Akaflieg Köln LS11
Encyclopedia
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The LS11 or AFK1 is a prototype Two-Seater Class sailplane currently in development at Akaflieg Köln e.V.
(Academic Flying Group of the University of Cologne
). The LS11 first flew on 5 November 2005.
initiated in 2000 the concept design for the AFK1. One of the design goals was to use as many standard LS components as possible in order to lower the development costs. This and the large contribution of Wolf Lemke
, who performed the aerodynamic and structural calculations, led to Rolladen-Schneider bestowing the type designation LS11 upon the Akafliegers' project.
The goal of the project is to design and build a thoroughly capable school glider with top performance for cross-country training, record flying and competition.
The LS11 gets its performance from an extended Rolladen-Schneider LS6 wing. The Akaflieg Darmstadt D41, a side-by-side two-seat glider which flew in 1993, demonstrated the feasibility of a high performance, multiplace glider based on the LS6 wing. The Akafliegers felt they could profit from and improve upon that design.
The wing structure was redesigned and resembles somewhat the Rolladen-Schneider LS9 structure. The wings, almost entirely made of Carbon fibre Reinforced Plastic, were manufactured at the Rolladen-Schneider factory in Egelsbach
in mid-2001, while the span extensions were built in the moulds developed by the Darmstadt group for the D41.
The LS11 prototype was featured as a work in progress at the 2003 and 2005 AERO Friedrichshafen exhibitions in Germany. The maiden flight was to be followed by a comprehensive flight test programme in 2006, to be carried out at Akaflieg Köln's home airfield, Dahlemer Binz in the Eifel
region in Germany.
The LS11 is slated for production by the Slovenian aircraft manufacturer AMS-Flight. If this comes to fruition, this will possibly be the first prototype developed by a German academic association that reaches serial production.
competition class.
Water ballast bags inside the wings enable loadings up to 50 kg/m². Two ballast tanks integrated into the rudder fin will keep the centre of gravity within its optimum range, compensating for ballast changes and heavier pilots.
The empty weight was a serious design concern for reasons beyond mere ease of ground handling. As the scope for increasing the wing area was limited, since it originated on a single-seat design, the Akafliegers strove to achieve an empty mass as low as possible, in order to keep the wing loading of the shorter 18 meter span within reasonable limits.
Some parts of the fuselage were adapted from existing production types, such as the tail boom of the LS4
and the empennage of the LS8
. Considerable redesign was required, however. The span of the horizontal stabiliser was increased; the vertical stabiliser was made both taller and longer, to provide the required steering power while keeping the top of the vertical fin at a height comfortable for the assembly of the horizontal empennage.
The cockpit, manufactured from carbon and aramid
reinforced plastic, was designed to accommodate pilots up to two meters tall. Available space is sumptuous for both pilots, exceeding that of all comparable production gliders. The front seat is similar to the LS4 cockpit, and both seats have enough leg and elbow room to preclude the mutual interference too often encountered in tandem sailplanes. The maximum cockpit load is 230 kg.
The large canopy is a single unit which integrates the instrument panels into the canopy frame. It is hinged at the back in the Piontkowski fashion and opens with an upward and rearward movement. The practicality of this concept for large glider canopies has already been tested by Akaflieg Köln through the modification of three Scheibe SF-34 gliders.
The hinge is a carbon reinforced element able to withstand wind speeds up to 75 km/h when open and was designed to sever the tubing and wiring looms from the instrument panels upon emergency release in flight.
The airplane stands on a sprung, retractable main undercarriage
with a six-inch hub, and a nose wheel which is likewise sprung and retracts simultaneously with the main wheel. A fixed tail wheel is also provided. This undercarriage scheme simplifies ground handling, since fuselage dollies
are not required. The main wheel is located near the glider's empty centre of gravity.
All controls connect automatically upon assembly in the habitual LS way. The control system is built mostly from standard LS parts. The wings are connected by two main pins inserted into the tongue-and-fork spar
ends, as in the LS6 and subsequent LS types.
A low landing speed is essential for a trainer. Wolf Lemke
and Siegfried Piontowski decided to depart from the typical LS system in which ailerons and flaps
act as flaperons. A mixed schedule as in e.g. the ASW 27 was implemented. In landing configuration the flaps assume a deflection of about 75 degrees while the ailerons remain in a neutral position. This enables slower landing speeds with good control response. Multiblade airbrakes
extend from the upper surfaces of the wings to give ample glidepath modulation.
The LS11 or AFK1 is a prototype Two-Seater Class sailplane currently in development at Akaflieg Köln e.V.
Akaflieg
Akaflieg is an abbreviation for Akademische Fliegergruppe, an academic group of pilots in pre and postwar Germany.-History:Otto Lilienthal published his book Der Vogelflug als Grundlage der Fliegekunst in 1889. This described the basics of modern aerodynamics and aircraft construction...
(Academic Flying Group of the University of Cologne
Akaflieg
Akaflieg is an abbreviation for Akademische Fliegergruppe, an academic group of pilots in pre and postwar Germany.-History:Otto Lilienthal published his book Der Vogelflug als Grundlage der Fliegekunst in 1889. This described the basics of modern aerodynamics and aircraft construction...
). The LS11 first flew on 5 November 2005.
Design and development
Akaflieg KölnAkaflieg
Akaflieg is an abbreviation for Akademische Fliegergruppe, an academic group of pilots in pre and postwar Germany.-History:Otto Lilienthal published his book Der Vogelflug als Grundlage der Fliegekunst in 1889. This described the basics of modern aerodynamics and aircraft construction...
initiated in 2000 the concept design for the AFK1. One of the design goals was to use as many standard LS components as possible in order to lower the development costs. This and the large contribution of Wolf Lemke
Wolf Lemke
Wolf Lemke is a designer of gliders who worked for Rolladen Schneider and after it was taken over in 2003, for DG Flugzeugbau GmbH.He was one of the student members of the Akaflieg Darmstadt who designed the revolutionary D-36 "Circe". This team also included Heiko Fries, Klaus Holighaus and...
, who performed the aerodynamic and structural calculations, led to Rolladen-Schneider bestowing the type designation LS11 upon the Akafliegers' project.
The goal of the project is to design and build a thoroughly capable school glider with top performance for cross-country training, record flying and competition.
The LS11 gets its performance from an extended Rolladen-Schneider LS6 wing. The Akaflieg Darmstadt D41, a side-by-side two-seat glider which flew in 1993, demonstrated the feasibility of a high performance, multiplace glider based on the LS6 wing. The Akafliegers felt they could profit from and improve upon that design.
The wing structure was redesigned and resembles somewhat the Rolladen-Schneider LS9 structure. The wings, almost entirely made of Carbon fibre Reinforced Plastic, were manufactured at the Rolladen-Schneider factory in Egelsbach
Egelsbach
Egelsbach is a community of 10,000 in the Offenbach district in the Regierungsbezirk of Darmstadt in Hesse, Germany.- Location :Egelsbach is one of 13 communities in the Offenbach district...
in mid-2001, while the span extensions were built in the moulds developed by the Darmstadt group for the D41.
The LS11 prototype was featured as a work in progress at the 2003 and 2005 AERO Friedrichshafen exhibitions in Germany. The maiden flight was to be followed by a comprehensive flight test programme in 2006, to be carried out at Akaflieg Köln's home airfield, Dahlemer Binz in the Eifel
Eifel
The Eifel is a low mountain range in western Germany and eastern Belgium. It occupies parts of southwestern North Rhine-Westphalia, northwestern Rhineland-Palatinate and the south of the German-speaking Community of Belgium....
region in Germany.
The LS11 is slated for production by the Slovenian aircraft manufacturer AMS-Flight. If this comes to fruition, this will possibly be the first prototype developed by a German academic association that reaches serial production.
General description
The LS11 is expected to have up to four interchangeable sets of wingtips for spans between 18 and 21 meters. The prototype currently has a 20 meter span in keeping with the new Two-SeaterGlider Competition Classes
Competition classes in gliding, as in other sports, mainly exist to ensure fairness in competition. However the classes have not been targeted at fostering technological development as in other sports...
competition class.
Water ballast bags inside the wings enable loadings up to 50 kg/m². Two ballast tanks integrated into the rudder fin will keep the centre of gravity within its optimum range, compensating for ballast changes and heavier pilots.
The empty weight was a serious design concern for reasons beyond mere ease of ground handling. As the scope for increasing the wing area was limited, since it originated on a single-seat design, the Akafliegers strove to achieve an empty mass as low as possible, in order to keep the wing loading of the shorter 18 meter span within reasonable limits.
Some parts of the fuselage were adapted from existing production types, such as the tail boom of the LS4
Rolladen-Schneider LS4
|-See also:-References:**Thomas F, Fundamentals of Sailplane Design, College Park Press, 1999*Simons M, Segelflugzeuge 1965-2000, Eqip, 2004*Brütting G, Die berühmtesten Segelflugzeuge, Motorbuch Verlag**German-language Wikipedia*...
and the empennage of the LS8
Rolladen-Schneider LS8
The Rolladen-Schneider LS8 is a Standard and 18 metre class single-seat glider developed by Rolladen-Schneider and in series production since 1995. Currently it is manufactured by DG Flugzeugbau.-Development:...
. Considerable redesign was required, however. The span of the horizontal stabiliser was increased; the vertical stabiliser was made both taller and longer, to provide the required steering power while keeping the top of the vertical fin at a height comfortable for the assembly of the horizontal empennage.
The cockpit, manufactured from carbon and aramid
Aramid
Aramid fibers are a class of heat-resistant and strong synthetic fibers. They are used in aerospace and military applications, for ballistic rated body armor fabric and ballistic composites, in bicycle tires, and as an asbestos substitute. The name is a portmanteau of "aromatic polyamide"...
reinforced plastic, was designed to accommodate pilots up to two meters tall. Available space is sumptuous for both pilots, exceeding that of all comparable production gliders. The front seat is similar to the LS4 cockpit, and both seats have enough leg and elbow room to preclude the mutual interference too often encountered in tandem sailplanes. The maximum cockpit load is 230 kg.
The large canopy is a single unit which integrates the instrument panels into the canopy frame. It is hinged at the back in the Piontkowski fashion and opens with an upward and rearward movement. The practicality of this concept for large glider canopies has already been tested by Akaflieg Köln through the modification of three Scheibe SF-34 gliders.
The hinge is a carbon reinforced element able to withstand wind speeds up to 75 km/h when open and was designed to sever the tubing and wiring looms from the instrument panels upon emergency release in flight.
The airplane stands on a sprung, retractable main undercarriage
Undercarriage
The undercarriage or landing gear in aviation, is the structure that supports an aircraft on the ground and allows it to taxi, takeoff and land...
with a six-inch hub, and a nose wheel which is likewise sprung and retracts simultaneously with the main wheel. A fixed tail wheel is also provided. This undercarriage scheme simplifies ground handling, since fuselage dollies
Dolly
Dolly may refer to one of the following:*Camera dolly, platform that enables a movie or video camera to move during shots*Dolly , a portable anvil*Dolly , for towing behind a vehicle...
are not required. The main wheel is located near the glider's empty centre of gravity.
All controls connect automatically upon assembly in the habitual LS way. The control system is built mostly from standard LS parts. The wings are connected by two main pins inserted into the tongue-and-fork spar
Spar
In sailing, a spar is a pole of wood, metal or lightweight materials such as carbon fiber used on a sailing vessel. Spars of all types In sailing, a spar is a pole of wood, metal or lightweight materials such as carbon fiber used on a sailing vessel. Spars of all types In sailing, a spar is a...
ends, as in the LS6 and subsequent LS types.
A low landing speed is essential for a trainer. Wolf Lemke
Wolf Lemke
Wolf Lemke is a designer of gliders who worked for Rolladen Schneider and after it was taken over in 2003, for DG Flugzeugbau GmbH.He was one of the student members of the Akaflieg Darmstadt who designed the revolutionary D-36 "Circe". This team also included Heiko Fries, Klaus Holighaus and...
and Siegfried Piontowski decided to depart from the typical LS system in which ailerons and flaps
Flap (aircraft)
Flaps are normally hinged surfaces mounted on the trailing edges of the wings of a fixed-wing aircraft to reduce the speed an aircraft can be safely flown at and to increase the angle of descent for landing without increasing air speed. They shorten takeoff and landing distances as well as...
act as flaperons. A mixed schedule as in e.g. the ASW 27 was implemented. In landing configuration the flaps assume a deflection of about 75 degrees while the ailerons remain in a neutral position. This enables slower landing speeds with good control response. Multiblade airbrakes
Air brake (aircraft)
In aeronautics, air brakes or speedbrakes are a type of flight control surface used on an aircraft to increase drag or increase the angle of approach during landing....
extend from the upper surfaces of the wings to give ample glidepath modulation.