fs35 "Harpyie"

Students present homebuilt aircraft

Akaflieg Stuttgart has developed a motor glider. Thanks to a special construction measure, students will be able to save a lot of money when flying in the future. The new plane is interesting for clubs, too.
[Photo: Akaflieg Stuttgart]

“This sight is leaving me speechless,” says Charifan Osso, smiling and pointing to her fellow students. They are attaching the wings to the motor glider fs35 'Harpyie'. The new aircraft of the Akaflieg student group from the University of Stuttgart is finished. For about 15 years, students have been investing into its development. On Thursday, 21 March, they presented their 'Harpyie' on the Vaihingen campus.

 (c) Künzler

Significant weight reduction

What's special about the aircraft: It has a relatively powerful engine and can tow other gliders, yet it is legally classified as a glider, because the students have reduced its weight to that of a glider by an extremely lightweight construction. “Specifically, this means that in future we won't need a motor aircraft to tow us during takeoff, but can use our aircraft tug 'Harpyie',” explains the second chairman of the Akaflieg. Another advantage is the cost saving that this class of aircraft offers to student pilots. “A pilot's license for a conventional motor aircraft costs about EUR 10,000. The pilot's license for a glider, on the other hand, can be obtained almost for free within the Akaflieg. In order to fly with a motor glider like 'Harpyie', you'll need a training course, which costs about EUR 1500, in addition to the pilot's license. This could be an interesting solution for many gliding clubs, too,” says the aerospace engineering student.

Meanwhile, more members and interested visitors are gathering in front of the now fully assembled two-seater. They are walking around the plane, talking and visibly happy. “A few years ago, the idea that I would see this moment still as a student would not have occurred to me,” the 23-year-old admits. Akaflieg member Janning Quint, however, was always convinced: “The fs35 will be finished, we can do it”, and he was right.

 (c) Künzler

More than 60 students involved

The idea for the construction was born in 2003. “The Akaflieg needed a tow-plane that would tow students in their gliders safely and at a reasonable price into the air,” relates 27-year-old Quint. “We found that the perfect tow-plane didn't exist. So we wanted to build it ourselves.” In total, more than 60 students helped with the construction, doing everything themselves: from the calculations for the construction to the production of parts. “That's why it took so long,” explains Osso. The process has not been without setbacks. During the load test, a wing broke sooner than it should have. “Which resulted in a temporary drop in motivation,” says Quint. Then everybody lent a hand, the calculations were revised and in the end the wing withstood the required breaking load.

Harpyie starts its first flight

In their work, students receive a lot of support from institutes of the University of Stuttgart and from industry sponsors. Numerous student theses have been completed during the project. The cooperation and perseverance have been worth it. In the next few weeks, “Harpyie” is scheduled for its inaugural flight. The Akaflieg named the plane after a bird species (“Harpyie”) that can carry particularly heavy prey such as a goat. “Likewise, our motor glider can tow relatively heavy aircraft, so we thought the name would fit,” says Quint.

New aircraft with fly-by-wire control

The Akaflieg is already working on a new aircraft, the fs36 FlybyWire. It is supposed to be the world's first glider with a fly-by-wire control. In contrast to conventional mechanical control, this is an electronic, computer-assisted aircraft control, as is common with airliners. The new technology aims to make gliding safer and more efficient.

fs35 “Harpyie“

Wingspan 17.8 m
Length 7.6 qm
Maximum takeoff weight 850 kg
Motorization 155 PS Continental Diesel
Maximum speed: 280 km/h

Akaflieg Stuttgart

The group Akaflieg Stuttgart has been around for more than 90 years. There, the students develop, build and fly powered aircraft and gliders. In addition to studying, they can put their theoretical knowledge into practice and at the same time pursue the hobby of flying. The group is open to all students interested in flying and who would like to volunteer their time to work on the aircraft in addition to their studies. “Most of us study engineering, but we welcome all study programs,” says Osso.
Anyone interested in the Akaflieg can contact us by email.