William Greene – Page 2 – Liquid Rocket Engines (J-2X, RS-25, general)

J-2X Extra Rocket Alchemy: How Paper Becomes Precious Metal

Alchemy isn’t practiced much these days in the medieval sense. That’s a shame. A little extra gold would be useful. But there is little doubt in my mind that alchemy is exactly what is going on behind the scenes, deep within the dungeons of NASA as we develop a rocket engine.

How do I know? Because I have been one of the chief alchemists for J-2X (…in fact, I kind of like that title: “Manager of Alchemy”). No, we don’t start with a heap of scrap metal and end up with bars of gold or the philosopher’s stone. Rather, we start with a heap of paper and end up with a rocket engine – and, well, a larger heap of paper. As much as bending and grinding and welding and balancing and casting and torquing, the story of the paperwork is big part of how a rocket engine comes to be.

Hold on! Yes, I am endeavoring to present here a blog article about paperwork and, further, I am endeavoring to make it (reasonably) interesting. Really. All along I have tried to convey the complexity and scope of what it takes to design and develop a rocket engine. It ain’t easy. That’s why not everyone does it and even we don’t do it very often. And, like it or not, paperwork is what makes it all happen.

Here is how we at NASA develop launch systems:

Joe Mega-genius wakes up with a vision for what NASA ought to be doing. He alone has the image in his mind for a launch system for exploring space. He single-handedly directs everyone at NASA and every contractor as to what to do, what analyses to run, how thick the metal of a feedline needs to be, how the launch pad should be configured, the shapes of the knobs on astronaut’s control panels, the material to be used for the springs in the check valves on the engine, everything. He personally takes care of all management and business and procurement activities so that there is a single, non-contradictory point of contact for everything. And nobody at any other NASA center or Congress or the Administration questions what he says so he gets all the money in the world to spend as he sees fit because, after all, he is Joe Mega-genius.

All it takes is one brilliant focal point and everything falls into place easily.

Guess what: That’s a lie. This is not how it works. Further, that is NEVER how it worked. Never. All cinematic or mythological approximations of that scenario are, simply, myths. Nobody can know that much or do that much. It takes many, many people and (good) paperwork is the key to get many, many people successfully coordinated.

Note that specifically what I want to talk about is the paperwork that enables and facilitates development. That is somewhat different than the many products that result from a development effort other than the hardware itself. Perhaps we can talk about all of those other products at another time. I also don’t want to talk about the paperwork at the highest levels, between the Federal Administration and Congress, the Office of Management and Budget (OMB) and agency authorization bills and appropriations bills, etc. Interesting stuff, but not quite right for this blog (to say the least).

Let’s start with the assumption that we have a mission. Let’s say that it is simply this: Get XX payload to low earth orbit. Okay, simple enough.

How? Well, there are lots of ways to launch something. There are different rocket configurations using different propellants in different combinations. Each potential solution brings with it certain positive and negative aspects, consequences far and wide. So, we have a trade study and come up with a “best” solution. That “best” solution has a particular configuration and piece parts that all have to work together. So, we write down what those various parts all have to do. Those are the top-level requirements.

So, we start with one mission objective and now we have requirements for the launch vehicle itself, for the launch pad, and for the launch control center. If we just focus on the launch vehicle, we then have to further break down the requirements into separate groups for the payload section – including, of course, a crew element if we’re putting people in space – and the various stages and boosters. And, on those stages there will be engines, so you have to break down the stage requirements into separate groupings for the engines and the tanks and propellant feed systems and the structures and the electrical systems and guidance and control systems.

Thus, you start with one extremely broad mission and, in just a few steps, have dozens of separate groupings of requirements for dozens of different things that all need to work together. At each step along the way, you need to figure out a conceptual design, i.e., a series of plausible configurations and functions for the various components, and then assign those necessary characteristics as requirements before you take the next step downwards. And if you should decide at any point along the way that you want to change something higher up in the chain, then, boom, you have repercussions throughout everything below.

This whole process is called requirements decomposition. The management of the process represents a huge task at the early part of a development program and remains important throughout as you head into the verification phase where you demonstrate that every requirement has been fulfilled. In the diagram below, you see the decomposition process. Every place where there is a dashed line and a red dot I’ve loft out details, i.e., lots more stuff.

What is the result of all this by the time it gets to, say, the J-2X? Well, for J-2X we’ve got just about 200 requirements dictated to our development effort from the vehicle project level. These requirements cover performance characteristics and physical properties and functionality and safety and operations considerations and standards as to how things are made and analyzed, plus a bevy of items dedicated to how the engine effectively interacts with the stage. These requirements define, at the top level, what the J-2X shall be when development is complete.

Now what? You’re at the beginning stages of a development effort and you’ve got in hand a book of requirements to fulfill, so what do you do next? You make plans.
• You create a plan for the overall development effort. This includes how many development engines are you going to build and test, how many tests you’re going to run, where you’re going to run those tests, what you’re going to do in terms of testing at the component level, what analyses are you going to do, what level of non-destructive and destructive evaluation will you be performing on built and/or tested hardware.
• You also make plans for how you’re going to manage the office and manage the various “office disciplines” such as risk management, business management, systems engineering and management, and configuration management.
• You have an overall plan for how and what safety-related assessments and analyses are going to be done and by when. This needs to be tightly coordinated with other elements of the launch architecture since the whole notion of safety is a wholly integrated consideration.
• You have to generate a clear plan and process for how decisions are going to be made since nearly all big decisions have budgetary or schedule or technical risk implications. To enable these processes you issue charters to delegate formal authority for decision-making boards.
• And there’s much more…

So, that’s how you get started. In the beginning, you don’t usually have any hardware. All you have is paper (or, these days, computer files). And you’ll hear lots of people complain about “paperwork this and paperwork that,” but without this foundation of documentation, nothing else can follow. What does come next beyond this foundation is that you fulfill your plans. You do the design, do the analyses, create the drawings, fabricate the hardware, assemble the engine(s), and then test the hardware to demonstrate that you’ve met the imposed requirements.

Thus, just as the rocket engine is itself a complex machine, so too is the infrastructure coordinating the efforts of hundreds of people to arrive at the final product. In some ways, it’s even more complex than the rocket itself: imagine a shiny rocket engine rising out of a pile of paperwork. It is truly, in the end, almost alchemy.

J-2X Progress: Engine Assembly, Volume 4

It’s been about three weeks since I last reported on the progress of J-2X Engine 10001 assembly. What I would like to do is show you pictures of great big additions to the engine, but the truth is that for the last few weeks the engineers and technicians have been diligently plugging away at smaller stuff, at the details.

“It’s the little details that are vital. Little things make big things happen.” – John Wooden

I would hazard to guess that Coach Wooden was talking about basketball – or maybe life in general – when he spoke these words, but on a rocket engine, everything has to work so the details of the big stuff and of the little stuff are equally vital.

So, here are some pictures and some details…

We’ll start with a picture of the overall assembly and the addition of the item in the dashed, red oval on the right-hand side of the picture. That is the gas generator. Yep, that little thing powers both turbopumps and therefore is the driving force behind the whole engine. Here is a closer picture.

As I’ve mentioned before, during the whole assembly process, things either have covers attached or are wrapped in tape and other protective media so that no debris gets in the engine and so that delicate parts are not damaged. You can see that here on the gas generator.

Note that in the image of the gas generator above, you will see the “U-duct” from an earlier blog series entry regarding Direct Metal Laser Sintering. This, right here on the engine, is the piece for which we may have found a future innovative manufacturing method.

Next is a picture of a mounting plate. This is not even a primary piece of the engine if you were looking at a schematic, but it’s a vital piece nonetheless. On this mounting panel sits the two Main Injector Exciter Units (MIEUs). An MIEU is analogous to the ignition coil in your automobile engine but with a good bit more punch. We use two units for redundancy to further ensure overall reliability. If, in the morning, your ignition coil goes dead in your station wagon, well you’re just stuck in your driveway. However, if during a launch mission you can’t get the J-2X started, then you’re stuck somewhere over the Atlantic Ocean at two or three hundred thousand feet. That’s a somewhat more treacherous situation. So we use very highly reliable parts and we use two parallel units.

What makes this mounting plate interesting is that it has vibration isolators so that the noise and shaking of the engine don’t impact the electrical components of the units. Those eight circles on the mounting plate are the tops of the isolators so there are four for each unit. Kinda cool little details.

Next, more mounts. In the picture below, you will see two rectangular items, each with eight holes. These are mounts on which will eventually reside pressure transducers. There are several such transducer mounts across the engine. These particular mounts are installed on the arms that hold the oxidizer turbopump. So, we have mounts installed on mounts and you can begin to understand the complex layering that an engine assembly represents.

One strategy that is used quite often during the assembly process is to do stuff unattached from the main assembly itself. Over on a separate bench, you put together a bunch of smaller pieces and then take this whole subassembly over to the engine for installation. Over the past couple of weeks, this is exactly what has been done with the ancillary line “raceway.” Below is the completed raceway subassembly.

All of the lines and brackets and nuts and bolts were separate pieces when the engineers and technicians began.

Each line in that assembly is different since each line represents different fluids coming to or coming from the engine at different pressures and temperatures. There is helium, oxygen, hydrogen, and even nitrogen. There are pressures over 3,000 psi and less than 50 psi. There are temperatures approaching the boiling point of water and those less than 400 degrees below zero Fahrenheit. Thus, some of these lines shrink from the cold. Some of them stiffen with high pressure. Yet all of them have to be flexible to accommodate the gimballing of the engine and every one of them is vital either to the engine or to the vehicle. In other words, it is a complex design, a complex manufacturing process, and a complex subassembly to put together. And it all has to be correct. Details, details, details!

Lastly, I’d like to toss in a cool picture from the test stand. Below is a picture from test stand A-2, with the engine mass simulator installed. This is where J-2X Engine 10001 will be tested. The brightly painted, yellow hunk of metal is supposed to weigh the same as a J-2X and have the same dimensions. It’s used for checkouts of various systems including the test stand.

Another thing of note in that picture from A-2 is large gray object to the right. That is half of a water-spray system that will be used during testing when no nozzle extension is installed on the engine. Near the top of the picture is a hinge painted bright red. When deployed, the gray water-spray structure will have been swung down so that its two pieces (the one shown and the other one to the left and out of the picture) join at the bottom of the engine nozzle. This is all part of the system to deal with the substantial, combustible, fast moving, and very hot exhaust from the engine during test. This water-spray system was installed specifically for J-2X testing.

That’s where we stand. The details of the engine assembly are coming together, with more parts arriving at the NASA Stennis Space Center every day, and with the test stand is being readied to accept installation of the engine. This is Volume 4 of the assembly saga. By the time Volume 5 is ready for the blog, we should be very close to having a fully assembled engine. Wahoo!

J-2X Progress: Engine Assembly, Volume 3

Assembly of J-2X development Engine 10001 “officially” commenced on Monday 21 February of this year, just about a month ago. In even more important news, my own household had an eight-pound, eleven-ounce new arrival on Friday 11 February. No, no, not that kind of arrival. Rather, it’s a new puppy named Kate (…had ya fooled for a moment, didn’t I?).

Thus, I have the great pleasure of spending this spring watching both J-2X Engine 10001 and Kate grow up and into what they will finally become. Here is a picture of Kate cuddled with our cat Cassady to give you an idea of her size when first she came home. By the way, the cats all thought that Kate was just swell so long as she was unconscious and inert. Their opinion changed significantly when she woke up.

And here was the “engine” as a pup, newly weaned and delivered to Stennis Space Center. It began as just the Main Injector stacked on the Main Combustion Chamber. Humble beginnings.

Here is the engine today. Awwwww, our little baby is growing up so fast!

The most noticeable additions since the last time that we checked in on the assembly progress are the two inlet ducts stacked on top of the two turbopumps. More stuff has been going on, like the attachment of brackets and mounts for parts to follow, but those two ducts are the biggest items. So, let’s talk about them…

In the picture of the stacked engine assembly, the inlet ducts are encased in protective coverings. In the picture above, however, these coverings have been largely removed from the fuel-side duct for inspection purposes. It looks kinda funky, huh? Well, despite the oft-demonstrated good fashion sense and excellent taste of your average rocket scientist, we don’t usually make thinks look funky just so they look cool. There is usually a function to our funky-ness.

Here is the function: The engine has to gimbal. What that means is that you have to be able to point the engine in slightly other directions besides straight down from the back of the vehicle stage. You can think of gimballing as being like a rudder on the back of a boat but in three-dimensions. Thus, the whole engine has to pivot around when pushed or pulled by two large hydraulic actuator arms from the stage.

In order to accommodate this movement of the engine, the inlet ducts need to be able to bend and flex and even twist a little bit. So, in order to make super-duper-strong metal ducts flexible, you have to add the convolutions like you see above. It’s very much like one of those twisty drinking straws that I absolutely loved as a kid (see, even then I was unconsciously thinking about rocket engine components). If you bend a regular drinking straw, the thing collapses in on itself. If you bend one of those twisty drinking straws with the convolutions, the straw remains useful as a duct. The external structures in the picture of the inlet ducts, those shiny triangular brackets hinged together, hold the whole thing together under operational conditions.

Here’s a neato little fact about the fuel-side inlet duct. In order for the convolutions to do their job by allowing movement, you can’t have any ice buildup in the convolutions. Liquid hydrogen is so cold that it can freeze nitrogen right out of the air. If you don’t have some way to insulate this duct, it would be covered in nitrogen ice while sitting in compartment at the back of the stage. But you can’t insulate it on the outside or, again, the thing can’t flex. So, what we’ve done is make the whole thing into a Thermos® bottle. There are actually two walls of convolutions, an inner wall and an outer wall. In between is a vacuum and that vacuum provides the insulation. This feature is not necessary on the oxidizer side since liquid oxygen will not freeze anything out of the air other than moisture. Thus, so long as you keep the compartment free of humidity, the oxidizer side is fine with only one layer and bare metal (though special accommodations are necessary on the test stand where the ambient environment cannot be so carefully controlled).

So, that’s the status of the J-2X Engine 10001 assembly and a description of its inlet ducts. The status of Kate is that she is growing like a weed. Every day her legs look longer. Of course, it was only after we adopted her that the shelter people seriously and openly speculated that the father might, in fact, have been a Rottweiler. Oh dear. She’s nearly 24 pounds at less than fourteen weeks old. The cats are more displeased with each passing day.

J-2X Doghouse: The Rocket Equation! Wahoo!

Welcome back to the J-2X Doghouse. We’ve talked before about what a rocket actually is and we’ve talked about different kinds of rocket engine cycles and where J-2X fits in that family. This time, in response to a couple of early requests on this blog, I’d like to talk about rocket engine performance characteristics and how they relate to successfully getting off the planet and into orbit. Because this comes down to a matter of equations – and therefore at least half of the reading audience will click on their Facebook icon as soon as they see any equations – let me start with an old joke:

Q: What do engineers use for birth control?
A: Their personalities.

Of course you know that joke can’t be entirely true if you’ve read any of the articles profiling the J-2X office. Just about everyone in the office have children. But somewhere, deep down, in order for that joke to have lasted so long, there must be a tiny sliver of truth. Okay, yes, I admit it, here it is: People who become engineers do so for a whole variety of reasons but typically share in common an aptitude towards mathematics and a desire to know how things work.

For me, this whole “future-engineer” notion translated to an appreciation of physics and the representation of the real world, to some approximation, in equations. Seriously, just think about that for a moment. You can pick up a pencil, draw a simple sketch, apply some fundamental laws, and, boom, you’ve got a prediction right there on your paper for how the real world will function. Now that’s darn exciting! At least it is to me. But, okay, word of advice: Showing this level of enthusiasm regarding physics and neato equations is generally NOT good fodder for a first date. Trust me.

However, since I’ve not had a “first date” in over a quarter of a century, I am now going to explain the derivation of the foundational equation for all rocketry: The Rocket Equation. Approximately 99.7% of the world’s population at large does not know this … and, yes, that is a 100% unverified, made-up statistic. Regardless, today you will join an elite, exclusive, and fashionably eccentric club.

[Warning: Some of the mathematics gets a bit heavy here, but some of y’all asked for it.]

First, we start with a simple drawing. Please note that my wife is the artist in the family; I “draw” in PowerPoint. Sorry.

What you have is a thing, a blob, at time equal to t0 with a mass of M moving at a velocity of v. At this point, don’t think of the blob as a rocket. It’s just a thing in an imaginary space where there is no gravity, no friction, no environmental impacts at all.

We then go to the next step in time, time = t0 + dt, where dt is a small increment.

Our blob has ejected from itself a small piece of mass, dm, in the opposite direction from which it was moving. The small mass has a velocity of vdm in the opposite direction of the original blob. The blob, by the way, has a mass now diminished by dm and a velocity that has changed by some increment dv.

Do you want to play the gray blob at home? Okay, do this. On a smooth floor, tile perhaps, sit in a rolling chair holding a basketball. Throw the basketball. You, still in the chair, will roll in the opposite direction from the flight of the basketball. Your initial velocity, v, was zero. Your initial mass, M, included you, the chair, and the basketball. Your new velocity is zero + dv. Your new mass is now minus that of the basketball, dm, flying in the other direction. Ta-da!

Now, how do we turn this simple concept and simplistic drawings into rocket science? Simple, we call up the work of our friend Sir Issac Newton (1642 – 1727). Newton’s First Law of Motion states: “An object at rest tends to stay at rest and that an object in uniform motion tends to stay in uniform motion unless acted upon by a net external force.” I told you that there were no external forces acting on our blob and I drew the box around the whole thing, blob and small piece together. Combining the philosophy of this First Law with the mathematics of the Second Law results in a simple conclusion that in absence of any external forces, momentum is conserved. So, the total momentum in the first drawing is the same as the total momentum in the second drawing with momentum defined as mass × velocity.

The second term in the right-hand box is negative since the velocity of the small piece is in the opposite direction as the original movement of the blob. Okay, now multiply this all out and eliminate redundant terms and – thanks to some niceties of differential calculus – eliminate second order terms to yield the following:

The dm = -dM switch-a-roo is possible since the incremental change in mass of the blob over the time period dt is exactly the negative of the piece ejected.

Rather than talking in terms of absolute velocity of the blob and the small piece, let’s instead talk in terms of ve, the “ejection velocity” of the small piece. So, this is a relative speed. Then the equation becomes:

Believe it or not, that’s it. In its most rudimentary, simplified form, that the Rocket Equation expressed over a very small time increment dt. If you add up a bunch of these very small time increments, or in other words integrate over a measureable time period [Oh no, integral calculus buried in a blog! Call the blog police!], you get the following:

What does this say? Equations always say something or they’re worthless. It says that the change in velocity of a blob is equal to the relative ejection velocity of small pieces flung away from the blob times the natural log of the ratio of initial mass, M0, to final mass of the blob MF. The natural log thing got in there thanks to the rules of integral calculus. You’ll have to trust me on that one.

Now, what does this have to do with rockets? Well, how about rather than ejecting small discrete chunks of mass we think about what a rocket engine does, which is spew out a continuous stream of mass in the form of high-speed hot gases. The whole derivation above holds for that case with one modification. The hot gases ejecting from the nozzle create a pressure field at the point of ejection. That pressure field creates a force acting on the system. Because there is a force involved now, momentum is not conserved. The derivation is a bit more complicated, but it’s not too bad. The result looks like this:

Where ueq is called the “equivalent exhaust velocity” and is defined as:

The first portion of that last equation deals with the pressure field. Basically, it is the exhaust pressure at the end of the nozzle, Pe, minus the ambient pressure outside, Pa, times the exit area of the nozzle, Ae. Force equals pressure acting over an area. Simple. The “m-dot” term is the mass flow of the hot gases out of the nozzle.

We’re almost there. Really. Hold on.

Next, I want to define thrust. We could have started this way by drawing a control volume around a rocket, but I like starting with the blob. Thrust, T, is the force that the engine imparts on the vehicle. So, it includes the pressure field aspect and it includes the aspect of ejecting hot gases at high speeds. Here it is:

If you put a rocket engine on the test stand, fire it, and measure how hard it pushes against the stand, this is what you are measuring. Sometimes you will see a rocket engine specification that will talk about “vacuum thrust” or “sea level thrust.” The difference between those can be found in the ambient pressure term, Pa, in the equation above. In a vacuum, Pa = 0. At sea level, Pa = 14.7 pounds-force per square inch. Note that depending on your system of measurements, there could be a “g-factor” conversion lurking in the mass flux term so be careful.

Substituting back into the Rocket Equation, we get this:

I have now cleverly introduced the concept of specific impulse, Isp, which is thrust divided by mass flowrate. When talking about rocket engines, we typically describe this parameter as being analogous to gas mileage so that people can understand, but here you can see that it’s an integral part of the basic physics of the acceleration of a rocket vehicle. (Again, beware of hidden g-factor conversions.)

Note that earlier I said that we didn’t have any gravity in our hypothetical situation and that we didn’t have any friction. I can now add these things into our system a simplistic manner to facilitate the final discussion and to present the final equation:

That, right there, believe it or not, tells you 90% of the whole story about how rockets get into orbit and even how they go from there into the rest of the cosmos. What do you need to get into and stay in orbit? A lot of velocity. And this equation tells you all about it. Listen carefully to rocket scientists talking about “delta-v” in movies or the news or in documentaries. “Delta-v” is everything. You need so much delta-v to get to orbit. You need so much delta-v to change orbits. You need so much delta-v to get out of orbit and head towards the moon or anywhere else. Whenever you hear this, they are referring to the Rocket Equation.

Let’s break it down by starting with the last two terms on the right-hand side. These are loss terms and that’s why they are negative. First, as long as you are gaining altitude, you are fighting against gravity. If we had some way to dial down gravity, we could launch rockets more efficiently because this term would lessen (we’d also all float away). That’s intuitive. It takes energy to lift something. Second, as long as you have friction caused by drag against the atmosphere, you’ve got losses. Compared to a vacuum, especially at high speeds, our atmosphere is like soup to a launch vehicle and you need energy to overcome it. Thus, both of these loss terms tell you that for greatest efficiency, it’s best to get up high, out of the atmosphere, and level out to stop fighting gravity as fast as you possibly can. And that’s exactly how we launch rockets. It’s not an accident or a whim. It’s physics.

Now, the first term on the right-hand side in that final equation has two pieces. First, there is specific impulse, Isp. That is a measurement of how efficiently the rocket engine produces thrust. For a given amount of propellant the engine produces this much thrust. Second, there is the ratio of masses within the natural logarithm. What this says is that the lower the final mass of the vehicle is relative to the starting mass, the more velocity can be gained. So, what you want is very low final, burn-out mass as compared to where you started. When you get to the end, you don’t want much by way of leftover, unused propellants, and you want as little superfluous structure as possible. Remember, part of your final mass is your payload, which is the satellite or your capsule filled with astronauts. That’s the important stuff. It’s this notion of discarding unnecessary and heavy stuff along the way that results in the reason why rockets typically have multiple stages. As you go along, you toss off heavy structures that you no longer need: The more stuff that you can shed, the less that you have to carry along, and the more velocity that you can pick up. Again, it’s intuitive.

If you’ve made it this far and if you’ve grasped the basic concepts of the physics involved, you truly know more about rocketry than almost anybody you’ll meet. And it’s amazing how intuitive it all ends up once you’ve plowed through the mathematics. Good equations are those that can tell a good story. The Rocket Equation is one such equation.

My recommendation is that you print this out and take it along with you on your next date. Really, you’ll be a big hit! (Or not.)

J-2X Progress: Engine Assembly Continues

Once upon a time, I used to consider myself reasonably handy with a saw and a drill and a miter box and various rudimentary woodworking tools. I certainly knew my limits, so I never did anything too complex, but most of the fun from pursuing such projects was the creativity involved. I didn’t plan out a great deal. I preferred an evolving, organic (i.e., lazy) approach. Given the nature of the forgiving materials involved, that was generally fine. In my wife’s art studio, there’s a cat tree with six or seven beds that fills an entire wall. I built it with no drawings, kind of on the fly, and it still turned out okay (or, at least, the cats seem to think so).

That is not, however, how you assemble a rocket engine. You don’t wing it. You plan everything. The materials are not forgiving. Just about everything is heavy and, if you drop it, or scratch it, or scuff it, or nick it, then you have the joyful experience of traipsing through a paperwork exercise to make sure that whatever you damaged is still usable. In other words, rocket engine pieces are both extremely rugged and rigid yet also precisely machined and fragile. Oh, and unlike two-by-fours, rocket engine parts aren’t cheap and as easily replaced as a trip down the street to Home Depot. Thus, a great deal of time spent poring through the planning documentation and lifting and moving things with exceptional care.

You can think of a rocket engine as a large, three-dimensional jigsaw puzzle. The pieces have to fit together exactly and properly. To make this happen, you first have to have really well-manufactured parts, but then you also need good ground support equipment (GSE) and knowledgeable, competent, and dedicated technicians. Below is a picture of one critical piece of GSE, the engine build dolly. This is essentially a rolling piece of elevated floor onto which you build in the engine. Considering with the engine sitting on it, plus tooling, plus the technicians themselves doing the work that the dolly could be holding well over 6,000 pounds, this is a stout piece of equipment.

When I built the big cat tree, I just moved around the mess in my garage and I pulled my pickup out of the driveway to lay out the bigger pieces. The picture below is the J-2X assembly area. Note that there aren’t any flower pots with last year’s dead petunias, or half-empty bags of bird seed, or cast-off, half-used rolls of duct tape scattered about the floor. In other words, it doesn’t look like my garage. It is extremely clean and orderly. It is a FOD-free zone: FOD = foreign object debris. When assembling an engine, you do not want ANYTHING in the engine that does not belong there. I will be showing you pictures below of various stages of engine assembly so far and you will notice that there is tape and/or plastic closures over every open hole where something might accidentally fall. One dropped nut or hunk of wire or wad of tape and you’re either forced into a costly disassembly exercise to get the stuff out or, worst case should the FOD be missed and left in the engine, you could have an engine failure in test and the loss of tens of millions of dollars of hardware.

The other thing that you will notice from the picture of the assembly area is how well the whole thing fits together. Pieces of the floor retract to allow for the dolly to be positioned in the middle. The kit carts have bays into which they can slide for convenient access to the necessary hardware. There is an overhead boom with commodities available for when the assembly and checkout processes require gasses or electrical power or a hookup to a simulated vehicle stage computer. And, of course, just above the boundary of the picture is an overhead crane for lifting operations.

Now, can you just imagine the magnitude and glory of my cat tree if my garage was so neat, well organized, and fully equipped? Difficult to fathom, huh?

So, where does the engine assembly stand? Since I last reported the initiation of assembly, great strides have been made. Let’s step through the biggest pieces of the sequence. First, the birdcage was put into place on the build dolly. Remember, the yellow birdcage is a simulator for the first portion of the nozzle. Later, it will be replaced with the real nozzle. The dolly was then wheeled into place in the assembly area.

Below is the next sequence. The picture farthest on the left is the MCE, i.e., the main combustion element (composed of the main injector attached to the main combustion chamber) sitting in its shipping box. In the middle is a picture of the MCE with the turbopump arms installed. From these four heavy arms will be hung the fuel turbopump and the oxidizer turbopump. And, on the right, is a picture of this the whole assembly of MCE with the turbopump arms mounted on top of the birdcage.

Next, the two turbopumps were installed, first the oxidizer turbopump and then the fuel turbopump. I can state that here quite simply in a single sentence, but go back to that series of pictures above: planning, lifting, moving, positioning, etc. A great deal of careful work went into each step.

Now, I don’t know about you, but this is getting darn exciting for me. If I squint hard at that last picture and add some ducts in my mind, then that really looks a whole lot like an honest to goodness rocket engine. J-2X is coming together! In another month or so, it will be fully assembled and early this summer we will be demonstrating the first new, human-rated NASA rocket engine since 1975 (…yes, 1975, think: the fall of Saigon, Patty Hearst still on the lam, the Thrilla in Manilla – Ali v. Frazier III, Tiger Woods and Kate Winslet born, sentences being handed down for Watergate, the very first episode of Saturday Night Live, and me as the star kickball player during fifth grade recess…).

Two final notes for this article. First, I would like to thank Brian West for all of the engine assembly pictures and background information for these pictures. Keep up the great work! Second, I would like to thank my cat Kesey for his starring role in the center of the cat tree picture. Being that round and that lazy takes years of dedicated practice.

J-2X Progress: Engine Assembly Starts!

Ready…
Set…
Go!!!

After so many requirements reviews and concept reviews and safety reviews and design reviews, and after so many trade studies and analyses and assessments, and after so much paperwork generation and processing, and after so many programmatic meetings and technical interchanges and integration exchanges and formal boards, after all that, we have finally begun assembling the very first J-2X, Engine 10001, at the NASA Stennis Space Center (SSC) in Building 9101.

In the end, truly, it all comes to this: the hardware. Everything that we do – and it is an astonishing amount of work – comes down to an operational piece of space launch hardware, a rocket engine (albeit a development unit first example). It is sometimes quite easy to forget that fact after being buried in the mountains of necessary details for several years. Yet that day has now arrived.

The Main Combustion Element (MCE), consisting of the Main Combustion Chamber (MCC) and the Main Injector (MI) mated together, arrived at NASA on 22 February 2011. While a number of piece parts and components have been arriving at SSC for weeks, it is the arrival of this sub-assembly that marks the start of assembly. It would not be too much of stretch to say that the rest of the engine, one way or another, hangs off the MCE. So you need that part to get the whole process started in earnest.

The drawing below shows the first steps in stacking the whole thing together.

Your first question should be, “What’s a Birdcage?” It’s actually a simulator for the nozzle. Because this is the first build of the engine and because the various components are not completing fabrication in the optimal sequence, we have found ways to expedite engine assembly such as the use of this nozzle simulator. The whole engine will be stacked and assembled with the Birdcage acting as the effective pedestal for the process. Then, when the nozzle does arrive, the assembled upper part of the engine will be lifted, the Birdcage will be removed, and then the assembled pieces will be lowered onto the actual nozzle assembly to be used for Engine 10001. Below is a photograph of the actual Birdcage sitting in its packing box at NASA SSC.

(Now, I’m not going to burst anyone’s bubble, but whoever first started calling this thing a “Birdcage” perhaps has a frightening impression of how large are the birds of southern Mississippi. Those are some awfully large holes.) Later, the Birdcage will be reused as the structural foundation for the assembly of the J-2X PowerPack Assembly to be tested next year.

The next picture is of the assembly area where the whole thing will be brought together. There is a raised floor on which the technicians will stand and there is a recessed area where the dolly will fit on which the engine is assembled. On the silvery metal carts shown – the so-called “bread carts” – the kits will be laid out for the next stage of assembly as the engine comes together.

One interesting little note about that picture of the assembly area is that in the upper left-hand corner you can see another engine within a big yellow piece of ground support equipment. That is an RS-68 engine that flies on the Delta IV vehicle. The J-2X assembly area sits right next to the RS-68 assembly area though they are distinctly separated.

Here are some other really cool pics:

Okay, so maybe “really cool” is a slight exaggeration. On the left is a corner of the kit staging area where, on a pallet in the back (can you see it?), sits the first pre-arranged kit of engine parts to arrive at NASA SSC. On the right are the two turbopumps for Engine 10001 still sitting in their shipping crates. Trust me, as the assembly process moves forward, the pictures will get better. Really.

So, J-2X is coming together. Over the next several weeks, I will be posting pictures and descriptions of the process. I do have to say, from a personal perspective, seeing this thing finally becoming a reality is quite gratifying. Thank you all for coming along and sharing the ride.

J-2X Extra: Shiny Metal Pieces

Finally, it has been discovered: Proof that rocket engineers can indeed have a sense of humor. This is an exchange that actually happened in a meeting here at NASA not too long ago.

Manager #1: What are those feedlines made of?
Manager #2: Really shiny metal.

Translation: He didn’t know, but he would find out. Okay, so it’s not Saturday Night Live material, but it was funny in context. (You had to be there…really.)

The truth is that we use lots and lots of different kinds of shiny metal in all kinds of strange shapes, under all kinds of severe conditions, and with uncompromising standards against failure. We use aluminum and steel and titanium and copper alloys and nickel-based super alloys and, sometimes, rare earth metals and precious metals. We cast it, forge it, roll it, spin it, weld it, you name it. Suffice it to say that if you like or know something about metal working or machining or welding or metallurgy, then even if you haven’t got a clue about rockets, we’ve probably still got a place for you. It’s a fascinating field that ranges from enormous factory tooling necessary for large structures production all of the way down to microscopic crystal formations deep within the parts being produced.

Now, the pursuit of new technology demonstrations has never been a primary objective for the J-2X development effort. We are supposed to make it work – that’s the prime directive. However, in the course of J-2X development, we came across a situation where we were forced to consider innovative solutions and, from that consideration, identified an opportunity to pursue something really pretty cool and it has to do with shiny metal.

So let’s start at the beginning. In order to avoid combustion instabilities in the gas generator assembly, we found that we needed a very short gas generator discharge duct. What is a combustion instability? In this case, think of a pipe organ. The size of the pipe determines the pitch. Big pipes make big booming sounds. Little pipes make little whistling sounds. What we found through component testing was that the pipe connected to the gas generator was acting like a pipe from a pipe organ and the sound was so big and so loud that it had the potential of ripping the whole thing apart. To find a place where we were de-tuned from the booming loud vibrations, we had to make the pipe quite short.

Now, though, we had a problem. We had a duct so short that it basically looks like a U as pictured in the drawing above. Note, however, that the unit used on the engine is welded on one end and flanged on the other. This picture is a drawing of the test configuration. But regardless of the flanges and such on the ends, this part is basically U made out of very high-strength “shiny metal” (a nickel-based super alloy). Given the diameter of the tube, the strength of the metal, the thickness of the walls, and the fact that we can’t allow the walls to get too thin from bending, we had a devil of a manufacturing situation for what looks like, on the surface, a relatively simple component. So, we (and that’s the big “we” of both NASA and our prime contractor, “Pratt & Whitney Rocketdyne”) started looking for solutions.

Below is a picture of the baseline solution illustrated with a manufacturing demonstration unit. Rather than trying to do the whole bend in one piece, it is done in three pieces, each with a 60-degree piece of the overall 180-degree bend. Those three pieces are then welded together; the end pieces are trimmed back; and the flange is welded on the end. It works. But it is labor intensive with all that welding and with all of work that comes along with welding along the lines of inspections and re-work cycles. To give you an idea of size here, the duct is 3.5 inches in diameter so it is a healthy hunk of metal.

Now comes the really interesting part.

In addition to the baseline solution, another solution was proposed. It’s called “Direct Metal Laser Sintering” or DMLS. The company that does this is called Morris Technologies (look them up!). And, like most high-tech stuff, if I knew the nitty-gritty details I wouldn’t be able to share them, but I can tell you the basics. First, you start with a whole bunch of very fine metal powder. Next, you load into the computer your three-dimensional CAD model for the part you want to make. The CAD model is analytically cut into thousands of horizontal slices. Then, in a special, automated chamber, a thin layer of metal powder is laid out and fused by a laser into the shape of the first slice of from your CAD model. Then another layer of powder and fused slice is added, and then another, and then another. With each slice, a layer of powder is laid out and fused to the previous layer precisely duplicating your CAD model a little bit at a time. So, any shape that can be decomposed into and built up from a series of thin layers can be made. Below is a picture of a small pump impeller with a relatively complex geometry that was made by Morris Technologies using this process.

Ignoring how it works, you’ve got this: you put in your computer model; you put in the powder; come back a week later; and, your part is cooked (actually there are post-process surface finishing operations, but that’s just a minor detail). It’s almost like something from The Jetsons cartoon series.

So, we asked, can you make our U-shaped tube? The answer was: almost. The size limitations of the existing chamber dictated that we could do the whole tube part but the flanges would have to be welded on. Still, it’s a pretty good demonstration. Below, you can see a couple of pictures of the finished part.

But that’s not the end. So, we made a fancy pipe. Big deal.

Here is the big deal: making it was very cheap and very fast. Of course, cheap isn’t always helpful if the thing doesn’t work. So, we have to prove that it works. Towards that end, we are performing materials properties tests on samples made in the chamber simultaneously with the duct, we are doing non-destructive evaluations of the duct itself, and we plan to incorporate it into a component level test series of the workhorse gas generator. Below is a kind of creepy picture of the duct after it was inspected for tiny flaws using a fluorescent penetrant solution and ultra-violet light.

Because of the severe environments that this duct will see, the material properties throughout the duct have to be consistently good. There can’t be any flaws on the surface that could lead to the development of cracks. So far, the piece has come through all of the inspections with flying colors. The next step will be actual hot-fire testing. Below is a photograph of previous testing of the workhorse gas generator.

If everything goes well and post-test inspections show that the part did not sustain damage, we will have taken a huge step towards making this fabrication approach viable for not only this particular piece of the J-2X engine, but for all kinds of parts on all rocket engines in the future. There are technology issues to overcome – notably current limitations on the size of the parts to be made – but this process is potentially an order of magnitude improvement in terms of the costs for building complex, severe environment components out of that ubiquitous substance that we’ve got all over in a rocket engine, i.e., “shiny metal.”

J-2X Progress: Test Stands Moving Towards Readiness

In the broadest sense, stepping back from the project, the J-2X development effort has three primary branches. First, of course, you have our prime contractor, Pratt & Whitney Rocketdyne (PWR) who is responsible for designing the engine and demonstrating that it meets the imposed requirements. Second, you have the team here at NASA responsible for management, technical oversight and insight, and, in a handful of specific cases, mainline work in support of PWR activities. And, third, you have the extensive efforts underway at the NASA Stennis Space Center (SSC) in southern Mississippi to provide a site for testing of the J-2X. If you scroll down a ways through previous articles you’ll see that I wrote an overview article about SSC and the test stands there. Here, for this article, I’m going to provide an update and show off some neato pictures of the ongoing work.

The first engine testing will take place on stand A2. In the picture below, technicians are using a locator tool to properly position the water spray ring to where it will need to be over the diffuser. The water spray ring is used to cool the top portions of the diffuser and is necessary since the first tests of the engine will not have any nozzle extension attached below the regeneratively-cooled nozzle. This means that the exhaust flow will not be entirely ‘turned’ and so it will impinge on the diffuser walls.

Next, after getting the spray ring close to the correct position using this tooling, the diffuser will be raised into position below the ring and a laser measurement system will be used to determine the exact location of the spray ring. At that point, the support arms will be installed so as to maintain that position.

In order to check out the extensive communications between the test control center, the test stand, and the engine itself, PWR shipped to SSC the first prototype engine controller. In the picture below what you see is the controller actually sitting on the test stand, on the same level where the engine will be during testing, talking back and forth with the stand. Of course, once the engine arrives, it will have its own controller mounted to the engine itself. This one is just being used for check-outs. Getting all such things checked out and running properly prior to installing the engine is crucial if you harbor any hopes of maintaining your schedule. This is a fine example of PWR and the crews at SSC working together towards a common goal.

When an engine is being tested, the area around it is pretty much cleared away. Almost anything close would be swept into the exhaust, or rattled apart, or melted from the heat in the plume. It’s truly a violent environment. But before and after the test, you need to be able to get your hands on the engine for a whole variety of reasons. For example: After a test, the engine needs to be dried. Remember that the combustion product for an oxygen-hydrogen engine is hot steam. When the engine cools after a test, that steam condenses and becomes water. In order to prepare for the next test, we have to dry out all that residual water and we do so by blowing heated gas, dry air or nitrogen, through the engine. So, we need access to the engine to hook up the hoses.

In the picture above are shown the lightweight, temporary platforms that have been created to allow for engine access. The engine will reside in the hole in the middle of the platforms. Prior to a test, these platforms are removed and after a test they are erected back in the position shown.

Okay, now we’re going to move over to the work being done on test stand A1. This is where we will first be testing the PowerPack Assembly (PPA). The PPA primarily consists of the turbomachinery and the gas-generator. It is essentially a special test bed for the propellant feed and turbine drive functions of the engine. Because the PPA does not have to feed a carefully balanced engine system and because we will be using special test equipment electro-mechanically activated, EMA, valves to control the PPA, we will have the freedom and ability to explore many more operational conditions for the turbomachinery than are possible during actual engine testing. This is a way to truly wring out the design with only a limited number of test articles. We will be calling the upcoming test article PPA2 since we had previously tested a PowerPack Assembly composed of legacy J-2S and XRS-2200 components back in 2007 and 2008. After PPA2 testing, test stand A1 will be converted back to a full engine test facility.

Just as we are using an engine controller to check out the communication systems, and just as we have special tooling for finding the right location for the spray ring on test stand A2, a special tool was developed by PWR to help the technicians at SSC properly position all of the plumbing that feeds into the engine. The tool is called a Master Interface Tool (MIT) and it is simply a bunch of fake interfaces all in the correct geometrical locations as though they were the real interfaces for an engine and PPA2. In the picture below, the MIT is the yellow item in the foreground. This portion of the MIT simulates the connections for all of the ancillary lines to the engine besides the main propellant flows.

Because the MIT properly emulates the engine, once all of the piping on the test stand side meets up with the tool, the technicians have much greater assurance that when an engine shows up, it will fit into the space provided. This is a much better approach than attempting to locate these lines in space with no solid reference point and it saves time since these lines can be installed now rather than waiting for the engine or the PPA2 to show up on the stand.

The MIT appears in the picture below as well. It is the yellow item on the bottom and here it is being used to position the installation of the liquid hydrogen and liquid oxygen feed lines. Thus, when we are actually up and running with an engine, it will hang right where the MIT is currently sitting.

The other yellow items in this picture, the beams that appear to extend up and into the rafters, are the structure that carries the thrust of the engine. These four beams will transmit a total of approximately a quarter of a million pounds-force of thrust into the thrust measurement system and into the test stand itself.

The last couple of pictures that I wanted to include here is intentionally less ‘glamorous’ than some of the previous ones showing where the engine will sit when tested or big pieces of tooling, etc. These pictures were taken in a couple of corners of the A1 test stand on the deck above where the engine will sit. These are the piping systems that will control and measure what on the vehicle would be the tank pressurization flows coming off the engine.

The intended point about these last two pictures is that the facilities necessary to properly test a rocket engine are quite involved and quite complex. The environments are vicious, the tolerances are tight, and everything that goes into or comes out of the engine needs to be controlled and measured. Indeed, the whole reason for doing engine testing is to gather data so as to better understand how well the design works.

Work continues. The formal Facility Readiness Reviews for these stands are currently scheduled for early March for test stand A2 and late April for test stand A1.

J-2X Progress: Valves, Commands into Action

Everyone seems to like analogies between the composition of a rocket engine and that of the human body. These are often colorful but not always helpful. In some cases, however, they work pretty well.

Okay, so let’s start with your body as it is. Now, imagine removing all of your bones. Guess what? You’re an immobile lump. Even if your brain is sending signals and your muscles are contracting, you’re not really moving anywhere.

This time, let’s instead start with your body as it is, but now imagine removing all of the muscles and tendons that connect the muscles to the bone. You’ve got a central nervous system and you’ve got bones, but with nothing to flex, the chain is broken and you’re stuck where you sit (assuming that you can still actually sit).

And, of course, if you instead start with your whole self and imagine removing your brain and/or your central nervous system that connects your brain to your muscles, again, you’ve achieved perfect immobility (i.e., you look like me on Saturday afternoons during college football season).

The point is that in order for you to be up and about, shoveling snow, doing laundry, playing pool, typing, whatever, you need both the command center that figures out what signals to send — your brain — and you need things that turn those signals into action — your muscles and tendons and bones. In a rocket engine, the analogue for the brain is the engine controller. It is a computer that receives instructions from the vehicle and sends out commands to the engine pieces so as to fulfill those instructions. The analogue for the muscles are the valve actuation systems. These are the things that “flex” and cause movement. And the analogue for the bones, the final effectors that make things happen, are the valves.

The controller sends out signals and then the actuation system responds by shuttling pressurized working fluid — helium for J-2X though some engines use hydraulic fluid instead — where it needs to go so that the valves move and the engine comes to life. The engine goes from being a lump of inert, shiny metal to a “living” beast of flowing propellants, spinning turbomachinery, lots of fire, and thundering, rumbling thrust.

On the J-2X, there are 42 valves. Most of this number is made up of small valves like check valves, solenoid valves, and valves in small lines like the bleed lines. There are also a handful of big valves — the primary valves — that directly control the flow of propellant and, in one case, combustion products along the plumbing of the engine. Each of these primary valves is connected to a valve actuator, i.e., the muscle. These valve actuators convert the energy of high pressure helium gas into mechanical rotation of the valve. This is accomplished by pressurizing cavities and moving pistons and, in this way, the valve is pushed opened or closed. I’ve used this schematic shown below before, but it is useful here as well since it illustrates the primary J-2X valves: Main Fuel Valve (MFV), Main Oxidizer Valve (MOV), Gas Generator Fuel Valve (GGFV), Gas Generator Oxidizer Valve (GGOV), and the Oxidizer Turbine Bypass Valve (OTBV).

The control logic for J-2X is relatively simple. The whole subject of different kinds of control logic is a good topic for a future article, but suffice it to say that for normal operation the J-2X: starts on command, can change between two power levels on command, and shuts down on command. The control system is designed to do other things as well, including monitoring the health of the engine, but these operations are the commanded functions. Start and shutdown can be simplistically thought of as: the valves open and the valves close. It’s a bit more complicated since the timing of opening and closing is extremely important, but the open/close notion is basically true. The oddball action is the one consisting of changing power levels. That is accomplished by controlling the power to the oxidizer turbine via the OTBV. This bypass valve effectively allows for limited, independent control of the two turbopumps. By altering the power to the oxidizer turbopump (OTP), you can control the engine thrust level (and, simultaneously, mixture ratio).

The OTBV for J-2X is designed and built by Pratt & Whitney Rocketdyne (PWR), the prime contractor for the whole engine. In addition to being responsible for the “oddball action” on the engine of changing power levels, it represents a challenging design due to the range of operating conditions. Unlike the other primary valves on the engine that see, essentially, one narrow range of environmental conditions, the OTBV has to function in temperatures approaching 420 degrees below zero Fahrenheit (liquid hydrogen conditions) immediately prior to start and then, suddenly, within 1 second of ignition of the gas generator, see temperatures approaching 750 degrees above zero Fahrenheit (combustion products). That broad range of operating conditions requires special design considerations and special materials. Not only do you have to worry about wear and tear under such harsh conditions, but you also have to think about simple operation under the extremes of thermal expansion.

The original, Apollo-era J-2 engine also had an OTBV, but it was used slightly differently and was designed much differently. It was a butterfly valve whereas the J-2X OTBV is a ball valve.

No, the valves shown in the picture are NOT rocket engine valves. I can’t show any internal workings of rocket engine valves. In fact, I am not even allowed to describe the general design details that make the J-2X OTBV kind of unique. However, the basic elements of rocket engine valve functionality for butterfly and ball valves are essentially the same as these water valves. The biggest difference is the replacement of the handles with pneumatically driven actuators. Back during the Apollo era it would seem that butterfly valves were most frequently used, but after many years of usage on the Space Shuttle Main Engine, ball valves are often preferred these days. They generally require less torque to move and they generate better flow characteristics and flow rate control capability.

The first OTBV unit for use on the upcoming development engine testing for J-2X is in the later phases of manufacturing at the PWR in Los Angeles. All of the individual piece parts are schedule to be complete by the beginning of February and assembly will begin the middle of February. The valve then will be integrated the actuator and shipped to the NASA Stennis Space Center to be put on the first engine.

J-2X Extra: The Faces Behind J-2X, NASA MSFC, Part 1

Years ago, I worked in support of the Space Shuttle Program, specifically on the Space Shuttle Main Engine (SSME) from the engineering side of the house. I was an analyst and sometimes Datadog. By happenstance, I learned from another relative that whenever a launch occurred my mother, back home in Pennsylvania, would routinely tell folks at work or at church or wherever that her son was responsible for that Shuttle launch. I said, “Mom, don’t tell people that. I’m just one of hundreds or, really, thousands of people behind the whole thing.” She replied, with biased motherly wisdom, “Yes, but you’re all responsible for doing a good job so that the whole thing works, right?”

Lesson learned #1: Don’t argue with Mom.

Lesson learned #2: She was right. Any venture as big and complex as Shuttle, or even as big and complex as the development effort for J-2X really does require that everyone does their job well. In that way, we’re all responsible.

So, I’m going to introduce you now to just a few of the people (out of hundreds) responsible for making J-2X a reality. Right now I’ll focus on the top leaders Upper Stage Engine Element office here at NASA Marshall Space Flight Center. In another posting, I’ll tell you all about the subsystem managers. And perhaps, later if I’m lucky, I’ll sneak some pictures of the good people out at Pratt & Whitney Rocketdyne as well.

So, here we go…

First, we have our Element Manager, Mike Kynard. He is a graduate of the University of Alabama [Roll Tide!], grew up not far from Tuscaloosa, and, to put it mildly, is a devoted fan of Crimson Tide football. He started working at NASA MSFC as a co-op in college back and accepted a full-time job in 1985. He spent a good spell supporting SSME from the resident office at NASA Stennis Space Center in Mississippi in the 1990s and eventually rose to become the deputy project manager for SSME back in 2004. He has two beautiful little girls and, in addition to everything else, somehow finds the time to play on a team with me in a billiards league. Sometimes, on rare occasions such as a blue moon, he even manages to beat me in a game of 8-ball.

Mike’s deputy is Tom Byrd. He is a graduate of Memphis State University who, once upon a time long, long ago was a competitive bicyclist. He started working here at NASA MSFC in 1983 in the area of valves and actuators, specifically supporting SSME (yes, you’ll see SSME as a recurring theme both here and when later tell you about the subsystem managers). Along the way since then, he was a subsystem manager for the Fastrac engine development effort (a NASA MSFC in-house project), was the NASA chief engineer for COBRA engine development effort, and he supported the Shuttle program in the area of systems engineering and integration. Plus, back in 1994, representing the NASA engineering community, he spent a total of four weeks in Russia studying their space transportation technologies. Tom has one young son who, given the uncanny resemblance, we suspect might be the product of a direct cloning experiment … but we don’t talk about that too much.

Our Chief Engineer is Eric Tepool. His job is to function as the balance point between technical and programmatic aspects of engine development. He also indirectly functions as a balance in another way, relative to our element manager’s tendencies, in that he is a graduate of Auburn University [War Eagle!]. After making his mark as a star high school athlete, just as his father was a star high school and collegiate athlete, Eric turned down athletic scholarship offers to settle into the pursuit of engineering. He started at NASA in 1990 in the turbomachinery branch, supported development and certification of the two new turbopumps for the Block 2 SSME configuration, moved on to be a subsystem manager for the COBRA engine development effort, resident manager for the Fastrac project, and the NASA-side lead systems engineer for the Integrated Powerhead Demonstrator project. He has two kids currently in college (one at Alabama, one at Auburn … yikes!) and one soon to be on her way to college.

The other “technical balance point,” in accordance with the NASA governance model, is our Chief Safety Officer Phil Boswell. He’s been working here at NASA MSFC since 1985. He started right after graduating from the University of Alabama at Birmingham (UAB). While he started in the Safety and Mission Assurance Directorate, and he’s back there now, in the interim he spent many years working within the Engineering Directorate on such projects as microgravity experiments for Shuttle and the MIR space station, the Orbital Space Plane program, and just about every propulsion element of the Shuttle itself including engines, tanks, and boosters. Phil played on the college tennis team, plays tennis still, and is an excellent golfer. His son, who will be attending UAB starting in the autumn (pre-med) follows in his father’s footsteps and is also an excellent golfer. Little known fact about Phil: he loves swing dancing and even took a year of lessons with his wife.

So, that’s the top leadership group for the J-2X development effort. Good guys, hardworking engineers and managers, all around.