The KLM-backed Flying-V test model has done a fairly positive first flight but will need further modifications to improve its handling characteristics. That has become apparent from the first test flight done with the model aircraft, the test team of Delft Technical University in The Netherlands announced on September 1 in a webinar session.
As reported on Airinsight, the model Flying-V was to fly in July. The actual flight took place on July 17 at Fassberg airforce base in Germany.
Flying V is a new aircraft architecture based on a V-shaped, almost blended wing concept. The cabin is fully integrated into both sides of the V, with the two engines sitting on top in between the wings. The full-scale version would have a span of 65 meters and use two Rolls-Royce XWB-engines similar to those on the Airbus A350. It would be twenty percent more fuel-efficient than the A350.
The concept has been designed by TU Delft with assistance from Airbus and sponsored by KLM. It caught lots of media attention when unveiled at last year’s IATA annual meeting in Seoul and again at KLM’s 100-year party in Amsterdam on October 7.
As project leader Dr. Roelof Vos explained, the flight test was to demonstrate that the Flying V could actually fly and land and that from the test its flight dynamics could be measured for use in the remaining part of the program.
The radio-controlled flight successfully took off at a very steep angle of attack, before stabilizing and steadily gaining altitude. “The positive thing was that the model was very controllable on the ground, did a good rotation, had a strong climb-rate, never stalled and was very responsive to inputs from the pilot on controls and engines”, Vos summarized what went well.
However, as is not unusual on a test flight, there were also some issues, Vos said: “We learned quickly that the center of gravity was too far rearwards. The pilot had to work hard. The aircraft also experienced some wobbling, known as Dutch roll. This is not uncommon on highly swept wings with a high sweep-angle. This gives a strong response to side winds and it is sensitive to the side-slip angle. It damped out but not very quickly. It is a well-known problem that can be used with a yaw damper, which is used on most aircraft.”
The Flying-V was also difficult to land and when it came in after its batteries had been depleted after five minutes, it landed on its nosegear. “It broke off and the model continued to slide on the runway before coming to a standstill. It has suffered some damage but not too much”, said Roelof Vos.
The gear will need repairs, but TU Delft will make some further modifications to move the center of gravity forwards. This will include repositioning the main gear.
Not all data has been analyzed yet, but as more become available it will be used for uploading in the flight simulator. “Then we can say something more about the handling qualities”, said Vos. Flying the model and the simulator are equally important, Vos stretched.
Suitable for hydrogen
Daniel Reckzeh, senior program manager Research and Technology at Airbus Hamburg, was very happy with what he has seen until now. “The perspectives look very encouraging, it is an interesting path beyond conventional tube-concepts and may open up different paths to go.”
He thinks the V-shape is ideally suited for integrating hydrogen, which could make a Flying-V aircraft a pathfinder for both new shapes and fuels. “It is easier to integrate tanks in the fuselage compared to a conventional tube-shaped aircraft. That makes it very interesting.”
TU Delft’s decan Henri Werij thinks the Flying-V might accelerate the development of new, more fuel-efficient airliners that use multiple sources of fuel. He hopes that the Dutch government will continue to support the program.
KLM CEO Pieter Elbers certainly will continue his support by offering both an unspecified amount of money as well as knowledge as to how the cabin of a V-shaped airliner might look like. “The Flying-V puts our money where our mouth is on sustainability. It is our objective to make aviation more sustainable, to make the next leap forward. We will not build aircraft ourselves, but every contribution from our side is welcome.”
Roelof Vos isn’t sure when the Flying-V will be airborne again. “No date has been set, but this will probably be in 2021.” If the project will result in an actual airliner concept remains to be seen. For this, Airbus must want to have access to data of more test flights, which could make the program a seven-year-long one. And there is more, said Vos. “We will look at all aspects to reduce the risks that we can’t comply with any safety requirements.”