Under the auspices of the newly formed Air Warfare Centre (AWC) the Australian Defence Force has, in conjunction with local industry, developed a non-intrusive means of instrumenting aircraft for flight test activities.
The Non-Intrusive Flight Test Instrumentation system, or NIFTI, has been developed as a means of instrumenting an airframe for flight testing without altering its original configuration or removing it from the line for an extended period while intrusive and sometimes very complex flight test instrumentation is installed and removed.
Initial trials with the system were carried out in late 2015 with promising results, and a program of further activities will be conducted later in 2016.
Formerly known as the Aerospace Operational Support Group (AOSG) the Air Warfare Centre oversees four directorates, one of which is the Testing and Evaluation Directorate, which in turn oversees the Royal Australian Air Force’s chief testing unit, the Aircraft Research and Development Unit (ARDU).
The NIFTI system is an example of the innovative approach to problem solving for which the Air Warfare Centre was formed, and embraces the principles of the RAAF’s Plan Jericho, a blueprint for innovation and forward thinking designed to develop informed processes for acquiring and developing capability and to position the service for the so-called ‘5th generation’ capabilities of the future.
The capture of flight test data, from something as simple as recording accelerometer information for monitoring g-force loadings, to complex flutter testing of aircraft structures under different loads and in varying configurations, has traditionally involved dedicated test fleets that are extensively modified for the purpose.
For a medium-size force like the Australian Defence Force, it is becoming more difficult to dedicate an aircraft such as the Lockheed Martin Joint Strike Fighter, each of which will cost around US$90m, purely for flight testing.
Traditional flight test instrumentation at least temporarily and often permanently requires the modification of small numbers of aircraft with customized equipment installations, which are designed specifically to collect the data required. Although this approach provides the testing organization with a responsive capability development support tool, it comes at the expense of operational availability, as the aircraft is off-line as a weapons system as a consequence.
Flight test instrumentation can also be installed on an as-required basis, for a single trial or a series of trials. This approach has the advantage of maximizing operational availability, but it comes at the expense of the responsiveness often required for problem solving. Both philosophies require the aircraft to be in maintenance for extended periods. This often has a negative impact on the capacity and willingness of operators to dedicate aircraft to a flight test program, or to contemplate undertaking projects that require complicated instrumentation fits, with consequential negative influences on operational capability.
“Our NIFTI system is designed to reduce or remove the bottlenecks created by conventional instrumentation by providing a generic system that can be rapidly installed on an aircraft, in any configuration,” explains Group Captain Tobyn Bearman of the Air Warfare Centre. “The time taken to install a conventional flight test instrumentation system is determined in part by the complexity of that system and the electrical wiring that is usually required. Typical installation times can be as short as two weeks, but they can be as long as two or three months.”
Gp Capt. Bearman is the current director of test and evaluation at the Air Warfare Centre and is an aeronautical engineer with experience in aircraft maintenance, sustainment, and flight test and engineering operations. Prior to his current role, he has held the positions of test manager for the RAAF’s Airbus KC-30A Multi-Role Tanker Transport (MRTT) program, chief engineer for Air Force Test and Evaluation, and director of enabling capabilities at Air Force Headquarters in Canberra.
The NIFTI solution was jointly developed in Australia by the companies AADI Defence and Procept, together with the Defence Science and Technology Group (DST Group) and the RAAF’s Aerospace Systems Engineering Squadron (ASESQN). The Defence/industry consortium formed an integrated project team (IPT), an Air Warfare Centre initiative designed to gather a small team of resources from diverse backgrounds to provide innovative solutions to complex problems.
Funding has also been provided by the US Air Force Seek Eagle project office, which sees the potential for NIFTI across the huge international Joint Strike Fighter program.
The NIFTI system comprises a series of battery-powered wireless sensors that can be temporarily mounted on any external surface of the aircraft. Because they are attached by adhesive, the entire system can be installed in hours, rather than days, weeks or months.
The sensors send data to a pod, which can be mounted on any standard pylon, using a bespoke wireless technology system. The sensors use wireless mesh network topology, which means the sensors do not need to be in line of sight with the instrumentation pod, which is typically mounted on an underwing hard point.
Up to 24 sensors can be used with the system, but the initial concept demonstration last year was carried out with a 10-sensor fit. The NIFTI system is also controlled wirelessly and can be controlled from the cockpit, by either the pilot or a dedicated flight test engineer.
The initial NIFTI prototype was developed in eight months and was installed on one of ARDU’s Pilatus PC-9/A aircraft before being flown in a series of concept demonstrations beginning in September 2015.
“The prototype system included 10 sensors mounted externally, as well as in the cockpit and baggage compartment, and a wing-mounted pod for system control,” explains Gp Capt. Bearman. “Once the prototyping was complete, control installation of the 10 sensors was completed in 15 minutes.”
The concept testing also considered NIFTI’s ability to reliably record accurate test points while being subjected to the extremes of the PC-9/A’s flight envelope, including the airframe’s maximum-permitted positive and negative g-force limits during aerobatic maneuvers.
“The trial successfully demonstrated how an integrated team can develop, prototype and then rapidly configure an aircraft to collect flight test data,” continues Gp Capt. Bearman. “The innovation of this system spans several domains. We used commercially available glue strips to fit the sensors to the aircraft and the sensors themselves use a version of wi-fi to communicate with the pod and to collect information. We don’t have to take an aircraft off-line for long periods of time to instrument it to obtain the desired result, be that for a problem investigation, to collect data required for certification, or to confirm the airworthiness of a system.”
One of the important steps in testing of the NIFTI system before flight trials took place was a series of tests to prove that electromagnetic interference (EMI) produced during operations would not have a negative effect on either the aircraft or its systems. Initial testing was carried out in the hangar at RAAF Edinburgh in South Australia (home to the AWC and ARDU) and also in a dedicated EMI chamber, where the aircraft was subjected to repeated tests under a range of conditions.
The technology used in the development of NIFTI is Australian industry intellectual property, which was originally developed for telecommunications, mining and medical applications.
“The effort to take this technology and optimize it for flight test was accomplished by a small integrated project team consisting of Air Warfare Centre engineers; pilots; Defence Science and Technology Group scientists; and design engineers from Australian industry,” adds Gp Capt. Bearman.
Flight test, trials and the future
The successful PC-9A concept demonstration marked the completion of the first phase of a three-phase capability development program aimed at producing a system that Gp Capt. Bearman says is expected to be able to be used on any aircraft type. The results of the demonstration have been combined with a series of evolved objectives to create a scope for the next phase of trials.
Phase two of the program will be demonstrated through an air-to-ground weapons clearance campaign on an RAAF F/A-18A/B Hornet strike fighter in October of this year.
“That system will be capable of capturing high-accuracy strain and vibration data and will include an improved ability to monitor system health and control system parameters from the cockpit,” says Gp Capt. Bearman. “In parallel with phase two, the team in the Air Warfare Centre is looking ahead to phase three and how we might apply that system to the Joint Strike Fighter environment.”
In conclusion, Gp Capt. Bearman says that, in order to meet the challenges posed by the rapidly evolving technical landscape and the constraints that come with some of the complex and evolved systems the ADF is introducing into service, the Air Warfare Centre is adopting the principles of Plan Jericho.
“Our mission is to help transform the way we develop and acquire capability. We’re doing this to help create a future combat capability that is highly adaptable and able to deliver decisive results whatever the context.”
Nigel Pittaway is an experienced freelance journalist for aviation and defence publications worldwide.