Flight International - 04

Environment Action
import oil from other sources. The second was in
South Africa, where since the 1950s synthetic fuel
has been made from coal, a capability started during
the apartheid era to overcome the oil sanctions
imposed by the UN.
Developing an entire industry from scratch in this
way requires a lot of state money, says Aboulafia,
drawing a parallel with the huge sums of government
support that will be required today to establish SAF
production globally.
Another attempt with alternative fuels took place in
the late 1950s, when Lockheed’s famous Skunk Works
unit used liquid hydrogen as a fuel in ‘Project Suntan’
to develop a long-range spy plane.
According to Michael Winter,
principal fellow advanced technology
at Pratt & Whitney, which
was the engine developer for the
CL-400 Suntan, while the project was
cancelled, it enabled P&W to understand
the challenges of making a gas
turbine engine powered by hydrogen.
P&W is one of several engine
innovators revisiting hydrogen today.
“We went back to the technology from
Project Suntan and we're now working
on a hydrogen engine variation on that
cycle,” says Winter.
Strategic questions
While the motivation to find
alternative pathways today is
predominantly about reducing
emissions, the strategic questions
around fuel and the need to maximise
fuel efficiency are basically the same
as in the past few decades.
“As far as sustainability is concerned
fuel burn has always been important to the military,”
says Winter. “Just as with commercial aviation
where 30-40% of the cost of running an airline
is fuel, it’s the same when running a modern air
force. In addition, fuel security matters in terms of
[operational] independence, mission readiness and
long-range supply lines.”
In commercial aviation the motivation to reach
net-zero emissions by 2050 is coming principally
from the customers: the airlines. In defence, it
is always about “mission first” – but the question
of sustainability is emerging in military aircraft
competitions, says Winter.
“This is an issue right now. When we go into foreign
military campaigns for F135 engines, among the 15
allied operators that we have for the [Lockheed] F-35
we now have countries asking us and the OEM to
perform life-cycle analyses on the engine and on the
aeroplane,” Winter says.
2050
Target date for aviation industry to reach net-zero status,
with militaries increasingly expected to do the same
Pratt & Whitney
For instance, in Switzerland’s recent fighter
competition, which featured a public referendum on
the aircraft choice, “there were hearings that included
discussions about the sustainability and fuel burn
associated with the various options for the Swiss
air force,” explains Winter. These considerations are
mostly prevalent in Europe and emerging in the USA,
but will grow, he adds.
Aboulafia draws on a historical comparison to
highlight another strong motivation for the military to
act. “If you are looking at a change in fuel source you
want to be at the leading edge of the transition,” he
believes, pointing to the example of British Sea Lord
Jackie Fisher, who championed the switch from coal
“Just as with
commercial
aviation where
30-40% of the
cost of running
an airline is fuel,
it’s the same
when running a
modern air force”
Michael Winter Principal fellow
advanced technology, Pratt & Whitney
to oil as the major type of warship fuel in the lead up
to the First World War.
“You want to be free of vulnerable fuel sources and
he [Fisher] could see a point where the alternative
succeeds,” he notes.
As the defence sector recognises and makes the
slow turn towards sustainability, practical questions on
the transition are being asked. The challenge for defence
is more complex than in the commercial world.
“The defence sector has peculiarities as countries
approach this challenge in a different way and at
different speeds,” says Jose Antonio Coll Guzman,
head of sustainability at Airbus Defence & Space.
“Depending on the product, different options
and technologies for decarbonisation need to
be addressed to find the right balance,” he says,
ensuring the technology is right for the mission.
“Many defence products have a long lifespan, which
means that, on one hand, sustainable solutions for
existing products are required, but also, new product
developments need to consider eco-design and
ensure adaptability for the future.
“For this, availability, cost and the development
of an ecosystem in the case of SAF for example is
an important element to be considered, as is the
identification of standards and for governments
to support industry in the inclusion of eco-design
parameters in the specifications and needs of new
product development,” says Guzman.
April 2023 Flight International 57