1. STRUCTURES & WEIGHTS PDR 2
TEAM 4
Jared Hutter, Andrew Faust, Matt Bagg, Tony Bradford,
Arun Padmanabhan, Gerald Lo, Kelvin Seah
December 2, 2003

2. OVERVIEW Vertical Tail Pod Attachment Aircraft Internal Configuration
Spar design
Pod Attachment
Aircraft Internal Configuration
Internal layout
Detailed weight analysis

3. CONCEPT REVIEW Empennage Empennage High Wing High Wing UPDATED
Horizontal and Vertical Tails sized using modified Class 1 Approach
(per D & C QDR 1)
High Wing
S = 39.3 ft2
b = 14.0 ft, c = 2.8 ft
AR = 5
UPDATED
Twin Booms
3 ft apart;
5.7 ft from Wing MAC to HT MAC
Twin Engine
1.8 HP each
Avionics Pod
20 lb; can be positioned front or aft depending on requirements
Empennage
Horizontal and Vertical Tails
High Wing
S = 47.8 ft2
b = 15.5 ft, c = 3.1 ft
AR = 5
Twin Booms
3 ft apart;
7.3 ft from Wing MAC to HT MAC
Twin Engine
1.8 HP each
Avionics Pod
20 lb; can be positioned front or aft depending on requirements

4. VERTICAL TAIL Bending moment analysis Deflection analysis
Spar selected based on results

5. VERTICAL TAIL Modeled as vertical fixed beam Equations:
base fixed in horizontal stabilizer
Free Body Diagram
Equations:
Deflection
Bending Moment: q
Where q is distributed load.
Estimate
q~8.3 lbf/ft
Deflection:

6. VERTICAL TAIL Plotted bending moment and deflection
Solved for moment of inertia
Obtained spar width and height
0.5 in
1 in
3 ft
1.2 ft
As seen from the rear of the aircraft

7. VERTICAL TAIL Bending moment decreases from root to tip
Increasing
deflection
Deflection greatest
at tip

8. HORIZONTAL TAIL Modeled as simply supported beamq
Encountered complications that require re-evaluation
More for CDR

9. POD ATTACHMENT
3 different analysis considerations in pod attachment (from Gere, Mechanics of Materials) :
1) allowable tensile stress in main base of connecting rail
2) allowable tensile stress around bolt holes
3) allowable shear stress in bolts

10. POD ATTACHMENT 1) Tensile Stress in Main Base
As seen from left rear view of pod
1) Tensile Stress in Main Base
where: P = load we are designing for
= allowable tensile stress in material
A = area under inspection
d2= hole diameter
t = rail thickness
= 370 psi (for spruce, tension perpendicular to grain)
d2= 3/8 in
t = 3/8 in
P = 50 lbf

11. POD ATTACHMENT Solve for and make sure it’s less than that for spruce
=355.6 psi < 370 psi

12. POD ATTACHMENT 2) Tensile stress in bolt holes
As seen from left rear view of pod
where d1= width of hole section
d1 =1.25 in
Other variables remain same as before

13. POD ATTACHMENT
Again, solve for and make sure it’s less than that for spruce
= psi < 370 psi

14. POD ATTACHMENT 3) Shear stress experienced in bolts
As seen from left rear view of pod
3) Shear stress experienced in bolts
where
= allowable shear stress in bolts
n = number of bolts required
= 91 psi
from plasticnutsandbolts.com

15. POD ATTACHMENT
This time, solve for n and find how many bolts are required for the given allowable shear stress and load P
n = 5, but use 6 for symmetry

16. AIRCRAFT INTERNAL LAYOUT
Total Weight = lbs

17. POD INTERNAL LAYOUT
Avionics + Structure = 20 lbs

18. POD ATTACHMENT METHOD

19. WING CONSTRUCTION
Wing + Required Structure = 13.1 lbs

20. CENTRAL WING INTERNAL LAYOUT

21. DETACHABLE SECTION INTERNAL LAYOUT

22. DETACHABLE SECTION INTERNAL LAYOUT

23. TAIL SECTION INTERNAL LAYOUT
Tail Section + landing gear = 1.59 lbs

24. REAR LANDING GEAR CONNECTION

25. WEIGHTS SUMMARY Component Weight (lbf) Wing & Structure 13.1
Tail Section & rear gear
1.59
Tail Booms
4.70
Basic Flight Systems
0.849
Propulsion & Fuel
6.61
Avionics & Structure 20
Main Landing Gear
2.36
Fiber-glass & Mylar Skin 1
Total Weight
50.21

26. QUESTIONS?
Got F.O.D. ?