Preliminary Design Review

1
Preliminary Design Review
16.00 Spring 2005 The Confused
Meteorologists LTA Design Project

• The Confused Meteorologists
• Massachusetts Institute of Technology
• March 17, 2005

2
Driving mechanisms
16.00 Spring 2005 The Confused
Meteorologists LTA Design Project
3
Number of balloons
16.00 Spring 2005 The Confused
Meteorologists LTA Design Project

• One
• Incapable of carrying large payload
• Lighter, simpler, minimum drag
• Unstable in turns

• Two
• Cannot carry maximum payload
• Difficulty with attaching truss

• Three
• Can carry maximum payload
• Arranged in a line to minimize drag
• Can support truss for carrying payload

4
Structure
16.00 Spring 2005 The Confused
Meteorologists LTA Design Project

• Considerations
• Resistance to flex and torque
• Minimizing weight
• Weight distribution of propulsion, control
  system, and payload to reduce load on spans
• 1 servo rotating both motors creates a special
  structures challenge

• Solutions
• Place weights (batteries, payload, controls)
  under balloons when possible to reduce weight on
  spans
• Carbon fiber rod to provide support to motors,
  significantly reducing weight and increase
  strength
• Suspension bridge - style support with posts
  under balloon and string

5
Structure
16.00 Spring 2005 The Confused
Meteorologists LTA Design Project

• Use trusses to support structure

6
Our design
16.00 Spring 2005 The Confused
Meteorologists LTA Design Project

• Differential thrust
• Three balloons arranged in a line to minimize
  drag
• Weights on suspension bridge - style truss and
  carbon fiber rod under balloons

7
Justification
16.00 Spring 2005 The Confused
Meteorologists LTA Design Project

• Stability
• Static and dynamic equilibrium
• Balance, performance
• Controllability
• Servos, motors, linkages
• RC, ease of use
• Ease of assembly
• Strength
• Simplicity
• Predictability

8
Vehicle analysis
16.00 Spring 2005 The Confused
Meteorologists LTA Design Project
Total Mass Servo 1 .034 kg Servo
Receiver 1 .043 kg Motor 2 .539
kg Propellers 2 .010 kg Battery 1 .156
kg Structure 1 .180 kg Helium Mass 1.57 m3
.283 kg In total 1.335 kg
9
Aerodynamic analysis
16.00 Spring 2005 The Confused
Meteorologists LTA Design Project
3 amps results in 5.8 N thrust per motor Thrust
Drag 11.6 N Drag 1/2?airv2CD 11.6
N Maximum V 13.41 m/s Minimum time 89.78m /
13.41 m/s 6.69 s -- However, since the blimp
doesnt always travel at maximum speed and its
course is not exactly a rectangle, the real time
should be longer.
10
Where to go next
16.00 Spring 2005 The Confused
Meteorologists LTA Design Project