in the payload being inserted into the Ocean, and there is nothing which can be done to even try to save the payload if it happens.   So health monitoring and extensive sensor packages are fairly minimal on cargo-only flights.   This has to change for human flights.

3) Software re-write.   The current software used in the RS-68 is commercial-grade and is fairly minimal in capability.   NASA will require the equivalent of mil-spec software, *really* extensive testing and multiple backups for in-flight engine controllers.   These do not exist currently.   Designed to prevent both LOM and LOC events.

Ross, you are way off base

1. The SSME doesn't even have have this.   It doesn't have redundant valves or actuators.   The SSME only has pneumatic backup to shut down valves, something not needed in a non reusable engine. Margins are what keeps an engine burning not redundancy.

2.  There is no difference in the placement of sensors for an unmanned or manned engine.  Only the numbers for redundancy.  Unmanned missions still need the same info used in LAS activation for anomaly resolution and margin analysis.  The health monitoring system is on the LV vs the engine.  The items needs to monitored are few and not extensive. Among them is turbopump RPM, turbine EGT, inlet and outlet pressures, combustion chamber pressure and temp. 

3.  There is no requirement for back up controllers.  The SSME does not have them.  NASA would not require mil-spec software.

 None of these is in the manrating spec

[Antares]

Eh, Ross is closer than Jim gives him credit for, just a little loose with terminology.  Pneumatic back-up is not exactly redundancy, but that's probably what he was referring to.  The current sensors would need to go into an LVHM system, which they don't now of course.  And, one could make the argument for additional real-time sensors for that LVHM suite - ones that could be derived from existing sensors when they are post-processed now, but would be needed real time for LVHM.  SSME has at least 3 control strings in the engine, no?

[cb6785]

3.  There is no requirement for back up controllers.  The SSME does not have them.

Well I may be waaaaay off here, but if my memory isn't totally nuts STS-93 had problems with at least one primary and one secondary engine controller, and they continued the ascent using the backup-controllers.....Primary, secondary and backup means 3 controllers per SSME doesn't it??