The Barn Owls Chris “Mo” Baughman Kate Brennan Christine Izuo Dan Masse Joe “Sal” Salerno Paul Slaboch Michelle Smith.

The Barn OwlsChris “Mo” Baughman

Kate BrennanChristine Izuo

Dan MasseJoe “Sal” Salerno

Paul SlabochMichelle Smith

Design Drivers• High Rate of climb• Max. cruise speed

Motivation• To build an aircraft

which will take off (multiple times without crashing)

• Accurately predict the performance of the designed aircraft

• Maximize the speed and rate of climb

Guidelines and Limitations

• 400 – 800 sq. in. planform area • Given Astro-Cobalt 615G motor • Must be statically stable• Takeoff run < 300 ft.• No rockets!?!?!?!?!?!?!?!?!?!?!?!?!?!?!?

Schedule and Deadlines

• February 5th – Present Conceptual Design

• February 26th – Present Detailed Design

• March 4th – Complete Parts List

• April 6th-9th – Ground Tests

WeightsStructure (estimation) 1.5

Misc. (glue, monokote, screws) 0.4

Engine (Cobalt 15) 0.56

Propeller 0.06

Servo (5) 0.50

Receiver & Battery 0.25

GPS & Transmitter 0.5

Electronics Box 1.5

Speed Controller 0.08

Main Battery 0.65

Total (lbs.): 6.0

PowerplantModel No. p/n 615G

Name 05 Geared

Gear Ratio 2.38 to 1

Armature Winding 7 turns

Armature Resistance 0.069 ohms

Magnet Type Sm Cobalt

Bearings Ball Bearings

Motor Speed 1488 rpm/volt

Geared Motor Speed 652 rpm/volt

Motor Torque/amp 0.91 in-oz /amp

Geared Torque 2.17 in-oz /amp

Voltage Range 8 to 12 volts

No Load Currrent 2 amps

Maximum Continuous Current 25 amps

Maximum Continuous Power 400 watts

Gear Motor Length 3.3 inches

Motor Diameter 1.3 inches

Motor Shaft Diameter 5/32 inch

Prop Shaft Diameter 1/4 inch

Gear Motor Weight 9 oz

www.astroflight.com

Thrust VS SpeedPropeller Thrust vs. Airpseed for NACA Clark Y section and Handout efficiency plots

0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

0 20 40 60 80 100

Airspeed (ft/sec)

Pro

pel

ler

Th

rust

(lb

f)

NACA

Handout

Airfoil – GO 769

Clmax 1.7000

Cl 0.0916

a.c. 0.2500

0L -6.0000

Cd0 0.0100

rle 0.0470

ClminD .22 - 1.22

(t/c)max 0.1330

Design Factors in Choosing Airfoil

• Appropriate Reynolds Number Data (low speed)

• Minimize Drag – t/c ~ 14%– wide drag bucket– Shallow increase in drag outside of drag

bucket

• Maximize Lift– High CL max

WingDesign Decisions• No sweep

• Maximize lift

• Ease of manufacture

• Taper ratio of 0.25

• Minimize drag

• Create large enough root chord length in order to provide clearance for payload

• Slight dihedral for roll stability

• Winglets enhance in-flight performance

Fuselage• Airfoil-shaped

fuselage serves as lifting surface

• Also serves as a wing box which carries electronics

• Conventional fuselage has been replaced by booms on order to minimize weight and drag

Horizontal Tail• NACA 0009 Airfoil

– Low drag, symmetric– Can Produce both Lift and Reverse Lift– Swept to maintain straight trailing edge

to maximize control surface while minimizing planform area

Take-off/Landing Estimations

Take-off Breakdown

1

34%

2

56%

3

7%

4

3%

Landing Breakdown

1

65%2

0%

3

22%

4

13%

Take-off Distance = 176 ft.

Landing Distance = 370 ft.

(does not take into consideration climbing over an obstacle)

Flaps• Slotted, 15% of total wing area• Used as flaperons

– Enhanced lift for take-off– Control during flight– Speed brakes during landing

Weight DistributionLoad Summary (fuselage)        

Load Type Magnitude x/L_start x/L_end resultant M @C_lift dw

  (lbs)     x/L f-lb (+ cw)  

Fuel 2.00 0 0.18 0.09 -0.4448 0.434783

Payload 1 0.18 0.36 0.27 0.0278 0.217391

Fus.Struct. 0.53 0 1 0.5 0.183773 0.025183

Engine(s) 0.50 0 0.18 0.09 -0.1112 0.108696

Wing Struct. 0.56 0 1 0.5 0.194413 0.026641

Horiz. Tail 0.03 2.2 2.4 2.3 0.086654 0.006082

Vert. Tail 0.03 2.2 2.4 2.3 0.087169 0.006118

Other 0.56 0 0.05 0.025 -0.17404 0.278247

L 5.205802     M -0.15023  

Tail Lift (req) -0.05272 2.2 2.4 2.3 -0.15023 -0.01054

Static StabilityStatic Margin: 0.029753 (stable)

CM,α= -0.78423 (stable)

CN,β = 0.015653 (stable)

CLβ = -0.015653 (stable)

Conclusions