Chat with a Typhoon test pilot, discuss progress on the latest helicopter program with a Eurocopter flight test engineer, or review coverage of the A350’s first flight, and datalinking, telemetry, modeling and simulation are soon revealed as key factors in high-technology flight testing. Examine a typical unmanned air system (UAS) test programme and those same factors are again to the fore. The only real difference is that the pilot stays firmly on the ground.
UAS testing follows manned test procedures very closely. The variance and challenges lie in the much higher demands for data transfer of the UAS and the need to create, prove and sometimes challenge nascent regulations governing UAS operations. At the top end of UAS test and experimentation, manufacturers are intricately involved in the process of defining the regulations that will govern the eventual operation of their craft, or at the very least the future applications of the technology.
Asked about approaches to UAS testing, Martin Rowe-Willcocks, head of business development for Future Combat Air Systems at BAE Systems, notes that the company has been building and testing military aircraft for many years and its approach to UAS testing is exactly the same as for a manned aircraft. “Roles and responsibilities that have been defined and matured over decades on Harrier, Tornado, Hawk and Typhoon are just as relevant to the unmanned world. The only real difference is that the person in control of the aeroplane isn’t physically sitting in it. It’s how you plan and deliver a trial in these circumstances that produces the quirks of unmanned testing, but everything is done under the same governance structure as our military flight testing, under the head of flight operations.
“He’s independent of the flight test team and qualifies crews to operate vehicles during the test phase. Some of the crew are test pilots, some are flight test engineers, but all have been through a set of internal assessments to ensure they understand the subtleties of testing an unmanned aeroplane. We also have to make sure they know how airspace works.”
For BAE Systems trials, Rowe-Willcocks says that crew experience is essential: “It’s important for crews to understand how airspace works, how to fly under air traffic control and how to work with the authority controlling the range and airspace in use,” he says. “That’s no different from how we run a manned trial.”
He also notes that little in UAS test is new, since the company has been doing the work for more than a decade, although only publicly since 2005, when the UK’s Defence Capability Plan was published, revealing programs including Raven and Corax.
As far as day-to-day testing is concerned, the major difference in UAS work is that BAE Systems is obliged to work away from its Warton site. This, Rowe-Willcocks says, is down to several factors: “It’s the maturity of the technology, public acceptability and the use of airspace. We want to be able to fly away from home but we don’t always want to do so physically. But we have to be able to do it in a safe, controlled manner. This is one of the reasons we’re among the leading lights on the ASTRAEA (Autonomous Systems Technology Related Airborne Evaluation & Assessment) program, where we use a modified, crewed Jetstream 31 as a surrogate UAS, controlled from Warton.”
The Royal Air Force began operating the General Atomics MQ-9 Reaper over Afghanistan in 2007, from ground control stations at Creek AFB, Nevada. A second Reaper operating unit went operational in the UK late in 2012 and began flying the aircraft operationally from early 2013. As it continued to expand its remotely piloted air system (RPAS) knowledge, the RAF went on to award wings to its first RPAS-specialist pilots on April 2, 2013. Responding to the author’s questions, Squadron Leader Chris Melville echoed Rowe-Willcocks’s opinion that airspace restrictions are the major challenge in testing and expanding UAS capability: “The utilisation of airspace for conducting UAS operations and testing is a known issue, and not just within the UK.”
All UAS testing involves separate datalink requirements for telemetry and command and control. In the former case there is no difference from a manned test, where an aircraft is telemetered for health and systems monitoring. BAE Systems works with a normal crew that controls and monitors the aircraft in regular flight, just as the pilots in a Typhoon would. A team of flight test engineers then works closely with – but discretely from – the crew, monitoring, analyzing and acting on telemetered data.
The system has considerable advantages, as Rowe-Willcocks explains: “We have a small crew focused on testing the aeroplane, but with the test engineers able to ‘look over their shoulders’ as the test unfolds. If something unexpected happens there can be a dialogue between crew and engineers, but we ensure that the roles are kept in place. The processes and techniques are essentially those of a manned test, so it’s very easy to move engineers between programs.”
Of course the teams could be geographically separated, but as Rowe-Willcocks explains, “There’s a fine line between having all your experts next to the aeroplane and maybe one or two ‘super experts’ at the end of a hotline back to the UK. It’s driven by the
type of test. For example, envelope expansion and communication work require different technicians, so it takes careful planning to make sure all those people are in the right place before and during a test, and for the post-flight debrief.”
The earliest of BAE Systems’ UAS work involved subscale aircraft, but recent programs have been with larger medium-altitude, long endurance (MALE) type machines, which provide plenty of space for telemetry equipment but are regulated by weight, or at least by the degree of damage that could be caused if they crashed.
Regulators typically look for the aircraft to be demonstrably as safe as a manned machine of similar size and weight. The BAE Systems HERTI (High Endurance Rapid Technology Insertion), for example, was based on a glider, but became increasingly heavy as systems were added, effectively raising it from EASA’s CS-22 category as a powered sailplane, to CS-23. This more demanding certification specification was then used as the reference in setting up the design process and test regime.
Vehicle weight also affects the level of test required for UK military UAS. Release to Service (RTS) testing is overseen by the Military Aviation Authority (MAA), which has different requirements from the Civil Aviation Authority (CAA). “At present,” says the RAF’s Chris Melville, “a UAS can be operated by a civilian without completing a Kinetic Impact Statement if its dry weight is less than 20kg. However, MAA Regulatory Article 1120 states that a military UAS must be registered if its dry weight is more than or equal to 60g. This means that some micro UAS (weighing less than 2kg) would have to go through the same RTS process as a tactical UAS (weighing between 150 and 600kg) and that the military operates to a more rigorous standard than its civilian counterparts.”
The flying phase of a UAS test program tends to come toward the end of the development cycle. Rowe-Willcocks notes: “If you look at the process, we start collecting evidence as we do the design, then test subsystems with the supplier and at our own facility. We do lots of work on mission and interactive rigs, simulators and the aircraft itself, long before we go flying to deliver the final proof of all the testing that’s gone before. We find that we don’t get that many surprises once flying starts.
“But it’s important to remember that the overall test environment is a mix of the equipment, people, training and location. On one of our early HERTI trials in Scotland we sat at Campbeltown airfield with lots of different regulators. Some wanted to see how we tested and qualified the crews, some how we designed and
built the aeroplane and others wanted to know how the mission plan was constructed. We had to go through all of those scenarios before they allowed us to do the mission. Now much of that learning process is encapsulated in the CAA’s CAP 722 (Unmanned Aircraft System Operations in UK Airspace
– Guidance), which has become something of a bible for the industry.”
The company also pursues the independent verification and validation of its UAS software, so that as a vehicle comes closer to production standard the regulatory evidence is available to show that it has been designed and tested to industry standards.
As a UAS operator, the RAF takes all its new aircraft types through a further level of RTS testing before they are deemed suitable for service. Melville explains that RTS has been modified for UAS applications: “For manned aviation, the focus of ‘release to service’ test and evaluation is on the vehicle/vehicle-human interface. In other words, the aircraft and the way the crew interact with it. For UAS test and evaluation, system assurance has to include the ground control station and the air vehicle.
“There are few differences in testing methodology, although because there is a requirement to show the safe operation of the air vehicle, the datalink between the ground control system and the vehicle, for example, must be tested and shown to be safe and reliable.
“Defence Standard 00-970 (Design and Airworthiness Requirements for Service Aircraft) is the source document against which all service aircraft are assessed for safety compliance. Since there are differences between conventional and remotely piloted systems – as there are between fixed and rotary-wing platforms – UAS have their own Defence Standard 00-970.”
‘Go Home’ Function
Command and control is a crucial aspect of UAS operations and among the systems that must be 100% understood and reliable before flying starts. BAE Systems uses a hardware-in-the-loop setup for command and control tests, simulating a flying environment on the ground, with the crew at their normal stations and with or without the vehicle’s engine running. The mission plan is tested and vehicle behavior assessed, but perhaps most importantly, BAE Systems can analyze failure cases and emergency procedures.
A broken communications link, engine failure and unexpected weather conditions are among the most extreme possibilities, and ensuring that the vehicle behaves in a predictable way is essential. The system’s possible failure cases are defined within the mission plan in advance of a flight. Depending on where the operation is being conducted, planned responses to a lost communications link can include the vehicle entering a loiter pattern, climbing in an attempt to obtain a stronger signal, initiating an automatic return to base or diverting to an alternative landing site. All these options will have been fully tested in simulated and operational flight trials.
Rowe-Willcocks remembers BAE Systems’ first ‘go home’ test in Australia: “We deliberately turned the comms link off, as planned, with the aircraft 20 minutes out. It came home on its own, as all the engineers had known it would, but the program managers were delighted as it touched down on the runway.”
BAE Systems boasts considerable synthetic training and physical testing facilities, with the latter including wind tunnels, radar cross section pole testing facilities and acoustic chambers. Synthetic capabilities allow end-to-end mission testing with real or simulated equipment, and synthetic material is increasingly replaced as development continues. The facility was originally developed for the battle management testing requirements of the Queen Elizabeth II-class aircraft carriers and has proved ideal for modification to UAS testing as well as for analysis of the human interface.
FanWing opts for UAS testbed
For FanWing, a UK company currently engaged in developing what the New York Times describes as “one of the few truly new aircraft since the Wright Brothers”, the UAS was the only option for testing its design based on distributed-propulsion vortex-lift technology. The unique FanWing configuration precluded building a manned aircraft test bed, but more importantly, the company’s limited budget required a subscale platform that could be modified and tested on a shoestring.
A distributed-propulsion vortex-lift system lends itself well to long-endurance UAS tasks requiring a maneuverable, stable and efficient platform – border surveillance or pipeline survey work for example – although it can also be scaled up to suit a range of manned applications.
Most of the testing to date has been very basic – inventor Pat Peebles built a wind tunnel in the family garage early on in the program, for example, as well as hand-holding models to assess their potential flying characteristics. After many years of demonstration, improvement and struggle, however, Fanwing director Dikla Peebles was delighted to reveal: “On October 1, 2013 we entered into a two-year EU project led by DLR to optimize wingshape and so on.” A new era in UAS testing and operation could well be with us.
Lone Star UAS Center of Excellence & Innovation
Facilities across the USA are awaiting the conclusion of an FAA
UAS test-site selection process that will designate six dedicated test sites tasked with the integration of UAS into national airspace and the provision of regulatory data. Somewhat optimistically, the program is scheduled for completion in 2015. Twenty-five prospective sites submitted proposals by the May 2013 deadline and an FAA decision is expected before 31 December.
Among the contenders, Texas A&M University Corpus Christi is already working extensively with UAS in its Lone Star UAS Center of Excellence & Innovation program. Ron George, senior research development officer with the university’s Research, Commercialization & Outreach organization, explains: “The university has a certificate of authorisation [COA] to operate a particular type of unmanned aircraft in a specified section of Texas airspace. We’re in south Texas where population is sparse and our airspace is over ranchland, the inter-coastal waterway and Padre Island. It extends up to 3,000ft. We operate a small RS-16 aircraft and we’ve flown more than 20 missions under our COA. We report all our data to the FAA, so it can be sure we’re operating safely, and we also report to all the local ATC towers.”
The RS-16 is flown in support of the university’s geospatial science program and marine science institute, examining the research potential of UAS sensors. Work is also underway
on sense-and-avoid techniques and improving communications and control.
As well as fueling lab research, the RS-16 supports a private sector sensor developer, and a typical mission has many goals, not least keeping the operating crew proficient. The aircraft
is flown under visual line of sight rules and, using a chase plane and two control centres, it is increasingly being operated to the limits of the airspace. In doing so it yields data that feeds back into FAA rule making.
Should the Lone Star UAS Center of Excellence & Innovation and its wider proposal team – including around 15 organizations and acting on behalf of the Texas governor’s office – be chosen as one of the six test sites, its authorised airspace will be expanded to around 6,100 square miles, for testing a wide range of aircraft and at higher altitudes.
However, Ron George says that even if the test-site decision does not go its way, the Lone Star UAS Center of Excellence & Innovation has already invested heavily in development and will continue to work and expand in what it considers a burgeoning sector, with a new command and control center already underway.
Paul E Eden is a UK-based writer and editor specializing in the aviation industry