Completed Design Review

Team Airblade Timothy Davenport

Brian GuerreroMark KastantinOscar KatauraWilliam PetersRobert Taylor

Overview

Structural Changes since PDRDescription of Finalized DesignDesign analysis: Stability and controlCalculations: mass, payload, course

completion time, etc.Timeline

Structural Changes since PDR

Trapezoidal cross-section >> triangular cross-section

Sides of craft: balsa boards >> triangular trussPitch propeller moved further forward

Side View

78.74 inches

3.94 in

3.75 in3.19 in

Large motors with servos

Small motor

Stabilizer

Top View

78.74 inches

3.75 in payload payloadbattery / control

• note: balloons removed from view

Front View

72º

Structural Specifics

Propulsion: 1 large propeller at front end, 1 large propeller at back end

Pitch: 1 small motor at front end Triangular truss for slanted sides, ladder

design for top side2 meters long, 8.5 meters wide. Balloons attached at front end, midpoint and

back end.

Materials

Balsa wood (3/8 inch squares)

2 large motors2 large propellers1 small motor1 small propeller2 servos

1 battery pack1 radio control

module3 balloons with

attachments (string)wire

1. Balloons and string are not included in mass calculations2. Wire is included in the mass of the other equipment

Balsa Wood Length

Each side piece requires 40 pieces (3.75 inches each)

Top piece requires 20 pieces (3.75 inches each)

3 pieces run the length of the structure (2 m each, or 78.74 inches)

Length Calculation   =3.75(40(2)+20)+(3)78.74

   =611.22 inches

Mass CalculationMaterial Unit Mass (g)* Units Total (g)

balsa wood 0.369 g/in 611.22 in 225.5large motor 249.9 2 499.8large propeller 7.9 2 15.8small motor 96.3 1 96.3small propeller 4.9 1 4.9servo 38.3 2 76.6battery pack 110.2 1 110.2radio control module 50.4 1 50.4*unless otherwise specified Vehicle Mass (g) 1079.5

Payload (g) 670.5

Roll Stability

Balloons are tied to bottom beam and top crossbars minimizing horizontal pull

All weight is centered

on bottom beamMotor, propeller mass

Battery, radio control mass

Balloon lift

Pitch Stability

Lift distributed evenlySmall motor provides pitch needed to maintain

flight

Variable

Propulsion

Two large motors running at 9.6V provides 2(0.79) = 1.58 N

Drag = 1.58 N (at steady state)

Drag

Motor thrust

Drag and Velocity

This means the blimp should be moving at a fast walking speed.

Drag coefficient for a sphere

€

Cdrag =0.5

€

vmax=2D

ρSCdrag

=2(1.58)

1.2π(0.52)(0.5)=2.59ms

Turning

The large motors work in tandemTorque = (2)(39in)(0.0254 m/in)(0.79 N) =

1.57 N/m

payload payloadbattery / control

Center of mass

78.74 inches

3.75 in payload payloadbattery / control

Battery Life

One battery pack providing

of lifetime Time of completion of race track

Ample lifetime for completion

€

τbattery=30amps⋅min

1.5amps=20min

€

tcoursemax=

87.8m2.2m/s

=39.9s

Timeline

Up to this point we have the truss structure complete and have attached the servos

For the rest of the time

Monday Tuesday Wednesday Thursday Friday Saturday Sunday

Week 1 Attach motors to structure

Week 2 Complete Wiring Attach Balloons Test Fly and

Week 3 Optimize Trials

Conclusion

So far the project has proceeded smoothlyAnticipate weight problems that will be

fixed by sanding the structureWe feel we have a strong structure with

great turning potentialReady to finish building and get flying