Aircraft Research & Development Unit

ARDU’s charter includes research and development to meet specific RAAF needs, air survey of military navigation aids and flight testing expertise, and aircraft to assist other organisations, such as Aeronautical Research Laboratories and Weapons Research Establishment.

ARDU comprises more than 200 personnel including civilian scientists and engineers, test pilots, flight test engineers and RAAF technical officers. They are functionally grouped in three squadrons – Flight Test Squadron, Research and Development Squadron and Maintenance Squadron.

The unit operated seven types of aircraft, the Airtrainer, Nomad, Iroquois, Mirage, Dakota, Macchi and Canberra, and conducts trials on other aircraft when required (ChinookF111C, Orion, Caribou and Hercules).

The unit’s capabilities include flight test performance data computation and analysis; design, manufacture and in­stallation of aircraft modifications; photography and photographic processing; electronic and instrumentation design, manufacture and installation; report production; and technical draughting.

ARDU currently is engaged in some 60 different tasks, ranging from assessment of aircraft handling characteristics, determination of aircraft performance, testing and evaluation of aircraft and aircraft equipment modifications and provision of flight trials expertise and aircraft for other government agencies.

The major part of the unit’s recent work has been on flight testing of the replacement for the Winjeel basic trainer, the CT4A Airtrainer, the most recent addition to the RAAF inventory.

Over the past several months ARDU has been committed almost fully to a comprehensive handling and performance testing program of the prototype of the military Nomad air­ craft built by Government Aircraft Factory for the Australian Army.

Evaluation of the Airtrainer inverted spinning characteristics was a typical aircraft handling task. Part of the RAAF pilot training is to teach student pilots to operate their aircraft to the boundary of its flight envelope.

Experience has shown that eventually an inexperienced or student pilot will cause the aircraft to depart from con­trolled flight. Indeed, an inadvertent excursion from the air­craft’s flight envelope under safe conditions is an object lesson to a student pilot. However, such a departure could lead to an inverted spin. ARDU was tasked to determine the inverted spinning characteristics of the Airtrainer.

Before starting flight testing, the trials aircraft was modified to include onboard photographic recording of a spin panel, and a spin recovery parachute. These modifications were designed and built by unit personnel in Research and Development Squadron and included stress analysis of critical components. The spin recovery parachute was deployed and tested during high speed taxi trials, in level flight and finally in an erect spin to ensure that it would func­tion effectively if required.

The same careful approach, tackling each phase of the trial in small increments, was followed in the test pilot’s preparation. Several sorties of erect spinning were flown in which he practised and developed his tolerance and obser­vational capabilities in the physiologically demanding environment of the spin.

In addition he trained on a specialised aerobatic aircraft, the Pitts Special, to refamiliarise himself with the sensation associated with invertes spinning.

Throughout the preparatory and trials flying a chase aircraft was used to photograph each spin and the test pilots comments were transmitted to ground station and recorded for post flight analysis. From this trial ARDU was able to con­clude that the Airtrainer could be spun inverted and was able to define the characteristics and the recovery technique.

This task, however, was small compared with the program planned for the Nomad which utilised a complex on board digitised magnet tape recording system.

The instrumentation will be used during flight trials to simultaneously measure, record and output up to 50 different aircraft, aircraft equipment and flight path parameters (such as rudder tab position, propeller pitch angle and sideslip) which can be selected by the testing aircrew according to the aim 0f the particular test. This system is being designed, con­structed and installed by unit personnel.

In parallel with th edevelopment of this hardware is that of the software, or computer programs, to reduce and analyse the data which the system will produce. Qualitative im­pressions of the aircraft handling characteristics by the test pilot will be complemented by quantitative data and the adapability of rapid interpolation for different aircraft con­figurations, weight and atmospheric conditions by means of a mathematical model.

All this has permi1ted ARDU, and ultimately the Army Aviation Corps to evaluate the aircraft’s operational capabili­ty, its flight and performance envelope and any limitations which may restrict its intended role.

To date, several engineering modifications proposed by ARDU in consultation with Army pilots and Government Air­craft Factory already have been incorporated in the military prototype to facilitate and expand safe operation of the air­craft in the field by the Army Aviation Corps. These include redesign of the pilot seating/control geometry, addition of an air conditioner and a weather radar for tropical operations, and an auto-pilot to assist single pilot operations in adverse aircraft loading/terminal weather situations.

The unit is sometimes asked for advice on aircraft procurement or in forming specifications_.

Occasionally, test pilots from ARDU are asked to conduct pilot assessments of aircraft which are under consideration for the RAAF. To this end all test pilots have a recent operational background and, after specialised training in the UK or the USA, constantly maintain and develop flying skills to permit evaluation of aircraft stability and control characteristics from a pilot’s point of view as well as inter­pretation of quantitative data.

Operating conditions in Australia and in the areas of her strategic interest are often markedly different from those for which many RAAF aircraft were originally designed. Further­ more, with limited resources available, the RAAF must con­stantly strive to increase flexibility and effectiveness of its operational aircraft. These factors have led to ARDU’s in­volvement in many trials: for instance, performance trials on Iroquois, Kiowa and Chinook helicopters to determine power available charts at high density altitude in Papua New Guinea or while carrying external loads peculiar to Australian Army equipment.

To support research, development, test and evaluation of other agencies ARDU has provided the aircraft and flight test expertise for such diverse tasks as aircraft fatigue trials on several aircraft types for Aeronuatical Research Laboratories, high altitude atmospheric sampling for the CSIRO, air delivery of large life rafts and marine supply containers for RAAF and DOT (ATG) SAR purposes and many more.

Thus this comparatively small establishment, using both well established and advanced techniques, fulfils the func­tions normally provided by several much larger units in other countries.

The staff of ARDU is engaged on both mundane and ex­citing work to increase the operational effectiveness of the RAAF and to provide a flight test service for Australia.

Article courtesy of “TRIAD”, Dept of Defence.