Giving Bertha!Giving Bertha!LTA CDRLTA CDR

David Dryjanski – Design/Construction, SolidWorks Expert Rachel Ellman - Design/Construction

Carl Engel - Team manager, Propulsion and Control, PilotViviana Serra - Design/Construction

Joshwa Wang - Design/Construction, Conceptual Artist

ObjectiveObjective

Explain design Explain design changes since PDRchanges since PDR

Present and analyze Present and analyze our updated design our updated design ideas and innovationsideas and innovations

Design EvolutionDesign Evolution

Threw out idea about each motor driving two Threw out idea about each motor driving two propellerspropellers

Decided to keep horizontal stabilizer Decided to keep horizontal stabilizer stationarystationary

Added 2Added 2ndnd rudder for better turning rudder for better turning Changed the front motor from stationary to Changed the front motor from stationary to

2-axis thrust vectoring2-axis thrust vectoring

Introduction to Final DesignIntroduction to Final Design Bertha is a good combination of stability and simplicityBertha is a good combination of stability and simplicity Good payload capacityGood payload capacity FastFast Truss is aesthetically pleasingTruss is aesthetically pleasing Intricate structure; very light and strongIntricate structure; very light and strong

Scaled DrawingsScaled Drawings

SolidWorks drawings by David Dryjanski

Side ViewSide View

SolidWorks drawings by David Dryjanski

Isometric ViewIsometric View

SolidWorks drawings by David Dryjanski

Control SystemsControl Systems

Dual rudder system to deflect prop-wash of Dual rudder system to deflect prop-wash of rear motor for yaw controlrear motor for yaw control

2-axis thrust vectoring (yaw and pitch) for 2-axis thrust vectoring (yaw and pitch) for front motorfront motor

Aerodynamic AnalysisAerodynamic 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) = 160greceiver, 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.)Aerodynamic Analysis (cont.)

Thrust: (measured) = 2.84 N per motor = 5.68 NThrust: (measured) = 2.84 N per motor = 5.68 N Coefficient of Drag: 0.5Coefficient of Drag: 0.5 Force of drag at VForce of drag at Vmaxmax= Thrust = 5.68 N= Thrust = 5.68 N Maximum Velocity: 3.1 m/sMaximum Velocity: 3.1 m/s Estimated time for course completion (assuming Estimated time for course completion (assuming

perfect turns): 28 secondsperfect turns): 28 seconds Realistic Time: appx. 1 minuteRealistic Time: appx. 1 minute Endurance: 3.6 minutes of battery powerEndurance: 3.6 minutes of battery power

ConclusionConclusion

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