In April 2004 the Australian Defence Forces selected EADS's Airbus A330-200 Multi-Role Tanker Transport as a replacement for its ageing Boeing 707-based aerial tanker aircraft.
Aside from supportability issues, the 707s had only a probe and drogue refuelling capability. Whenever its General Dynamics F-111s needed to air refuel, the Royal Australian Air Force had to rent a tanker with a boom. Several additions to the RAAF fleet, such as the Boeing 737-based Wedgetail, Boeing C-17 and future Lockheed Martin F-35 need a boom-equipped tanker to fully exploit their capabilities.
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Test and development flights are being conducted to certificate the aircraft. One highlight was in June, when two A330 MRTTs built for the RAAF performed buddy refuelling. Airbus expects to deliver its first A330 MRTT to the RAAF by the end of this year.
The civil A330-200 widebody twinjet undergoes numerous modification to make it fit for military service. The KC-30A is powered by two General Electric CF6-80E1s, with most of the modifications related directly to the air refuelling role. An air refuelling receptacle is installed on top of the fuselage aft of the cockpit.
For the RAAF, two underwing Cobham 905E air refuelling pods are installed in the wings, while other operators have chosen to add a third centreline fuselage hose and drogue refuelling unit. An EADS-developed aerial refuelling boom system is installed in the tail section of ghe RAAF aircraft.
To control the air refuelling operation, a two-place remote air refuelling operator (RARO) console is installed on the flightdeck. As the air refuelling operator does not have a direct view of the boom or refuelling aircraft, EADS also installs a boom enhanced vision system (BEVS).
Finally, military-specific avionics as well as a directed infrared countermeasures system are also installed. The A330 MRTT can carry a mix of cargo and passengers while having the ability to offload 45t of fuel. Airbus advertises a passenger capability of up to 300, but in the RAAF KC-30A configuration 270 passengers can be accommodated.
CAE, under contract to EADS for the simulators, and the government of Australia for the after-training services, is developing a turnkey training system for the KC-30A. The system has three major components: a full-flight and mission simulator (FFMS), air refuelling operator part-task trainer (PTT) and a cockpit integrated procedures trainer (IPT).
When all three components are fully developed they will be shipped to RAAF base Amberley in Australia for installation. CAE will also provide training services to the RAAF for five years. Before final certification, Flight International was able to sample first hand each of the training system's three components in CAE's Montreal production facility.
The centrepiece of the system is the FFMS with Medallion-6000 image generator system. The Medallion system used for the KC-30A simulator is similar to CAE's civil market 7000 series products. The simulator is a Level D equivalent, certificated to the equivalent of Australian Part 60 JAR Amendment 3. Like the A330 simulator I reported upon earlier this year, the KC-30A cockpit cab is articulated by CAE's True electric motion system.
The Moog-sourced motion system offers a full range of smooth lurch-free motion. No corrosive hydraulic fluid is used in the system and power consumption is about one quarter of that of a comparable hydraulic system.
One major difference between the civil and KC-30A simulator is the visual system. Both use liquid crystal on silicon projectors, but rather than having just three channels, the KC-30A has five. While civil operators make do with a nominal 180 x 40e_SDgr field of view, the KC-30A has a much larger 220 x 50e_SDgr field of view.
PROJECTORS
The projectors for the two extra channels are located on top of the simulator cab. These sidewards facing projectors add about 1m (3ft) to the overall height of the simulator cab, requiring a measurably larger bay for installation than the civil A330.
For my simulator flight I was accompanied by Scott Johnson, an instructor evaluator employed by Allied Defense Services International, an EADS subcontractor. A former US Air Force KC-10 instructor and evaluation pilot, Johnson brings extensive air refuelling experience to EADS's developmental team.
The FFMS's flightdeck simulates the two pilot positions only. The two aft-facing RARO positions, air refuelling operator and mission co-ordinator, are simulated in the fixed-base PTT. Although in separate rooms, the FFMS and PTT can be networked for full mission simulation.
The KC-30A's flightdeck is nearly identical to an A330's, with the exception of changes needed for the air refuelling system. On the overhead panel the fuel system control panel incorporates switches for six air refuelling specific pumps and several valves.
A rotary knob on the panel allows the pilots to set the fuel panel up for operation as either a tanker or receiver.
For operations as a receiver, a receptacle control switch is on the right-hand half of the fuel overhead panel. An air refuelling status light board, for receiver operations, is mounted on the windscreen's centre pillar.
Finally, a rotary bank angle control knob is added to the A330's flight guidance control panel. The variable bank angle feature allows the KC-30A tanker to tailor the refuelling pattern to specific receiver aircraft requirements.
For the demonstration flight the KC-30A was placed on Amberley's Runway 15. With flaps set to 2, a FLEX power take-off was accomplished, followed by a climb to 10,000ft. Once level at our planned refuelling altitude, I hand-flew the aircraft to gain a feel for the tanker.
Our first exercise was to receive fuel from a KC-10. Once the air refuelling door was opened, the KC-30A went into air refuelling law.
This up and away control scheme is nearly identical to a civil A330's, except that it gives faster responses to roll control inputs. Our initial condition was about 1nm (1.85km) in trail and slightly below the KC-10 at a calibrated airspeed of 285kt (525km/h).
The visual scene was set for daylight conditions and as we neared the KC-10, details came into focus. I was able to quite easily stabilise the KC-30A in the just aft of the pre-contact position, about 15m behind the tanker.
While I had much experience in the USAF air refuelling the F-111 and Lockheed Martin F-16, I had none in a large aircraft such as the KC-30A. Initially, I found it susceptible to pilot induced oscillation. Maintaining lateral line-up behind the tanker was best accomplished by using just two fingers on the base of the sidestick, flying the aircraft in an open loop manner.
High bypass fan engines are great for fuel economy, but their "laggy" response made fore aft station keeping the hardest part of the air refuelling exercise. With much coaching from Johnson, I was able to close into the contact position and take fuel from the KC-10. Visual references on the simulated KC-10 were easily discernible.
Familiar pilot director lights were clearly visible on the underside of the fuselage forward of the main gear well.
I found resolution and large field of view of the visual system adequate for the task at hand, which should allow for useful training to be accomplished in the simulator.
Johnson remarked that air refuelling the actual aircraft was easier than the simulator: that made me feel much better about my formation flying skills. As our simulator session drew to a close, the KC-10 tanker was replaced by a KC-135 and then a KC-30A.
The KC-30A can receive fuel from both of these aircraft and seeing them in the simulator should allow pilots to learn their differences and improve initial performance once airborne behind the real thing.
The KC-135 and KC-10, the most widely deployed boom-capable air refuelling tankers, place the boom operator "boomer" in the tail of the aircraft. The view afforded through direct view windows and mirrors, in the case of the KC-10, gives the boomer sufficient references to guide the boom into the receiver's receptacle.
While the field of view from the tail of the aircraft was acceptable for the boom air refuelling task, the limited field of view often made it difficult for the boomer to maintain situational awareness of the entire tanking package.
Advances in imaging have allowed EADS to place the boomer on the flightdeck, in an aft-facing RARO console. The console has two places. Behind the co-pilot is the air refuelling operator/boomer, while the mission co-ordinator is behind the pilot.
The essential ingredient for this system is the BEVS, which is comprised of seven cameras with normal and near IR capabilities. For the air-refuelling task a 23.1in (585mm) stereoscopic display is provided at both stations of the RARO console. Three 12.1in LCD displays are installed above the stereoscopic display of the air refuelling operator station. Called the panoramic display, it enhances the boomer's situational awareness. Two inspection cameras in the BEVS system can be slewed to view a large portion of the KC-30A itself as well as receiver aircraft at all three of the refuelling stations.
Two sticks are used to control the fly-by-wire boom, the left-hand one controlling boom extension and the right flight-control stick flying the boom's ruddervators. Pushing forward on the left telescopic control extends the boom, while pulling aft retracts it.
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Control stickstick operation is intuitive, left/right displacement moving the boom left/right relative to the boomer's aft-facing view. Fore/aft movement of the control stick lowers/raises the boom in elevation.
As with the stereoscopic display, each station has its own boom controllers, allowing for hands-on instruction. When special goggles are worn, the stereoscopic display provides a 3D view of the boom envelop and receiver aircraft. A back-up 2D display is available for boom operations.
John Reigelsberger, a former USAF KC-10 boomer and current instructor evaluator for Allied Defense Services International, sat in the air refuelling operator position for my familiarization with the RARO console. The four-way adjustable seat allowed me to find the design eye position, by reference to white and red alignment balls, in the mission co-ordinator's seat.
Reigelsberger selected the 3D display mode for the stereoscopic display, and when we put on the polarised goggles we were presented with a sharp 3D display. I flew the boom while awaiting the arrival of our first receiver aircraft.
Control stick displacement in each axis commanded a corresponding boom displacement from its neutral position. Releasing the stick allowed the boom to return to the neutral position. Boom position in all three axes was graphically shown on three tapes on the stereoscopic display. When the receiver aircraft type is entered into the multifunction control and display unit, these three tapes also display boom envelop limits. While the boom has a fly-by-wire control system, I found there was some motion coupling in the lateral and elevation axes.
When an RAAF C-17 appeared in the pre-contact position, Reigelsberger manually actuated the pilot director lights to guide it into the contact position. Once stabilised in position, he extended the boom and plugged the transport.
When contact was established, the boom's flight mode, as shown on the stereoscopic display, changed from "free flight" to "coupled." In "coupled", the boom's position is controlled by receiver aircraft motion. Numerous receiver aircraft types are available, and to further enhance the training experience, three levels of receiver aircraft smoothness are available.
For a short time the 2D mode was selected. While Reigelsberger could deftly control the boom, the positions represented on the 2D display appeared slightly offset to the 3D view. After commanding a breakaway with a switch on the left stick, the C-17 was removed from the simulation in preparation for our next task - two Boeing F/A-18 Hornets, about 1nm in trail of the tanker. Using pod control switches, the drogues were extended to their full 28.6m length. The Hornets were initially cleared into the pre-contact position, 15m behind the drogue.
When cleared to the contact position, both Hornets engaged the drogues and continued forward until the pod mounted "traffic lights" showed they were receiving fuel. After receiving their scheduled fuel offload, the Hornets backed out and disconnected from drogues.
The final exercise at the RARO console was a demonstration of the BEVS dusk and night time capability. Three receivers were placed in the contact position at each of the refuelling points: two drogue and boom (although this is not an authorised operational scenario). The ambient lighting was reduced to a dusk setting. With the 3D stereoscopic display set to normal, the receivers were visible, but details indiscernible.
Reigelsberger selected the stereoscopic display's IR setting and small details became visible. The display presentation was monochromatic, but seemed to provide a near daylight visual field. Ambient lighting was next set to represent a middle of the night moonless condition, and the IR presentation remained unchanged from the dusk condition.
Finally, the BEVS was returned to normal light range, the three receiver aircraft now disappearing into the pitch-black night. The ability to accomplish lights-out night-time air refuelling greatly enhances the KC-30A's combat effectiveness. Having a hardwired IR display at the RARO console means that depth-perception limiting night vision goggles are not required.
The final piece of the training solution is the Simfinity cockpit IPT. Large LCD displays are arranged like the flightdeck to provide a training environment for key KC-30A systems, a valuable learning tool. Basic operational procedures and systems familiarisation can be taught in the IPT, freeing the FFMS for flight-specific tasks. Maintainers will also benefit from it.
My brief exposure to CAE's A330 MRTT convinced me that it will prove to be an effective training tool. As the FFMS is a Level D device, I have no doubt that, it will be used to provide most if not all of the KC-30A pilot's non-mission specific "airborne" training.
For tasks such as acting as the tanker, it again may carry most of the training load. For receiver training, the FFMS may provide a strong procedural foundation, but the actual skill of refuelling this large aircraft will in all likelihood be learned once airborne in a KC-30A.
The RARO console part-task trainer gave me a wonderful insight into how technology has now enabled boom refuelling to be conducted from a remote location. I have never been a boomer, but my first impression is that procedures and techniques learned on the PTT will significantly reduce the amount of airborne training required for the RAAF's air refuelling operators.
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Source: Flight International
