AME 441: Conceptual Design Presentation
B-19
Group 5: Andrea Doyle, Tim Kacmar, Ryan Kirker, Meghan
Perry-Eaton, Denis Sullivan, Mike Trela, Thomas Zieg
February 5, 2004
Overview
•
•
•
•
•
•
•
Introduction
Main Wing Selection
Engine Selection
Takeoff and Landing Distances
Passive Lift Enhancement
Static Stability
Conclusions
Introduction
• Design Drivers
– Maximum Level Speed at Constant Altitude
– Maximum Climb Rate
• Allowable Parameters
–
–
–
–
–
Total Planform Area between 400 and 800 in2
Power Plant Consisting of an Electric Motor
Internal Cargo Bay of Specified Dimensions
Sport Propeller of Specific Pitch and Diameter
Digital Radio Control System (7 Channels)
Why a Flying Wing?
• Advantages
– Minimum Drag
– High Speed
– Absence of Horizontal Tail Maximizes Climb Rate Given
AC and CG locations
– Maximizing Excess Power
Weight Breakdown
Aircraft Weight By Component
Component
Receiver & Battery
Servos
GPS & Transmitter
Electronics Box
Motor & Battery
Speedcontrol
Fuselage Protrusion
Landing Gear
Structure Weight
TOTAL WEIGHT
Weight (lbs)
0.25
0.5
0.5
1.5
1.9
0.1
0.25
1
2
8
Removable
NO
NO
YES
YES
NO
NO
NO
YES
NO
Wing Loading
• Design Drivers:
– Max Level Cruise  High Wing Loading
– Max Rate of Climb  Low Wing Loading
• Large aircraft are not a good comparison.
• R/C Model Aircraft Wing Loading
– Professional Kit Models: 12 oz/ft2.
– Conceptual Design: 27 oz/ft2.
• Maximize Available Power, Decrease Drag
Overall Wing Design
•
•
•
•
Taper Ratio, 0.4 – Like Elliptical Planform
Wing Sweep, 20% – Historical Data
Winglets – Decrease Drag, Stability
Dihedral, none
– Winglets & Wing Sweep are effective
Dihedral
– Twist takes away from effective Dihedral
Wing Airfoil Section: EH 3.0/12.0
• Low Moment
about A.C.
– -0.002
• Thick Section
– Structure
– Stability
• Designed for
Flying Wing
model
Aircrafts
Lift versus Angle of Attack for EH 3.0/12.0
1.2
1
0.8
2-D Airfoil
0.6
3-D Wing
0.4
0.2
0
-5
0
5
10
Wing Specifics
• Flaps for increase lift at take off and acceleration to
cruise.
• Dimensions
– Wing Area, 600 sq. in.
• Compromise between low drag and low CL.
– Wing Span, 5.4 ft
– A = 7.1, 8.1 with winglets
– Root Chord, 1.09 ft & Tip Chord .44 ft
• CL @ cruise, .225
Estimated Cruise Velocity Importance
Wing Twist as a Function of Cruise
Velocity
CL at Cruise as a Function of Velocity
CL
1.5
1
0.5
0
20
40
60
Velocity (ft/s)
80
100
Degrees of Twist
from Root to Tip
2
0
0
20
40
60
80
-10
-20
-30
Velocity (ft/s)
• Velocity estimation greatly effects the design
of the wing.
100
Estimated Velocity
Power Required and Power Available Curves
Power Available (100%)
250
Power Required
Power Available (80%)
200
150
100
50
0
0
20
40
60
80
100
120
• Theoretical Estimate: 100 ft/s
– Based on a propeller efficiency ranging from .4 to .6
• Conservative Estimate: 80 ft/s
– Battery will not be fully charged and other losses will
occur.
Wing Twist & Angle of Attack
• Twist: For Stability & Control of Aircraft
– Minimize Moment @ A.C.
– Low Stability Factor, 8%
– Longer Wing Span
– Good Weight Estimate
• Calculated -4° of Twist from Root to Chord
• Root Chord, α = 4 °
• Tip Chord, α = 0 °
• Mean Aerodynamic Chord, α = 2.5°
– .817 ft long at 1 ft from the root chord.
Propulsion System
Cruise Conditions:
Cruise Alt. (ft)
500
M
0.07
V
80.00
r
0.075474
Tot. Drag
1
ft
f/s
lbm/f^3
lbf
Propeller Design:
V_tip
360.00 f/s
M_tip
0.33
D
1f
SHP
0.35 hp
blade no.
2
Calculations:
n
114.5916
J
0.480969
C_P
0.05458
h_P
0.6
h_P (COR)
0.618
C_T
0.048315
T_cruise
1.487
n
6875
rps
1/rev
(Fig. 7.5)
lbf
rpm
Static Thrust:
C_T/C_P
6 (Fig 7.6)
T_static
10.07928 lbf
T_(COR) 9.776898 lbf
•Astro 15 Motor
•12” X 8” Pitch Propeller
•9.78 lbs. Static Thrust
•2.16 lbs. Cruise Thrust (2 lbs. of Drag at Cruise)
Take-Off and Landing Analysis
•
•
•
•
•
•
S_G (f)
S_R (f)
S_TR (f)
S_CL (f)
S_T-O (f)
CDO= 0.015
Aspect Ratio=7.15
CLG=1
Take-off Weight= 8lb
=0.1, wet grass
5 foot obstacle
33.19448988
145.0472423
58.98253289
11.34082313
248.5650882
Take-off Breakdown
3
24%
4
5%
1
13%
2
58%
• Wing Loading= 1.687 lb/ft2
• VTD= 43.34 ft/sec
• Landing Weight= 7lb
• Dropped landing gears
• =0.3, wet grass, large
surface area interaction with
ground
S_A (f)
S_TR (f)
S_FR (f)
S_B (f)
385.895355
42.80720382
130.0259684
184.3920479
S_L (f)
1.6(S_L) (f)
743.1205752
1188.99292
Landing Breakdown
4
25%
1
52%
3
17%
2
6%
• 3-D with flaps
•ΔCLmax = 0.0189
•CLmax = 0.9189
•αs 3-D flapped = 11.629 degrees
•ΔCD0 = 0.0156
2-D (flaps)
2-D (no flaps)
lift coeff.
lift coeff.
1.5
1
0
-10
0.5
-10 -0.5
10
10
alpha
alpha
3-D (flaps)
3-D (no flaps)
1.5
1.5
lift coeff.
•
Airfoil Data
• EH3.0-12.0
• Cl max = 1.0
• αs 2-D no flaps = 10 degrees
• CLmax no flaps = 0.90
• αs 3-D no flaps = 13.129 degrees
Flap Information
• Plane
• δf = 30 degrees
• Sf/Sw = 0.20
• cf/cw = 0.25
lift coeff.
•
Lift Enhancement
0.5
-10 -0.5
10
alpha
0.5
-10 -0.5
10
alpha
Stability
Fuselage Length
Wing Center of Lift
mean chord
Center of Gravity
Static Margin
SM no GPS/trans.
1.1
0.628
0.8
0.6142
0.1831
0.151
ft
x/L
ft
ft
stable
stable
C_M_
-0.891 stable
C_n_
0.0056 stable
C_L _
-0.0056 stable
Cross Wind -0.0032 [rad]^-1
C_R/C_VS
0%
Conclusions
• Flying Wing Configuration
– Estimated 8 lb Takeoff Weight
• Wing Dimensions
–
–
–
–
Area: 597 in2
Span: 4.7 ft
Root Chord: 1.08 in Tip Chord: .44 in
Wing Twist: 5°
• EH 3.0-12.0 Airfoil
– Cl max-1.0
– 3% Camber
– 12 % Thickness
• Wing Loading
– 27 oz/ft2
• Power Plant
– Astro Cobalt 15 Electric Motor
-Shaft Output Power: 268 W
-12 Cell Pack
-2.38:1 Gear Ratio
-12x8 Propeller
• Takeoff and Landing
– Takeoff Speed: 48.34 ft/s
– Takeoff Distance: 248.57 ft
– Landing Distance: 743.12 ft
• Flap Information
– Plane
– Δf = 30 degrees
– Sf/Sw = 0.20
– cf/cw = 0.25
• Cruise Speed
– 80 ft/s
Questions??