© Sierra Space Corporation

The Ideal Tool
When It Just
Has to Be Right
Sierra Space readies theDream Chaser ® spaceplane
for flight with FDM technology.

Case StudySpace is an unforgiving place. Temperature extremes,radiation, and orbital debris stand ready to cause havocwith any ill-prepared spacecraft. Ever since humans
first ventured beyond Earth’s protective atmosphere,
the vehicles used to get there and back have pushed
the limits of engineering and material science. It’s achallenge the team at Sierra Space faces every day, butarmed with the right technology, it’s one the company
is well prepared to meet.

Bringing 3D printing
in-house opened theeyes of a lot of thedesigners to utilize andtake advantage of thetechnology, using it fordifferent types of things.”
Bob Gjestvang

Sierra Space lead
TPS manufacturing engineer

2 2The Right Solution
for Unique Parts
Sierra Space builds the Dream Chaser spaceplane,
a multi-mission utility vehicle for transportingcargo into low-Earth orbit destinations like theInternational Space Station. Being a reusable
spacecraft means the Dream Chaser has to endure
the intense heat of reentry to Earth’s atmosphere.
Surviving this critical part of spaceflight requires athermal protection system (TPS). The TPS forms aprotective layer on the outside of the spacecraft,comprised of 2000 heat-resistant tiles, similar towhat cloaked the space shuttle.
The tiles are adhered to the skin of the Dream
Chaser using “chucks” – tools that correctly

position the tiles and also verify a proper bondduring pull testing. Manufacturing these chucks
the traditional way involves casting them from resin
using the thermal tiles as a mold. But becausea matching chuck is required for each tile, thisbecomes a time- and labor-intensive process.
Looking for a better solution, the Sierra Space
manufacturing team opted to 3D print the chucks
instead of casting them, to capitalize on several of
the technology’s benefits. For starters, 3D printing
offers hands-off production, alleviating the timeconsuming resin casting process for each chuck.

Document
Case
StudyTitle HereThe 3D printed bond verification chuck (middle white block) used to adhere and check the thermal protection system tiles.

© Sierra Space Corporation

3 3© Sierra Space Corporation

Qualification of the 3D printed chuck.

DocumentCaseStudyTitle Here

“When you look at the time it takes to do all of thatmanual casting and do a trade study on the timevs. the cost for 3D printing, it’s just a slam-dunk
to automate this process,” says Bob Gjestvang,
Sierra Space’s lead TPS manufacturing engineer. Infact, the labor savings alone essentially paid for theacquisition of the printer, a Stratasys F900™.
But beyond saving the time to physically cast eachchuck, Sierra Space leveraged the digital natureof 3D printing to automate the development ofthe chuck design. Using the tile CAD models,engineers autogenerated the chuck CAD models,saving development time for the individual chuck
designs. “If you were going by an old manual
process for CAD design, there would havebeen tens of thousands of hours involved in
manufacturing those chucks. The labor savings
alone has been impactful for the program,” says
Gjestvang.

4 4When It Just Has to Be Right
Perhaps even more significant, however, isthe precision that 3D printing brings to themanufacturing process, a critical factor for safe
spaceflight. As Gjestvang puts it, “You can’tpull this vehicle over to the side of the road if
something doesn’t work.” It means Sierra Space
must get things right the first time. TPS is a
critical flight system with no redundancy. It has
to withstand reentry heating, so it’s essential theSierra Space team gets it right during design, build
and test, before the first flight.

According to Gjestvang, 3D printing helps achievethat in a number of ways. “It’s time- and costeffective, which allows our personnel to focus onother issues instead of performing repetitive tasks.
Also, 3D printing allows us to bring additionalmethods and tools to bear with more precision
than previously available.” Examples include
simulator parts printed to test-fit their location orprecision tooling to align components, all of which
can be produced quickly and effectively with 3D
printing. “These types of advantages raise the barof quality and ensure we get things right,” says
Gjestvang.

Document
Case
StudyTitle HereThe colored components are 3D printed simulators being used for a fit-check mock-up.

© Sierra Space Corporation

5 5© Sierra Space Corporation

This 3D printed tool aligns the tube to be welded to the housing.

No Going Back

Document
Case
StudyTitle HereNot satisfied with just avoiding the laborious handcasting process, Sierra Space engineers worked
on perfecting the chuck’s initial design, looking
for additional savings. Optimizing the strength
geometry paid off by reducing material usage, but
it also cut the original print time projection by 75%.
This opened up printer availability and it didn’t takelong before other engineers were taking advantageof the opportunity.
“Bringing 3D printing in-house opened the eyes ofa lot of the designers to utilize and take advantageof the technology, using it for different types ofthings,” says Gjestvang. In his estimation, about
80% of the 3D printing utilization is now made up
of other projects, outside of chuck production.
They include various types of tooling, mock-ups,
and simulators, the latter being full-sized parts

used for fit checks or testing prior to final design
release. “Once you have the technology andengineers have access to it, they find ways to usethat technology to solve problems in ways different
than they would have before,” Gjestvang adds.
Like other aerospace manufacturers thatexperience the advantages of 3D printing with
FDM® technology, for Sierra Space, there’s nogoing back. Beyond the production of thermal tile
chucks and other forms of tooling, Gjestvang sees
qualifying ULTEM™ material for flight parts as thenext logical application of the technology. Besides
being the best solution for efficiently making tile
chucks, additive manufacturing gives Sierra Space
the capability to do things right the first time.
Because in space, there’s not much room for error.

6© Sierra Space Corporation

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