JEC COMPOSITES MAGAZINE - Issue #118 - January/February 2018 - 52

SOLUTlONS aeronautics

Software helps optimize the structure
of world's largest all-composite aircraft

craiG collier,
President
Collier Research

How do you get the biggest aircraft in the world off the ground? It helps if you make it
out of composites instead of metal. Lightweighting has been an aerospace and other
industry imperative for some time now, but in the case of the Stratolaunch air-launch
platform, it was essential to take as much weight out as possible - while still achieving
flight certification. So the platform manufacturers used Collier Research's automated
sizing and analysis software to inform laminate design and production.

W

hen the Stratolaunch
aircraft rolled out
of
the
Mojave
(California) Air and Space Port
hangar this spring in preparation
for ground testing, it was a clear
example of how far the design
and manufacturing of composite
materials have progressed in
recent years. The first phase of
engine testing on the aircraft's
six Pratt & Whitney turbofan
engines was recently completed.
Extensive use
of composites
The world's largest aircraft by
wingspan (wider than a football
field is long) is almost entirely
fabricated from composite materials, which provide light weight,
high stiffness and strength

Stratolaunch aircraft rolling out of the
hangar in spring 2017 (Image courtesy
Stratolaunch Systems Corp.)

52

characteristics that are increasingly in demand in the aerospace,
automotive, sports, medical and
industrial fields.
The Stratolaunch aircraft is
the brainchild of Stratolaunch
System Corporation founder
Paul G. Allen. It has two fuselages
connected by a giant single wing
and is powered by six engines
that will enable it to take off from
a runway carrying a payload of
up to 250 metric tons. At the
cruising altitude of a commercial
airliner, the Stratolaunch airlaunch platform will release the
space launch vehicle payload and
return to the airport for reuse.
The first launch demonstration is
anticipated to take place as early
as 2019.
Collier Research's HyperSizer
optimization software was used
extensively by manufacturer
Scaled Composites to optimize
the aircraft's composite fuselage
and wing structure. HyperSizer,
the first software package to be
commercialized out of NASA,
has been employed in a wide
variety of aerospace and other
industry projects fabricated with
composite or metallic materials.
The software automatically performs design, stress analysis and

Early construction phase of one of the two fuselages of the all-composite Stratolaunch
aircraft and (inset) a screenshot showing a HyperSizer analysis of the structure
(Images courtesy Stratolaunch Systems Corp.)

sizing optimization, typically
reducing the weight of structures
by 20-40%.
Optimization tools
Ensuring the most efficient use
of materials in an all-composite
structure of any size requires
effective employment of design
and manufacturing optimization
tools from the very earliest stages.
For the massive Stratolaunch
wing, deflection limits were a
significant factor to be taken into
account. The panels of the duel
fuselages were sized for strength,
stability and honeycomb sandwich failure modes. By using
HyperSizer, the stress team had
access to a comprehensive set of
automated failure analyses including rapid free-body analysis,

jec composites magazine / N°118 January - February 2018

discrete laminate sizing, plybased composite failure analysis,
honeycomb sandwich analysis
methods such as wrinkling, core
shear, flatwise tension and
intracell dimpling, and scripting
API to push in loads from Excel
spreadsheets.
Collier is seeing continuing
evolution in the integration of the
toolsets used for composite design
and manufacturing. HyperSizer
software can provide insights
into how producible a structure
is and whether there might be
any manufacturing issues. It can
incorporate laminate fabrication
preferences in early-stage design
thought; ease-of-manufacturing
is becoming a major influence
with strength design of laminate
structures. More information:
www.HyperSizer.com
http://www.HyperSizer.com
Table of Contents for the Digital Edition of JEC COMPOSITES MAGAZINE - Issue #118 - January/February 2018
