XCOR Aerospace and ULA Announce Successful Hydrogen Piston Pump Tests

[Chris Bergin]

June 8th, 2010, Mojave, CA, USA and Littleton, CO, USA:   XCOR Aerospace, the developer of the Lynx, a manned suborbital spacecraft and related technologies, and United Launch Alliance (ULA), the primary launch services provider to the US Government, announced the first successful demonstration of XCOR’s long life, high performance piston pump technology with liquid hydrogen.

            XCOR has been developing piston pumps for space applications for more than eight years as an alternative to turbopumps, demonstrating longer life and lower cost.  XCOR’s piston pumps have other advantages including the ability to operate over a wide range of speeds and inlet conditions.  After XCOR performed risk reduction and demonstration projects in 2009 that validated high performance cryogenic (liquid oxygen and liquid nitrogen) piston pump operations, ULA asked XCOR if the pump technology could be extended to liquid hydrogen.  Implementing rapid prototyping techniques and working on a fixed price basis, XCOR developed a single piston work-horse test article and test bench, and then successfully tested the pump with hydrogen in less than four months.  Based on this success, ULA and XCOR have begun the next phase of the project to further mature the technology.

            During the tests, the XCOR team of Chief Engineer Dan DeLong, Chief Test Engineer Doug Jones, Senior Engineer Mike Valant and Systems Engineer Mark Street, demonstrated successive rounds of pumping liquid hydrogen at conditions relevant to a flight type multi-cylinder pump.   Possible applications include pump-fed liquid hydrogen rocket engines for upper stages, on-orbit propellant transfer operations, and other cryogenic fluid management applications.  A unique capability demonstrated during the tests was the ability to pump through cavitation events when liquid hydrogen returned to partial gaseous form, a sign of robustness of the design to handle anomalous events that would cause other high performance pump schemes to cease operations.

            ULA’s Vice President of Business Development and Advanced Programs, Dr. George Sowers noted, “XCOR has demonstrated the beginnings of an important technology development path that has the promise to significantly improve the competitiveness of future ULA launch vehicles.”

            Frank Zegler, Senior Staff Engineer in ULA’s Advanced Programs group, commented, “XCOR is doing things with piston pumps that no one else has done.”

“ULA has taken a very innovative and commercially focused approach for future technology insertion into their long range product planning roadmap, and XCOR is very pleased to support the ULA team by further enhancing and extending our technology to their unique needs for lower cost launch vehicles, new on-orbit applications and capabilities, and future deep space exploration systems,” said XCOR President and Founder Jeff Greason. 

            XCOR Chief Operating Officer Andrew Nelson said, “ULA’s use of our high performance, light weight cryogenic piston pump technology is very exciting and this effort is a demonstration of how a large and established aerospace company can effectively work with smaller, innovative New Space companies to improve the prime contractor’s product lines while simultaneously helping to restore the second and third tier aerospace supplier base our country has lost over the last twenty years. We are very pleased and fortunate to have such a good long term partner in ULA.”

 

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XCOR Aerospace is a California corporation located in Mojave, California. The company is in the business of developing and producing safe, reliable and reusable rocket powered vehicles, propulsion systems, advanced non-flammable composites and other enabling technologies for responsive private space flight, scientific missions, upper atmospheric research, and small satellite launch to low earth orbit. The Lynx is a piloted, two seat, fully reusable, liquid rocket powered vehicle that takes off and lands horizontally.  The Lynx production models (designated Lynx Mark II) are designed to be robust, multi-commercial mission vehicles capable of flying to 100+ km in altitude up to four times per day.  XCOR’s web address is: www.xcor.com. 


United Launch Alliance was formed in December 2006, and is a 50-50 joint venture owned by Lockheed Martin and The Boeing Company.  ULA brings together two of the launch industry’s most experienced and successful teams – Atlas and Delta – to provide reliable, cost-efficient space launch services for the U.S. government.  U.S. government launch customers include the Department of Defense, NASA, the National Reconnaissance Office and other organizations. ULA program management, engineering, test and mission support functions are headquartered in Denver, Colo. Manufacturing, assembly and integration operations are located at Decatur, Ala., Harlingen, Texas, and San Diego, Calif. Launch operations are located at CCAFS, Fla., and Vandenberg Air Force Base, Calif. For more information on the ULA joint venture, visit the ULA website at www.ulalaunch.com, or call the ULA Launch Hotline at 1-877-ULA-4321 (852-4321).

 

[zaitcev]

This is very amazing, but the next stage is to demonstrate it in space. I wonder if ULA plan for something like Cryote 2.

[kevin-rf]

RL-10 replacement? Excellent work, way to go!

[Namechange User]

How do you get an entire engine replacement out of this?  Cool work with applications, no doubt, but a pump does not make an entire engine. 

[Downix]

How do you get an entire engine replacement out of this?  Cool work with applications, no doubt, but a pump does not make an entire engine. 

I'd see it more useful for... oh, I dunno... a fuel depot.

[bad_astra]

It could lead to cheaper cryo engines, not dependant on turbopumps. It's not an engine replacement, but it's certainly valuable.

[Antares]

RL10 pumps are one of the banes of the EELV existence.

[Downix]

RL10 pumps are one of the banes of the EELV existence.

I always understood that the RL10's pumps are its best feature.

[ugordan]

Maybe not the pumps per se, but the relatively more benign expander cycle that drives them.

[neilh]

RL-10 replacement? Excellent work, way to go!

What are the pros/cons of using piston pumps compared to whatever RL10 uses? (this is something I know nothing about)

[mmeijeri]

Great news. Also very good to see interaction between Old Space and New Space.

[neilh]

Also, it's really cool seeing ULA making these kinds of independent R&D investments.

[mmeijeri]

BTW, why is it XCOR that's doing the piston pumps? Did they buy Flometrics?

[jongoff]

BTW, why is it XCOR that's doing the piston pumps? Did they buy Flometrics?

Flometrics is doing *pistonless* pumps, XCOR's pumps have an actual piston in them.  Both approaches have their pluses and minuses, but one of the big advantages of an actual piston pump is that it enables you to run expander-type cycles easier.  You can do almost expander cycles with pistonless pumps, but there's a bit of efficiency loss.  Pistonless pumps are probably better matched for large booster engines and areas where you'd normally want to use a pressure-fed system (like storable in-space propulsion), while the piston pumps are better matched for small to medium sized high-performance boosters (ie stuff in the less than 50kblf size range).

Jeff mentioned this briefly in his talk at Space Access two months ago.  It's cool news in my book.

~Jon

[mmeijeri]

Ah, thanks for that clarification! I guess I should read more carefully before bursting into joyful exclamation...

EDIT: Think more carefully even, since I see I typed piston pump in my previous post...

[kevin-rf]

Yes, thanks for clearing that up Jon, I also was a little puzzled on the Flometrics point...

[robertross]

Great news! Thanks!

Balancing should be fun...hehe

[neilh]

RL-10 replacement? Excellent work, way to go!

What are the pros/cons of using piston pumps compared to whatever RL10 uses? (this is something I know nothing about)

I came across the following on XCOR's site regarding their earlier work with LOX/hydrocarbon piston pumps:
http://www.xcor.com/products/pumps/index.html

These latest piston pumps are powered with engine heat, which, when used with XCOR's patent pending thermodynamic cycle, can achieve an Isp as high as the staged combustion cycle, which is the most efficient cycle for LOX/hydrocarbon engines and used on the best engines now.

XCOR’s proprietary piston pumps can pump like  turbopumps but are able to stop and start quickly.  They are also less expensive. A benefit of a piston-style design is that the pump is capable of pumping more fuel at a higher operational speed. Using this innovative pump design, drive gas to operate the pumps can be delivered by any of the three classical methods: staged combustion, gas generator, or expander. We have chosen a fourth, however, which is a proprietary thermodynamic cycle that is most similar to the expander. XCOR has patented this cycle, which has the advantage of not lowering the engine specific impulse, as a gas generator would.

While our pumps are designed for LOX and kerosene propellants, they can be easily adapted to pump any other commonly used propellants.

I wonder how much of the above is potentially applicable to their new LOX/hydrogen work.

[Jose]

I wonder if ULA plans to use these in their Integrated Vehicle Fluids (IVF) program? They need "small pumps" to "enable system operation".

http://forum.nasaspaceflight.com/index.php?topic=20950.0

[zaitcev]

Since we're on topic, does anyone know what the specific impulse is for XCOR's pumped engines 4K14 and 5K18?

[mmeijeri]

So what are the drawbacks of piston pumps? Weren't they replaced by turbopumps in the olden days because they are heavier? Are the newer ones much more competitive or is cost a bigger factor than it used to be?

[FinalFrontier]

Neat! I see this as having a role in future commercial resupply activites.

[yinzer]

So what are the drawbacks of piston pumps? Weren't they replaced by turbopumps in the olden days because they are heavier? Are the newer ones much more competitive or is cost a bigger factor than it used to be?

It's probably the same as with airplane engines.  Turbines scale up well, weigh less, are more reliable, and more efficient when operating at their design condition.  Piston engines scale down well, cost less, and are more efficient over a wide range of operating conditions.

I think there are two main issues scaling down turbines - the clearance between the tip and the housing can only be so small and this gap and associated losses becomes proportionally larger as the turbine shrinks, and a lot of a turbine's performance is related to tip speed which requires progressively higher rpm at smaller sizes.

[mmeijeri]

Isn't a higher rpm actually easier at smaller sizes? At least that's the case for hard disks I think.

[jongoff]

Since we're on topic, does anyone know what the specific impulse is for XCOR's pumped engines 4K14 and 5K18?

No, XCOR has been pretty consistent about not publishing their engine Isp data.  They usually cite ITAR as the reason, though that's kind of weird since almost everyone else in the industry cites Isp values.  They may just have an overly paranoid ITAR lawyer.

~Jon

[Namechange User]

They may just have an overly paranoid ITAR lawyer.

~Jon

Nah, they don't exist and are stuff of legend and folklore. 

[Patchouli]

Isn't a higher rpm actually easier at smaller sizes? At least that's the case for hard disks I think.

Thermodynamics also gets harder on a smaller scale ie keeping stuff want to stay hot at a high temp and the stuff you want to keep cool at a low temp.
Turbines don't always scale down well because they require high temps for efficiency but the bearings and seals need to be kept relatively cool.
I'm talking the power head vs the pump part.

But I really suspect the piston pump may not be for an engine at all but instead for a fuel depot.
I could also see it being used with an accumulator on thrusters or OMS engines vs main engines as a piston pump can start and stop easier.

[Robotbeat]

Isn't a higher rpm actually easier at smaller sizes? At least that's the case for hard disks I think.

Thermodynamics also gets harder on a smaller scale ie keeping stuff want to stay hot at a high temp and the stuff you want to keep cool at a low temp.

There are certain things that work better at a smaller scale. If you scale up an internal combustion (piston) engine by 2 in every direction, you will have a hard time keeping the rpms up as high (because greater inertia... more mass has to travel more distance in the same time, thus the inertia of the piston increases faster than the mass of the engine at the same rpms, thus reaching material limits). And since power is proportional to volume x rpms (and compression ratio), and (if operating at material limits) volume (and pressure) is proportional to mass, then larger engines of that type will have lower specific power than smaller engines.

Think of those high-performance crotch-rocket motorcycle engines going up to 15,000 rpm and compare to the huge diesel engines found in ocean-going ships (100 rpm). Although the power is far greater in the bigger engines, the power-per-kg is _far_ greater in the smaller engines due to the higher rpm (and also the heavier diesel engine, but that's a separate issue).

[Patchouli]

There are certain things that work better at a smaller scale. If you scale up an internal combustion (piston) engine by 2 in every direction, you will have a hard time keeping the rpms up as high (because greater inertia... more mass has to travel more distance in the same time, thus the inertia of the piston increases faster than the mass of the engine at the same rpms, thus reaching material limits). And since power is proportional to volume x rpms (and compression ratio), and (if operating at material limits) volume (and pressure) is proportional to mass, then larger engines of that type will have lower specific power than smaller engines.

Think of those high-performance crotch-rocket motorcycle engines going up to 15,000 rpm and compare to the huge diesel engines found in ocean-going ships (100 rpm). Although the power is far greater in the bigger engines, the power-per-kg is _far_ greater in the smaller engines due to the higher rpm (and also the heavier diesel engine, but that's a separate issue).

True smaller engines can have a higher power to weight.
But that big diesel engine in the ship has a much higher Carnot efficiency then the motorcycle engine.

Some large diesels such as those found in ships can exceed a Carnot efficiency of 50% while most small engines struggle to achieve 22%.

This is partly due to the laws of squares there just is less surface area for the for a given volume of gas to leak heat into the head and cylinder walls so that heat can do work instead.

Turbines also are subject to similar rules though much worse then a piston engine.

[butters]

So this is essentially a Sterling engine running on nozzle heat?

[mlorrey]

Isn't a higher rpm actually easier at smaller sizes? At least that's the case for hard disks I think.

Thermodynamics also gets harder on a smaller scale ie keeping stuff want to stay hot at a high temp and the stuff you want to keep cool at a low temp.

There are certain things that work better at a smaller scale. If you scale up an internal combustion (piston) engine by 2 in every direction, you will have a hard time keeping the rpms up as high (because greater inertia... more mass has to travel more distance in the same time, thus the inertia of the piston increases faster than the mass of the engine at the same rpms, thus reaching material limits). And since power is proportional to volume x rpms (and compression ratio), and (if operating at material limits) volume (and pressure) is proportional to mass, then larger engines of that type will have lower specific power than smaller engines.

Think of those high-performance crotch-rocket motorcycle engines going up to 15,000 rpm and compare to the huge diesel engines found in ocean-going ships (100 rpm). Although the power is far greater in the bigger engines, the power-per-kg is _far_ greater in the smaller engines due to the higher rpm (and also the heavier diesel engine, but that's a separate issue).

This is why you pile the pistons on. My grandfather, back in the 30's when he was a student at WPI, built a 36 cylinder engine out of three 12 cylinder blocks. Built a hellacious drag racer with it. Had a very short drive shaft, and the driver had to sit in the back seat of the original car cabin. Couldn't turn for anything.

Sadly, the Depression forced him out of school and he became an executive in the publishing industry. A loss for Detroit.

[Swatch]

Isn't a higher rpm actually easier at smaller sizes? At least that's the case for hard disks I think.

Easier to spin fast, but there's still a penalty to be had just rotating at those RPM's... primarily with friction losses but also structural since your centripetal force goes up with the square of velocity and is inversely proportional to your radius (think figure skater).

[docmordrid]

Turbochargers and turbopumps share a lot of features.  Those in automobiles turn at ~100,000 RPM with a turbine diameter of ~76mm (Garrett GT3076R) and with high reliability. 

[mlorrey]

Turbochargers and turbopumps share a lot of features.  Those in automobiles turn at ~100,000 RPM with a turbine diameter of ~76mm (Garrett GT3076R) and with high reliability. 

I wonder if one could mock up a cheap turbopump with a couple turbochargers... I imagine that turbopumping liquids would require a different turbine wheel than one uses to turbocharge air...

[strangequark]

I wonder if one could mock up a cheap turbopump with a couple turbochargers... I imagine that turbopumping liquids would require a different turbine wheel than one uses to turbocharge air...

The turbine itself would still see a gas. It's the compressor you'd have to worry about.

[FutureSpaceTourist]

Here's an update on the XCOR & ULA project: http://www.spacenews.com/article/launch-report/36548xcor-ula-engine-project-taking-page-from-auto-industry

[uranium]

More progress:

“The test marks the first time liquid hydrogen and liquid oxygen have been supplied to a rocket engine with a piston pump,” says Jeff Greason, XCOR’s chief executive. “It is also the first time an American LH2 engine of this size has successfully fired liquid hydrogen and liquid oxygen together in pump-fed mode. We are happy to be making solid progress on the engines. This will also bring us to a new phase in our plans for orbital flight.”

Full text at http://www.xcor.com/blog/lh2progress/

[Planetaryduality]

Does anyone know the performance specifications on the piston fed engine? Better/comparable/worse than a similarly sized expander cycle?

[dcporter]

(Who owns what in this kind of relationship?)

[Moe Grills]

More progress:

“The test marks the first time liquid hydrogen and liquid oxygen have been supplied to a rocket engine with a piston pump,” says Jeff Greason, XCOR’s chief executive. “It is also the first time an American LH2 engine of this size has successfully fired liquid hydrogen and liquid oxygen together in pump-fed mode. We are happy to be making solid progress on the engines. This will also bring us to a new phase in our plans for orbital flight.”

Full text at http://www.xcor.com/blog/lh2progress/

Liquid hydrogen with LOX?  I can understand the use of kerosene and LOX..... Jeff is really pushing the propulsion envelope for commercial spaceflight; makes me nervous.  LH2 with LOX require special handling
and care. Look how long it took the Soviets/Russians to use the propellant on Briz upperstages, etc.

[Kryten]

Liquid hydrogen with LOX?  I can understand the use of kerosene and LOX..... Jeff is really pushing the propulsion envelope for commercial spaceflight; makes me nervous.  LH2 with LOX require special handling
and care. Look how long it took the Soviets/Russians to use the propellant on Briz upperstages, etc.

Briz is UDMH/N2O4, and this isn't the first time commercial outfits have looked into hydrolox. Blue Origin have a tested engine (BE-3) with about forty times the thrust of this thing, and four times the ultimate target for this program.

[TrevorMonty]

More progress:

“The test marks the first time liquid hydrogen and liquid oxygen have been supplied to a rocket engine with a piston pump,” says Jeff Greason, XCOR’s chief executive. “It is also the first time an American LH2 engine of this size has successfully fired liquid hydrogen and liquid oxygen together in pump-fed mode. We are happy to be making solid progress on the engines. This will also bring us to a new phase in our plans for orbital flight.”

Full text at http://www.xcor.com/blog/lh2progress/

I can think of one potential use for this engine (2.5klb), the small landing engines on Masten/ULA Xeus lander. Four pairs ( redundancy) of these, one each corner would land 20t(3.5t moon weight) on moon.

[mheney]

More progress:

“The test marks the first time liquid hydrogen and liquid oxygen have been supplied to a rocket engine with a piston pump,” says Jeff Greason, XCOR’s chief executive. “It is also the first time an American LH2 engine of this size has successfully fired liquid hydrogen and liquid oxygen together in pump-fed mode. We are happy to be making solid progress on the engines. This will also bring us to a new phase in our plans for orbital flight.”

Full text at http://www.xcor.com/blog/lh2progress/

I can think of one potential use for this engine (2.5klb), the small landing engines on Masten/ULA Xeus lander. Four pairs ( redundancy) of these, one each corner would land 20t(3.5t moon weight) on moon.

That would require keeping liquid hydrogen actually liquid for 3+ days - which I believe is a bit beyond the state of the art for a rocket stage.