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Critical Design Review AAE451 – Team 3 Project Avatar December 9, 2003. Brian Chesko Brian Hronchek Ted Light Doug Mousseau Brent Robbins Emil Tchilian. Aircraft Name. Avatar av·a·tar - n. - 1. <chat, virtual reality> An image representing a user in a multi-user virtual reality.
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Critical Design Review AAE451 – Team 3 Project Avatar December 9, 2003 Brian Chesko Brian Hronchek Ted Light Doug Mousseau Brent Robbins Emil Tchilian
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/
Introduction • Walk Around • Design Requirements and Objectives • Sizing • Propulsion • Aerodynamics • Dynamics and Controls • Structures • Performance • Cost • Summary • Questions
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
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
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
Chosen Propeller 4-blades • Zinger 16X7 Wood Pusher Propeller • 16 inches in diameter with 7 inch pitch • 4 blades Ref. www.zingerpropeller.com
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
Takeoff EOM Integration Drag + Rolling Friction Thrust Velocity vs. Position at Takeoff Velocity [ft/s] Position [ft] Takeoff Distance Within Constraint
Max Velocity Maximum Velocity Thrust Thrust/Drag [lbf] Drag Flying Velocity [ft/s]
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
Airfoil Selection Region of Interest Clark Y Clark Y Airfoil has low drag over range of interest
Airfoil Selection Section Lift Coefficient Cl Section Drag Coefficient Cd Section Lift Coefficient Cl Angle of Attack (AOA)
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
Wing Performance Required CL at stall CD CL
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
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
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
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
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
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
Trimming • Incidence of Horizontal Tail calculated from trimmed flight during cruise (0 Angle of Attack) • Analysis set incidence at -2
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)
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
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
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
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
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
Aircraft Performance (with 2.2lbf fuel) 90 ft/sec
Total Aircraft Cost What Purdue Will Pay For This Project
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
Summary – Internal View Internal Pod Camera View
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
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.