P14651: Drop Tower for Microgravity
Simulation
Adam Hertzlin
Dustin Bordonaro
Jake Gray
Santiago Murcia
Yoem Clara
Week 3 Review – Open Items
 How many pumps are needed?
 Benchmark NASA Drop Tower components
 Research designs to hold vacuum pressure
 Determine location for Drop Tower
 Create working design w/o cost considerations
 Meet with Deans
 Meet with Grad Students
Agenda
 Background




Problem Statement
Stakeholders
Customer Requirements
Engineering Requirements
 System Analysis
 Requirements Matrix
 Benchmarked Components
 Functional Analysis





Concept and Architecture Development
Engineering Analysis
Risk Assessment
Test Plan
New Focus as of Sep 30
BACKGROUND
Problem Statement
 Current State
 Ex) NASA Space Flight Center
 100 meter – 4.5 sec drop
 Ultimate Pressure: 10-9 Torr
 Limited Visibility
 Desired State
 P14651 Drop Tower
 9-12 meter ~ 1.5 sec drop
 15-30cm diameter tube
 Object visible during drop
 Continuous Lift / Release System
 Appropriate pump(s) for required pressure
 Educational and fun for all ages
Problem Statement Cont’d
 Project Goals:
 Fast Cycle Time
 Cost efficient
 Aesthetically pleasing
 Precision in measurements
 (1% estimation of standard gravity)
 Adaptability for multiple / future uses
 Minimal vacuum loss
 Constraints:
 Location and design approval from the Dean(s).
 Material availability/size (ex. tube, pump)
 Budget $3,000
Additional Deliverables
 User’s Guide for operation
 Designed Lab Experiments:
 Determine gravity in the vacuum within 1% error
 Compare drag at different pressures and drag vs. acceleration
 Additional vacuum related experiments
Project Stakeholders
MSD Team
Dr. Kandlikar
Middle School
Students
RIT Graduate and
Undergraduate Students
RIT Faculty
Middle School Teachers
RIT College Dean(s)
RIT Prospective Students
Customer Needs
Importance
Description
9
Minimal Down Time of Tower
9
Clear Visibility of Entire Drop
9
Capable of Dropping more than (1) object
9
Educational, but exciting for middle school students
9
Calculate Drag Coeffecient
9
Calculate Gravity (within 1% error)
9
9
Effective Data Collection
Safety
3
3
Maximum Justified Drop Tower Height
Multiple Use Capabilities
3
3
Intuitive Operation
Adjustable Pressure (Atmospheric to High Vacuum)
3
Minimize Production Cost
Engineering Specifications
Importance
Main
Source
9
CR7
Measure Relative Object Position
9
CR7
9
Engr. Requirement (metric)
Unit of
Measure
Comments/Status
m
With postion/time sensor
Measure Relative Object Drop Time
sec
With postion/time sensor
CR12
Measure Pressure
kpa
Pressure gage
9
CR1
Cycle Run Time
min
Time from one test to another
9
CR1
Continuous Lift Mechanism
Yes / No
Tower runs on its own
9
CR10
Pressure Leak Rate Minimized
kpa / sec
9
CR14
Aesthetic Structure with Supports
Yes / No
Seal all gaps
Visually Pleasing, permanent
structure
9
CR7
No Horizontal Motion
3
CR9
Tower Height
m
Tall as possible in chosen location
3
CR3
Tower Cross - Section (Diameter)
cm
3
CR12
Pump Flow Rate
m3/sec
3
CR7
Measure Temperature
Celcius
Availaility and least view distortion
Value determined by tube size and
desired time
Thermocouples, inside or outside
environment
mm
No horizontal motion
SYSTEM ANALYSIS
Requirements Matrix
Benchmarked Components
Microgravity
Device
NASA Marshall
Space Flight
Center (100m
drop~4.5sec)
Existing
Technologies
Description/Notes
Feasibility
1) Good feasibility of
detachable base and CAM
locks
1) Detachable base has integrated catch
2) Isolation valves may not be
system, and is attached via CAM locks
1) Detachable Base
feasible for budget constraints
2) Isolation valves allow for section off of
2) Isolation Valves
3) Vacuum pump feasibility
pipe sections
3) Drop Tube
depends upon pump
3) Multiple vacuum pumps for uniform
4) Vacuum Pumps
availability and budget
vacuum within the tube, roughing pumps
5) Control Panel
constraints due to high cost of
for starting from atmospheric pressure
6) Gaskets/ Connections
turbo molecular pumps
and turbo molecular pumps for higher
4) We can use the same
vacuum
surface finish and gasket
material potentially in our
design
1) Inside 142m long 6.1m
diameter vacuum
NASA Zero
chamber
Gravity Research 2) 5 Stage Vacuum Pump
Facility (132m Process
3) Overhead Crane
drop~5.18sec) 4) Release Mechanism
5) Catch Mechanism
1) Vacuum reaches 0.05 Torr.
2) Drag is reduced to less than 0.00001g
3) ~ 1 hour to evacuated chamber
4) Experiment vehicle protects hardware 1) Catch mechanism/beads
5) Catch mechanism is composed of
could be a possible solution
polystyrene beads which dissipate the
2500 lb. experiment vehicle's kinetic
energy
Picture
Benchmarked Components Cont’d
Microgravity
Device
Existing
Technologies
Description/Notes
NASA Glenn
1) Drag Shield System
1) Drag shield removes air resistance
Research Center 2) Rectangular Frame 2) Airbag dampens force of impact and
3) Lift Mechanism
protects components
(24m
4) High Speed Cameras 3) Cameras and onboard computer
5) Airbag Catching System monitor drop
drop~2.2sec)
Dryden Drop
Tower (22.2m
drop~2.13 sec)
1) Cable Guided Drag
Shield
2) Open Enclosure
3) Magnetic Field/Eddy
Current Deceleration
4) Air Collet Release
Mechanism
5) Single Floor/ Single
Person Operation
6) Aesthetically Pleasing
7) Usuable for PSU
students, grad students,
and k-12 level activities
1) Tower height is 31.1m
2) Can routinely drop in 10 minutes
3) Deceleration takes 3.5m
4) Automated retrieval takes 5 min
Feasibility
1) Drag shield is not feasible,
we are using a vacuum tube
2) Lift mechanism may have
possible similarities
3) Catching system may not
work in a vacuum
environment
1) Can take design cues for
aesthetics
2) Could use some ideas for
educational aspect for
students, grad students and k12
3) Release mechanism could
have merit
4) Deceleration method
probably not feasible
Picture
Functional Decomposition
Demonstrate Microgravity
Concepts
Remove / Load
Items
Pressurize
Chamber
Access
Chamber
Add Air
Molecules
Open
Chamber
Open Valve
Break Seal
Isolate
Chamber
Section
Demonstrate Microgravity
Concepts
Depressurize Chamber
Remove Air
Molecules
Seal Chamber
Seal Doors
Seal Valves
Seal Piping
Close Valves
Turn Pump On
Demonstrate Microgravity Concepts
Position Objects at Top of
Tower
Grab Object
Apply Lifting Force
Supply Power
Vertical Lift
Release Object
Center Object
Remove
Supporting Force
Realease (No horizontal
motion)
Demonstrate Microgravity
Concepts
Collect Data
Collect
Pressure
Pressure Gage
Catch Object
Collect Temp
Collect
Position &
Time
Absorb Energy
Thermo
Couple
Sensor(s)
Dampening
Material
Vacuum
Independent
Material
Morph Chart
Possible Solutions
#
Components
1
2
3
4
5
1
Break Door Seal
Release Lever Clamp
Undo Bolts
Unscrew Cap
-
-
2
Close Isolation Valve
Manual
Pnematic
Electrical
-
None
3
Carry Object to Tower Top
Walk Upstairs
Throw Object
Pulley System
Elevator
None
4
Supply Power
Electrical
Battery
Natural Gas
-
None
Hoist Device
6 Release Platform
Claw & Cable
Capsule Grabber
Slingshot
Robotic Arm
None
Shaped Platform
-
-
-
-
5
7
Seal Doors
Lever Clamp
Bolted
Pipe Cap Screw
-
-
8
Seal Valves
PTFE Tape
Melting Together
-
-
-
9
Seal Piping
Sealant Compound
Melting Together
Silicon Seal
-
-
Close/Open Level Arm
Twist Valve
Check Valve
Electrical Power Valve
-
Digital-High Vacuum
Analog Display
-
-
-
12 Thermo Couple
Wire Type
Infered Sensor
-
-
-
13 Position/Time Sensor
Laser Sensor
Motion Sensors
Stop Watch / Ruler
Video Tape
-
Magnet
Doors
-
-
-
Net
Rubber
Gel
Spring Locking Device
-
Close/Open Level Arm
Twist Valve
Check Valve
Electric Valve
-
Drill into Walls
Tee w/
Removable Cap
Connecting to Railing
Detachable Base
(NASA)
Attach to Ceiling
All
-
Door Base
-
-
10 Close Valve
11 Vacuum Pressure Gage
14 Release Mechanism
15 Damping Material
16 Open Valve
17 Tower Anchoring System
18 Tower Base
Morph Chart
Possible Solutions
#
1
2
3
4
5
6
7
Components
1
2
3
4
5
Lever Arm
Twist Valve
Check Valve
Electrical Valve
None
Release Lever Clamp
Undo Bolts
Unscrew Cap
None
Manual I.V.
Pneumatic I.V.
Electrical I.V.
None
Seal Doors
Release Lever Clamp
Undo Bolts
Unscrew Cap
None
Seal Valves
PTFE Tape
Melting Together
Seal Piping
Pipe Sealant Compound
Melting Together
Silicon Seal
Close Valve
Lever Arm
Twist Valve
Check Valce
Mechanical Switch
Through Software
Open Valve
Break Door Seal
Isolate Tube Section
None
None
Electrical Power Valve
None
8
Turn Pump On
9
Grab Object
Magnet
Claw
Angled Platform
Supply Power
Electrical
Battery
Natural Gas
None
Magnet
Capsule
Platform
None
Magnet Locator
Capsule Locator
Shaped Platform
None
Magnet
Door Hatch
None
Digital-High Vacuum
Analog Display
None
Wire Type
Infrared Sensor
None
Vertical Sensor
Motion Sensors
Stop Watch / Ruler
Camera
None
Net
Plastic
Gel
Spring Locking Device
None
Drill into Walls
Connect to Railing
Attach to Ceiling
All
None
10
11
Vertical Lift
12
Center Object
13
14
15
16
17
18
Release
Pressure Gage
Thermo Couple
Position/ Time Sensor
Damping Material
Tower Anchoring System
CONCEPT &
ARCHITECTURE
DEVELOPMENT
Early Concept Draft
Pugh’s Matrix Component Concepts
Baseline
Ideal
Cheap
Feasible
Random
Pugh’s Matrix
Iteration #
Criteria
No horizontal motion during free-fall
Vacuum environmental control
Fast cycle time
Data accuracy
Properly restrained
Aesthetically pleasing
Low cost
Can be done in 2 semesters
Educational and fun
# of operators
Baseline
s
+
+
-5
Ideal
s
+
+
+
+
+
+
+
5
Cheap
s
s
+
s
s
-4
Feasible
s
s
s
+
s
+
s
+
1
Random
s
+
+
s
s
s
-2
Ideal
Cheap
s
+
+
-5
Feasible
s
s
s
+
s
s
-3
Random
s
s
s
+
-5
DATUM
2
Baseline
DATUM
1
Criteria
No horizontal motion during free-fall
Vacuum environmental control
Fast cycle time
Data accuracy
Properly restrained
Aesthetically pleasing
Low cost
Can be done in 2 semesters
Educational and fun
# of operators
Capsule Designs
Selected Concept
Selected Concept: Architecture
 Piping
1.
2.
3.
4.
5.
6.
Main Tower Piping
Tee Shape Base w/
Removable Cap
Tee Shaped Couplings
Standard Couplings
Base Flange for Tower Support
Sealing Cap
 Valve / Clamps
1.
2.
3.
Release Level Clamps
Pressurizing Valve
Manual Isolation Valves
 Sensors
1.
2.
3.
Laser Sensors
Thermocouple Sensor
Multifunctional DAQ
 Pump
1.
2.
3.
Vacuum Pump
Digital Vacuum Gage
Fittings
 Catch / Release
1.
2.
Release Platform
Polystyrene Beads for Deceleration
 Other
1.
2.
Pulley System
Basket
Selected Concept: Theory of Operation
Power up
computer
program and
components
Measure Pressure
w/ Digital Gage
Collect
Temperature
Reading
Latch Bottom
Cap
Depressurize
Bottom Chamber
Close Top
Isolation Valve
Only
Open Isolation
Valve
Start Laser Sensor
Data Collection
Remove Object
Pressurize Top
Chamber
Depressurize
Chamber under
Top Isolation
Valve
Depressurize Top
Chamber
Activate Platform
Release
Mechanism
Unlatch Bottom
Cap
Repeat as needed
Bring Object to
top of tower
Close Top
Watch Objects
Fall
Pressurize
Bottom Section
Unlatch Top and
Open Chamber
Load Object on
Drop Platform
Record results
before next test
Close both
Isolation Valves
Selected Concept: Approximate Cost
30ft Drop Tower Pricing
Item
2 Stage Rotary Pump
Bulk Head Fittings
Clear Acrylic Sheet
DAQ
Glue (1 Quart)
Ideal VacSeal
Isolation Valve
Laser Distance Sensor
Pipe (8ft)
Polystyrene Beads
Pressure Sensor
Slip Cap
Slip-Flange
Slip-Slip Coupling
Slip-Slip-2inFPT Tee
Slip-Slip-Slip Tee
Thermocouples
TAX (Based on 8%)
Material
Plastic
Clear Acrylic
Clear Cement
Thermal-plastic
Clear Cast Acrylic
Polysteren Beads
White PVC
Dark Grey PVC
White PVC
White PVC
White PVC
-
6in Diameter
Quantity
2
1
1
1
2
1
2
2
4
1
4
2
5
3
4
1
1
Total Cost:
8in Diameter 12in Diameter
Price
$352.34
$13.16
$24.59
$99.00
$76.04
$49.75
$4,012.00
$1,000.00
$1,022.72
$40.00
$700.00
$75.14
$382.00
$109.23
$556.00
$125.37
$30.00
$693.39
Price
$352.34
$13.16
$24.59
$99.00
$76.04
$49.75
$4,880.00
$1,000.00
$1,568.64
$40.00
$700.00
$109.48
$275.64
$217.86
$697.40
$125.37
$30.00
$820.74
Price
$352.34
$13.16
$24.59
$99.00
$76.04
$49.75
$9,984.00
$1,000.00
$3,925.80
$40.00
$700.00
$1,355.76
$347.38
$486.40
$9,360.73
$11,080.01
$20,098.36
$125.37
$30.00
$1,488.77
Engineering Analysis
Engineering Analysis
 Gravity Calculations
 % Error in gravity calculations
 Drag Force Calculations
 Tube Conductance
 Pump down (evacuation) time
 Ultimate Pressure Required
 Critical Pressure for Tube Dimensions
Gravity Calculation with 1% Error
 Constant Acceleration Equations
 Assumes no air resistance / perfect vacuum
 𝑥 = 𝑥0 + 𝑣0 𝑡 + 0.5𝑎𝑡 2
𝑔 =
2𝑥
𝑡2
, where x is position and t is time
 Error in Gravity
 Assumes perfect Vacuum
 1% 𝐸𝑟𝑟𝑜𝑟 𝑔 = % 𝐸𝑟𝑟𝑜𝑟 𝑥 + 2(% 𝐸𝑟𝑟𝑜𝑟 𝑡)
Free Body Diagram of Object
 Force Balance
 𝐹𝑦 = 𝑚𝑎
 𝐹𝐷 − 𝑚𝑔 = 𝑚𝑎
 At Terminal Velocity, acceleration = 0
 𝐹𝐷 = 𝑊
 At Vacuum Pressure, drag force = 0
 −𝑚𝑔 = 𝑚𝑎, where a is downward (negative)
Drag Force (Air Resistance)
 𝐹𝐷 = 0.5𝜌𝑉 2 𝐶𝐷 𝐴
 FD = Drag Force
 ρ = Air Density
 V = Velocity of Object
 CD = Drag Coefficient (Fudge Factor)
 A = Projected Area of Object
𝑃
𝑅𝑇
 P = Air Pressure (Pa)
 R = Specific Gas Constant = 287.05 J/kg*K
 T = Air Temperature = 21°C = 274K
𝑘𝑔
−5
 𝜌 = 1.185 ∗ 10
∗𝑃
𝐽
 𝜌=
Conductance
 The flow of air in a tube, at constant temperature, is dependent on
the pressure drop as well as the cross sectional geometry.
𝐷4
 𝐶𝑉 = 𝐹1 Ṗ , (Viscous Flow 760Torr  1Torr)
𝐿
3
𝐷
 𝐶𝑀 = 𝐹2 , (Molecular Flow 1Torr Vacuum)
𝐿
 C = Conductance (liters/sec)
 Ṗ = Average Pressure(torr) =
𝑃1 −𝑃2
2
 F1 = Viscous Flow Scale Factor = 2950
 F2 = Molecular Flow Scale Factor = 78
 D = Pipe Diameter (in)
 L = Pipe Length (in)
Effective Pump Speed

1
=
1
𝑆𝑃
+
1
𝐶
𝑆𝐸𝑓𝑓
 C = Conductance (cfm)
 We assume that for Viscous Flow, 𝑆𝑃 = 𝑆𝐸𝑓𝑓
 𝑆𝑃 = Given Pump Speed (cfm)
 𝑆𝐸𝑓𝑓 = Effective Pump Speed for Tube Dimensions
• Example: Single 6” x 30’ Tube
 𝑆𝑃 = 10 cfm (assumed)
 𝐶𝑀 = 99 cfm
 𝑆𝐸𝑓𝑓 = 9.1 cfm
Evacuation Time
 𝑡=
𝑉
𝑃0
ln
𝑆𝑃
𝑃1
+
𝑉
𝑆𝐸𝑓𝑓
l𝑛
𝑃1
𝑃2
VP10D CPS
Vacuum Pump
 𝑃0 = 760 Torr
 𝑃1 = 1 Torr
 𝑃2 = Final Pressure
• Example: Single 6” x 30’ Tube
 𝑃2 = 15 micron or 0.015 Torr
 𝑆𝑃 = 10 cfm (assumed)
 𝑆𝐸𝑓𝑓 = 9.1 cfm
 𝑡 = 6.63 𝑚𝑖𝑛𝑢𝑡𝑒𝑠
2 Stage Rotary Pump
15 micron Ultimate Vacuum
Pump Speed – 10 cfm
Price: $417.89
Pressure Requirement
 The pressure required for accurate gravity calculations can be
calculated using the previous equations and the following
assumptions:
 Max Tube Height = 12 meters
 Constant Acceleration
 Max Object Mass = 2.27 kg
 Max Drag Coefficient = 2.0
 Max Projected Area = Cross Sectional Area for 10 cm Diameter
 Allowable Error in Gravity due to Pressure = 0.01%
 These assumptions yield an allowable pressure of 103 Pa
(0.773 Torr or 773 microns)
Effect
Pipe Implodes under •
1
Pressure
•
Safety Hazard
Project ruined
2
Damages to pipe
•
•
Loss of visibility
Loss of Vacuum
Cause
•
•
•
•
Pipe wall
thickness
Material
Shipping
Human Error
1
2
3
2
Importance
Risk Item
Severity
I
D
Likelihood
Risk Assessment
Action to Minimize Risk
a)
Determine critical pressure of pipe, with
safety factor
a)
b)
Careful shipment and assembly
Pick location where pipe is safe from
accidental damages
Determine pipe resistances to scratches,
crack, etc.
Adequate space around pump for
ventilation
Turn pump off when not in use
Limit the number of consecutive runs if
needed
Analyze pump specifications
Ensure tower can withstand its own
weight
Develop sturdy design
Attach tower to surrounding wall,
railings, etc. at different heights
3
4
c)
a)
3
4
Pump Over heat
Tower Falls Over
•
•
•
•
•
•
Loss of efficiency •
Fire hazard
Pump
•
replacement
•
Safety Hazard
Damages to
Surroundings
Project Ruined
Improper pump
size
Poorly ventilated
Left on
1
2
2
b)
c)
d)
a)
•
•
•
Poorly supported
Earthquake
1
Weak structure
3
3 b)
c)
I
Risk Item
D
5
6
7
8
9
Effect
•
•
Any sealing leak
•
Object Impact
breaks Base
Laser Sensor
Looses item
•
•
•
•
Loss of Vacuum
•
Noisy
•
Increased depressurize
•
time
Bad Sealant
Gaps in o-rings
Surface impurities
Object destroyed
Safety hazard
Pipe base broken
Loss of vacuum
• Cannot support
objects force
• Loss of data(position
and time)
• Improper sensor
alignment
• Sensor range
inadequate
• Power loss
Inaccurate
• Improper data display
Gauge Reading • Improper vacuum
Stolen
components
Cause
• Device unusable
L
S
3 2
Action to Minimize Risk
I
6
a)
b)
c)
a)
1 2
2
b)
a)
2 2
4
b)
c)
a)
• Cheap gages
• Not calibrated
correctly
1 1
1
• Components left
out/unlocked
1 2
2
b)
a)
b)
Require minimal seal points
Research proper sealing techniques for
each component
Monitor pressure change
Determine maximum force on impact
(including safety factor)
Properly correct for that force with
cushion, net, etc.
Determine whether vertical position
sensor can detect all objects
Properly align sensor(s) with object
Ensure pipe connection can withstand
that force
Calibrate all gage regularly (note in
manual)
Purchase accurate & Reliable gages
(tolerance)
Bring components out when needed
Lock components up when not in use
(near or away from tower)
ID Risk Item
Effect
•
10
11
12
13
Loss of Data
Unsuccessful
Release of
objects
Lifting device
Malfunction
•
•
•
•
•
Improper use of •
system
Cant calculate
gravity, drag and
other data
Items does not fall
Horizontal motion
occurs
Unsynchronized
release
Item does not lift
No dropping
experiment
Compromises
system integrity
Cause
L
S
Action to Minimize Risk
I
a)
•
•
Loss of power
Software malfunction
•
Mechanism doesn’t
open
Release timing off
Loss of power
•
•
•
•
•
Broken wire/ claw
Loss of power
Improper motor
power
•
Poorly written
manual
Complicated
operation
Unauthorized use
•
•
1
2
2
2
2
2
2
4
b)
c)
Ensure Proper Electrical
Connections
Capture all required data
Possible sore multiple run data
a)
b)
c)
Release objects simultaneously
Platform adequately centers objects
Robust latching mechanism
a)
b)
No lifting device, load form top
Ability to easily hold weight & size
of objects
Ensure wire/cable does not get
stuck
4
c)
1
1
1
a)
b)
c)
Create intuitive design
Create detailed operators manual
Limit use to qualified individuals
Top Locations: #1 selection
Thomas Gosnell Hall
Thomas Gosnell Hall – Floor plan
Available Height:
1- 46’
2 - 43’
3 – 39’
Top Locations: #2
James E. Gleason Hall
James E. Gleason Hall – Floor plan
Top Locations: #3
Institute Hall
Institute hall – floor plan
North
Door
Stairs
Available Height:
77’-6”
Top Locations: #4
Golisano Institute of Sustainability
Golisano Institute of Sustainability –
Floor plan
Test Plan
#
Test Description
Comments/Status
1 Lift Mechanism (scaled model)
Small model if needed, without tube
2 Test Release Mechanism
Drop Object from any height with chosen mechanism
3 Position sensor accuracy
Sensors can be mounted and tested without tube
4 Vacuum pump quality
Connect vacuum to pressure gage only
5 Pressure gage accuracy
Connect vacuum to pressure gage only
6 Temperature gage accuracy
Calibrate Sensor
7 DAQ device inputs
temp, pressure, position, & time captured
8 Computer Software Outputs
computer outputs based on certain inputs
Schedule
MSD I Project Schedule
Select & Approve Location
Development Calculation
Components Calculation
Research Components
Obtain Costs
System Design
Sub-System Design
Detailed Design
Complete Design
Develop Bill Of Materials
Order Long Lead Time Items
September
2
3
4
5
October
6
7
8
November
December
9 10 11 12 13 14 15 16 17 18
New Focus
 Tower should be capable of running continuously
 Minimize time when tower is not is use
 Declare priorities
 What range of experiments will we be performing
 Do cost / benefit analysis for tower height
 Not simply based on “wow factor”
 Consider other stakeholder opinions
 Dean Palmer, Undergraduate Professors
 Possibly make a scale model of final concept
 3-5ft tall prototype
 Money is not an issue, with a great design
 Up to $20,000 if the ideas are worth the investment
Questions?