Adam Hertzlin Dustin Bordonaro Jake Gray Santiago Murcia Yoem Clara P14651: Drop Tower for Microgravity Simulation

Pros and Cons of Project Types Vacuum Tube and Continuous Lift Vacuum TubeContinuous Lift Easy approval for location High cost Satisfies majority of current requirements Slow cycle time Baseline for "both" operation Does not satisfy current requirement Museum functionality Long completion time (>2 Semesters) Simplicity of design Approval by dean for certain locations Fast, but useless cycle time Requires continuation by another SD group Educational and fun for all Completion in 2 semesters Possibly unreliable due to complexity Fast cycle time and meets all requirements Can be done in budget May have time for system design of lift May have time for system design of vacuum tube Larger diameter, possibility of 2 tubes Not Feasible Limits Teams Vision for Project

1 Tower Vs. 2 Towers Reduced price due to less parts. Larger diameter tube. 2 objects dropping, 2 position sensors and larger release system. 1 Vacuum pump. Larger volume to evacuate. Only one environment can be created. The two objects must be drop at same pressure. Occupies less space at location. Lasers can conflict with each other. Reduced price due to less parts. Larger diameter tube. 2 objects dropping, 2 position sensors and larger release system. 1 Vacuum pump. Larger volume to evacuate. Only one environment can be created. The two objects must be drop at same pressure. Occupies less space at location. Lasers can conflict with each other. Increase in price due to all infrastructure materials multiplied by 2. Smaller diameter piping. 1 objects dropping, 1 position sensor and smaller release system per tower. 2 Vacuum pumps. Less volume to evacuate. Two different environments can be created, which means that the 2 objects can be drop at different pressures. More interactive to public. Lasers are independent from each other. Increase in price due to all infrastructure materials multiplied by 2. Smaller diameter piping. 1 objects dropping, 1 position sensor and smaller release system per tower. 2 Vacuum pumps. Less volume to evacuate. Two different environments can be created, which means that the 2 objects can be drop at different pressures. More interactive to public. Lasers are independent from each other.

Isolation Valve – Cost vs. Time Time to Evacuate (min) No Isolation Valves Time to Evacuate (min) Isolation Valves Price, Single Tower, 2 Isolation Valves 15ft Tower40ft Tower 15ft / 40ft Tower 6" Dia $4, " Dia $6, " Dia $9, Assumptions: No losses due to connection points, 10 cubic foot per meter pump, 15 micron ultimate pressure, 2ft above & below valves, single tower

Isolation Valves Pros and Cons + Quicker cycle time The air needed to be taken out of the pump is independent of tower height  Can use less costly pump (Lower pump speed) - Costly Disrupts view of items falling Can not alter for a continuous system in the future More pipe / pump sections  need more parts More chance of pressure leak Our Conclusion: Although isolation valves would save a substantial amount of time, the time benefit does not outweigh the cost for the tower height we are considering. At this scale it would be more beneficial to increase the pump size instead.

List of Experiments Dropping two objects simultaneously Measure Gravity Measure Drag Balloon Expansion Marshmallow Expansion Sound Insulator Plastic Bottle Compression Note: The following slides will attempt to justify the required tower pressure and size to complete these experiments

Engineering Analysis  Tower Height

Free Fall – No Air Resistance (Vacuum Conditions)

Free Fall –Air Resistance (Atmospheric Conditions) Fall Time Differs Per Object; Depends on Drag Coefficient, Projected Area and Mass of Object Dropped. Equations Dependent on Terminal Velocity (Vterm or V ∞ ); The Highest Velocity the Object Reaches, at the Point Downward Acceleration Becomes Zero

Free Fall –Air Resistance (Atmospheric Conditions)

Free Fall –Air Resistance (Atmospheric Conditions)

Results Assumptions 0.5 – 1.0 drop time difference is adequate Steel Ball Bearing vs. Feather Result 10 – 15ft Tower Height

Engineering Analysis  Ultimate Pressure

Gravity Calculation with 1% Error

Free Body Diagram of Object

Drag Force (Air Resistance)

Objects to calculate gravity Based on a certain vacuum pressure and other parameters, center objects will be suitable of calculations while others are not Objects vary by their mass, projected area and drag coefficient Assumptions: Allowable Error in Gravity due to Pressure = 0.01% This can increase if the error from the position and time measurements are minimized Pressure = Torr = 2 Pa This can be decreased if a more efficient pump is available (cost / benefit) Max Tube Height = 5 meters Constant Acceleration Ideal Gas Room Temperature Standard Gravity

Results For the assumptions on the previous slide the following equation must be satisfied: m/(CD*A) >= 1.19 kg/m^2 Where: m = mass (kg) CD = Drag Coefficient A = Projected Area Note: Error % and Pressure can be adjusted to change this threshold 1" Steel Ball 1.625" Steel Ball Ping Pong BallFeatherCoffee Filter Drag Coefficient, CD Projected Area, A (m^2) Mass, m (kg) m/(CD*A)

Engineering Analysis  Evacuation Time

Conductance Viscous Molecular

Equivalent Pipe Length Pipe fittings can cause losses within a piping system These include: elbows, tees, couplings, valves, diameters changes, etc. Tabulated values for Le/D can be used to adjust L in the conductance equations D = Diameter of Pipe Le = Equivalent Length Total Length = L + Le 1 + Le 2 + Le 3 + ….

Effective Pump Speed

Evacuation Time VP6D CPS Vacuum Pump 2 Stage Rotary Pump 15 micron Ultimate Vacuum Pump Speed – 6.25 cfm Price: $241.15

Results For the tube and pump size listed, the evacuation time is 9.24 minutes This will increase if: Tube diameter increases Tube length increases Pump speed decreases Ultimate pressure decreases Note: The pressure is suitable for most objects, based on slide 18

Engineering Analysis  Critical External Pressure

Pipe Critical Pressure Calculations Desired Factor of Safety = 3-4 Pipe Dimensions Courtesy of Engineeringtoolbox.com *Specifications for white PVC

Summary Proposed Requirement Metrics Tower height: 5 meters Tower size: 8” Diameter Number of Towers: 2 (if budget allows) Pump Speed: 6.25 cfm (2 tubes) Pump Type: 2 stage Rotary (mechanical roughing pump) Evacuation Time: 9.24 mins Ultimate Pressure: 15 microns (0.015Torr or 2Pa) Negative (Critical) Pressure – Factor of Safety: 3.94 No Isolation Valves Manual Object Lifting

Concept Designs

Bill of Materials NOTE: This Bill of Materials does not include the pipe, valves, and fittings that connect the pumps to the tube.