The first in-flight refueling mission of the future Brazilian Air Force (FAB) freighter, the KC-390, was successfully completed. From February 1 to Feb 22, FAB’s military personnel and Embraer professionals worked together on yet another flight test campaign, this time to test the Wing Air Refueling Pod (WARP). The device is located under the wings of the freighter, and operates refueling hose, which is 30 meters long. Air force F-5M fighters were used as receivers.
This time, although the contact was dry -- that is, no fuel was transferred -- all other procedures involved in the In-Flight Refueling were carried out. Raphael Leme, leader of the KC-390 in-flight test engineering, says this is an important test, as the aircraft is the first tanker ever produced by Embraer. "We are working with the novelty factor," he says. He further explains that the main thing to be tested is the ability of the WARP software to strain the hose: it cannot form waves, nor can it be called 'dead hose,' when there is no lift.
Another challenge faced in this test is that, when there are two aircraft in contact, it is necessary to find common parameters for the correct flight profile. In the tests, flights are carried out throughout the so-called 'envelope' of the aircraft, i.e. within the most critical conditions of the airplane in terms of minimum and maximum speed and altitude.
"Since the F-5M and KC-390 have different envelopes, it is necessary to find a third envelope, at the intersection of the between the two aircraft, to carry out refueling," explains Lieutenant-Colonel Fernando Benitez Leal, technical manager of the air force’s KC-X program.
Major Kildary Sena, a test pilot who flew an F-5M during one of the refueling tests, explains some specificities of the new aircraft, such as the ability to refuel, to be refueled and also to refuel helicopters. "Other aspects that make a difference are the fly-by-wire system and the turbofan engine - like those used in commercial aviation," he says. They make the plane more stable and the air comes out less turbulent for the aircraft behind, albeit at a higher speed.
The KC-390 test campaign's end schedule will run until the end of 2018. Currently, there are two prototypes performing in-flight testing in parallel, and a third is in the finalization phase.
In all, there will be more than 2,000 flight hours for the development and certification tests.