1. VEHICLE SIZING PDR AAE 451 TEAM 4
Jared Hutter, Andrew Faust, Matt Bagg, Tony Bradford,
Arun Padmanabhan, Gerald Lo, Kelvin Seah
September 30, 2003

2. OVERVIEW Preliminary Weight Estimate Constraint Analysis
Using design database of existing UAVs.
Using mission segment weight fractions.
Constraint Analysis
Requirements and assumptions.
Wing area estimate.
Power estimate.
Aircraft Sizing Summary

3. PRELIMINARY WEIGHT ESTIMATE
Design database included UAVs under 550 lbf, and excluded jet-powered aircraft.
Plotted the Empty Weight (WE) versus the Gross Take-Off Weight (GTOW).
Empty Weight estimated to be lbf using the linear trend line at a GTOW of 55 lbf.

4. PRELIMINARY WEIGHT ESTIMATE
Plot of Empty Weight vs. GTOW for Existing UAVs
Equation of Linear Trend Line:
WE = ·GTOW
Target Weight:
GTOW = 55 lbs
WE = lbs

5. WEIGHT ESTIMATION using Mission Segment Weight Fractions
Details of this approach are presented in Chapter 6 of Raymer.
Mission profile considered:
Loiter
Cruise
Cruise
Climb & Accelerate
Descent
Engine Start, Warm Up
Landing, Taxi &
Shut Down
Taxi
Take-Off

6. WEIGHT ESTIMATION using Mission Segment Weight Fractions
Some equations used:
Climb and Accelerate
Cruise
Loiter
Raymer, Eq (6.9)
Raymer, Eq (6.11)
M_cruise = 0.054
M_take-off = 0.028
R = Range = 2,000 ft
C_bhp for cruise = 0.4 (empirical data, from Raymer, lbf/hr/bhp)
eta_p = 0.8
L/D for cruise = 11.89
E = 15 mins (or 0.25 hrs)
V at loiter is approx 30 ft/s (2 ft/s above V_stall)
C_bhp for loiter = 0.5 (empirical data, from Raymer, lbf/hr/bhp)
L/D for loiter = 10.31
Raymer, Eq (6.15)

7. WEIGHT ESTIMATION using Mission Segment Weight Fractions
Engine Start, Taxi and Take-Off:
Climb and Accelerate:
Cruise:
Loiter:
Descent:
Landing and Taxi:
Overall:

8. WEIGHT ESTIMATION using Mission Segment Weight Fractions
Based on and a take-off weight of 55 lbf,
Fuel Weight = 9.42 lbf
Dry Weight = lbf

9. CONSTRAINT ANALYSIS Requirements: Cruise Speed (Vcruise = 60 ft/sec)
Stall Speed (Vstall = 28 ft/sec)
Climb Gradient (gclimb = 5.5°)
Endurance (30 mins)

10. CONSTRAINT ANALYSIS Assumptions: Maximum CL = 1.3
Oswalds Efficiency Factor, e = 0.8
Propeller Efficiency, hp = 0.8
SHPcruise = 0.75 SHPmax,cruise
Drag Coefficient, CD = 1.1 CD0 where CD0 = 0.03
Aspect Ratio = 7
Take-Off Distance (100 ft)
Landing Distance (100 ft)

11. CONSTRAINT ANALYSIS Cruise Requirement Stall Speed Requirement
Roskam Vol. 1 Page 162
Roskam Vol. 1 Page 90

12. CONSTRAINT ANALYSIS Climb Gradient Requirement Endurance Requirement
Roskam Vol. 1 Page 138
Derived in Lecture,
Sept 9, 2003

13. CONSTRAINT ANALYSIS Take-Off Distance Requirement
Landing Distance Requirement
Roskam Vol. 1 Page 95
Roskam Vol. 1 Page 171,
Homebuilt Aircraft Data

14. CONSTRAINT ANALYSIS Climb Gradient Endurance Stall Speed
Take-Off Distance
Stall Speed
Cruise

15. CONSTRAINT ANALYSIS – CLOSE UP
Cruise
Stall Speed
Take-Off Distance
W/P = lbf / SHP
W/S = lbf / ft2

16. SUMMARY Required Power = 4.45 HP Required Wing Area = 48.16 ft2
With an AR of 7.0,
Span = ft
Chord = 2.62 ft
Fuel Weight = 9.42 lbf
Dry Weight = lbf

17. PROFILE & FRONT VIEWS
2.62 ft
18.36 ft

18. TOP VIEW
18.36 ft
2.62 ft
Aspect Ratio: 7

19. SIZING WITH OTHER ASSUMPTIONS
Increase CLmax to 1.5, keeping AR = 7.0
Required power is 4.83 HP
Required wing area is ft2
Span = ft
Chord = 2.44 ft
Decrease AR to 5.0, keeping CLmax = 1.3
Required power is 5.81 HP
Required wing area of ft2
Span = ft
Chord = 3.10 ft

20. QUESTIONS?