South Africa desperately needs a new long range strategic airlift aircraft. In 2010 the South African Air Force (SAAF) was supposed to have begun replacing its aged C130s with Airbus A400Ms – but that was cancelled by government.
The Americans were keen to sell South Africa their Boeing C-17 heavy lifter, but that is massively sophisticated and expensive, and it is unlikely that the level of regional cooperation, or indeed budget, could be assembled to share such a large investment – as was the case with the Strategic Airlift Capability based out of Hungary.
The hot contender was the Airbus A400M and indeed South Africa had ordered eight and successfully participated in successful industrial offset programmes. But as South Africa became poorer and the A400M more expensive, with delays upon delays, South Africa took the opportunity to withdraw from the A400M programme – supported by grossly inflated acquisition costs having been fed to the then parliamentary defence committee.
So it was up to the SAAF to keep soldiering on with 60 year old Hercs. The most recent efforts have required R1 billion in financial year 2023/24 to upgrade and maintain the six remaining C-130s at Marshall Aerospace in the UK.
Lockheed Martin has naturally tried to convince SA to buy the new and enlarged J version – and the Russians stood on the sidelines with their old IL-76 and An-124, perhaps hoping for a deal on the still in development Antonov An-77.
Meanwhile – while the Hercs fly on – and on, the Brazilians brought their KC-390 to market. And it may just be everything that the SAAF needs.
Enter the KC-390
Embraer saw a gap in the middle of the market – for an airlifter smaller and a lot cheaper than the American and Russian heavyweights, as well as the over-engineered Swiss army knife that is the multi-role A400m, yet larger than the venerable Hercules and the twin turboprop Alenia C-27J Spartan and the even smaller Airbus C-295.
The Brazilians’ objective was to create a fast and flexible multi-mission, midsize tanker and transport aircraft using advanced but proven technology, which included fly-by wire, which Embraer had invested a lot of school fees getting right for their Legacy 450/500 business jets and then E2 regional jets.
ON THE APRON
A team from AW&ST flew the KC-390 at the factory in Brazil. They report that on the ground what strikes you first is the large anhedral wing with the two high bypass turbofan engines beneath it. This was Embraer’s first big design decision – whether to go with turboprops as the A400m and C130 have, or modern turbofan jets. Their choice of jets gives the KC-390 significantly better performance in terms of speed and altitude over the turboprops – which is preferable for long range missions, but questionable when it comes to short and austere rough-field operations.
Their engine choice was the ubiquitous International Aero Engines V2500-E5 turbofans, rated at 31,330 pounds thrust each, which propel the KC-390 to cruise at Mach 0.8 at up to FL360. These have been adapted for military use but are fundamentally the same engines that power airliners such as the Airbus A320ceo.
The faster cruise speed has real operational benefits. Embraer says that for search and rescue missions with a typical 1,250 nautical mile radius, a KC-390 could cover the ground two hours faster than even the fastest turboprop. But the jet engines are not without their downsides. The KC-390 consumes more fuel than the C-130J and while the KC-390 is also designed to operate from short, unimproved airstrips, Embraer hasn’t specified the aircraft’s actual runway requirements.
To cope with soft and rough airstrips, the nose gear has two wide low-pressure tyres and the main gear has four similar tyres on bogies on either side. Embraer claims the KC-390 can takeoff and land five times without any required maintenance – and tyre changes can be done anywhere.
The aircraft was designed around the interior dimensions of its cargo bay. To provide an unconstrained space, the wheels and ancillary equipment such as the APU had to be accommodated in large sponsons on either side of the fuselage. From the front, the size of these sponsons is striking.
Embraer first determined the required size of the interior, then built the aircraft around it. The hold has a width of 3.45 m (11.3 ft.) over its entire length and a minimum height of 2.95 m over a length of 18.5 m, including the ramp that stores two of seven standard 463L pallets. Its floor is 1.24 m above ground to allow easy roll-on/roll-off loading via the ramp. Behind the main gear are two hydraulic struts to stabilise the aircraft on soft ground or high winds.
The KC-390 can carry a maximum 26,000 kg, allowing it to transport two tracked armoured personnel carriers or a Sikorsky H-60 helicopter. One of the design goals was maximum flexibility, and the KC-390 can be reconfigured between roles in 30 minutes.
For disaster relief or medical evacuation, 74 stretchers can be installed with room for staff and life-support equipment. The KC-390 can carry up to 80 soldiers or 66 paratroopers with full gear. Two jump-doors with wind deflectors are located behind the wings. A novel feature is that the doors can be exchanged in flight, for example when reaching the target area on a SAR mission, to switch to doors with large bubble windows for better downwards visibility.
The Flight Deck
The first impression of the cockpit is one of light and spaciousness. Large windows with low sills provide a great view out. All six windows are protected against ammunition up to 7.62 mm. For further protection in hostile environments, removable Kevlar mats can be added to the lower cockpit area.
The flight deck has an optional third crewmember station behind the pilot seats, equipped with a display and tailored functions for missions such as aerial refuelling and S&R. In the rear of the cockpit are two bunks.
Four Rockwell Collins Pro Line Fusion 15.1-in. displays face the pilots. A fifth is located on the centre pedestal. Aft of it are keyboard, scratchpad and cursor control devices. Avionics are commercial but with numerous additional functions for military tasks. The cockpit operates on the ‘dark cockpit’ principle of commercial airliners: Lights illuminate only if the system condition is ‘in transit’ or ‘non-normal’.
In front of the pilots the large head-up display (HUD) is supported by an Enhanced Vision System (EVS) using four cameras installed in the nose. These provide daylight and thermal imagery generated by a synthetic vision system.
Ground handling has to be agile for tight airports. The aircraft can be steered with the tiller from either front seat. This steers the nose wheel up to 67 degrees left or right, so the aircraft can turn through 180 degrees within a radius of only 23 metres.
The feature of the cockpit is the interconnected and active sidesticks. Active means that, unlike Airbus and similar fly-by-wire (FBW) systems, the Embraer stick provides force feedback to the pilots. The force feedback is claimed to provide significantly improved pilot situational awareness. The sticks operate the digital flight control system for precise hand-flying control. This is not only a first for Embraer, but for this aircraft category.
On each control stick is an autopilot disconnect/priority button and next to it is the usual conical trim hat that enables pilots to keep hands on throttle and stick (HOTAS) while adjusting trim for pitch and roll. It is also used for small adjustments, as many pilots prefer using the hat to moving the stick.
On the upper left side of the control stick, a touch-control button is mainly used for speed stability on approach after the final configuration and attitude have been attained. In addition to the usual push-to-talk button, there is a trigger on the stick that is used for cargo drop missions. It activates the flight-control law for these missions and signals the loadmaster that the pilots are ready to drop the cargo. This is done by releasing the locks of the container-delivery system. Then either gravity, or for larger loads, a drogue chute, pulls out loads of up to 42,000 lb.
The FBW has two flight-control laws: Normal and, as a fallback option, Direct. In Normal Law the sidestick commands pitch rate until the landing gear is selected up, after which gamma-dot and pitch-rate command is applied. Gamma-dot is the rate of change of the flightpath angle. In backup mode, it is a direct stick-to-surface command.
Embraer has defined a complex flight envelope to meet the various requirements using FBW, changing laws for specific missions and allowing varying G-loads, depending on the task and factors such as aircraft weight. Military certification will allow flight load factors up to 3G. To use the basic changes in capability, there is a master mode switch on the overhead panel with the positions Main, Max Effort, Tactical Nav, Airdrop, SAR (search and rescue) and AFF (aerial firefighting).
Flying the KC-390
For the assessment flight the temperature was 23C with a QNH of 1014. Calculated speeds for takeoff were V1: 117, VR: 121 and V2: 124 KIAS, with a final-segment speed for flap retraction of 180 KIAS.
Acceleration was brisk. Rotation was to 8 degrees, with the target for initial climb of 11 degrees. An electronic tail strike avoidance system increases stick force on reaching 13 degrees pitch, before an actual tail strike of 15 degrees. Moving the relatively large sidestick a few degrees revealed the aircraft’s agility and the reviewers used every chance during the flight to use the maximum roll rate of up to 20 degrees/second. This increases to 30 deg./sec above Mach 0.7, as the higher dynamic pressure translates into a higher rate, and the aircraft is not limited by loads during manoeuvres.
Going down without having the braking effect of the large propellers of a turboprop could have been a challenge. So the KC-390 has huge spoilers for a fast and steep tactical descent. When the Master Mode switch is moved to Max Effort position and the aircraft is slowed to 230 KIAS to extend slats only, it will descend with idle thrust and flight spoilers out to 40 degrees nose down at 11,000 fpm while accelerating to the maximum operating speed of 300 KIAS. At maximum speed it will still descend at about 9,000 fpm.
To test the upper end of the speed envelope they flew a shallow descent and watched the FBW protection system smoothly pull up the nose to bring the aircraft back to its maximum speed as they accelerated through 304 KIAS. This protection does not use the auto-thrust or speed brakes but tries to keep pilots in the loop by handing back the aircraft once it is within the envelope.
To demonstrate maximum-G protection, they slowed to 200 KIAS, extended the Flaps to 2 and started a 45-50-degree banked turn while quickly pulling the stick fully aft. Because G-load is permanently displayed in the left upper corner of the PFD, they could watch how the FBW’s programmed envelope protection constantly kept the aircraft at not more than 2G. The G indication increases situational awareness and lets pilots know when they could overload the aircraft in Direct Law without the protections.
Stable slow speed flying is a key requirement for this type of aircraft. In the before-flight briefing to the AWS&T team on the techniques for an airdrop, the variable-flap system required detailed instruction. This enables the use of slats only, flaps only, or every combination of flap extension, from 1-40 degrees. This is done by moving the flap lever to 1, for example, which drives the flaps to 10 degrees, then selecting a number between 1-9 on the scale next to the handle and hitting the execute button. Using 3 on the flap-unit scale, the flaps are driven to 13 degrees. By calculating the cargo loads that should be dropped, with the desired aircraft speed of 130-140 KIAS and the weight of the aircraft, a flap position is derived to achieve an aircraft pitch angle of 5-7 degrees. Beyond the 40-degree position is a notch designated Full. This drives the flaps to the maximum 40 degrees but also sends the flight control computers a signal that a landing is now the objective.
An unusual feature is that the AirDrop mode enables the horizontal stabiliser to be deliberately mistrimmed, so that when the cargo leaves the ramp and the aircraft experiences a swift trim change as the centre of gravity moves forward, it is in trim and allows full elevator authority.
For an engine failure after takeoff (EFATO) demonstration, thrust was reduced on the right engine to idle just after liftoff, and no rudder input was applied. The Beta (sideslip) target turned blue in the upper part of the primary flight display (PFD), showing an asymmetry had been detected, and the FBW envelope protection system added rudder.
The other unusual and demanding flight control regime is in-flight refuelling, in this case both as a receiver and as a dispenser. The KC-390 can refuel in flight through the probe above the left cockpit window. The control laws can be changed for aerial refuelling. In Normal Law it is difficult to get the aircraft into a stable position behind the tanker to approach the drogue, but the Refuelling Law changes the damping on the sidestick to make small, precise changes easier.
As an air to air refuelling tanker, the KC-390 can refuel helicopters at speeds as low as 120 KIAS and jets up to 300 KIAS from 2,000-32,000 ft using two wing-mounted Cobham hose-and-drogue pods. These deliver up to 400 gallons per minute. The KC-390 can offload a maximum of 12,000 kg from three tanks that can be loaded on pallets into the cargo hold to feed their fuel via the aircraft’s centre tank. The centre tank can carry 10,000 kg of the aircraft’s 23,000 kg internal fuel capacity. Using more palleted tanks extends that range.
Final approach is flown with the full 40 degrees of flap. For a mid-weight approach, the speed was calculated as 134 KIAS with a Vref of 127 KIAS. For the round-out and hold-off thrust is reduced to idle and the ground effect below the large anhedral wing helps with a smooth touchdown.
The KC-390 uses a Derotation Law on touchdown to quickly lower the nose to the ground for shorter landing distances. It is advisable not to provide any backpressure on the side stick, as that would work against the control law, and the FBW would increase downward pressure in response.
Thrust reversers can be armed for landing, to open automatically as the aircraft enters Ground Mode and the engines reach idle RPM. The aircraft has powerful braking for operation on short and unpaved runways, with its spoilers extending to 50 degrees, huge brakes on all eight main wheels and reverse thrust.
Conclusion
Is it better than a C130J? In one word Yes. As a fly-by-wire digital aircraft which can carry up to 57,000 pounds of cargo at a maximum speed of 470 KTAS (540 mph), the KC-390 beats out the C-130J’s max carrying weight (42,000 pounds) and max speed when at full capacity (340 KTAS). Depending on the configuration, that means the KC-390 can carry: 80 troops, or 66 paratroopers, or three HUMVEEs, or a Sikorsky S-70 Black Hawk helicopter almost 2000 nm – or 3300 nm for ferry or long range maritime reconnaissance.
And, like any proper military airlifter, the KC-390 has self-protection systems including ballistic protection against small arms fire, critical systems redundancy, radar, laser, and missile approach warning receivers and infrared countermeasures.
Given that the average age of the 2,700 airlifters that the KC-390 could replace is 30 years, Jackson Schneider, President and CEO of Embraer Defence and Security said, “We are convinced the KC-390 will be successful. It’s faster, carries a heavier load, and has state-of-the-art mission capability and avionics, and lower maintenance and operating costs.”
Perhaps as a fellow BRICS member, the Brazilians can give the SAAF a big discount and easy payment terms?