Every construction company should be looking to leave the surrounding environment as untouched as possible during projects. For some sectors however, that goal poses significant challenges. The forestry industry is a good example of this, where delicate work is constantly done in direct proximity to living ecosystems. Keeping the environment as free from any impact as possible is particularly challenging when you consider the size and weight of the machines in use. When heavy machinery is placed, or is in operation on soft ground, it risks damaging the soil, and can lead to an increase in accidents. Higher fuel consumption resulting in more emissions is also a concern.
Looking at the aerospace sector, there are obviously no fuelling stations at 10,000 meters, so aircraft designers must find ways to reduce the ‘multiplier effect’ of the plane’s weight plus the weight of the fuel needed to keep them airborne for periods of many hours. The lighter the aircraft is, the less fuel it will burn and the fewer emissions it will produce.
Changing materials used and reconfiguring the balance are two areas being looked at within the aerospace industry. In fact, manufacturers have already started along the journey by switching from steel to titanium on many areas of the aircraft’s structure. As a superior metal, titanium is more resistant to corrosion than steel; it also fares better against alkalis and other environmental conditions. Perhaps most importantly however, is that it is 56% less dense and therefore lighter than steel, (4.44g/cm3 compared to 7.85g/cm3). It is not all good news though: titanium is much more expensive than steel, meaning the cost may be too high to use it extensively as an otherwise beneficial substitute.
Manufacturers are also making extensive use of composite materials such as epoxy resins, glass fibre, and carbon fibre amongst others. Their use is equally applicable to a range of parts from major structural items such as wings and the fuselage, to many of the myriad of smaller components all over the aircraft. Even with small parts their sum effect is a lighter, more fuel-efficient assembly.
Perhaps the most cutting-edge technology of all right now is additive manufacturing, where precise 3D parts are printed from various materials. The 3D printing process allows engineers to optimise the design of each part for each aircraft; this can help significantly when it comes to achieving overall weight reduction. One case study shows fuel nozzles that were once made up of 18 parts welded together. Once they were printed as a single part, a 25% reduction in weight was achieved. Whilst this study showcased the tremendous potential of 3D printing, it is worth acknowledging that the final weight saving may not be this extreme. This is because of several factors: not only is the process still being proven in terms of the material properties, but some parts are well optimised and aligned with existing manufacturing techniques. Because of this, not every part is going to present the same opportunity for saving weight.
Methodology for lighter, more efficient aircraft
To lighten the load on any one part of an aircraft, traditional and non-traditional methods are being examined to achieve better weight division. Much as forestry machines add more wheels or adapt their tracks to distribute weight more evenly to avoid unnecessary soil damage, aircraft must adhere to tarmac loading standards. Regulations state how much weight per wheel is allowed, keeping aircraft from damaging the critical surface on which they take off, taxi and land.
In pursuit of a more energy efficient strategy, conventional approaches to system design are being challenged, for example the older aircraft utilised centralised hydraulic systems to power their operations. Pipes lead from the centre and ran through the entire aircraft to deliver fluid power and actuation to any area that required it.
New approaches seek to divide the hydraulic system into several smaller, localised circuits, each of which achieves the delivery of power to various tasks around the aircraft. The immediate effect and key benefit if this is the removal of any unnecessary piping, resulting in a significant weight saving. Typical aircraft traditionally used three main hydraulic systems, but we are seeing an increasing trend towards the removal of one of them, with their functionality being replaced by electrically controlled ‘power packs’. This again can reduce the equipment weight as well as a reduction in the amount of hydraulic fluid used which correspondingly lessens concerns and the occurrence of leaks. However, we must remember that an electrical approach adds the weight of wiring back into the equation.
Because of the vastly different working environments of aircraft versus land-based construction equipment and machinery, the new technology solutions being embraced and adopted by the aerospace industry do not provide a completely transferrable ‘one size fits all’ methodology. The best practices of new aircraft can be inspiring for construction machinery applications: lightweight materials applied to certain parts and the switch from hydraulic to electrical systems are solutions that can make a major difference and ensure future construction equipment is both lighter and more energy efficient while still maintaining its overall durability and effectiveness.
Companies like Parker Hannifin are supporting this transfer of knowhow and technologies, providing solutions for alternative manufacturing materials as well as machine weight reduction innovations to cut costs and the environmental footprint of construction equipment.