JEC COMPOSITES MAGAZINE - Issue #130 - September/October 2019 - 42

FEATURE aerospace
rials are themselves in short supply and unsustainable.
In comparison, hydrogen represents a longterm, sustainable solution. Hydrogen fuel
cells have already been used in buses, cars,
trucks and trains, and there is growing interest in an entire hydrogen economy. Aviation
is only one part of the picture.

Would you say that reducing the plane's
weight is even more important with this type
of energy?

L.M.: Actually, the energy density per unit
weight is three times higher for hydrogen
than for kerosene. If the efficiency of fuel
cells, which is around double that of a turbofan engine, is taken into account, the weight
advantage quickly becomes apparent. For
the same flight, a hydrogen-powered aircraft therefore requires 6 to 10 times less fuel
weight than its conventional, kerosene-powered counterpart.

The scaled prototype will take flight late 2019.

weight reduction of one or two kilograms
can make a large difference over time. As we
have seen with modern airliners such as the
Airbus A350, composites have the potential
to drastically reduce the weight while also
being very versatile. Certainly, composites
will have an ever-increasing impact on the
aviation industry.
What is the role of composite materials in
your project?

L.M.: Sailplanes are at the very pinnacle

of aerodynamic efficiency. In order to minimise drag, the surface of the wing must be
as clean as possible. Any dent, deficiency or
rivet in the wing skin will cause the boundary layer to transition prematurely, increasing
drag. Glass fibre, and more recently carbon
and aramid fibres, have become the standard in glider design because of their ability to
produce strong and smooth structural skins
without the need for a heavy internal structure. Both our 1:3 scale prototype and fullscale aircraft consist almost entirely of either
carbon or glass fibre.

The disadvantage with hydrogen is the energy density per volume, which is substantially lower than kerosene. This larger volume
could result in a larger aircraft. This has a
negative effect on the aircraft's fuel efficiency,
since a larger aircraft generates more drag.
Reducing the weight of an aircraft is therefore as crucial as it has always been. A lighter aircraft is more fuel efficient and even a

Do you think you can use them even more in
the future?

Fourteen million holes
The engineers in the student team calculated
that the manned aircraft should be able to fly
from Delft to Morocco on a single tank of
fuel. To achieve this, it has to fly as efficiently
as possible. One of the revolutionary aspects
of attempts to achieve this is the "laminar
boundary layer suction" system, which

involves making 14 million minuscule holes
in the wings. This technology ensures that
the thin layer of air that sticks to the wing in
normal aircraft, known as the boundary layer,
is sucked away. This can lower air resistance
by 15%, reducing the aircraft's fuel consumption.
The team of 35 students of 23 different

jec composites magazine / N°130 September - October 2019

L.M.: Since our focus is on making aviation
more sustainable, we have also given thought
to how sustainable aircraft production is.
Carbon and glass fibre composites have
many weight and strength advantages, but
cannot be produced sustainably. In general, a
metal aircraft is more sustainable than a composite aircraft, since metals are much easier
to recycle. Most thermosetting carbon fibre
matrices are impossible to reuse, although
advances in thermoplastic resins are very
promising in this regard. Even so, it is still difficult to reuse the fibres themselves.
For this reason, we are very interested in developments in flax and other organic composites. After we complete the current phase
of our project, we will start looking at how
we can incorporate organic composites into
our work, potentially remaking parts of the
existing aircraft or starting on the design of
an entirely new aircraft.

A few challenges still need to be overcome,
especially regarding hydrogen production.
One of the main advantages with hydrogen
is that it can be produced sustainably using
electrolysis powered by solar panels, wind
turbines or similar. Hydrogen can also be
produced on-site, negating the need for expensive and/or unsustainable shipping.
It thus makes sense that hydrogen has the potential to become established as the aviation
fuel of the near future, enabling emission-free
aviation within the next 10 years.

What is your main challenge in this case?

L.M.: One of the main concerns using organic composites is fire safety. We need to
conduct tests to prove to ourselves, to the authorities and to the general public that these
materials are safe to use in aircraft.

nationalities will test an initial downsized
version of the aircraft and hopes the first test
flights of the final version can take place at
Rotterdam airfield in 2021.
More information:
www.aerodelft.nl

http://www.aerodelft.nl

JEC COMPOSITES MAGAZINE - Issue #130 - September/October 2019

Table of Contents for the Digital Edition of JEC COMPOSITES MAGAZINE - Issue #130 - September/October 2019