Alexander Schleichers ASG 29 Sneak into the Design Process
Overview Introduction What is the ASG 29? Going into Detail Shaping the Ship: Aerodynamics Flaperons under Control: Control Systems Getting into the Hard of it: Structure
Alexander Schleicher Company Alexander Schleicher is the oldest still existing glider manufacterer, founded in 1927. Still sailplane production is a handcraft job for skilled professionals. yearly production: 90 to 100 gliders and motorgliders about 110 employees about 65% of production delivered worldwide
ASG 29, the new 18m racing ship ASG 29 Flapped single seater with 18m/15m wingtips and an option for a sustainer engine Concept: Take from the ASW 27 what is worth keeping - Optimise, where there is potential for improvement
ASG 29, the new 18m racing ship Dedicated to Performance High Aspect Ratio Wing (AR = 30.9) High Variability of Wing Loading Schleicher Passive Safety Standards Rigid Cockpit Cell with Frontal Crumble Zone Landing Gear: Energy Absorbing beyond Normal Suspension Unique Flap Landing Setting for Slow Approaches and Better Aileron Response Easy Handling 4 Part Wing (Heaviest Part about 64kg) Modified Aerowtow Hook Position and Water Ballast Sustainer Engine Optional
ASG 29, the new 18m racing ship Basic Data (may be subject to change) Span Max. Take-off Mass Wing Area Aspect Ratio Max Wing loading Min Wing loading (approx) 18m 600kg 10,5m² 30.9 57,1kg/m² 33kg/m² 15m 550kg 9.2m² 24.4 59,7kg/m² 36kg/m² High wing loading can be reached with the help of water ballast tanks in wings (approx. 85 Ltrs each) and optional fuselage ballast tank (33 Ltrs., only without engine).
Going into Detail Aerodynamics Wing Geometry Flap Deflections Control Systems Flap/Aileron Control Systems reworked Structure Load Analysis Spar Design Flaperons
Aerodynamics: Wing Geometry Outer wing over ellipse Wing chord Center wing section below ellipse Corresponding ellipse Lofting section between outer and inner airfoil Transition to fuselage Soft transition to winglet For high roll rate: Outer Flaperon stretches over 55% of wing span Possible to reuse airbrake from ASW 27? Wing and ellipse fit by 4% - Outer wing pronounced for handling reasons
Aerodynamics: Flap Deflections Dynamic pressure higher at wing sections with more distance from center of turn Lift distribution in a turn (example) giving a rolling moment, which must be counteracted by a constant aileron deflection Other constraints: - More differentiation to cope with the bigger span - Landing: Slow approach and good aileron response Since deflections upwards have to be bigger than those downwards more loss of lift than gain -9 Inner flaperon has smaller -8 arm, -7 not -6 so -5 lever suited-4to produce rolling moment Thus: During turns, using the inner flap as aileron causes more loss of lift than gain in rolling moment. Therefore its deflection is reduced -3-2 -1 0 1 2 Span Position y [m] 3 4 5 6 7 8 9
Control Systems: The Flaperon System Schleicher gliders with flaps have sophisticated devices to combine the pilot s input for aileron and flap To achieve the given targets, we performed calculations of the flaperon control system movements, regarding all nonlinearities
Control Systems: More Differentiation -40-30 Upwards deflection may not exceed limits here More upwards deflection here, gives better handling in turns -20-10 Flap Setting Deflection [ ] 0 10 20 1 2 3 Range of Deflections of the outer Flaperon 4 5 6 L 30 40 50 Despite the small available space for the mechanic controls system, with a precise calculation regarding all non-linear effects, improvements can still be achieved Dots: deflection of outer flaperon with stick centered Asterisks: deflection of inner flaperon with stick centered
Structure: Load Analysis 6 5 Manoeuvring Envelope 600kg 4 Load factor [n] 3 2 1 0 80 100 120 140 160 180 200 220 240 260 280 300-1 Airspeed [km/h] -2-3 Airbrake loads determine most of the wing
Structure: Spar Design 40000 35000 ASG 29 Spar Cross Section 2 feet from root rib Wing Bending Moment [Nm] 30000 25000 20000 15000 10000 ASW 27 +30% ASW 27 Flanges 5000 0 Light weight design made it necessary to provide spar with 0 1 2 3 4 5 6 7 8 more relative height than 9 in previous Half-span y [m] Schleicher types Wing Bending Moment
Structure: Spar Design 40000 35000 ASG 29 Spar Cross Section 2 feet from root rib Wing Bending Moment [Nm] 30000 25000 20000 15000 10000 ASW 27 +30% ASW 30% 27 more strengt but Flanges 80% more cross section 5000 0 Light weight design made it necessary to provide spar with 0 1 2 3 4 5 6 7 8 more relative height than 9 in previous Half-span y [m] Schleicher types Wing Bending Moment
Structure: Spar Design Wing Bending Moment [Nm] 40000 35000 30000 25000 20000 15000 10000 ASG 29 ASW 27 +30% Spar Cross Section 2 feet from root rib ASG ASW 30% 29 27 more ASW strengt 27 but Only 30% Flanges more 80% cross section more cross section 5000 0 Light weight design made it necessary to provide spar with 0 1 2 3 4 5 6 7 8 more relative height than 9 in previous Half-span y [m] Schleicher types Wing Bending Moment
Structure: Wing Skin Design Fewer & smaller holes in foam for the vacuuming process Reinforced skin above and below spar High performance foam with less shrink Wings pre-cured in molds Water ballast extends through complete inner wing Higher temperatures during curing By the way: Spar is built as separate part independently from wing, cured and fully inspected in advance Measures to improve long-term stability of surface
Structure: Flaperon Design Outer flaperon has aspect ratio of 65! Flutter protection demands high torsional stiffness ( carbon fibres) On the other hand, flaperons are far more damage tolerant on outfield landings, when made of aramid fibres Solution: Carbon fibres at the inner end, aramid fibres at the wing tip end, giving maximum stiffness, low weight and damage tolerance
Day of Maiden Flight: 09th of Nov, 05 filmed from the front seat of the ASK 21Mi
Summary We did our best to develop the ASG 29 as uncompromising 18m racing ship for High performance - Superb handling - Outstanding safety Categories, in which she has already inherited a lot from her predecessors (just cherishing Gerhard Waibel and Loek Boermans)
Questions..? ASG 29