Critical Design Review
The Fab Four

Jeremy Conrad


Electronics Expert
Javier Matamoros
 Thrust Guru
“Airship…
Greg

Wood Working Specialist
Luis

Williams
Perez
Computer Technician
Critical Design Review
The Fab Four

Jeremy Conrad


Electronics Expert
Javier Matamoros
 Thrust Guru
“Airship…
of Doom!”
Greg

Wood Working Specialist
Luis

Williams
Perez
Computer Technician
Outline
I.
II.
III.
IV.
V.
VI.
VII.
VIII.
IX.
Mission
Final Design Introduction
Scale Drawings
General Structure
Materials
Weight Analysis
Control Systems
Other Adjustments
Conclusion
Fab 4 World Domination Plans
To Crush All
Who Oppose
Us
The Fab 4 Mission
Through the use of knowledge acquired
during the semester and extensive testing
of our various options to produce a final
product. This final product should be of a
caliber that will meet our design
requirements, and allow us to participate
competitively in the race.
Final Design Introduction
We arrived at our final design
after careful consideration of
other options. The other
designs were eliminated after
consideration of weight, drag,
number of motors, and ability
to steer. Four and two balloon
designs, as well as the 2 other
designs presented at PDR
were eliminated because they
were not as competitive.
Scale Drawings (side view)
Scale Drawings (top view)
Scale Drawings (front view)
General Structure
As previously presented, we chose a “net”
design. We have a basic frame around
the balloons, which will be supported by
the netting. In this configuration, most of
the load is taken by the balloons and nets.
General Structure
Nets have been replaced by lightweight,
strong fabric paper. Holes will be cut in
the paper in non-crucial spots to further
reduce weight while keeping necessary
strength.
Materials





Main structure: Balsa
wood
Standard Elmer’s
wood glue
Fabric paper “netting”
Balloons
Electronics package
Weight Analysis

Balsa:
Motors (2):
Props (2):
Servos (2):
Receiver :
Receiver Bat:
Netting:
Batteries +wire:
170 g
420 g
10 g
86 g
27 g
94 g
80 g
235 g

Total:
1.122 kg







Control Systems (Yaw)
Yaw control will be achieved through differential
thrust. The two large motors are placed on the long
crossbar to enable a turning moment.
Control Systems (Pitch)
The original design involved a rotating
crossbar manipulated by a single servo.
We decided this would be difficult to
implement, and might require much
additional weight. Our final design
involves a servo attached to each motor,
both on a single control channel.
Control Systems (Roll)
Roll instability was a concern during
PDR. This issue was resolved by
lowering the center of weight by
hanging the electronics package and
additional payload under the balsa
frame with wires.
Other Design Adjustments
Joints between lengthwise and crosswise
members originally had a very small
contact patch. Small pieces of balsa were
attached to the sides of contact patches to
increase contact area and joint strength.
 Motors will be attached to the servos,
instead of directly to the crossbars to
provide pitch control

Conclusion
Though there remains some testing to be
done, and some minor issues to resolve,
there are no major problems which stand
between us and a final product. We see no
obstacles between us and a smooth finish.