Presentation by Dick Butler about the extensive modifications that he made to his ASW-22 in the early 2000s. This was presented at the 2003 Soaring Society of America (SSA) convention in Atlanta, Georgia.
Project Phases• Phase I- Build ASW22BL with 30% Less Horizontal Tail Area• Phase II- Modify HQ17 Airfoil Inboard Wing• Phase III- New Vertical Stabilizer and Retractable tail wheel• Phase IV- New Outboard Airfoil Profile, Span Increase to 28m, Internal Air Flow Improvement
Anticipated Performance Gains From Project Phases• 9% Performance Gain at Best L/D• 11% Performance Gain at High Speeds, (160km/hr)• Improved Climb Performance From Reduced Span Loading• Equal flying qualities with 28m Span by Maintaining Vertical Tail Volume Coeff. (V/S.b)
Phase I- Build ASW22BL With Smaller Horizontal Stabilizer• 2.6% Less profile drag relative to wing• Good stability/elevator authority on tow & low speed flight (Minimum pilot wt. 88kg)
Phase II- Modify HQ 17 Airfoil• Prof. Loek Boermans Designs Modification to HQ17 Airfoil Lower Surface for 7.5% Less Skin Friction Drag at High Speeds (6.0 percent relative to wing).
Flight Test Verify Theoretical Calculations Parasite Drag ASW22DB 0.9 0.8 flap -8.6deg, HQ17M,zz tape TE 80% , no blowing 0.7 Flap -8.6deg, HQ17, blow holes at 73% 0.6 0.5 Cl 0.4 0.3 0.2 0.1 0 0 0.001 0.002 0.003 0.004 0.005 0.006 0.007 Cd
Blowing Articulation• Blow Holes at 72%• Blowing Set as a Function of Flap Position• NACA Ducts Opened & Closed by Servos Mounted Over Plenum
Delft HQ17M Airfoil DesignWas Implemented and Flight Tested
Phase III- New Vertical Stabilizer & Retract Tail Wheel• Reasons For Building -Drag reduction with modern profile -Maintain 22BL tail volume coefficient(V/S.b) with 28m span (add 30cm tail boom, 10cm span) -Center hinged rudder -Drag reduction with retract tail wheel• Benefits - 25% Less profile drag - 2.2% Less drag relative to wing - Better handling from new profile and center hinged rudder
Phase IV- New Airfoil on Outboard Wing, Span to 28m• Reasons for Changes - Improve lift distribution to near elliptical - Less profile drag with Delft DU99-138 - Improve low speed, 1.8m more span - Strengthen wing for 850kg max weight• L. Boermans & M. Hulst designed new airfoil and winglet for outer wing panel• 2% Less profile drag at high speeds & 4% at low speeds relative to wing.