Application of light emitting diodes is expanding as the luminous output and efficiencies of these devices improve. At the same time, the number of LED package types is increasing, making it challenging to determine the appropriate device for use in lighting product designs.
A range of factors should be considered when selecting a LED for an application including color coordinates, luminous efficacy, cost, lumen maintenance, application life, packaging and manufacturability. Additional complexities can be introduced as LED packages become obsolete and replacement parts must be selected. The replacement LED characteristics must be understood and assessed against the parameters of the original device, in order to determine if the change will be relatively simple or will force other end-product changes.
While some characteristics are readily measured and compared, other factors, such as lumen maintenance, are difficult to verify. This paper will discuss the characteristics of a LED that should be considered during the design process as well as methods to validate these characteristics, particularly those which are not typically on data sheets or, are critical to the design and warrant additional validation. Particular attention will be given to LED lumen maintenance. While published manufacturer data typically provides temperature versus performance curves, the data may not be useful depending upon the application's operating environment. Models must be created to estimate the LED's junction temperature and degradation curve at the applied temperature in order to develop a more precise life estimate. This paper presents one approach to a LED device life and performance study designed with application environments in mind.
Solid state lighting (SSL) has made substantial inroads into the aviation lighting market in recent years. In many aircraft applications, the unique characteristics of this technology make it superior to the light sources presently employed. However, the novelty of this technology also brings new challenges to successful implementation within rigorous aerospace environs. This paper provides an overview of how the advent of solid state lighting has benefited the aerospace lighting industry, examines some of the current applications and looks forward to future uses of SSL in the aviation market. The discussion will include an examination of aerospace requirements and how SSL technology meets those requirements. The authors will address some of the challenges presented by solid state light relative to the aerospace industry and explore how these issues can be overcome.
As LEDs continue to improve in efficacy and total light output, they are increasingly finding their way in to new applications in the aviation industry as well as adjacent markets. One function that is particularly challenging and may reap substantial benefits from this new technology is the fuselage mounted anti-collision light. Anti-collision lights provide conspicuity for the aircraft by periodically emitting bright flashes of light. The color, light distribution and intensity levels for these lights are all closely regulated through Federal Aviation Regulation (FAR) documents. These lighting requirements, along with thermal, environmental and aerodynamic requirements, drive the overall design. In this paper, we will discuss the existing technologies used in anti-collision lights and the advantages and challenges associated with an LED solution. Particular attention will be given to the optical, thermal, electrical and aerodynamic aspects associated with an LED approach. A specific case study will be presented along with some of the challenges that have arisen during the design process. These challenges include the addition of an integrated covert anti-collision lighting.
Operating at altitude and often in turbulent, low visibility conditions, in-flight refueling of aircraft is a challenging endeavor, even for seasoned aviators. The receiving aircraft must approach a large airborne tanker; take position within a "reception window" beneath and/or behind the tanker and, dependent upon the type of receiving aircraft, mate with an extended refueling boom or hose and drogue. Light is used to assist in the approach, alignment and refuel process of the aircraft. Robust solid state light emitting diodes (LEDs) are an appropriate choice for use in the challenging environments that these aircraft operate within. This paper examines how LEDs are incorporated into several unique lighting applications associated with such aerial refueling operations. We will discuss the design requirements, both environmental and photometric that defined the selection of different LED packages for use in state-of-the-art airborne refueling aircraft Formation Lights, Hose Drum/Drogue Unit lights and Pilot Director Lights.
Solid state lighting devices have made their way into a number of niche markets and continue to make inroads into other markets as their price / performance ratios improve. One of these markets is aviation lighting. Although this paper will focus on the use of LEDs for aircraft position lights, much of the discussion is applicable to other installations on the interior and exterior of the aircraft. The color, light distribution and intensity levels for a position light are all closely regulated through Code of Federal Regulation (CFR; formerly Federal Aviation Regulation (FAR)) documents. These lighting requirements, along with harsh thermal and environmental requirements, drive the design. In this paper, we will look at these requirements and discuss what is required in order to use LEDs for this type of application. We will explore the optical, thermal and electrical issues associated with the use of LEDs for position lights and examine the specific case study of the Astreon forward position lights. Finally, we will discuss some of the challenges that we see with solid state lighting in current and future aircraft applications.