JEC COMPOSITES MAGAZINE - Issue #80 - April 2013 - 47

sandwich

A high-performance sandwich
composite container concept

The Envirotainer RAP e2 composite container is an optimal sandwich composite solution that uses virtually all of the beneficial
features of sandwich design.

Håkan Johansson, Head of Composites
David Egertz, R&D Composite Engineer
Envirotainer Engineering AB

wo years ago, after a four-year-long development programme, Envirotainer
launched its new RAP e2 container, a
sandwich composite container with extreme
requirements on structural integrity, thermal
performance and impact resistance.

A new temperature-controlled
air cargo container design

Manufacturing process
The decision to move to a
sandwich composite design
challenged Envirotainer
engineers to develop a
VARTM (Vacuum Assisted
Resin Transfer Moulding)
manufacturing process that
would allow efficient series
Fig. 1:Envirotainer RAP e2 active temperature-controlled air cargo container production of the container

while at the same time maximizing the
properties of the sandwich composite. The
result was a glass-fibre-reinforced vacuum
infusion polyester, with 70% fibre fraction
by weight, using a sandwich construction
with a foam core offering excellent structural
performance. The container is designed
to load and encase 5 tonnes of unhinged
cargo in extreme aviation conditions that
correspond to up to -4g (negative gravitational force). For example, this means that the
container shell can withstand loads above
20 tonnes.
With the VARTM manufacturing process,
matched rigid and flexible moulds are used
to create the two sandwich components
that make up the entire structural part of the
container in a single shot. Glass fibre, core
material, inserts, floor panels and cavities for
door locking rods are all integrated in the
infusion process so that, except for removing
mould residue, minimal post-processing is
needed before assembly.
An additional feature of the Envirotainer
VARTM manufacturing process is the
ability to achieve square internal corners
to maximize cargo space, meaning that the
mould has no release angles. Usually, mould
release angles would be necessary for this
type of process.

No80 April 2013 /

Feature Aeronautics

The RAP e2 is a so-called refrigerated
ULD (Unit Load Device) with an integrated forkliftable base which also acts as
a standardized restraint interface to the
aircraft cargo floor. The container consists

of two compartments: a cargo hold and a
climate control unit compartment. The two
compartments are connected via an insulated partition wall with ingenious air guides
and canals that distribute the air evenly all
around the cargo hold. The internal size of
the container cargo hold is 6.38 m3, equivalent to five Euro pallets or four US pallets,
and it has the capacity of loading a net
weight of 5 tonnes (4,933 kg). Envirotainer
is investing heavily in the development of
composite containers, adding to the existing
fleet of more than 4,000 active temperaturecontrolled containers.
The RAP e2 programme was launched
to offer improved thermal, structural and
impact/damage performance compared to
the traditional aluminium/polyurethane foam construction.

jec composites magazine 47

JEC COMPOSITES MAGAZINE - Issue #80 - April 2013

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