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An exlanation of the methedology used in the sizing of the Blackbird UAV
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Using Electric UAV sizing Methodology
Philip Asante
Aircraft Aerosonde Aerosonde BSST Observer I Xian ASN-15 Qods Talash Fokker Space MATE NPS Remez-3 Cyberflight CyberOne Cyberflight Swift-Eye
Country Australia China China Iran Netherlands Ukraine United Kingdom United Kingdom
Launch Car Cradle Hand Hand/Rail Conventional Mortar Tube Conventional Conventional Hand
Power(hp) 1 Unknown Unknown Unknown Unknown 2.5 2.5 unknown
Engine 1 cyl; 4-stroke piston 4-stroke piston 1 cyl piston 1 cyl piston Electric 1 cyl piston 1 cyl piston (x2) 1 cyl piston
Range(km) 2778 5 10 8 5 20 32.2 3.2
Endurance(h) 32 1.5 1 0.5 0.5 2 2 1
Cruise spd(kph) 104 120 90 90 Unknown 105 160 153
Loiter(kph) 74 74 56 56 Unknown 58 57 48
Alt Upper (m) 4500 1600 500 Unknown 300 Unknown 6100 4265
Alt Lower (m) 100 200 50 Unknown Unknown Unknown 50 50
We (kg) 8.2 4.2 2 7.1 6 6.5 5.4 1.8
Wo (kg) 13.4 10 6.5 12 6 10 12.2 6.4
We/Wo 0.611940299 0.42 0.307692308 0.591666667 1 0.65 0.442622951 0.28125
• 8 UAV’s Studied Selected for Greater Study.
•Weight and Endurance were of Particular Interest.
•Found that UAV’s of this size usually use Piston Engines.
Philip Asante
Pusher Motorc
H-Tail Configuration
Camera Dome
Philip Asante
T-Tail configuration
Mounted pusher motor and fairing
High wing for increased roll stability
Philip Asante
Philip Asante
Philip Asante
Similar Design Used By Highlighted UAV’s of Similar Weight.
Good Low Speed Flight Stall and Stability Characteristics. (Tail Wing Will not stall Due to Prop Airflow.
Philip Asante
Philip Asante
Wtakeoff = Wstruc + Wpayload + WBattery+ WMotor+ Welec
•Structure Weight Typically between 25-30% of the Take-Off Weight.
•US Airforce Cadets in the Aerospace Program use a wing loading contribution of 0.2 lb/ft^3 for their UAV Designs.
•Fair assumption When using Carbon Fiber and Epoxy Composite Skin over a Styrofoam Core.
Philip Asante
0
2
4
6
8
10
12
14
16
0 2 4 6 8 10
Take-O
ff W
eig
ht
Empty Weight
Take-off Weight vs Empty Weight Trend
Series1
Log. (Series1)
Philip Asante
High Definition TV Camera and/or IR Sensors
Video Downlink Communication Package
Motor
Above Payloads Included in Research Weight
Extra Battery for Avionics and Camera?
Sensitivity Study To be Conducted to see effect of Payload weight changes
Philip Asante
Wetted Area Estimate = 10.87 units^2
Reference Area=3.42 units^2
Wing Span = 5.7 units
A.R. = 2.9
L/Dmax = 13.5
L/D cruise = 13.5 (for prop)
L/D cruise = (0.866)(13.5)=11.691
Philip Asante
Climb important in determining Battery Weight
Climb to 500 ft
Climb
Cruise Cruise
Loiter
Philip Asante
Calculated as a Function of L/D ratio.
Energy Density of Li-Ion Battery (0.46 MJ/kg)
Assumed Motor and Prop Efficiency (0.8)
Calculated Estimate of 2.03 kg
Philip Asante
USAF Academy Estimates 0.2 lb/ft^2
Assumed Nominal for Aircraft using Carbon Fiber and Epoxy Composite skin Over Styrofoam Core.
Expect Structural Weight of 0.97 kg/m^2 of referemce area.
Philip Asante
Propulsion Method
Philip Asante
Battery Sizing Explained Further
•D-Drag Force, estimated from Obtained L/Dmax and aircraft weight of 8 kg•V- Aircraft Speed•t- Total Desired Flight Time•(|)- Energy Density of Lithium Ion Battery•Motor and Prop Efficiencies. (0.8 for motor and 0.7 for prop)•Divided by reference area to obtain wing-loading contribution.
Philip Asante
Battery Weight Sensitivity
0
1
2
3
4
0 5 10 15
Lif
t
Drag
Drag Sensitivity
Drag Sensitivity
0
0.5
1
1.5
2
2.5
3
0 20 40
Speed Sensitivity
Speed Sensitivity
0
1
2
3
4
0 5000 10000
Endurance Sensitivity
Endurance
Sensitivity
•1N increase = 0.35 kg
•5 m/s= 0.081196 kg
•Every Half Hour = 0.016916 kg
Philip Asante
Maximum Takeoff Weight Calculation
Wtakeoff /s= Wstruc /s + Wpayload /s + WBattery /s + WMotor /s + Welec /s
Wtakeoff /s = 52.67 N/m^2 (Obtained from constraint diagramand typical for UAV’s of this size)
Wstructure /s= 9.58 N/m^2
Philip Asante
Calculating Wing Reference Area
Wetted Area Estimate = 10.87 units^2
Reference Area=3.42 units^2
Wing Span = 5.7 units
A.R. = 2.9
L/Dmax = 13.5
L/D cruise = 13.5 (for prop)
L/D cruise = (0.866)(13.5)=11.691
Philip Asante
Motor Wing Loading ContributionSpecifications:•Weight 58g including motor mount.9 T, 23AWG, DLRK, delta, 14 Magnet poles.•Shaft 3mm•No load 13200 RPM, 10.06V, 1.22A.28 AMP Max continuous.33 AMP Max Burst.
Prop and Thrust:GWS 12x8 APC E Propeller
Drag force calculated based on L/D and an aircraft of 8kg and used to determine motor Prop/Motor combination
13.4 N of Thrust With Selected combination
Philip Asante
Next Step
•Create Program That adjusts Take-off Weight and Wingspan w.r.t. Payload mass.
•Prepare concept structural design proposal
•Perform stability and control analysis
Philip Asante