When The Going Gets Tough...

As airline operators continue to struggle with volatile fuel prices, aircraft manufacturers are striving for lighter and more fuel efficient planes which, in turn, are pushing engine manufacturers to focus on powerplant design and development. Initially, manufacturers looked into using lighter structural materials, which were usually exotic alloys and proved too costly – the solution therefore was composite materials. The focus has now moved to the internal workings of the plane, much like in the automotive industry, to optimise design or replace the traditional mechanical, hydraulic or pneumatic systems with electronics.

One of the key success stories is the design of a more efficient engine for mid-range aircraft; the Lean Burn Engine, which is installed on the new A320 Neo, is said to achieve fuel savings of 15% and an additional flight distance of 500 nautical miles (950 kilometres), or the ability to carry two tonnes more payload at a given range. For the environment, fuel savings translate into some 3,600 tonnes less CO2 per aircraft per year, as well as a double-digit reduction in NOx emissions and reduced engine noise.

Through this development process the connector industry has worked closely with engine manufacturers to produce interconnect solutions that can cope with extreme conditions and temperatures of up to 250°C, without signal degradation. For these environments, the material selection process is crucial and must be considered early on in the design process. With experience already gained in the industrial, medical and automotive environments, Molex had already met this design challenge with its EXTreme Power 150A low-profile power connectors.

Electric Flight

Another route being followed is the All Electric and More Electric Aircraft (AEA/MEA) concept; the idea to replace the traditional hydraulic and pneumatic secondary power systems (SPS) with electrical systems was first proposed back in 1945 but was not actively researched until the 80s, at a time when fuel prices began to soar. Since then, the AEA/MEA concept has been adopted and implemented in new aircraft designs, such as the Boeing B787 and Airbus A380.



Moving on into further weight savings, aircraft manufacturers are now turning their eyes to fibre optic technology. Until recently, fibre optics has been seen as a ‘black art’ — in terms of mechanical and environmental stability and cost of active components — however as the commercial market has shown for many years, this is no longer true. Cabling systems that use rugged cables and interconnect products, and the transceiver technology, is advancing apace, while costs are reducing. Away from the PCB, a solid OEM acceptance has grown as the termination, test and cleaning of systems have become much more robust and repeatable processes.

When comparing copper telephone wire used in the Plain Old Telephone System (POTS) with fibre cabling, it is clear that fibre is faster than copper, offers a wider bandwidth and its distance performance with respect to losses is greater, as the table describes below. It is for this very reason that fibre technology was used in the Typhoon Eurofighter, which was developed in the 1980s, and in today’s Joint Strike Fighter (JSF) Programme as well as many other civil aviation platforms.



Getting Tougher

Ruggedisation, weight reduction, micro-miniaturisation and performance are all key elements for the Military and Aerospace industry's selection process of interconnect solutions. Complex C4ISR applications, for example, require incredible speed, enormous bandwidth, signal integrity and analytic capabilities, without adding heat to the system. Lightweight design is a priority in unmanned vehicles; here, the smallest interconnect systems can help keep the system light and nimble. With these design criteria, fibre optics is becoming the transmission medium of choice and, due to the intrinsic benefits of security and immunity to RFI/EMI, the use of such links is not just desirable but is now essential.

In parallel with these fundamental design changes, the Military/Aerospace market is gradually adopting the use of COTS (Commercial off the shelf) or MOTS (Modified off the shelf) components for cost saving purposes — previous to this, mil-grade components were designed specifically for a particular task and were often over-engineered and extremely costly. Many connector manufacturers, such as Molex, actively work in the automotive and industrial markets that have similar harsh environments and strict demands for longevity of supply. For one of these products to be considered for mil/aero COTS use, it is often just a matter of retesting the connector according to the relevant military standards — whether it’s a round, rectangular or power connector.

COTS optical cable assemblies, such as Military 38999- and 28876-style circular connector cable assemblies and ARINC 400- and 600-style avionic optical assemblies, provide readily available cost-effective and short lead-time solutions. Uniquely designed connectors, which can be terminated to both discrete fibre and optical ribbon cable, are ideal for use in avionics, flight-control equipment, mobile tactical field command platforms, EMI sensitive equipment, security and other harsh-environment applications.



Flexible circuitry, backplane systems and standard connectors (FC, LC, MT, MPO, MTP, SC and ST) are all available for customised terminations to meet specific application requirements. State of the art aircraft will use more and more fibre optic technology to support the requirement for more efficient airframes in terms of weight reduction, while supporting more services, such as control, communication and infotainment, on the various platforms. Standards Committees, such as the SAE, JEDEC and ARINC, are working with the leading connector manufacturers focusing heavily on fibre technology, particularly transceiver modules, backplane and on-board infrastructure in support of these high-speed intra-platform links.

Let’s not forget the role of copper however; with the advent of unshielded-twisted-pair cabling (UTP) the margins between copper and fibre are narrowing. Connector and cabling manufacturers have marched through at least five generations, each time to keep up with the increasing bandwidth requirements of Local Area Networks (LANs). We are now seeing 10Gbit Ethernet, as opposed to the 10Mbit/s Ethernet networks we had 15 years ago. This technology is now ruggedised for the industrial environment and it is anticipated that it will also migrate into military and aerospace applications, complementing fibre optic technology.