Transcript Giving Bertha

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
Objective
 Explain design
changes since PDR
 Present and analyze
our updated design
ideas and innovations
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
Introduction to Final Design
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Bertha is a good combination of stability and simplicity
Good payload capacity
Fast
Truss is aesthetically pleasing
Intricate structure; very light and strong
Scaled Drawings
SolidWorks drawings by David Dryjanski
Side View
SolidWorks drawings by David Dryjanski
Isometric View
SolidWorks drawings by David Dryjanski
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
Aerodynamic Analysis
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10% over-inflation of balloons
He volume: 1.39 m3
Lift capacity: 1.47 Kg
Vehicle mass estimates2 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
Aerodynamic Analysis (cont.)
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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
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.