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The number of flights worldwide continues to grow each year, in spite of growing environmental concerns about the impact of carbon dioxide emissions from airline travel. With almost 40 million flights in 2019, this shows no signs of slowing.1
The impact of this is not debated: indeed, the aviation industry contributes 12% to all transport to carbon dioxide emissions from transport worldwide,2 and as a result there is much interest in replacing heavily polluting hydrocarbon-based fuels or the improving their efficiency.
Moving towards all-electric aircrafts powered by electric motors is one environmentally-friendly possibility. Batteries that are recharged by renewable energy are another possibility of power source, as well as solar cells which can be used for charging during a flight. The 1970s saw development begin on the first electrical aircraft which was solar-powered becoming and today the concept of an electrical aircraft for passengers is booming.3
Modern commercial aircraft also increasingly use fly-by-wire systems, in addition to all-electric aircrafts which rely on electronic interfaces for piloting and control. Fly-by-wire systems are often found in modern automatic vehicles, which removes the need for conventional throttle cables in order to minimize emissions. In addition, these systems minimize the numberof moving components and, most significantly, save weight, a vital aspect of the move to electric vehicles.
How does Fly-By-Wire work?
A manual sidestick or yoke which can be directed by the pilot is still a key component of a fly-by-wire system for piloting. Instead of direct mechanical control of the aircraft being hinged on the sidestick, however, the input signals are converted by a series of sensors and on-board computers to the flight control actuators, which steer the aircraft.
There are many advantages to this approach. For instance, fewer mechanical moving parts and an enhanced ‘artificial feel’ - feedback that a pilot receives from the controls in response to an input- are just some of these benefits. Indeed, the use of electronics facilitates fast communication which offers the ability to assist the pilot’s steering with additional computer input, given that any physical movements can be compensated by an onboard computer, to avoid overly large changes in pitch or roll. The performance of a fly-by-wire system, however, is highly dependent on the use of sensors across all types of aircraft, whether that’s fixed-wing or rotary-wing.
In order to create a high-quality fly-by-wire system for use in complex aircrafts, many different types of sensor are required in order to provide feedback on potential types of mechanical motion – in particular, if this is integrated into an autopilot system.
There are certain types of sensors which must be incorporated in a system in order for it to succeed, which include the following: force and torque sensors for flight controls, electric actuators, force and torque sensors for flight controls, health, secondary load path sensing, as well as usage monitoring systems (HUMS).4 Each of these reflects significant growth applications as demand for all-electrical aircraft and more automated transport continues to increase.
Meeting Safety Legislation
Of course, some of the most stringent safety legislation in the world can be found in the aircraft industry. The result of this is that any sensor which is designed to be included as a feature part of aircraft must meet certain legislative requirements, like 14 CFR Part 21 (Code of Federal Regulations) or EASA Part 21, both necessary legal requirements for aviation sensors.
In addition, the sensor must have been both designed and produced in a facility which is approved to AS9100 (the International Quality Management System standard set for the industries of Aviation, Space and Defense). Every single aspect of the sensor must be compliant with these regulations and standards, not just its operation but also its design and manufacture.
There is another layer of requirements which are application-specific, that covers sensors which are designed and built for in-flight applications, which also requires the sensor’s creator to have certain skills and specific expertise. This requirement is necessary in order to be compliant with industry standards like DO-160, DO-254 and MIL-STD 461/464.
These standards and regulations determine the test procedure for the environmental testing of avionics, including the considerations of hardware design safety as well as the many and diverse elements of electromagnetic compatibility, including the effects of lightning on the equipment.
HITEC Sensor Developments
These particularly strict regulations designed for the aviation industry naturally limits the number of suppliers that can comply with these complex regulations thanks to the experience and testing facilities. One such experienced supplier is HITEC, with over a decade of experience specifically in designing and building airborne sensors. HITEC’s products have already amassed over six million hours in total of in-flight service.
The wide range of torque and force sensors that is offered by HITEC is ideal for integration into either fly-by-wire or all-electrical aircraft applications. HITEC offers numerous and varied sensors for all parts of a fly-by-wire system. This variety means that HITEC can offer sensors to suit each aspect of the system, including secondary load path monitoring or HUMS.
HITEC additionally has a wealth of expertise in the design and installation of strain gauge systems used for airframe fatigue testing, and has experience installing 7500 measurement nodes in a single airframe with no failures.
The majority of sensors can operate with no detrimental impact on accuracy as they are temperature compensated between – 68 °F and 160 °F, which is imperative for what are the often-extreme environmental conditions that the average aircraft experiences HITEC’s sensors are also designed to ensure that altitude has a negligible effect on their accuracy.
Though a huge array of sensors is widely available from HITEC, they additionally design and create bespoke testing solutions, for strain gauges in particular. Full-field or on-site support is available and HITEC offers full-field and on-site support testing services, in order to ensure that the components or constructions meet the necessary regulatory requirements.
The testing capabilities of HITEC include mechanical, thermal, and residual stress analysis in addition to static, dynamic and endurance testing, which can often be difficult for aircraft applications. HITEC has proven expertise in sensor design and applications for aviation, and can assist with installation, technical support and calibration requirements in addition to test assemblies and sensor supply.
References and Further Reading
- E. Mazareanu (2020) Number of Flights 2004-2020, https://www.statista.com/statistics/564769/airline-industry-number-of-flights/, accessed 28 March 2020
- Air Transport Action Group (2020) Facts and Figures, https://www.atag.org/facts-figures.html, accessed 28 March 2020
- Zhu, X., Guo, Z., & Hou, Z. (2014). Solar-powered airplanes: A historical perspective and future challenges. Progress in Aerospace Sciences, 71, 36–53. https://doi.org/10.1016/j.paerosci.2014.06.003
- Traverse, P., Lacaze, I., & Souyris, J. (2004). Airbus fly-by-wire: A total approach to dependability. IFIP Advances in Information and Communication Technology, 156, 191–212. https://doi.org/10.1007/978-1-4020-8157-6_18
This information has been sourced, reviewed and adapted from materials provided by HITEC Sensor Developments, Inc.
For more information on this source, please visit HITEC Sensor Developments, Inc.