UAV Research International “Providing integrated consultation to MAV project engineers at Eglin...

UAV Research InternationalUAV Research International““Providing integrated consultation to MAV project Providing integrated consultation to MAV project

engineers at Eglin AFB”engineers at Eglin AFB”

Chris McGrathChris McGrathNeil GrahamNeil Graham

Alex von OetingerAlex von OetingerJohn DascombJohn Dascomb

Sponsor :Sponsor :Dr. Gregg AbateDr. Gregg Abate

April 6, 2006April 6, 2006

OverviewOverview

Problem StatementProblem Statement Design SpecificationsDesign Specifications Design SolutionDesign Solution Scale Model Design/FabricationScale Model Design/Fabrication TestingTesting

Problem StatementProblem Statement

To design a means of characterizing MAV To design a means of characterizing MAV handling during flighthandling during flight

Test must be repeatableTest must be repeatable

Data must be collected to characterize the Data must be collected to characterize the MAVMAV

Project SpecificationsProject Specifications

Weight Weight 100 – 200 grams (g) 100 – 200 grams (g) Flight Speed Flight Speed 0 – 25 meters per second 0 – 25 meters per second

(m/s)(m/s) Exterior Material Exterior Material Carbon Fiber Composite Carbon Fiber Composite Wing Tip Length Wing Tip Length 15 – 30 centimeters 15 – 30 centimeters

(cm)(cm) MAV Flight Control MAV Flight Control Both 2 and 3 axis Both 2 and 3 axis Type of Thrust Type of Thrust Pusher, Puller, None Pusher, Puller, None

Design Selection:Design Selection:Free Flight Wind TunnelFree Flight Wind Tunnel

The free flight wind tunnel The free flight wind tunnel has been successfully has been successfully created before created before

Design is a conventional Design is a conventional wind tunnel with wind tunnel with unobstructed test sectionunobstructed test section

Relative velocity of MAV to Relative velocity of MAV to

the ground is zerothe ground is zero

MAV Handling:MAV Handling: Initial Set-up Initial Set-up

MAV Handling:MAV Handling:Reel and Restraint Set-upReel and Restraint Set-up

Wind Tunnel DesignWind Tunnel Design

In wind tunnel design In wind tunnel design Three properties are Three properties are most important to most important to consider:consider:

– Tunnel geometryTunnel geometry

– Flow qualityFlow quality

– Fan SelectionFan Selection

Wind Tunnel DesignWind Tunnel Design

Wind Tunnel Geometry:Wind Tunnel Geometry:Test section DimensionsTest section Dimensions

For the minimum analysis For the minimum analysis of the flight, the MAV of the flight, the MAV needs to move laterally or needs to move laterally or vertically twice its vertically twice its wingspan wingspan

Minimum cross section for Minimum cross section for 12” wingspan is 4.5 ft x 4.5 12” wingspan is 4.5 ft x 4.5 ftft

Allow ten feet for Allow ten feet for longitudinal motionlongitudinal motion

Wind Tunnel GeometryWind Tunnel Geometry

Wind Tunnel Geometry:Wind Tunnel Geometry:11stst Diffuser Diffuser

Expands the ducting from area of test Expands the ducting from area of test section to the area of the fansection to the area of the fan

Diffuser angle < 5Diffuser angle < 5° for laminar flow° for laminar flow

Wind Tunnel Design:Wind Tunnel Design:Turns 1 and 2Turns 1 and 2

Corner Vanes assist flow Corner Vanes assist flow around the 4 90 degree turnsaround the 4 90 degree turns

Corner Vanes improve Corner Vanes improve efficiency by decreasing efficiency by decreasing pressure losspressure loss

Even with vanes 61% of all Even with vanes 61% of all pressure loss occurs at the 1pressure loss occurs at the 1stst two turnstwo turns

Wind Tunnel Design:Wind Tunnel Design: Fan SelectionFan Selection

Fan selection based on volume flow rate Fan selection based on volume flow rate and static pressure loss in tunneland static pressure loss in tunnel

Volume flow rate at maximum of 25 m/s is Volume flow rate at maximum of 25 m/s is 100000 CFM100000 CFM

Total pressure loss in tunnel = 600 PaTotal pressure loss in tunnel = 600 Pa

Wind Tunnel Design:Wind Tunnel Design: Fan SelectionFan Selection

Howden Buffalo 54-26 series fan Howden Buffalo 54-26 series fan Fan has a 54 in diameter, and a 125 HP motor Fan has a 54 in diameter, and a 125 HP motor

Wind Tunnel Design:Wind Tunnel Design: Flow Quality Flow Quality

Motor housing Motor housing

Anti-swirl vanesAnti-swirl vanes

Wind Tunnel Geometry:Wind Tunnel Geometry: 22ndnd Diffuser, Turns 3 and 4 Diffuser, Turns 3 and 4

Diffuser increases area final area ratio of 6Diffuser increases area final area ratio of 6

Final area ratio is most important factor in tunnelFinal area ratio is most important factor in tunnel

Turning vanes keep flow as laminar as possibleTurning vanes keep flow as laminar as possible

Wind Tunnel Design:Wind Tunnel Design: Flow QualityFlow Quality

Honeycombs - remove Honeycombs - remove lateral components of lateral components of turbulenceturbulence

3 Screens – remove 3 Screens – remove axial components of axial components of turbulenceturbulence

Wind Tunnel Geometry:Wind Tunnel Geometry: Contraction ConeContraction Cone

Contraction cone Contraction cone quickly increases flow quickly increases flow velocityvelocity

When condensing, When condensing, flow will not separate flow will not separate like diffuserlike diffuser

Wind Tunnel Geometry :Wind Tunnel Geometry : Tunnel Geometry – Constrained tunnelTunnel Geometry – Constrained tunnel

Total tunnel length is 36.6 ftTotal tunnel length is 36.6 ft

InstrumentationInstrumentation

On-Board MeasurementOn-Board Measurement

Flow Quality MeasurementFlow Quality Measurement

Traversing SystemTraversing System

Data Collection SoftwareData Collection Software

Data Acquisition SystemData Acquisition System

On-Board Measurement On-Board Measurement

Kestrel AutopilotKestrel Autopilot– 16.65 grams (2” x 1.37” 16.65 grams (2” x 1.37”

x .47”)x .47”)– Three-axis rate gyrosThree-axis rate gyros– AccelerometersAccelerometers– Air pressure sensorsAir pressure sensors

Data Collection SoftwareData Collection Software

Virtual CockpitVirtual Cockpit

LabviewLabview

Cost AnalysisCost Analysis

Scale ModelScale Model

Too expensive to build the designed tunnelToo expensive to build the designed tunnel

Built a 1/12 scale model Built a 1/12 scale model

Physically test flow quality of full scale Physically test flow quality of full scale design to determine if free flight is feasibledesign to determine if free flight is feasible

Scale EffectsScale Effects

Scale model Reynolds number 1/12 that of full Scale model Reynolds number 1/12 that of full scale modelscale model

Use hot-wire Anemometer to measure velocity Use hot-wire Anemometer to measure velocity fluctuation though test sectionfluctuation though test section

Velocity is not dependent on Reynolds number, Velocity is not dependent on Reynolds number, scaling effects can be ignored for our testsscaling effects can be ignored for our tests

Scale ModelScale Model

Contraction ConeContraction Cone


Total Elapsed Time:Total Elapsed Time:

2 Hours2 Hours 20 Hours20 Hours


Total Elapsed Time: 41 HoursTotal Elapsed Time: 41 Hours

Joining MethodJoining Method

Turning VanesTurning Vanes

DiffusersDiffusers

Settling ChamberSettling Chamber

Fan Fan

Model ResultsModel Results

Manufacturing CompleteManufacturing Complete

TestingTesting– Initial correction of flow through turning vanesInitial correction of flow through turning vanes– Inconclusive analysis of tunnel due to lack of testing Inconclusive analysis of tunnel due to lack of testing

Potential TestingPotential Testing– Fine tune internal geometry Fine tune internal geometry – Correction of all Turning vanesCorrection of all Turning vanes– Measuring Pressure fluctuations through test sectionMeasuring Pressure fluctuations through test section

Problems Encountered Problems Encountered

Wait time on ordered partsWait time on ordered parts MSC acrylic sheetsMSC acrylic sheets McMaster-Carr fan orderMcMaster-Carr fan order

Fabrication of contraction coneFabrication of contraction cone

Testing Time Constraints Testing Time Constraints

Questions?Questions?

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