American rocket engines

Paging @Stranger_On_A_Train.

With the hostilities in Ukraine, Russia is no longer supplying the United States with rocket engines. I’d always thought it a mistake to rely on Russia for engines and transportation, but my early employment was at an Air Force base in the last (almost-)decade of the Cold War. I thought, ‘The U.S. built the mighty F-1 engines. What happened to our industry?’ It surprised me when I went to this page and saw quite a number of current and upcoming orbital rocket engines with American flags next to them.

So how is the U.S. rocket engine-building industry doing? Have we learned our lesson regarding relying on foreign countries for them?

The Lockheed Martin Atlas V and Northrop Grumman Antares are the only American large launch vehicle that still use Russian-built engines. The Atlas V uses the RD-180 built by NPO Energomash for the first stage, and previously, the Orbital Sciences Taurus II/Antares rocket used the Aerojet AJ-26 which is a refurbished and modified NK-33 in the first stage, but now uses a downrated RD-181. The last launch of Atlas V is scheduled for 2022, after which it will be replaced by the Vulcan using a Blue Origin engine, while the Antares is is only used for NASA Commercial Resupply Services program. Since that program is only to support International Space Station (ISS) logistics and it is now questionable that the ISS will continue in service until the planned retirement in 2030 without Russian partnership, it probably isn’t the issue that it might seem to be. I don’t know how many engines that Northrop already has in inventory but it is probably sufficient to cover the CRS-2 flights through 2023, after which additional bids are still open to other CRS-2 contractors (SpaceX, Sierra Space (formerly Sierra Nevada Space)). I would assume that SpaceX would be pleased to pick up more missions provided they can fit it into their launch tempo, while Sierra has yet to launch and is predicated on a successful qualification of Vulcan in 2023.

The “U.S. rocket engine-building industry” in general is not doing great. The heritage of legacy liquid engine manufacturers (Rocketdyne, Pratt & Whitney, Aerojet General, TRW) has pretty much been lost through attrition. There is still some native knowledge in building cryogenic upper stages and small thrusters by the inheritors of these companies but building large primary booster stage engines is a complicated activity requiring many different engineering disciplines and a lot of empirical knowledge that has not been captured by another generation. The same is true for solid rocket motors (Thiokol/ATK, Aerojet, P&W CSD, Lockheed Propulsion) to the point that only Northrop Grumman (which purchased ATK/Orbital) still has the knowledge and capacity to build large solid motors, and their production is mostly limited to the US Navy Fleet Ballistic Missile (FBM) program (i.e. the D-5 ‘Trident II’ first and second stage).

SpaceX, of course, builds engines for their own use and is actively engaged on an ambitious plan to build very large, high thrust methane/LOX full flow combined cycle engines, but Elon Musk and Gwyenne Shotwell have made it clear that they have no intentions of selling engines to other launch vehicle manufacturers or integrators, so while that is good for SpaceX it doesn’t benefit competitiveness in the spaceflight industry as a whole. Blue Origin has been developing and building engines (most notably the BE-4 used on Vulcan) but their development has been slower than expected and halting, indicating problems during development which is entirely expected. Beyond that there are a number of companies building smaller liquid and hybrid rocket engines for smallsat/nanosat launch vehicles using a variety of approaches but it remains to be seen how many will be successful, and scaling up a small engine to much higher thrust is a non-trivial exercise; the features that work in small engines often cause fundamental stability problems in larger combustion chambers as well as the scale of heat flow and problems with propellant delivery, et cetera.

I would say that aside from reliance on Russian engines (which was problematic but necessary at the time; attempts to produce a licensed version of the RD-180 by Pratt & Whitney resulting in a setting a billion dollars on fire without successful production) the United States has a lot of problems in just sourcing materials and critical components because even if we have the ability to produce specialty components there are thousands of other materials and components that are ultimately commercially sources from foreign suppliers, including nearly all mechanical fasteners, ‘normal’ commercial steels, carbon fiber and resin precursors, et cetera. A purely domestic supply chain is really important for being able to maintain a secure rocket manufacturing capability and we no longer have anything like the capacity we had even circa 1990 when globalization was already in progress.

I know a lot of people like to think that we can just ‘3D print’ everything that is needed but in fact components like valves, fasteners, sensors, microprocessors, et cetera, are all things that have an enormous and mostly invisible infrastructure of supply chain logistics, knowledge base, materials, et cetera behind them that would need to be reestablished to have a truly domestic supply of rocket engines and other critical flight structures and components that could not be compromised by disruptions in the global supply chain system. It has become a major issue with the aforementioned FBM system (because domestic sourcing of materials is required and has to go through a lot of gyrations to make things like Toray fiber a ‘domestic’ product) and with the upcoming development of the Ground-Based Strategic Deterrent (the long-overdue replacement for the Minuteman III ICBM) it may actually become a show-stopper without a lot of waivers, and even then a lot of foreign suppliers have severe restrictions when it comes to supplying materials used in the manufacture of weapons of mass destruction. So it is generally a huge problem even beyond the loss of heritage knowledge and manufacturing experience with engines and motors.



It’s a shame when knowledge is lost.

That’s understandable from a business standpoint. It’s why I think NASA should oversee engine and vehicle development to a greater extent than it does.

It’s true that virtually everything comes from somewhere else. The current situation should highlight the need to develop domestic sources, and to be wary about foreign sources.

That is something that hadn’t occurred to me! (‘Cause, I’m old an’ shite.)

Thank you for your detailed answer. Your depth of knowledge about – well, everything – is amazing, and I, for one, appreciate your willingness to share it – and in such detail.

Well, yes and no. NASA has a lot of great facilities for testing engines and other components (and also for filming action films, apparently) but no particular knowledge base or expertise on building engines. Nearly all of the engine development that has been done in the history of US rocketry has been done by university-affiliated labs like the Guggenheim Aeronautical Laboratory or Charles Stark Draper Laboratory or by private contractors like Rocketdyne, Thiokol, Aerojet, Pratt & Whitney, TRW, et cetera. One can argue that NASA, while providing funding and acting as a clearinghouse for technical information, has actually negatively interfered in engine development to a significant degree; in the case of the RS-24/RS-25 Space Shuttle Main Engine they actually selected the Pratt & Whitney staged combustion design that was used versus the aerospike design that Rocketdyne designed and qualified on IRAD funding, ostensibly because the aerospike was considered too great of a technical risk (never mind that the turbopumps on the P&W engine ran at such high pressures and speeds that the engines could only survive two flights before requiring complete refurbishment) but in reality because using the P&W design meant that they could divide work up between both engine contractors with Rocketdyne building the combustion chamber and P&W would make the turbopump.

In general, NASA has made a number of rather poor decisions, in part as a consequence of inconsistent funding and direction, but also because it is a large bureaucracy that often just can’t get out of its own way and is reluctant to put money into technology development versus going to a known contractor even if that contractor (cough Lockheed cough) has a history of poor technical and programmatic performance. NASA is at its best in the role of a top level systems integrator, a role it gave up with Shuttle because of the assumption by some that private industry (in the form of the United Space Alliance) would be able to support mission operations cheaper even though mission costs went way up during USA (albeit for reasons that were not entirely in control of the contractor such as age-out and obsolescence of components, increasing labor costs of an aging workforce, et cetera).

So, I don’t think NASA needs to get its fingers into engine and vehicle development at a detail level, but they should be operating as more than just an end user or purchaser of commercial services because the “low cost” option is not always the best overall value in terms of maintaining continuity and capability, and certainly not for fostering independent and competitive development. But then, we don’t really have a consistent national enthusiasm in maintaining a space industry despite all of the potential benefits and have done very little in terms of establishing an actual infrastructure for future space development, instead favoring the approach of launching individual missions and putting an enormous amount of money into an ‘international’ collaboration on a waystation that is only from and to Low Earth Orbit.

It is my pleasure to share, and I assume that others have knowledge and their own opinions which I encourage people to share. I wish I did not have such a pessimistic view of our current space launch industry because I think there are potentially enormous gains to be made in space in terms of both knowledge and commerce (albeit not in ‘space tourism’ or mining the Lunar surface for helium-3) that we are missing out on in a focus on crewed space and the increasing reliance upon commercial providers which may or may not perform as advertised.


For those interested the video below features Tory Bruno, CEO of United Launch Alliance (IIRC a venture of Lockheed and Boeing). They make Delta rockets in the US.

The video is two years old now and in it, Bruno says they had already ordered their last engine from Russia. Engines were still being delivered but they would not be ordering any more and were now building their own engines.

As an aside Tory Bruno is one of the more impressive CEOs I have ever seen. He really knows his business (and, I think, he was originally an engineer so he knows the tech and processes well).

Is there any work under Title III of the Defense Production Act to address this issue? A couple of years ago I space qualified an image sensor IC for star trackers. The program was funded by Title III when it became known that there was no domestic source for appropriate space-qualified CMOS image sensors, just older CCD sensors. The funding basically covered NRE for process and chip development, otherwise even with the incredibly high margins on space-qualified silicon there was no business case for private investment because low production volumes put a limit on the top-line numbers. I assume that for the sorts of critical supplies you mention there is a similar situation - not enough volume to provide adequate return on investment.

In theory, yes, the DPA could be invoked to incentivize manufacturers to produce needed materials and components, and in fact may need to be for GBSD because there are some very specialized components and systems that could not be bid out without guaranteeing to a potential manufacturer that they would be reimbursed for all of the development and guaranteed production quantities that would not be allowed in the normal FAR competitive procurement process. Carbon fiber is a prime example; there is no domestic manufacture of polyacrylonitrile (PAN) suitable for aerospace-grade carbon fiber. (There is some research done on using genetically engineered lignins as a replacement for PAN but thus far it has not produced viable precursors.) In order to establish domestic manufacture of a suitable grade of PAN would require establishing that capacity even though it would not otherwise be commercially competitive.

In reality, setting up a manufacturing infrastructure for all components necessary for non-strategic government and commercial spaceflight would require the federal government to set up an enormous system of producers and suppliers for all kinds of materials and components that would be dependent upon that subsidy. Imagine setting up your CMOS image sensor project but hundreds of times over. That was marginally justifiable during the Cold War (and at a time when the United States was the unquestioned leader in manufacturing and scientific research) but it would be prohibitive today. And even during the Cold War, the US had to do get creative with some of its procurements such as the titanium used in the SR-71 ‘Blackbird’ and SR19 Minuteman II/III Stage II motor case, which actually came from the Soviet Union via intermediaries.


Stranger, please write a book sometime. I’d buy it. About NASA, DoD, DARPA, FBI, whatever.