AAE 451 Aircraft Design
Critical Design Review
BolierXpress
Team Members
Oneeb Bhutta, Matthew Basiletti , Ryan Beech, Mike Van Meter
3-D Views
6ft
11ft
Aerodynamic Design Issues
Lift
• Low Reynolds Number Regime
•
Slow Flight Requirements
Drag
• Power Requirements
•
Accurate Performance Predications
Stability and Control
• Trimmability
•
Roll Rate Derivatives
Low Reynolds Number Challenges
Separation Bubble-to be avoided!
•Laminar Flow -more Prone to Separation
•Airfoil Sections designed for Full-sized Aircraft
don’t work well for below Rn=800,000
•Our Aircraft Rn=100,000-250,000
Airfoil Selection
Wing:
Selig S1210
CLmax = 1.53
Incidence= 3 deg
Re = 150e3
0.06
0.05
flat plate for Low Re
Incidence = -5 deg
0.04
Cd
Tail sections:
FX63137
S1210
0.03
S1223
0.02
0.01
0
-0.2
0
0.2
0.4
0.6
0.8
1
Cl
1.2
1.4
1.6
1.8
2
2.2
Drag Prediction
Assume Parabolic Drag Polar
CD  CD0  KCL
1
K
Ae
e  0.75
2
Based on Empirical
Fit of Existing Aircraft
Parasite Drag
Drag Build-up Method of Raymer
C Do  
C f QFFS wet
S ref
(Ref. Raymer eq.12.27 & eq.12.30)

 Blasius’ Turbulent Flat Plate0.455
C f  1.2
2.58 
Adjusted for Assumed
log
10
(Re)


Surface Roughness
Drag Polar
Aircraft Drag Polar
0.16
CD
CDi
CDo
0.14
0.12
0.1
0.08
0.06
0.04
0.02
0
0.2
0.4
0.6
0.8
1
CL
1.2
1.4
1.6
1.8
Power Required
32
Predict:
• Battery energy for
cruise
28
Power Required [ft-lb/s]
• Power required for
cruise
30
26
24
22
20
18
16
15
20
25
30
Velocity [ft/s]
35
40
Aerodynamic Properties
Wetted area =
44.5 sq.ft.
Span Efficiency Factor = 0.75
CLa =
5.3 / rad
CL de =
0.4749 /rad
L/Dmax =
15.5
Vloiter =
24 ft/s
CLmax =
1.53
CLcruise =
1.05
Xcg =
0.10-0.38 (% MAC)
Static Margin = 0.12 at Xcg = 0.35
Stability Diagram
0.3
elev deflect=-8 deg
-4
0
4
8
0.2
Cmcg
0.1
elev deflect=-8 deg
-4
0
0
4
8
-0.1
-0.2
-0.3
-0.4
0
0.2
0.4
0.6
0.8
1
CL
1.2
1.4
1.6
1.8
Flow Simulation
Parasite Drag

CDo for Wing and Tail surfaces
t


4
FFW ing  1 0.6 c 100 t  1.34M 0.18
c 
x

c


 


For Fuselage, booms & pods
FFPOD
0.35
 1
f
 60
f 
FFFuselage  1  3  100 

f
400


(Ref. Raymer eq.12.31 & eq.12.33)
l
f 
d
Tail Geometry
Horizontal Tail:
Area = 2.2
Span = 3.0ft
Chord = 0.73ft
Vh = 0.50
xh S h
vh 
Sc
Vertical Tail- 25%
added
Area = 1.75 sq.ft
Span = 1.63 ft
Chord = 0.60 ft
Vv = 0. 044
X v Sv
Vv 
Sb
Control Surface Sizing:
Elevator
Area Ratio = 0.30
Chord = 2.7 in.
Rudder
Area Ratio = 0.40
Single rudder of chord = 7.5 in.
Ailerons
Area Ratio = 0.10
Aileron chord = 3 in.
Equipment Layout & CG.
Rotation angle = 10deg
Tip Back angle= 15deg
17.54 in.
Controls equipment
Propulsion component
Airframe component
Miscellaneous Weight
Equipment Layout (3-D)
Landing Loads
2
Ke  12 Wg Vvert
 7.6in  lb Vvert=2.2ft/s
d
Work   kSds  0.5k
0
Vland=1.3Vstall=25ft/s
For d = 1 in., k = 15.2 lb/in
For 1 inch strut travel, peak load = 15.2 lb
sspar = 240 psi on landing
g = -5 deg
Static Margin, Aerodynamic
Center, and c.g.
SM  X ac  X cg
Xac = 0.46
Xcg = 0.35
SM = 0.11
Horizontal and Vertical Tail
Sizing
Sh 
Vh S ref c
xh
Sv 
Vv S ref b
xv
Vh - Horizontal tail volume coefficient = 0.50
Vv - Vertical tail volume coefficient = 0.044
S h  2.2 ft
2
S v  1.75 ft
2
Control Surface Sizing

Based on historical data from Roskam
Part II Tables 8.1 and 8.2.
Homebuilts
Single Engine
Sa
S ref
0.095
0.08
Sr
Sv
0.42
0.36
0.44
0.42
Se
Sh
Control Surface Sizing (cont.)




Sa = 1.35ft2
Sr = 0.80ft2
Se = 1.00ft2
Max. surface deflection is 15 deg.
Climb Performance

Max. Climb Angle, G
T  D
  sin 

 W 
1
G = 7.3 deg.
Turning Performance
Maximum turn rate
r = 50ft
Vmax = 28ft/s
Y= 0.28 rad/s

Propulsion Design Issues
Power
Power required
Power available
Endurance
Can we complete the mission
Verification
Motor test to take place this week
Power
55
50
Power Required
Power Available
45
Power Required [ft-lb/s]
Power
required is
determined
by aircraft
Power
available
comes from
the motor
40
35
30
25
20
15
15
20
25
30
35
Velocity [ft/s]
40
45
50
System Efficiencies
Propeller
60-65%
Gearbox
95%
Motor
90%
Speed Controller
95%
Total System Efficiency
50.7%
System Components
Propeller
Freudenthaler 16x15 and 14x8 folding
Gearbox
“MonsterBox” (6:1,7:1,9.6:1)
Motor
Turbo 10 GT (10 cells)
Speed Controller
MX-50
Economics
Preliminary Design
525 man-hours @ $75 = $39,375
Testing
50 man-hours @ $75 = $3,750
$81.70 in materials
Economics
Prototype Manufacturing
300 man-hours @ $75 = $22,500
$417.35 in materials
Flight Testing
$900
Prototype manufacturing budget
$200 max
The Budget
Total Project Cost
The Bottom Line
$67,024.05
Questions?