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UAV Research International

UAV Research International. “Providing integrated consultation to MAV project engineers at Eglin AFB” Chris McGrath Neil Graham Alex von Oetinger John Dascomb Sponsor : Dr. Gregg Abate April 6, 2006. Overview. Problem Statement Design Specifications Design Solution

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UAV Research International

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  1. UAV Research International “Providing integrated consultation to MAV project engineers at Eglin AFB” Chris McGrath Neil Graham Alex von Oetinger John Dascomb Sponsor : Dr. Gregg Abate April 6, 2006

  2. Overview • Problem Statement • Design Specifications • Design Solution • Scale Model Design/Fabrication • Testing

  3. Problem Statement • To design a means of characterizing MAV handling during flight • Test must be repeatable • Data must be collected to characterize the MAV

  4. Project Specifications • Weight  100 – 200 grams (g) • Flight Speed  0 – 25 meters per second (m/s) • Exterior Material  Carbon Fiber Composite • Wing Tip Length  15 – 30 centimeters (cm) • MAV Flight Control  Both 2 and 3 axis • Type of Thrust  Pusher, Puller, None

  5. Design Selection:Free Flight Wind Tunnel • The free flight wind tunnel has been successfully created before • Design is a conventional wind tunnel with unobstructed test section • Relative velocity of MAV to the ground is zero

  6. MAV Handling: Initial Set-up

  7. MAV Handling:Reel and Restraint Set-up

  8. Wind Tunnel Design • In wind tunnel design Three properties are most important to consider: • Tunnel geometry • Flow quality • Fan Selection

  9. Wind Tunnel Design

  10. Wind Tunnel Geometry:Test section Dimensions • For the minimum analysis of the flight, the MAV needs to move laterally or vertically twice its wingspan • Minimum cross section for 12” wingspan is 4.5 ft x 4.5 ft • Allow ten feet for longitudinal motion

  11. Wind Tunnel Geometry

  12. Wind Tunnel Geometry:1st Diffuser • Expands the ducting from area of test section to the area of the fan • Diffuser angle < 5° for laminar flow

  13. Wind Tunnel Geometry

  14. Wind Tunnel Design:Turns 1 and 2 • Corner Vanes assist flow around the 4 90 degree turns • Corner Vanes improve efficiency by decreasing pressure loss • Even with vanes 61% of all pressure loss occurs at the 1st two turns

  15. Wind Tunnel Geometry

  16. Wind Tunnel Design:Fan Selection • Fan selection based on volume flow rate and static pressure loss in tunnel • Volume flow rate at maximum of 25 m/s is 100000 CFM • Total pressure loss in tunnel = 600 Pa

  17. Wind Tunnel Design:Fan Selection • Howden Buffalo 54-26 series fan • Fan has a 54 in diameter, and a 125 HP motor

  18. Wind Tunnel Design:Flow Quality • Motor housing • Anti-swirl vanes

  19. Wind Tunnel Geometry

  20. Wind Tunnel Geometry:2nd Diffuser, Turns 3 and 4 • Diffuser increases area final area ratio of 6 • Final area ratio is most important factor in tunnel • Turning vanes keep flow as laminar as possible

  21. Wind Tunnel Geometry

  22. Wind Tunnel Design:Flow Quality • Honeycombs - remove lateral components of turbulence • 3 Screens – remove axial components of turbulence

  23. Wind Tunnel Geometry:Contraction Cone • Contraction cone quickly increases flow velocity • When condensing, flow will not separate like diffuser

  24. Wind Tunnel Geometry :Tunnel Geometry – Constrained tunnel Total tunnel length is 36.6 ft

  25. Instrumentation • On-Board Measurement • Flow Quality Measurement • Traversing System • Data Collection Software • Data Acquisition System

  26. On-Board Measurement • Kestrel Autopilot • 16.65 grams (2” x 1.37” x .47”) • Three-axis rate gyros • Accelerometers • Air pressure sensors

  27. Data Collection Software • Virtual Cockpit • Labview

  28. Cost Analysis

  29. Scale Model • Too expensive to build the designed tunnel • Built a 1/12 scale model • Physically test flow quality of full scale design to determine if free flight is feasible

  30. Scale Effects • Scale model Reynolds number 1/12 that of full scale model • Use hot-wire Anemometer to measure velocity fluctuation though test section • Velocity is not dependent on Reynolds number, scaling effects can be ignored for our tests

  31. Scale Model

  32. Contraction Cone

  33. Contraction Cone Total Elapsed Time: 2 Hours 20 Hours

  34. Contraction Cone Total Elapsed Time: 41 Hours

  35. Contraction Cone

  36. Joining Method

  37. Turning Vanes

  38. Diffusers

  39. Settling Chamber

  40. Fan

  41. Model Results • Manufacturing Complete • Testing • Initial correction of flow through turning vanes • Inconclusive analysis of tunnel due to lack of testing • Potential Testing • Fine tune internal geometry • Correction of all Turning vanes • Measuring Pressure fluctuations through test section

  42. Problems Encountered • Wait time on ordered parts • MSC acrylic sheets • McMaster-Carr fan order • Fabrication of contraction cone • Testing Time Constraints

  43. Questions?

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