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Critical Design Review AAE451 – Team 3 Project Avatar December 9, 2003

Explore the critical design review of Team 3's Avatar aircraft project, covering propulsion, aerodynamics, structures, and more. Detailed analysis of components like the engine, propeller, fuel tank, wing design, aerodynamic modeling, and structural integrity is included.

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Critical Design Review AAE451 – Team 3 Project Avatar December 9, 2003

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  1. Critical Design Review AAE451 – Team 3 Project Avatar December 9, 2003 Brian Chesko Brian Hronchek Ted Light Doug Mousseau Brent Robbins Emil Tchilian

  2. Aircraft Name Avatar av·a·tar -n. - 1. <chat, virtual reality> An image representing a user in a multi-user virtual reality. Source: The Free On-line Dictionary of Computing http://wombat.doc.ic.ac.uk/foldoc/

  3. Introduction • Walk Around • Design Requirements and Objectives • Sizing • Propulsion • Aerodynamics • Dynamics and Controls • Structures • Performance • Cost • Summary • Questions

  4. Aircraft Walk Around Wing Span = 14.4 ft Wing Chord = 2.9 ft A/C Length = 10 ft T-Tail – NACA 0012 Pusher Internal Pod Tricycle Gear Low wing – Clark Y

  5. Design Requirements & Objectives Maximum weight < 55 lbs Cruise speed > 50 ft/sec Stall speed < 30 ft/sec Climb angle > 5.5° Operating ceiling > 1000 ft Flight time > 30 minutes Payload of 20 lbs in 14”x6”x20” pod Carry pitot-static boom Spending limit < $300 T.O. distance < 106 ft (~60% of McAllister Park runway length) Rough field capabilities Detachable wing Easy construction

  6. Constraint Diagram

  7. Propulsion

  8. Chosen Engine • O.S. Max 1.60 FX-FI • 3.7 BHP @ 8500 RPM • 1,800-9,000 RPM • 2.08 lbs • Fuel Injected Ref. www.towerhobbies.com

  9. Chosen Propeller 4-blades • Zinger 16X7 Wood Pusher Propeller • 16 inches in diameter with 7 inch pitch • 4 blades Ref. www.zingerpropeller.com

  10. Chosen Fuel Tank • Fuel tank chosen is: • Du-Bro 50 oz. fuel tank • Available from Tower Hobbies • Located at the C.G. of aircraft • Good for up to 32 min. of flight time (when completely full). Ref. www.towerhobbies.com

  11. Takeoff EOM Integration Drag + Rolling Friction Thrust Velocity vs. Position at Takeoff Velocity [ft/s] Position [ft] Takeoff Distance Within Constraint

  12. Max Velocity Maximum Velocity Thrust Thrust/Drag [lbf] Drag Flying Velocity [ft/s]

  13. Aerodynamics

  14. Wing Dimensions Prandtl’s Lifting line theory used for aerodynamic modeling of the lifting components Input parameters: AR, a0, aL=0, a. Lifting Line Model Gives CL, CDiat prescribed a CDvisc found using Xfoil which was used to obtain CD = CDi+CDvisc 5° Dihedral

  15. Airfoil Selection Region of Interest Clark Y Clark Y Airfoil has low drag over range of interest

  16. Airfoil Selection Section Lift Coefficient Cl Section Drag Coefficient Cd Section Lift Coefficient Cl Angle of Attack (AOA)

  17. Wing Stall Performance • CL needed = 1.19 • Wing without flaps reaches CL at a=13° • Wing stall possible • Wing with 15° flap deflection reaches CL at 11° Required CL CL Angle of Attack (degrees) Flaperons necessary to meet stall requirements

  18. Wing Performance Required CL at stall CD CL

  19. Drag Build Up At Cruise

  20. Wing Operating Parameters

  21. Dynamics and Controls

  22. Center of Gravity & Aerodynamic Center • Aircraft Center of Gravity is 3.2 ft from nose. • Calculated from CAD program Pro-E • Aircraft Aerodynamic Center is 3.7 ft from nose. • Position where pitching moment of aircraft doesn’t change with angle of attack • Calculated using Lift from Wing and Horizontal Tail Aerodynamic Center Center of Gravity

  23. Static Margin Aerodynamic Center of Aircraft Static Margin = 15% Center of Gravity Static Margin = 20% • Desired Static Margin is 15% - 20% • Dependent on C.G. and A.C. location • Static Margin is 15% • Contributes to Horizontal Tail Sizing

  24. Horizontal Tail Sizing • Tail sized based on desired static margin for static stability and take-off rotation ability •  double-dot should be at least 10 deg/sec2 Ref. Roskam, Airplane Flight Dynamics 2 ft 6 ft

  25. Vertical Tail Sizing Ref. Roskam, Airplane Design • Value of yawing coefficient due to sideslip angle should be approximately 0.001 = 10e-4 • Tail area should be ~2 ft2 2 ft 1 ft

  26. Dihedral Angle Recommendations • Survey of Roskam data on homebuilt & agricultural low-wing aircraft: ~5° • “Wing and Tail Dihedral for Models” - McCombs • RC w/ailerons (for max maneuverability, low wing): 0-2° EVD (Equivalent V-Dihedral ≈ dihedral) • Free Flight Scale model low wing: 3-8° EVD 5° dihedral is a good compromise

  27. Control Surface Sizing Ref. Roskam, Airplane Design • Sizes calculate from traditional lifting device percentages. 0.6 ft 0.58 ft 0.9 ft 6.25 ft 0.6 ft 2.8 ft

  28. Trimming • Incidence of Horizontal Tail calculated from trimmed flight during cruise (0 Angle of Attack) • Analysis set incidence at -2

  29. Structures

  30. Wing Spar Design 2 Spar Design (at .15 & .60 chord): • Resist Bending • Assuming 5-g loading • 53 lbf weight • Safety factor of 1.5 • Resist Torsion • Less than 1o twist at tip under normal flight conditions Spar Results: • Material of Choice: Bass or Spruce Wood • Front Spar: • 3.6” high (based on airfoil) • 0.37” thick (0.73” at root) • Rear Spar: • 3” high (based on airfoil) • 0.16” thick (0.25” at root)

  31. Longitudinal Beam Design 2 Beam Design: • Resist Bending from: • 20 lbf payload • Horizontal tail loads • Resist Torsion from: • Rudder deflections • Prop wash over tail Beam Results: • Material of Choice: Bass or Spruce Wood • Beam Dimensions: • 3” high • 0.25” thick • 8” between the beams

  32. Tail Structures Foam core with carbon fiber shell • Horizontal and vertical tails comprised of carbon fiber w/ foam core • Possible to make two foam cores, and cure entire tail at one time • Control surfaces just need to be cut out of tail structure • Tail spars allow attach points and transfer load to beams

  33. Rear Gear Design • Blue lines represent pin joints • Black tie-downs absorb energy from landing • Up to a 33 ft/sec “crash” from 5 feet high • Need 18” relaxed length tie-down • Square aluminum tube transfers landing load to tie-downs and surrounding structure • 1” x 1” x 0.065” thick – 6063-T6

  34. Front Gear Design Aluminum Bolt • Provides pivot for gear (does not break) Elastic Band & Nylon Bolt • Elastic Band Absorbs some energy from landing • Nylon bolt breaks during hard landing Front Gear Aluminum Tube • Designed not to break • Designed not to bend • Al tube: 1” x 1” x 0.065” thick 6063-T6

  35. Other Odds and Ends • Covering for Wing: • Coverite 21st Century Iron on Fabric • 0.34 oz/ft2 • Stronger, and resists tears better than MonoKote • Covering for Fuselage: • Fiberglass • Either mold or foam core • Not conductive – won’t interfere with internal electronics Ref. www.towerhobbies.com

  36. Final Weight Estimate

  37. Performance

  38. Aircraft Performance (with 2.2lbf fuel) 90 ft/sec

  39. Cost

  40. Airframe Cost

  41. Electronics Cost

  42. Propulsion Cost

  43. Total Aircraft Cost What Purdue Will Pay For This Project

  44. Total Aircraft Value • Total Aircraft Value = (Engineering Pay) + (Cost) + (Value of Already Possessed Parts) • Engineering Pay = 823.75 hr x $100/hour = $82,375 • Aircraft Cost = $13,966.15 • Value of Already Possessed Parts = $10,000 • Micropilot = $5,000 • Carbon Fiber & E-Glass = $5,000 (estimate) TOTAL AIRCRAFT VALUE = $106,341.15 What Purdue Would Pay to Outsource This Project

  45. Summary

  46. Summary – Internal View Internal Pod Camera View

  47. Summary – 3-View

  48. Aircraft Description Aspect Ratio = 5 Wing Span = 14.4 ft Wing Area ~ 42 ft2 Aircraft Length = 10 ft (not including air data boom) Engine = 3.7 hp O.S. 1.60 FX-FI – Fuel Injected Weight = 53 lbf Aircraft Configuration T-Tail Low Wing Pusher High Engine Tricycle Gear Internal Pod Summary -Major Design Points

  49. Questions?

  50. References (I) [1] MATLAB. PC Vers 6.0. Computer Software. Mathworks, INC. 2001 [2] Raymer, Daniel P., Aircraft Design: A Conceptual Approach, AIAA Education Series, 1989. [3] Roskam, Jan., Airplane Flight Dynamics and Automatic Flight Controls. Part I. DAR Corporation, Kansas. 2001 [4] Gere, James M., Mechanics of Materials. Brooks/Cole, Pacific Grove, CA. 2001 [5] Tower Hobbies. 9 December 2003. http://www.towerhobbies.com [6] XFoil. PC Vers. 6.94. Computer Software. Mark Drela. 2001. [7] Niu, Michael C., Airframe Structural Design, Conmilit Press Ltd. Hong Kong. 1995. [8] Halliday, et al., Fundamentals of Physics, John Wiley & Sons. New York. 1997. [9] Roskam, Jan, Airplane Design (Parts I-VIII), Roskam Aviation and Engineering Corp. Ottawa KS. 1988. [10] Kuhn, P., “Analysis of 2-Spar Cantilever Wings with Special Reference to Torsion and Load Transference”. NACA Report No. 508. [11] McMaster-Carr. 9 December 2003. http://www.mcmaster.com [12] Pro/ENGINEER. PC Release 2001. PTC Corporation. [13] Roskam, Jan., Methods for Estimating Stability and Control Derivatives of Conventional Subsonic Airplanes. Publisher Jan Roskam. Lawrence, KS. 1977.

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