Akaflieg Stuttgart postwar aircraft (Stuttgart Academic Flying Group)

[Stargazer]

The Akaflieg Stuttgart fs28 Avispa (Spanish for "Wasp") is a single engine, light sports and utility twin-boom pusher aircraft which was designed at the University of Stuttgart in West Germany, started in 1969 and first flown on December 20, 1972. It was designed to investigate the transfer of knowledge about high-performance aerodynamics and composite materials gained from glider design to light powered aircraft. Two interesting features were its large rounded canopy and its inverted V-tail. Materials used were glass-reinforced plastic, rigid foam, and aluminum, the power plant was an 115 hp four-cylinder horizontally-opposed, air-cooled Lycoming O-235-E2A.

The fs28 was seriously damaged in an accident in May 1981 and its permit to fly (PTF) lapsed that November. With no rebuild under way, the registration [D-EAFS] was reallocated to another type in 1990. However, V-1 was rebuilt, regaining its PTF in July 1997, when it was registered as [D-EKFS], remaining active well into the 2010s.​

More info and specs:

• https://akaflieg-stuttgart.de/en/projects/fs28-avispa/
• https://en.wikipedia.org/wiki/Akaflieg_Stuttgart_fs28

 

[Stargazer]

The Akaflieg Stuttgart fs26 Moseppl (meaning unknown) was first flown on Sept. 25, 1970. It represented the group's first foray into the field of motor gliders. It was decided however to keep the construction of the aircraft as conventional as possible. For instance, the forward fuselage was taken over from the Phoebus sailplane. The already tight space inside the aircraft was made even tighter as the addition of an engine necessitated the addition of seven levers and three display instruments. Nevertheless, it was possible to make even the nose wheel retractable. Due to the lack of space inside the fuselage, exacerbated by the addition of a propeller and the length of the main undercarriage, the decision was made to make the undercarriage operate hydraulically. The Hirth F 10A engine was chosen to power the plane. When gliding, standard procedure is to feather the propellers and close all air inlets. In addition to being an experimental motor glider, the fs26 was also used to test the feasibility of cooling pusher engines using regular methods.

While designing the connections for the three-piece wings, a point of consideration was that the fs26 should still be easily road transportable and that unnecessary weight should be dispensed with. On the fs26, the forces on the wing spars are transferred via bolts from one flange to the other. This connection was extensively tested to check its feasibility. A weight reduction of 23% was achieved using this connection when compared to a tongue-fork connection.

The sole fs26 [D-KFFS] can be found at the International Luftfahrt Museum Manfred Pflumm, in Villingen-Schweninngen (Germany).​

More info and specs:

• https://akaflieg-stuttgart.de/en/projects/fs26-moseppl/
• https://www.j2mcl-planeurs.net/dbj2mcl/planeurs-machines/planeur-fiche_0int.php?code=156
• https://en.wikipedia.org/wiki/Akaflieg_Stuttgart_fs26

 

[Stargazer]

The Akaflieg Stuttgart fs35 Harpyie [D-KTOW] was conceived as a plane that could quickly and cheaply tow the group's sailplanes, therefore a plane with optimized for climb performance. All the factors that affected climb along with ways to keep costs for aerotows down were quickly examined, and this led to a two-seater touring motor glider with a side-by-side seating arrangement and a MTOW of 850 kg — weight being an important factor as it had a major effect on climb.

The seating arrangement was no accident, such a configuration made introducing and training new pilots on the fs35 easier. This was further simplified by the ergonomic layout of the cockpit, allowing for straightforward operation of the plane. The wings of the aircraft were optimized for climb performance, as per the goal of the project. On the flipside, the fs35 is equipped with a relatively large fuel tank. While this may seem counterproductive, having a large fuel reserve allows for multiple takeoffs before needing to refuel.​

On the 13th of August 2019, the fs35 finally took to the skies and met all the expectations, being easy to fly and climbing like a rocket. The fs35 will soon be operated in Akaflieg Stuttgart's regular flight operations.

More info and specs:

• https://akaflieg-stuttgart.de/en/projects/fs35-harpyie/
• https://akaflieg-stuttgart.de/en/2019/08/24/first-flight-fs35-harpyie/
• https://blog.topmeteo.eu/en/stuttgart-akaflieg-is-performing-test-flights-for-their-tow-plane-fs35/

 

[Apophenia]

The Akaflieg Stuttgart fs26 Moseppl (meaning unknown) ...​

Seppl is a German diminutive for Josef. So, I'm going to guess Moseppl = 'Motor-Joe'

Problematically, in slang, 'Seppl' can also refer to being slow-witted rustic. Not a promising name for an aircraft!

And the cartoon character Seppl wore a sepplhut - that pointy Tyrolean hat. Hey, maybe those enormous tailplanes reminded someone of a sepplhut?

 

[Stargazer]

Seppl is a German diminutive for Josef. So, I'm going to guess Moseppl = 'Motor-Joe'

Problematically, in slang, 'Seppl' can also refer to being slow-witted rustic. Not a promising name for an aircraft!

And the cartoon character Seppl wore a sepplhut - that pointy Tyrolean hat. Hey, maybe those enormous tailplanes reminded someone of a sepplhut?

OR... it's a contraction of MOSes and SEPPL: the airplane that will take you out of bondage of gliding and into the promise land of motored flight!

 

[riggerrob]

View attachment 759603The Akaflieg Stuttgart fs28 Avispa (Spanish for "Wasp") is a single engine, light sports and utility twin-boom pusher aircraft which was designed at the University of Stuttgart in West Germany, started in 1969 and first flown on December 20, 1972. It was designed to investigate the transfer of knowledge about high-performance aerodynamics and composite materials gained from glider design to light powered aircraft. Two interesting features were its large rounded canopy and its inverted V-tail. Materials used were glass-reinforced plastic, rigid foam, and aluminum, the power plant was an 115 hp four-cylinder horizontally-opposed, air-cooled Lycoming O-235-E2A.

The fs28 was seriously damaged in an accident in May 1981 and its permit to fly (PTF) lapsed that November. With no rebuild under way, the registration [D-EAFS] was reallocated to another type in 1990. However, V-1 was rebuilt, regaining its PTF in July 1997, when it was registered as [D-EKFS], remaining active well into the 2010s.​

More info and specs:

• https://akaflieg-stuttgart.de/en/projects/fs28-avispa/
• https://en.wikipedia.org/wiki/Akaflieg_Stuttgart_fs28

View attachment 759597

Cute airplane.
I have long wondered why we don't see more inverted V-tails as they have some advantages with regards to adverse yaw and up trim during steep turns.
I also wonder if the width between tail booms limits tail volume?????????

 

[fabulousfour]

When sailplanes are also qualified for this thread there is the Akaflieg Stuttgart fs.24 Phoenix, the first sailplane to be built from fibreglass.

https://en.wikipedia.org/wiki/Akaflieg_Stuttgart_fs24
First flight was nearly 70 years ago in November 1957!

 

[Stargazer]

When sailplanes are also qualified for this thread there is the Akaflieg Stuttgart FS-24 Phoenix, the first sailplane to be built from fibreglass.
First flight was nearly 70 years ago in November 1957!

Of course, I started with the three powered aircraft from Akaflieg Stuttgart, but I was also planning to cover the postwar gliders eventually.

 

[Nicknick]

OR... it's a contraction of MOSes and SEPPL: the airplane that will take you out of bondage of gliding and into the promise land of motored flight!

Seppl is often used as term for people from the Alps (at least in the upper 60 % of Germany,....) because Sepp is there a very common name. The same "Josef" istformed to "Jupp" in the very west and was traditionally also very common, so "Jupp" und "Seppl" has the same meaning...

 

[Maveric]

To be correct: it is not called FS.24, but fs.24. The Akaflieg Stuttgart names its developments in lowercase letters.

 

[fabulousfour]

Thanks, I have corrected it.

 

[belchengeist]

View attachment 759607The Akaflieg Stuttgart fs26 Moseppl (meaning unknown) was first flown on Sept. 25, 1970. It represented the group's first foray into the field of motor gliders. It was decided however to keep the construction of the aircraft as conventional as possible. For instance, the forward fuselage was taken over from the Phoebus sailplane. The already tight space inside the aircraft was made even tighter as the addition of an engine necessitated the addition of seven levers and three display instruments. Nevertheless, it was possible to make even the nose wheel retractable. Due to the lack of space inside the fuselage, exacerbated by the addition of a propeller and the length of the main undercarriage, the decision was made to make the undercarriage operate hydraulically. The Hirth F 10A engine was chosen to power the plane. When gliding, standard procedure is to feather the propellers and close all air inlets. In addition to being an experimental motor glider, the fs26 was also used to test the feasibility of cooling pusher engines using regular methods.

While designing the connections for the three-piece wings, a point of consideration was that the fs26 should still be easily road transportable and that unnecessary weight should be dispensed with. On the fs26, the forces on the wing spars are transferred via bolts from one flange to the other. This connection was extensively tested to check its feasibility. A weight reduction of 23% was achieved using this connection when compared to a tongue-fork connection.

The sole fs26 [D-KFFS] can be found at the International Luftfahrt Museum Manfred Pflumm, in Villingen-Schweninngen (Germany).​

More info and specs:

• https://akaflieg-stuttgart.de/en/projects/fs26-moseppl/
• https://www.j2mcl-planeurs.net/dbj2mcl/planeurs-machines/planeur-fiche_0int.php?code=156
• https://en.wikipedia.org/wiki/Akaflieg_Stuttgart_fs26

View attachment 759610

„Moseppl“: Meaning: MOtorSEglerEPPLer.
Motorsegler: motorized glider. Eppler: The applied airfoil E515 was developed by Prof.Dr. Richard Eppler, who was also a former member of the Akaflieg Stuttgart.