The Depla Project : lighter aircraft impact protection systems

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Aeronáutica Andaluza nº13
Septiembre - Diciembre 2009
2 Septiembre 2009

The Depla Project will use hybrids of composite materials to meet the different needs of aircraft, crew and passenger protection from the impact of birds, ice, armed attacks or landings on unprepared terrain, with a resulting saving in terms of both weight and costs.

Airbus Military has recently initiated an R+D+i project with the financing of the Andalusian Technological Corporation (CTA) to develop a new, lighter system using composite materials for the protection of aircraft and passengers from the impact of ice, stones, shards of metal from the turbine or engine, birds or landings on unprepared terrain. It will also encompass the manufacture of the protected parts, from their conception through to the actual manufacturing process, and the application of these techniques to land-based vehicles as well.

Entitled Depla (Development of light Protection for Aviation), the project will be carried out from 2009 through to 2012, mainly at the Andalusian centres of Airbus Military at Puerto de Santa María (Cádiz) and San Pablo (Seville), and includes funding of 1.4 million euros from CTA. Aircraft structures and systems need to be protected from certain situations and potential damage which may arise due to incidents such as explosions of certain components or systems of the aircraft itself and external factors such as the impact of stones or birds. In the case of military transport these needs are even more demanding as it is also necessary to protect aircraft and their crew from more aggressive impacts, such as armed attacks from the ground or air.

The product which Airbus Military plans on developing through this project must meet the requirements of personal protection (guaranteeing the safety of the occupants), improvement of features (minimum weight penalisation in order to optimise the payload), viability (technological solutions which result in applications which may be industrially developed with an admissible cost) and performance in extreme situations (guaranteed performance in desert zones, zones with high levels of saline corrosion, etc). The ultimate aim of the project is accordingly to achieve technological solutions which improve aircraft protection from the threats indicated above, but without any penalty in terms of the aircraft's features and the end cost.

This project involves the participation of three research groups from the university of Cádiz (Corrosion and Protection), Jaén and Córdoba (Biosahe Group) and Seville (Elasticity and Resistance of Materials), along with the collaboration of the companies IDEC and Ghenova. The engineering and tooling is also expected to be subcontracted to Andalusian auxiliary companies. last 26 November the project launch was presented to all the participants at the Tecnobahía Technology Park in Cádiz.

Airbus Military hopes to obtain patentable results from the project, although the number and scope of the patents will not be defined until 2011. It will also support collaborating research groups to generate their own patents for techniques and methods developed during the course of the project. New materials The new product will consist of an improved aerostructure capable of providing suitable protection from possible impacts, ranging from those of lesser intensity (bird impacts) through to those with greater risk (ballistic impact) and including aerial waves (seismic waves, heat radiation, crater formation), abrasion and erosion. The protective element must be capable of integration with traditional structural elements, even forming part of the same using new hybrid concepts.

Airbus Military will study the possibility of using uHMW PE (ultra High Molecular Weight Polyethylene), which results in a more resilient material with extraordinary resistance to impacts, as well as good protection against corrosion and chemical agents, low moisture absorption, low coefficient of friction and very high resistance to abrasion. Nonetheless, it must be borne in mind that improvements to the protection capacities of a structure are inextricably linked with their capacity for integration into the same; in other words, it must be integrated into the structural concept of the aircraft, providing it with superior properties but also contributing in an efficient manner to its general performance. Accordingly, one of the keys to success will be to identify solutions involving hybrids of different materials.

The materials to be taken into account under the project include carbon fibres of different types, fibreglass, aramid fibres, uHMW PE and other types of fibres such has PBO. Terrorist threats Apart from the protection needs defined in current civil regulations (mainly the American FAA Regulations and the European EASA Regulations), certification authorities are requiring changes in designs due to the new threat of terrorist attacks and to prevent intrusions in the cockpit and provide greater protection for the crew.

These new requirements will require the protection and shielding of certain sections of the cockpit, passenger area and systems, as well as the design of specific zones which support certain explosions without catastrophic failure of the aircraft. Civil aircraft are not currently designed to be equipped with this type of protection and steps have only been made in relation to the locking and opening systems for cockpit doors to prevent intrusions of unauthorised persons. In addition, the potential protection for doors, partitions, walls, etc consists of steel plating with good ballistic protection but with a very heavy weight, giving rise to problems of excess weight for aircraft, problems with the handling of certain elements such as doors due to their weight and even problems of corrosion and rusting as these are interior elements without access and in zones with frequent use of liquids.

For all these reasons, the need exists to search for lighter alternative materials with good protection against bullet impacts and expansive waves of explosions and possible additional use as standard protection against ice, birds, stones, etc. All military programmes identify a series of requirements as to vulnerability to certain threats and the need for a series of protective measures. In order to reduce the specific weight of this protection, military airlifters tend to be equipped with shielding using materials which are more effective than steel, such as ceramic materials or aramid fibre (Kevlar).

Even so, the weight of these features with current protection materials is notable: for example, the weight of the shielding for the cockpit and the payload operator is around 350 kilos for a C-295. In addition, this weight is concentrated in specific areas, resulting in problems of localised overloading and for the centre of gravity.

In addition, military aircraft and particularly airlifters need to be prepared for use on inadequately paved runways below civil standards and even fields with practically no preparation at all. The possibilities of abrasion and damage to the underbelly of the aircraft mean that the need for specific protection is generally very high. Accordingly, the need exists in the case of both civil and military aviation for the development and use of lighter protection and shielding than that which is currently used.

A cutting edge project

The DEPLA Project (Development of Light Protection for Aviation) by Airbus Military incorporates a highly innovative series of technological developments. The protection of aircraft from the wide range of possible aggressions and impacts, ranging from birds through to armed attacks, has a long way to go in terms of research and development.

That is why the DEPLA Project by Airbus Military is at the cutting edge of innovation in the area of protection of lives in the aeronautical sector. Among the most striking technological innovations of the project is the description of advanced light materials for protection, techniques for the manufacture of complex elements, simulation and description of the performance of these materials in the event of high and low energy impacts and assembly of aerostructures.

The results of the project will be applicable to impact protection for civil aviation of any new design (A350, XWB, A30X, GRA…) and for military airlifters of all sizes and ranges (FATM, customer versions of the A400M, refuelling aircraft based on the Airbus Military Boom system and A-330 and A310 aircraft). In addition, they may be applied to aircraft currently in use to substitute current ceramic protection and may also be applied to both civil and military land-based vehicles, such as police or patrol vehicles, armoured civil vehicles, high speed trains, etc.

An estimated weight saving of 40% as opposed to current aramid fibre protection would in itself be very attractive for any user due to the benefits in terms of operating costs and gains in payload and range. The project fosters the generation of knowledge in Andalusia in what is a strategic area, and the network of enterprises and research groups which participate have the potential to develop into leaders in a field which may have extensions to civil applications related with personal protection and safety.