---BREAKAWAY CIVILIZATION ---ALTERNATIVE HISTORY---NEW BUSINESS MODELS--- ROCK & ROLL 'S STRANGE BEGINNINGS---SERIAL KILLERS---YEA AND THAT BAD WORD "CONSPIRACY"--- AMERICANS DON'T EXPLORE ANYTHING ANYMORE.WE JUST CONSUME AND DIE.---
Monday, April 15, 2013
How NASA brought the monstrous F-1 “moon rocket” engine back to life
The story of young engineers who resurrected an engine nearly twice their age.
There has never been anything like the Saturn V,
the launch vehicle that powered the United States past the Soviet Union
to a series of manned lunar landings in the late 1960s and early 1970s.
The rocket redefined "massive," standing 363 feet (110 meters) in
height and producing a ludicrous 7.68 million pounds (34 meganewtons) of
thrust from the five monstrous, kerosene-gulping Rocketdyne F-1 rocket engines that made up its first stage.
At the time, the F-1 was the largest and most powerful liquid-fueled
engine ever constructed; even today, its design remains unmatched
(though see the sidebar, "The Soviets," for more information on engines
that have rivaled the F-1). The power generated by five of these engines
was best conceptualized by author David Woods in his book How Apollo Flew to the Moon—"[T]he
power output of the Saturn first stage was 60 gigawatts. This happens
to be very similar to the peak electricity demand of the United
Kingdom."
Despite the stunning success of the Saturn V, NASA's direction shifted after Project Apollo's conclusion; the Space Transport System—the
Space Shuttle and its associated hardware—was instead designed with
wildly different engines. For thirty years, NASA's astronaut corps rode
into orbit aboard Space Shuttles powered by RS-25 liquid hydrogen-powered engines and solid-propellant boosters. With the Shuttle's discontinuation, NASA is currently hitching space rides with the Russians.
But there's a chance that in the near future, a giant rocket powered
by updated F-1 engines might once again thunder into the sky. And it's
due in no small part to a group of young and talented NASA engineers in
Huntsville, Alabama, who wanted to learn from the past by taking
priceless museum relics apart... and setting them on fire.
Enlarge/ An F-1 engine on display at NASA's Marshall Space Flight Center. Author's wife at right for scale.
Lee Hutchinson
Enter our young rocket scientists
Tom Williams is the kind of boss you want to have. He's smart, of
course—that's a prerequisite for his job as the director of the NASA
Marshall Space Flight Center's (MSFC) Propulsion Systems Department. But
he doesn't mind stepping back and giving his team interesting
challenges and then turning them loose to work out the details. Case in
point: NASA's Space Launch System
(SLS), intended to be an enormous heavy-lift system that will rival the
Saturn V in size and capabilities. In thinking about propulsion for the
SLS, NASA for the first time in thirty years is considering something
other than solid rocket boosters.
The decision to use a pair of solid rocket boosters for the Space
Shuttle instead of liquid-fueled engines like the F-1 had been partly
technical and partly political. Solid fuels are hugely energy dense and
provide an excellent kick to get a spacecraft moving off of the ground;
also, selecting solid fuel boosters allowed the government to send some
available contracting dollars to companies involved with building
intercontinental ballistic missiles, leveraging that expertise and
providing those companies with additional work.
But solid boosters have several downsides, including an inability to
stop combustion. Without pumps to switch off or valves to close, solid
boosters work a lot like the "morning glory" sparklers my dad used to
buy on the Fourth of July—once lit, they burn until they're done. Solid
rocket booster design decisions, specifically in regard to containing
combustion, contributed to the destruction of the Space Shuttle Challenger and the death of its crew (though Challenger's destruction was more a failure of NASA management than of technology).
Still, as the Space Shuttle program drew to a close and potentialsuccessors
came and went, the inertia of solid boosters and the facilities and
people that produced them ensured that they remained a part of the
plans.
SLS gave NASA the chance to do a total rethink. As design studies got
underway, Williams realized it might be a good idea to re-familiarize
the MSFC Propulsion Systems Department with huge kerosene gas generator
engines like the F-1 (referred to in shorthand as "LOX/RP-1" or just
"LOX/RP" engines, after their oxidizer and fuel mixture of liquid oxygen
and RP-1 kerosene).
Scale aside, the F-1 is conceptually a relatively simple design, and
that simplicity could translate into cost reduction. Reducing cost for
space access is a key priority—perhaps even the overriding priority—outside of safety.
There was a problem, though. SLS' design parameters called for a
Saturn V-scale vehicle, capable of lifting 150 metric tons into low
Earth orbit. No one working at MSFC had any real experience with
gigantic LOX/RP-1 engines; nothing in the world-wide inventory of launch
vehicles still operates at that scale today. So how do you make
yourself an expert in tech no one fully understands?
Nick Case and Erin Betts, two liquid engine systems engineers working
for Williams, found a way. Although no launch vehicles that used F-1
engines are still around, actual F-1s do exist. Fifteen examples sit
attached to the three Saturn V stacks on display at NASA facilities,
including MSFC; dozens more are scattered around the country on display
or in storage. Williams' team inspected the available engines and soon
found their target: a flight-ready F-1 which had been swapped out from
the launch vehicle destined for the to-be-canceled Apollo 19 mission and
instead held in storage for decades. It was in excellent condition.
Case and Betts spearheaded the paperwork-intensive effort to
requisition the F-1 from storage and get it into their workshop. They
were aided by R.H. Coates, a more senior member of Williams' team and
lead propulsion engineer for the SLS Advanced Development Office.
Williams offered encouragement and assistance from the management side,
but the team was otherwise given free rein on how to proceed. After some
study, they came to Williams with a request that was pure engineer:
"Why don't we just go ahead and take this thing apart and see what makes
it work?"
Williams said yes. "It allowed some of our young engineers to get
some hands-on experience with the hardware," he told me, "what we would
term the 'dirty hands' approach to learning, just like you did when you
took apart your bicycle when you were a kid, or your dad's lawnmower or
his radio. One of the best ways to learn as an engineer, or in anything,
is to take it apart, study it, ask questions."
And then, hopefully, build a better one.
The plans! The plans!
The F-1 teardown started in relatively low-key fashion. As the team
dug into the engine, it became obvious that the internal components were
in good shape. In fact, though there was some evidence of rainwater
damage, the engine overall was in great shape.
The team initially wanted to build an accurate computer model of
every component in the engine so that its behavior could be modeled and
simulated, but another goal soon began to take shape: maybe, just maybe,
they could mount some of the engine components on a test stand and make
the F-1 speak again after 40 years.
Why was NASA working with ancient engines instead of building a new
F-1 or a full Saturn V? One urban legend holds that key "plans" or
"blueprints" were disposed of long ago through carelessness or
bureaucratic oversight. Nothing could be further from the truth; every
scrap of documentation produced during Project Apollo, including the
design documents for the Saturn V and the F-1 engines, remains on file.
If re-creating the F-1 engine were simply a matter of cribbing from some
1960s blueprints, NASA would have already done so.
A typical design document for something like the F-1, though, was
produced under intense deadline pressure and lacked even the barest
forms of computerized design aids. Such a document simply cannot tell
the entire story of the hardware. Each F-1 engine was uniquely built by
hand, and each has its own undocumented quirks. In addition, the design
process used in the 1960s was necessarily iterative: engineers would
design a component, fabricate it, test it, and see how it performed.
Then they would modify the design, build the new version, and test it
again. This would continue until the design was "good enough." Further, although the principles behind the F-1 are well known, some
aspects of its operation simply weren't fully understood at the time.
The thrust instability problem is a perfect example. As the F-1 was
being built, early examples tended to explode on the test stand.
Repeated testing revealed that the problem was caused by the burning
plume of propellent rotating as it combusted in the nozzle. These
rotations would increase in speed until they were happening thousands of
times per second, causing violent oscillations in the thrust that
eventually blew the engine apart. The problem could have derailed the
Saturn program and jeopardized President Kennedy's Moon landing
deadline, but engineers eventually used a set of stubby barriers
(baffles) sticking up from the big hole-riddled plate that sprayed fuel
and liquid oxygen into the combustion chamber (the "injector plate").
These baffles damped down the oscillation to acceptable levels, but no
one knew if the exact layout was optimal.
Enlarge/
Detail on an F-1 engine injector plate at the forward end of the
nozzle. Fuel and liquid oxygen are sprayed out of these holes under
tremendous pressure, with each ring alternating propellant and oxidizer.
Lee Hutchinson
The baffle arrangement "was just a trial and error thing," explained
Senior Propulsion Engineer R.H. Coates. "But we'd like to model that and
say, well, what if you took one of those baffles out?" Because the
baffles are mounted directly to the injector plate, they take up surface
area that would otherwise be occupied by more injector holes spraying
more fuel and oxidizer; therefore, they rob the engine of power. "So if
you want to up the performance on this thing, we can evaluate that with
modern analytical techniques and see what that does to your combustion
stability."
But before any "hot-fire" testing could occur, the team had to take
the very physically real F-1 engine and somehow model it. It's
easy—well, relatively easy—to turn a set of CAD files into a real
product. Turning a real product into a set of CAD files, though,
requires a bit of ingenuity, especially when that product is a gigantic
rocket engine.
To tackle the task, NASA brought in a company called Shape Fidelity, which specializes in a technique called "structured light scanning." If you don't have access to the laser from TRON, structured light scanning is just about the next best way to cram something inside of a computer. Listing image by Lee Hutchinson
Firing my laser
Enlarge/
The structured light scanner assembly. The middle lens is the
projector, and the outer two lenses are cameras that look at how the
projector's light falls onto the surface being scanned.
Lee Hutchinson
The exterior of the F-1 was meticulously photographed and then mapped
with a structured light scanning rig, which uses a projector to paint a
pattern of stripes onto the surface being scanned. Mounted on the side
of the projector are two cameras which each record how the pattern falls
on the surface being scanned. For every exposure, the projectors and
camera capture sixteen different stripe patterns.
The structured light rig can focus on an area ranging from 65mm in
size all the way out to 1.5 meters, so getting a surface scan of the
entire F-1 engine required a lot of crawling around and manually aiming
the scanner rig. It wasn't immediately obvious how a bunch of handheld
scan images could maintain coherency—how do you indicate to the scanner
that picture 2 is linked to picture 1?
Enlarge/
Scanning a small object with the structured light scanner. The
alternating horizontal bars in the purple projection are used by the
cameras to detect surface detail. Note positional decals around the
object's perimeter.
Lee Hutchinson
The answer was both simple and brilliant. "You notice these little
targets? These little stickers?" said Shape Fidelity engineer Rob Black,
who was demonstrating the equipment for me. Black indicated the small
white-on-black circular dots pasted on the test material on the table in
front of us. All around us were disassembled F-1 engine pieces, and I
noticed that every single component was peppered with the little dots.
"We stick these things on by hand, and the scanner sees these targets,
so when we move from one position to the next, it can see what's
coming... and stitch everything together. That way, we don't have to use
encoders or robots."
Each part gets tiny dots hand-applied in what is effectively a
random, unique pattern. The structured light software can use the unique
layout of dots to stitch together all pictures of the object being
scanned, without requiring the camera to be mounted in a motion
controlled rig. "We took just a regular digital camera and walked around the engine
and took photographs," Black said. "The software took all those
photographs and built a 3D coordinate for each of the targets, and what
you get is a very sparse data set—it's basically the X-Y-Z value of the
center of these points."
Enlarge/
The rough point-cloud assembled by the structured light scanning
application, using the black and white positional dot stickers.
NASA
After the point map was assembled, Black performed a detailed
structured light scan of the entire outside surface of the engine. "But
what we wanted was a scan of the inside—the vanes, the clearances, all the definition of the interior," explained Black.
Taking the F-1 apart to get at its insides was always part of the
plan, but as the team proceeded, it became obvious that actually
cracking the thing open without breaking it was going to require
specialized tooling—tooling that might have existed 40 years ago but
which has long since been destroyed or lost.
The exterior scan was therefore used to develop the specialized
tooling needed to fit the F-1's nuts, bolts, and fasteners. Some of the
bolts were annoyingly unique—Betts noted that at least one high-torque
bolt in the turbopump assembly required its own special torque adapter
to remove.
Enlarge/ Detail structured light scan model, showing connectors against which custom tooling needed to be manufactured.
NASA
The team was able to use the structured light scan of that particular
bolt and, in less than half a day, to fabricate a tool using an
additive manufacturing method called electron beam melting
to quickly "print" 3D projects out of metal powder. Armed with this and
other custom tools, Case, Betts, and Coates took the engine apart, down
to its tiniest components. "So what that let us do was scan the parts—all the individual pieces
and parts," Black said. He pulled up a PowerPoint presentation on his
laptop and pointed at one particular slide. "This is an example of one
of the scanned pieces. You'll notice the gray is the scanned data, like
we got on the screen here, but it also maps to points. Well, those
points are the same points that were mapped in the assembly [the initial
scan]. There's only one way that part will fit into that constellation
of points, and that's what you see on the lower right."
Enlarge/
The randomly placed dots are left on each part's surface as it is
scanned inside and out. After scanning, the computer fits the now highly
detailed part back into the model, using the arrangement of its surface
stickers as a guide.
NASA
"And so what you get now is a true 3D definition, inside and out, of
all the relationships—not just the part geometry, but the relationship
between the parts. And we did this for all the parts that you see on the
shelves here," Black added.
Touching the past
Enlarge/ The final composite model, accurate inside and out, made up of all the rocket's thousands of pieces carefully fitted together.
NASA
The result was a complete and highly accurate CAD model of the entire
F-1 rocket engine, down to its tiniest bolt. The fidelity was so good
that the scanner even picked up tiny accumulations of soot left on the
turbine blades from the engine's previous test firing back in the 1960s.
The engineers removed the soot and re-scanned, but even this seemingly
trivial accumulation yielded valuable data—sooting is a problem with
kerosene-powered engines, so understanding how it builds up inside the
engine could reduce its occurrence. "Because they didn't have the analytical tools we have today for
minimizing weight, everything was very robust," noted Betts, when I
asked what they found as they tore down the engine. "That's apparent in
really every aspect of the engine. The welds—"
"Oh, the welds!" interrupted Case. "The welds on this engine are just a work of art, and everything
on here was welded." The admiration in his voice was obvious. "Today,
we look at ways of reducing that, but that was something I picked up on
from this engine: just how many welds there were, and how great they looked."
"You look at a weld that takes a day," he continued, "and there are thousands
of them. And these guys were pumping engines out every two months. It's
amazing what they could do back then and all the touch labor it took." "Their ability to withstand imperfection, too," said Betts. "There
were a few things on the engine that we disassembled, where today you
may throw that part away because of the imperfections, but it goes to
show that they fully understood what the big drivers were in their
design. That's one thing we were trying to get knowledge on: what
imperfections were OK to live with versus what imperfections are going
to give us problems?" "Like with the injector," said Case, speaking of the 44-inch (1.1
meter) metal plate that spewed the propellent into the engine's nozzle.
"There are hundreds of holes drilled into the main injector—all drilled
by hand, too. And one of the holes you can actually see where the drill
bit came down at the wrong spot, and the guy just stopped—you can see
where he moved over to where the hole was supposed to be and finished
drilling the hole. They kept that and would have flown with that engine.
Those kinds of things were pretty neat."
Close-up of the rear of an F-1 engine injector plate. Note mis-drilled injector hole at center.
NASA
"One thing I notice when I look back at older engines," commented
Coates, the senior engineer, "was just like Nick and Erin were alluding
to: the complexity of the welds. You didn't have the kind of advanced
manufacturing we had today, so quite honestly, these were hand-made
machines. They were sewn together with arc welders, and it's
pretty amazing to see how smooth and elegant it came out. Today, you'd
look at doing precision casting, not these thousands of welds."
Enlarge/ Connection point of an F-1's gimbal (one of three), showing a huge amount of welding.
Lee Hutchinson
Lighting a 40-year old candle
The engine disassembled by Betts, Case, and Coates was number F-6090, assembled in December 1968 just as Apollo 8
was carrying three astronauts further away from Earth than any human
being had ever before traveled. F-6090 had been test-fired for 240
seconds and then mounted on the S-IC stage of the Saturn V that would
have flown as Apollo 19, but the engine was eventually pulled and placed
into storage at MSFC. As the team methodically stripped engine F-6090
down, it became obvious that a test-fire of some of the engine's
components was within the realm of probability. With F-6090 being torn apart to learn from, the team turned to engine F-6049, which had served for years as a display engine at the Udvar-Hazy Center
at the Smithsonian National Air and Space Museum. F-6049 was in even
better condition than F-6090, but simply firing the entire F-1 engine
straight away wasn't practical. For one thing, though the F-1s were
originally tested
at MSFC in the 1960s, that test infrastructure has since been
repurposed. In addition, the city of Huntsville has grown up
considerably since the Apollo era; lighting off an engine the size of an
F-1 at Marshall today would likely blow out every window in the entire
city.
Enlarge/
The test stand used for the F-1 engine firing in the 1960s has been
repurposed many times since then. Retrofitting it for use with an F-1
engine again would be cost-prohibitive... and the test would blow out
every window in Huntsville.
Lee Hutchinson
Instead, the team decided to start with a series of firings on
F-6049's gas generator. An engine like the F-1 is sort of like two
separate rocket engines: one small, one large. The smaller one consumes
the same fuel as the larger, but its rocket exhaust is not used to lift
the vehicle; instead, it drives the enormous turbopump that draws fuel
and oxidizer from the tanks and forces them through the injector plate
into the main thrust chamber to be burned.
As with everything else about the F-1, even the gas generator boasts
impressive specs. It churns out about 31,000 pounds of thrust (138
kilonewtons), more than an F-16 fighter's engine
running at full afterburner, and it was used to drive a turbine that
produced 55,000 shaft horsepower. (That's 55,000 horsepower just to run the F-1's fuel and oxidizer pumps—the
F-1 itself produced the equivalent of something like 32 million
horsepower, though accurately measuring a rocket's thrust at that scale
is complicated.)
Getting the gas generator ready for firing would be a huge step in
teaching Betts and Case about LOX/RP-1 engines, and it would provide
modern data on just how well the old components operate. Betts, Case,
and Coates pulled the gas generator, the gas generator injector, and the
gas generator combustion chamber from F-6049, along with one of the
ball valves for the propellent. Every "soft good" in the gas
generator—every seal and gasket—had to be recreated from scratch, since
all had hardened or rotted. In the process, the team had to spend quite a
bit of time ensuring that they were creating functional seals and
gaskets, since plastics technology had changed considerably since the
1960s. Just creating the soft goods required a lot of chemistry work.
As the preparation for the gas generator tests continued, though,
something happened that caused the exercise to shed its academic roots
and turn very, very practical.
Rocketdyne returns
NASA's SLS will most likely be a multi-stage vehicle, with boosters
attached to its first "core" stage, but NASA is holding a competition to
determine whether those boosters will be fueled by solid or liquid
propellent. The Advanced Booster competition
has finally brought liquid-fueled contenders into a space dominated for
decades with solid fuel boosters built by a company called ATK.
One of the companies selected to compete for the Advanced Booster contract is Dynetics,
a 1,300-employee company headquartered in Huntsville, near MSFC.
Dynetics has primarily done work for the Department of Defense, but
within the past five years it has expanded into aerospace. It's one of
three companies proceeding into the design phase of the contract, and it
might have a secret weapon: Dynetics is partnered with Pratt &
Whitney Rocketdyne (PWR), and its entry into the booster competition
will be powered by an enormous LOX/RP-1 engine called the F-1B (based on the F-1 and its uprated but never flown F-1A variant).
The F-1 gas generator tests that Betts, Case, and Coates were
preparing for were set to happen at an extremely opportune time: their
exploratory work on the F-1 started near the end of 2012, right around
the time Dynetics was selected as a competitor for the Advanced Booster
contract. Dynetics had an absolutely golden opportunity; right down the
street, NASA was about to start test-firing an F-1 gas generator,
something that hadn't been done in decades.
Through a complex set of letters of agreement, MSFC allowed Dynetics
and PWR engineers to use the resurrected gas generator and engine test
facilities. The engineering effort even included cooperation with
heritage Rocketdyne engineers in California and Huntsville—folks who
were involved in the original design and testing of the F-1 and who had
engineering expertise and advice to contribute to the effort. MSFC
conducted 11 hot-fire tests of the gas generator, ranging from 5 to 30
seconds each, with Dynetics and PWR representatives present and
assisting.
After Dynetics and its Pratt & Whitney Rocketdyne subcontractor
worked out the agreements and paper, the company needed to run its own
set of tests on the F-1 gas generator to gather additional data beyond
what Betts, Case, and Coates had gleaned. This necessitated a second
series of gas generator test firings in the latter half of February, so
Ars headed out to Huntsville to watch.
Watching the test
On the morning of February 20 I found myself perched on a set of
metal bleachers under an iron-gray Huntsville sky, with the thermometer
reading 33ºF—quite a bit cooler than this Texas boy is used to enduring,
especially since the wind wouldn't stop gusting. The payoff was that
the observation area sat only a short distance from the gas generator
test stand. Through a clearing in a row of evergreens and scrub,
separated from us by a dirt path, I saw the test stand itself: a
jungle-gym pile of metal and pipes, with personnel scurrying around to
make last-minute adjustments.
Enlarge/ The view from the bleachers, looking at the gas generator test stand.
Lee Hutchinson
The gas generator test firing I was there to witness was neither the
first nor the last, but it still drew a hefty crowd of folks—civil
servants, family members, and no small number of Dynetics/PWR employees.
As the clock ticked down toward firing, we packed ourselves into the
rickety bleachers and the buzz of conversation gradually quieted; I
focused on holding my camera steady and trying not to touch any of the
exposed metal of the heavy (and freezing) telephoto lens.
Enlarge/
Engine F-6049's gas generator mounted on the hot-fire test stand prior
to firing (with test personnel setting things up still visible). The gas
generator itself isn't really visible—it's mounted behind the red
thrust take-up plate.
Lee Hutchinson
The blast, when it came, was loud without being overwhelming. We were
close enough that there wasn't more than a quarter second's delay
between the flash and the sound, and I felt the warmth of burning
kerosene exhaust roll over me. The gas generator spoke with a deep
rumbling, topped with a rocket's crackle-crackle-crackle—a
sound I'd always thought was just the microphone clipping when listening
to recordings of rocket launches. The overall noise of the thing was
impressive—probably about as loud as a loud rock concert—but we were far
enough away not to need hearing protection. The gas generator produced a
long horizontal column of flame, which held steady for the entire test.
It was impressive, but it was even more impressive when I
reminded myself that in a real F-1 all this fire and noise and smoke was
merely used to drive the machinery that fed fuel into the engine for
the real fireworks.
Enlarge/
The gas generator firing. Visible emerging from the nozzle is the dark,
fuel-rich exhaust, which takes a bit of time to completely burn. This
is characteristic of gas generator exhausts.
Lee Hutchinson
After perhaps fifteen seconds, the exhaust wavered and went out, and
enormous clouds rose around the test area. Sprinklers had been spraying
the stand throughout the test, and the water from those sprinklers was
now noisily transforming itself into steam. The assembled crowd
applauded, muffled claps rising from hands which were mostly gloved or
mittened against the chill.
Video of
one of the second set of gas generator firings, taken on January 23
(this is much shorter than the test firing we attended) - Courtesy NASA
Second
video of one of the second set of gas generator firings, taken on
January 23 (this is much shorter than the test firing we attended) -
Courtesy NASA
3D printing goes to space
The Dynetics advanced booster itself—tentatively codenamed Pyrios,
after one of the fiery horses that pulled the god Apollo's
chariot—typifies the "big dumb booster" design. The booster's
construction will be as efficient and minimal as possible, using simple
3/4-inch (1.9cm) aluminum barrel segments friction-stir welded
together over the propellant tanks. One advantage of using RP-1 as a
fuel is that it doesn't need heavy thermal protection—it won't boil off
at sea level pressure and temperature like liquid hydrogen does. (The
Pyrios booster concept might have to include some external thermal
protection for the liquid oxygen tankage.) Even though the performance goals of the engine will be close to its
predecessor, its manufacturing will be done through radically different
methods. The Dynetics folks echoed Betts, Case, and Coates when
reflecting on the F-1's construction, making many of the same
observations about the jaw-dropping amount of hand-done work in the old
design. In the name of affordability and efficiency, modern
manufacturing techniques will be brought firmly to bear on the new
version.
Each Pyrios booster will feature a pair of F-1B engines, built with
techniques that more resemble 3D printing than traditional casting or
milling. The main combustion chamber and nozzle in particular will
undergo tremendous simplification and consolidating; the parts count for
those two assemblies together will be reduced from 5,600 manufactured
elements in the original F-1 down to just 40.
Enlarge/
Photo of the F-1/F-1B comparison chart Dynetics/PWR had on display at
the test firing, showing several key differences between the F-1 and
F-1B.
Lee Hutchinson
Using state of the art manufacturing processes where possible
actually reduces cost—even if a newer manufacturing method is more
expensive, the cost reductions gained from the design simplifications
more than tip the scales. In particular, Dynetics and PWR are using
techniques like selective laser melting and hot isostatic pressing (HIP)
to "grow" entire complex engine parts out of metal powders. The
Dynetics team is focusing as much as possible on reducing welds and
joins, and therefore reducing assembly and manufacturing.
(We've got lots more on Dynetics and their F-1B-powered Pyrios booster in this companion piece.)
Engineers and their engines
After the test-firing, Betts, Case, and Coates showed me around the
MSFC lab where the F-1 disassembly effort was still underway. We stopped
in to visit engine F-6049, mounted up on its trolly with its gas
generator conspicuously missing. I crawled all over the thing while the
trio of engineers talked about the big old machine with which they'd
become so familiar. "These guys came up with the idea," said Tom Williams, gesturing
toward Betts and Case, "that LOX/RP looks like something we need to get
smart on again, so how about we take apart one of these?" The two
engineers were standing next to the F-6049, along with Coates. "These
guys started thinking how to go about it and got the structured light
guys into it, but it was just a small group of engineers who got the
idea to get their hands dirty."
Enlarge/
The team that brought the F-1 back to life. From left: R.H. Coates,
Erin Betts, Nick Case, and manager Tom Williams. Behind them is engine
F-6049. Its gas generator would normally occupy the space just above and
to the right of Betts' head—note the white covering in place where the
gas generator's exhaust would feed into the turbopump.
Lee Hutchinson
That's engineering at its finest. The disassembly and hot fires have
yielded a tremendous amount of data, and the Dynetics/PWR team is in the
midst of turning that data into a practical, usable engine. There are
plans later this year to mate the gas generator back to its pumps and
turbines, recreating the F-1's entire "powerpack" (the entire engine
except for the combustion chamber). The powerpack will then be tested at
NASA's Stennis Space Center in Mississippi. It's not much of a leap
after that to a completed engine.
The Advanced Booster competition runs at least another two years,
with a final decision expected in 2015 or 2016. Solid fuel remains a
major contender—possibly the front-runner—but the Pyrios booster does
stand a real chance of thundering past its competitors.
When NASA's SLS rocket flies, she may well be drawn into the sky by Apollo's fiery steed.
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