Giving Bertha!

1
Giving Bertha!

• LTA CDR
• David Dryjanski Design/Construction, SolidWorks
  Expert
• Rachel Ellman - Design/Construction
• Carl Engel - Team manager, Propulsion and
  Control, Pilot
• Viviana Serra - Design/Construction
• Joshwa Wang - Design/Construction, Conceptual
  Artist

2
Objective

• Explain design changes since PDR
• Present and analyze our updated design ideas and
  innovations

3
Design Evolution

• Threw out idea about each motor driving two
  propellers
• Decided to keep horizontal stabilizer stationary
• Added 2nd rudder for better turning
• Changed the front motor from stationary to 2-axis
  thrust vectoring

4
Introduction to Final Design

• Bertha is a good combination of stability and
  simplicity
• Good payload capacity
• Fast
• Truss is aesthetically pleasing
• Intricate structure very light and strong

5
Scaled Drawings
SolidWorks drawings by David Dryjanski
6
Side View
SolidWorks drawings by David Dryjanski
7
Isometric View
SolidWorks drawings by David Dryjanski
8
Control Systems

• Dual rudder system to deflect prop-wash of rear
  motor for yaw control
• 2-axis thrust vectoring (yaw and pitch) for front
  motor

9
Aerodynamic Analysis

• 10 over-inflation of balloons
• He volume 1.39 m3
• Lift capacity 1.47 Kg
• Vehicle mass estimates-
• 2 small motors with 2 large propellers 80g (x2)
  160g
• receiver, wiring, and 3 servos 40g 10g 110g
  160g
• battery (2 packs) 300g
• balsa structure and stabilizers 100g
• Total 720g
• Payload capacity 0.75 Kg

10
Aerodynamic Analysis (cont.)

• Thrust (measured) 2.84 N per motor 5.68 N
• Coefficient of Drag 0.5
• Force of drag at Vmax Thrust 5.68 N
• Maximum Velocity 3.1 m/s
• Estimated time for course completion (assuming
  perfect turns) 28 seconds
• Realistic Time appx. 1 minute
• Endurance 3.6 minutes of battery power

11
Conclusion

• Based on our Preliminary Design Review, we
  narrowed down our options to create an optimal
  LTA vehicle. Through extensive meetings and
  discussions of pros and cons of different design
  implementations, we have concluded that our
  current arrangement will provide maximum
  performance.