ASW-22DB (Eta Biter) Evolution
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The document summarizes the evolution of the ASW22DB glider through four phases from 1998 to 2003. Phase I involved building the ASW22BL with a smaller horizontal tail. Phase II modified the wing airfoil. Phase III included a new vertical stabilizer and retractable tail wheel. Phase IV added a new outboard airfoil profile, increased the span to 28m, and improved internal airflow. Performance gains anticipated included up to 11% at high speeds and improved climb. Flight tests verified the theoretical calculations and aerodynamic modifications. The completed glider met expectations by winning national competitions.
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ASW-22DB (Eta Biter) Evolution
- 1. ASW22DB (ETA BITER) Evolution Feb98 to Jun03
- 2. 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
- 3. 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)
- 4. 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)
- 5. 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).
- 7. 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
- 8. Blowing Articulation • Blow Holes at 72% • Blowing Set as a Function of Flap Position • NACA Ducts Opened & Closed by Servos Mounted Over Plenum
- 9. Delft HQ17M Airfoil Design Was Implemented and Flight Tested
- 10. 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
- 15. Perspective
- 16. 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.
- 17. Skin Removal & Contouring
- 18. Skin Replacement & Aileron Construction
- 19. New Airfoil & Wing Contouring
- 25. Ship met All Expectations Winning 03 Open Class Nationals
- 26. Remaining Work • Build Lighter Weight Ailerons • Build and Test Delft Winglets per Boermans & Hulst Design • Obtain Performance Polar for Completed ASW22DB
- 27. ASW22BL, wt 1279, New VS, Retract Tailwheel, Exhaust in Turtle Deck,New Delft Airfoil to Sta 8.25, NACA Duct Driven by Servo, No Winglets, W/S 7.13lb/sq ft 700 flap -8.6deg, no blowing" 600 flap -6.5deg, blowing Measured factory polar for ASW22B corrected to BL 500 rate of sink, ft/sec flap -4.4deg, blowing 400 Flap 0deg, blowing 300 flap- 2.2deg, blowing 200 100 0 0 20 40 60 80 100 120 140 airspeed, kts
- 28. Comparisons ASW22BL Nimbus 4 ASW22DB ETA Span 26.4m 26.4m 28.0m 30.9m Wing Area 16.7m^2 17.8m^2 17.0m^2 18.6m^2 Aspect Ratio 41.8 39.2 46.1 51.3 MTOW 750kg 750kg 750 (850)kg 850kg Wing Loading 45.0kg/m^2 42.1kg/m^2 44.1kg/m^2 44.8kg/m^2 Span Loading 28.4kg/m 28.4kg/m 26.7kg/m 27.5kg/m V/sb .05 .04 .05 ?
- 29. Design Team