1. Dynamics & Controls PDR 1
Team 2: Balsa to the Wall
Ashley Brawner
Neelam Datta
Xing Huang
Jesse Jones
Matt Negilski
Mike Palumbo
Chris Selby
Tara Trafton

2. Overview Previously fixed parameters Class 1 tail sizing
Center of gravity location
Location of aerodynamic center (aircraft and tail)
Static margin
Static stability/control surface sizing
Revisit tail sizing: Class 2 method
Dihedral angle

3. Previously fixed parameters
Value
Payload Weight
1 [lb]
Payload Volume
30 [in3]
Horizontal Tail Span
1.5 [ft]
Wing Span
4.95 [ft]
Aspect Ratio 5
Wing Root Chord
1.352 [ft]

4. Tail Sizing – Tail Volume Method
Raymer Method
Historical coefficients used.
Horizontal Tail
cHT = 0.475
SH = ft2
Vertical Tail
cVT = 0.04
SV = 0.4 ft2

5. Center of Gravity Fuselage and Wing CG position from CATIA
Weight estimated by structures team

6. Center of Gravity Tail and Boom Internal Components
Tail size from volume method
Boom size and position from trade study
Internal Components
Historical data
Specification sheets
Total Mass: pounds
CG Position: feet ahead of AC
Component
Mass [lb]
Position [ft]
From Nose
Moment [ft-lb]
Tail
0.161
4.370
0.704
Boom
1.31
2.995
3.923
Payload 1
0.200
Battery
1.25
0.167
0.209
Gyro
0.01
0.917
0.009
Servo
0.02
1.083
0.022
Motor
0.59
1.800
1.062
Speed Controller
0.1
0.583
0.058
Receiver
0.04
0.750
0.030
Receiver Battery
0.28
0.250
0.070

7. Aerodynamic Center Wing & Horizontal Tail Locations Respective values
25% of the respective chord (Roskam Table 2.2)
Respective values
Xacw = feet
Xach = feet
From NASA Glenn Website

8. Aerodynamic Center Aircraft Found to be: Calculated with:
0.41 feet from LE

9. Static Margin (SM) Static Margin SM obtained: 11.4% Range of CG
With Payload
0.071 feet ahead of AC
Without Payload
0.134 feet behind AC
Empty SM = 33%

10. Longitudinal Static Stability
Pitching Moment (Cmα)
Cmα = rad-1
Believability Checks:
Comparable to previous Purdue classes
Flat Earth Verified

11. Trim Diagram CL CL α [deg] Cm0.25c CLmax Cm = 0 Xcg forward Cm = 0
Xcg design
Cm = 0
Xcg aft δe 5 -5
-10
CLmax
δe=0 CL
δe = -10 CL
δe = 5
δe = -5
α [deg]
Cm0.25c

12. Control Surface Sizing
Use of historical data to elevator and rudders.
Aerodynamics sized flaperons.
Approximately 15% of wing chord
Raymer recommends:
Elevator 25-50% of tail chord
Rudder 25-50% of tail chord

13. Aileron Size Wing root chord = 1.353 feet Aileron chord = 0.1825 feet
Clδa = rad-1
Flat Earth believability check: to 0.2 rad-1

14. Elevator Size Horizontal tail chord = 0.75 feet
Elevator chord = 0.3 feet
40% of H-tail chord
Cmδe = rad-1
Flat Earth believability check: to -2 rad-1

15. Rudder Size Vertical tail chord = 0.75 feet Rudder chord = 0.3 feet
Cnδr = rad-1
Flat Earth believability check: to rad-1

16. Tail Sizing – Longitudinal Stability
Roskam Method: Longitudinal X-Plot
Comparison of how the c.g. and the a.c. move as the horizontal tail area is increased.
Horizontal tail area range based on tail volume method sizing.
Fixed horizontal tail span of 1.5 feet.

17. Longitudinal X-Plot

18. Tail Sizing – Directional Stability
Roskam Method – Directional X-Plot
Consideration of vertical tail area on the yawing moment coefficient with sideslip angle.
Weathercock Stability (Cnβ )
Desire a Cnβ of at least deg-1

19. Directional X-Plot

20. Tail Size Horizontal Tail Vertical Tail Span: 1.5 feet
Chord: 0.75 feet
AR: 3.0
Vertical Tail
Vertical Span: 1 foot
AR:

21. Dihedral Angle McKombs (D&C Sourcebook) Dihedral angle = 0°
Recommends with use of ailerons 0 to 2°
Dihedral angle = 0°
Ease of manufacturing.
Dihedral effect (Clβ)
Clβ = rad-1
Flat Earth believability check: to -0.3

22. QUESTIONS???

23. Appendix – Useful Equations

24. References D&C Sourcebook Airplane Design Series by Jan Roskam
Methods for Estimating Stability and Control Derivatives of Conventional Subson Airplanes by Jan Roskam
Airplane Design Series by Jan Roskam
Airplane Flight Dynamics and Automatic Flight Controls by Jan Roskam
Aircraft Design: A Conceptual Approach by Daniel P. Raymer