Transcript The Barn Owls Chris “Mo” Baughman Kate Brennan Christine Izuo

The Barn Owls
Chris “Mo” Baughman
Kate Brennan
Christine Izuo
Dan Masse
Joe “Sal” Salerno
Paul Slaboch
Michelle 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
Weights
Structure (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
Model No.
Powerplant
Name
Gear Ratio
Armature Winding
p/n 615G
05 Geared
2.38 to 1
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
Thrust VS Speed
Propeller Thrust vs. Airpseed for NACA Clark Y section and Handout efficiency plots
4.5
4
Propeller Thrust (lbf)
3.5
3
2.5
NACA
Handout
2
1.5
1
0.5
0
0
20
40
60
Airspeed (ft/sec)
80
100
Airfoil – GO 769
Clmax
1.7000
Cla
0.0916
a.c.
0.2500
a0L
-6.0000
Cd0
0.0100
rle
0.0470
ClminD
(t/c)max
.22 - 1.22
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
Wing
Design 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
3 4
7%3%
Landing Breakdown
4
13%
1
34%
2
56%
3
22%
2
0%
1
65%
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 Distribution
Load Summary (fuselage)
Load Type
Magnitude
x/L_start
x/L_end
(lbs)
Fuel
resultant M @C_lift
x/L
dw
f-lb (+ cw)
2.00
0
0.18
0.09
-0.4448
0.434783
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
Payload
SL
5.205802
Tail Lift (req)
-0.05272
SM
2.2
2.4
2.3
-0.15023
-0.15023
-0.01054
Static Stability
Static Margin: 0.029753 (stable)
CM,α= -0.78423 (stable)
CN,β = 0.015653 (stable)
CLβ = -0.015653 (stable)
Conclusions