1. Propulsion PDR 1
Team 1
September 21, 2006

2. Propulsion System Design Method
Goal: Design a single propulsion system capable of performing the design mission (one prop, one gearbox, one battery system).
Undesirable to require two propulsion systems to complete design mission
Superior marketability of multi-functional aircraft
Method:
1.) Select P/D ratio for largest efficiency flexibility (P/Dmax=1.0 ~ MaxCim Motors)
2.) Size propulsion system to meet dash requirements
2a.) Maximum propeller diameter 10 in (minimize landing gear length)
2b.) Select motor capable of providing necessary power to propeller
2c.) Set gear ratio to ensure efficient motor operation
2d.) Select batteries to supply the necessary voltage and current
3.) Ensure that loiter requirement can be met with dash-optimized system
3a.) 500 ft radius circular flight path
3b.) 50 ft/s air speed
3c.) 7 minute requirement
AAE 451 Team 1

3. Propeller Pitch & RPM Initial Starting Point for Pitch and RPM
Design Region
Initial Starting Point for Pitch and RPM
RPM ≈ 9000 – 10000
Pitch ≈ 9 – 10 in
Source: The Basics of R/C Model Aircraft Design, p. 89
AAE 451 Team 1

4. Propeller Diameter Based on RPM and Vdash D ≈ 11 in Vdash = 100 mph
Initial Estimate
Based on RPM and Vdash
D ≈ 11 in
Source: Simons, Model Airplane Aerodynamics, p. 217
AAE 451 Team 1

5. Pitch/Diameter Ratio (P/D)max = 1.0 Higher P/D
Broader Efficient Range of J
Greater J for Max Efficiency
AAE 451 Team 1

6. Aircraft System Aircraft Constants: Dash Observations
CD0=0.25
Aspect Ratio=8.5
Oswalds Efficiency e=0.75
Weight = 5 lbf
Wing Area = 4.16 ft2
Dash Observations
CL very low at high speed
Two Propulsion Systems:
Ideal: 150 ft/s requires 0.89 hp
Cost-conscious alternative: 100 ft/s requires 0.27 hp
AAE 451 Team 1

7. Ideal Propulsion System
Max Speed 150 ft/s ~ 102 mph
Propeller
APC 10x10 Sport Propeller ($2.49)
Gearbox
Kontronik Planetary Gear Drive 4.2:1 for 480 Motor ($59.99)
Motor
Kontronik Fun A Brushless Motor ($129.99)
Speed Controller
Kontronik Jazz Brushless ESC ($169.99)
Batteries (in series)
2 x Apogee 2-Cell 7.4 V 2500mAh 20C LiPo ($62.99)
Total Propulsion Chargeable Cost = $ (neglects speed controller)
AAE 451 Team 1

8. Alternative Propulsion System
Max Speed 100 ft/s ~ 68 mph
Propeller
APC 10x10 Sport Propeller ($2.49)
Gearbox
Great Planes ElectriFly Gearbox S :1 ($9.99)
Motor
MEGA ACn 16/15/2 ($84.50)
Speed Controller
Phoenix 35 Brushless Speed Controller ($89.95)
Battery
1 x Great Planes LiPo 7.4V 1500mAh 20C Discharge ($34.99)
Total Propulsion Chargeable Cost = $ (neglects speed controller)
AAE 451 Team 1

9. Propeller Selection CP, CT, h found from gold.m
Assumed Inputs (to be refined when blade purchased)
azero_lift = -6°
bflat_meanchrd= 0.5°
slopelift_curve= 2p
CD0= ;
kinduced_drag= .01
Num_Blades= 2
chord/radius=.09
Max h for 18* in prop
10 in propeller suffers small efficiency hit h=85.5%
* This was true despite different motors/power requirements.
AAE 451 Team 1

10. “Ideal” System Motor/Battery
Dash
Motor Voltage input: 13.0 V
Motor Current input: A* (Motor Max Surge 65 A)
Motor RPM: 53,500 RPM (Motor Maximum 60,000 RPM)
Motor h: 92.6%
Mtip,prop < 0.6
* Max battery continuous output: 50 A
AAE 451 Team 1

11. “Ideal” System Motor Loiter
Estimated Loiter Time: 49.4 mins (far exceeds requirement)
Motor Voltage input: 4.6 V
Motor Current input: 9.8 A (Motor Max Continuous 45 A)
Motor RPM: 18,900 RPM
Motor h: 79.0%
AAE 451 Team 1

12. “Alternate” System Motor/Battery
Dash
Motor Voltage input: 7.3 V
Motor Current input: 33.8 A* (Motor Max Surge 35 A)
Motor RPM: 31,800 RPM (55,000 Motor Maximum RPM)
Motor h: 86.2%
Mtip,prop < 0.3
* Max battery continuous output: 30 A
AAE 451 Team 1

13. “Alternate” System Motor
Loiter
Estimated Loiter Time: 13.7 mins (exceeds requirement)
Motor Voltage input: 3.8 V
Motor Current input: 12.5 A
Motor RPM: 17,100 RPM
Motor h: 73.3 %
AAE 451 Team 1

14. Summary No need for multiple propulsion systems
Battery required for dash exceeds loiter requirements
Tradeoff between cost and desired performance
AAE 451 Team 1