P14651: Drop Tower for Microgravity
Simulation
Adam Hertzlin
Dustin Bordonaro
Jake Gray
Santiago Murcia
Yoem Clara
Agenda
 Background
 List of experiments
 Engineering Requirements
 Concept Design
 Subsystem / System Analysis
 Data Analysis Software Files
 Risk Assessment
 Test Plan
 MSD II Schedule
 Bill of Materials
Project Summary
 Problem Goals
 Design & Build Drop Tower
 Vacuum Piping Structure
 Cost Effective
 Effective Cycle Time
 Aesthetically Pleasing
 Precision in Measurements
 Intuitive User Interface
 Access for Object Transfer
 Adaptability for Future Development
 Constraints
 The device is aesthetically pleasing
 The tower 6” – 12” Diameter
 The device can be operated year round
 The device must be moveable
 The system is safe to operate
 The project budget is $3,000
 The project must be completed in 2 semesters
Project Deliverables
 Installed drop tower
 Detailed Design Drawings and Assembly Manual
 Bill of materials
 User’s Guide for operation
 Designed Lab Experiments
 Fun and Educational Experience for Students
 Technical Paper
 Poster
Customer Requirements
Customer
Rqmt. #
Importance
CR1
CR2
CR3
CR4
CR5
CR6
CR7
CR8
CR9
CR10
CR11
CR12
CR13
CR14
CR15
CR16
CR17
CR18
9
9
9
9
9
9
9
9
9
9
9
9
3
3
3
3
3
3
Description
Appropriate Tower Height
Allow for Adjustable Pressure
Display Tower Pressure
Drop 2 objects simultaneously
Drop objects with no horizontal motion
Demonstrate standard local gravity within 1%
Display important outputs accurately
Allow full drop visibility and limit distortion
Demonstrate drag vs. pressure
Allow objects to be changed out
Safe / Intuitive operation
Educational and Inspiring
Moveable Structure
Design considers noise and power requirements and limits
Components are properly maintained and stored
Aesthetically pleasing
Generate object lift mechanism concepts for future MSD
Allow for further static experiments
Engineering Requirements
Rqmt.
#
I
SR1
SR2
SR3
SR4
SR5
SR6
SR7
SR8
SR9
SR10
SR11
9
9
9
9
9
9
9
9
9
3
3
SR12
3 Pump Flow Rate
SR13
3 Impact Energy Dissipation Method
SR14
SR15
SR16
3 Air Intake - Tower Pressure Change Rate
3 Minimal Error in Calculations
3 Aesthetic Data Display
liter/min
% error
Yes / No
SR17
3 Platform for Stationary Experiments
Yes / No
Engr. Requirement (metric)
Measure Relative Object Position
Measure Relative Object Drop Time
Measure Pressure
Cycle Run Time
Pressure Leak Rate Minimized
Aesthetic Structure with Supports
No Horizontal Motion
Tube Collapse Pressure
Timing difference of object release
Tower Height
Tower Cross - Section (Diameter)
Unit of
Measure
Marginal Value
Ideal Value
meter
% of Drop
Pa
min
Pa / sec
Yes / No
meter
F.O.S.
Millisecond
Meter
Meter
0 - 4.6
95 - 100%
0 - 101325
1-10 mins
Unknown
Yes
0 - 0.005
0-5
0-5
2.1 - 4.6
0.1524 - 0.2032
>Tower Height
100%
0 - 101325
1 min
0
Yes
0
5
0
15
8
liter/min
56 - 283
(mminvfinal2/2)(mmaxvfinal2/2)
10
Joule
(mmaxvfinal2/2)
Low to High Speed Moderate Speed
0 - 1%
0%
Yes
Yes
No or Yes
Yes
List of Experiments
1.
Vacuum vs. Atmosphere
Time
– Fall
4.
 Undergraduate Level (Fluids / Numod)
 Middle School Level (Science)
 Requires Complete System
 Requires Vacuum Chamber
 Start and End Time Required
 No Calculations Needed
2.
Calculate Drag Coefficient
 High School Level (Physics)
Decreasing Object Acceleration (Air
Resistance)
 Requires Complete System
 Undergraduate Level (Fluids)
 Start and End Time Required
 Requires Release / Laser System
Gravity in Vacuum Conditions
5.
 Multiple Data Points Required
3.
Gravity in Atmospheric Conditions
 Undergraduate Level (Physics)
 Requires Release / Laser System
 Start and End Time Required
6.
Extra Vacuum Experiments
 Middle School Level (Science)
 Requires Vacuum Chamber
 No Data Required
Drop Tower Design
Tower Height Distribution
Total Height of Tower
11’ 1.30”
3.385 m
Drop
Distance
8’ 3.77”
2.535 m
Total Height Available
11’ 7”
3.53 m
Results
 Total available height: 3.530m (11ft 7in)
 Total used height: 3.385m (11ft 1.3in)
 Total clearance: 0.145m (5.7in)
 Total drop distance: 2.535m (8ft 3.77in)
 In Vacuum:
 Total drop time with standard gravity is 0.719 s
 Speed at impact is 7.05 m/s (23.14 ft/s)
Full System Analysis
Release Mechanism Analysis
Solid Model
Section View
Motor Type w/ Specifications
 Speed at 6V
 0.12 sec/60°
 0.04 sec/60°
 0.24 m/s
 Torque
 61 oz-in
 3.81 in-lb
 0.43 Nm
 Weight
 43g
Max Applied Force
Max Weight Calculation
𝑇𝐹 = 𝑇𝑟
 Gear Ratio
 3
 Length of the door
 1.5 in (0.038 m)
𝑇𝑠
𝐹𝑙 =
𝑚𝑔
3.81 𝑖𝑛 ∗ 𝑙𝑏
𝐹 1.5𝑖𝑛 =
3
𝐹 = 0.846 𝑙𝑏 (3.768 𝑁)
Micro-Controller
Future Use Compatibility
•
The tower that will be built will have the capabilities of hosting a
continuous lift system within the pipe. All the other subsystems would
be able to work as regular with the moving system.
•
The only thing that would have to be address would be the modification
of the software so it can monitor the displacement of the platform.
Displacement
Platform
This platform would be the
one responsible to catch the
objects at the bottom of the
tower and to bring them to
be pick up by the release
mechanism.
Object
Positioning
Assembly
This assembly will allow the
object to be picked up by the
release mechanism doors.
A stopper in the release
mechanism fixture will
activate the motion upwards,
and gravity would do the work
to bring it back to a regular
position.
Object Positioning Assembly
Frame Analysis
Tube Deflection
 Assumes a worst case, where the entire structure is laying
horizontally, 3.048 m (10ft) tower.
 The tube is fixed at the riser clamps pictured above, and is
analyzed with two or three riser clamps, at either 8 or 4ft (2.44 to
1.22m) apart.
 With 2, ymax is -1.5mm (-.058in)
 With 3, ymax is -.093mm (-.0037in)
 So, three riser clamps will be used as deflection is decreased
dramatically
Riser Clamp Connections
Critical Tipping Scenario
Tower Supports
Frame Subsystem Analysis
Subcomponent Selection
 Rotation joints at top (for laser adjustment):
 From McMaster-Carr
 ¼” binding post
 ¼” bolt
 Wheels and axels:
 Wheels from McMaster-Carr, each supports 250 lbs.
 Axels from McMaster-Carr, analysis follows.
 Height adjustment/leveling:
• From McMaster-Carr,
6 required, each supports 250 lbs
Axel Calculations
I= 1.27698E-09 m^4
a=.0381m
F2 (fixed)
fy=0: F1+W-F2=0
b=.026m
M(wheel)=0: -F1(.0381+.026)+F2(.026)=0
F1=522.2N; F2=1287.4N
x
Singularity Functions:
F1 (fixed)
=
Reaction at Wheel (weight) (free)
Deflection
M(x)=F1x-F2<x-a>^1
0.060
EI(d2y/dx2)=F1x-F2<x-a>^1
0.050
EIY=(1/6)F1x^3-(1/6)F2<x-a>^3+c1x+c2
@x=0,y=0: c2=0
@x=a,y=0: c1=-(1/6)F1a^2
deflection-mm
EI(dy/dx)=.5F1x^2-.5F2<x-a>^2+c1
0.040
0.030
0.020
Deflection
0.010
0.000
so, y=(1/EI)*((1/6)F1x^3-(1/6)F2<x-a>^3-(1/6)F1xa^2)
Also, shearing of axels:
τ= 6.69E+06 Pa
FOS=
55
-0.010
-0.020
0
10
20
30
40
x-mm
50
60
70
80
Laser & DAQ Analysis
Specifications & Setup
 Micro-Epsilon ILR 1030-8/LC1
 10ms response time -- over ~2.54m (8’3.8”) this is ~ 70 data points









(fall time ~0.72 seconds in a vacuum)
+/- 2.5mm accuracy in position
4 - 20 mA output related to distance fallen, and must be calibrated.
So, 4mA = 0m
and 20mA = 2.6m
Divergence of 0.0859° gives a ~4mm dot at 2.54m (8’3.8”)
Voltage will be created from mA output via a 249 ohm resistor, for DAQ purposes; DAQ
will be NI USB-6008; 10 kS/s acquisition speed.
Can see though polycarbonate, as long as it passes through before start of data collection
(data collection starts at 0.2m (7.9in) and angle of entry +/-5° from perpendicular to
surface
Laser is visible dot (important for alignment and calibration)
M12 connector for power and interface, requires 10-30 VDC
M12 cable has pigtail bare lead ends
Mounted via M5 through holes
Frame Mounting Components
Bending of Links
Assumptions:
-Treat multiple distributed loads as a point
load on the end
-Treat as a solid beam 250mm to mass
application
apllication
Total weight of all components is ~5N
Applying twice this at 250mm:
I= (1/12)*b*h^3
I=
4.06E-10 m^4
Beam dimensions:
l=
b=
h=
250 mm
19.05 mm
6.35 mm
E= 2.05E+11 Pa
y=
y=
y=
-0.000625 m
-0.63 mm
-0.024608 in
Pipe Analysis
CAD Drawing
Critical Negative Pressure
Critical Pressure Calculations for Clear PVC
P
14.7 psi
v
0.37
E
429000 psi
Formula
PCrit=(2*E/(1-v^2))*(1/((OD/t)-1)^3)
SCH 40 Pipe Maximum Pressure
Size (in)
OD (in)
Thickness (in)
Max Pressure (psi)
Factor of Safety
6
6.625
0.28
85.43
5.81
 Desired Factor of Safety > 3 ✔
Max Pressure Rating of Schedule 40 PVC*, from HARVEL
Size (in)
6
Max Pressure (psi)
90
*Specifications for white PVC
Pipe Dimensions Courtesy of Engineeringtoolbox.com
Factor of Safety
6.12
Energy Dissipation Analysis
Material Selection
 Polystyrene Beads (Bean Bag)
Critical Dimensions of Impact
Absorption material
Critical Dimensions of Impact Absorption material
Required Height vs. Object Mass
0.18
.
Height required (Meters)
0.16
𝑚𝑏=
𝑚𝑎
𝐶𝑅
0.14
0.12
0.1
0.08
0.06
0.04
0.02
0
0
• Assuming a Coefficient of
Restitution (𝐶𝑅 ) of 0.712
0.2
0.4
0.6
0.8
Mass of object being dropped (Kg)
1
1.2
Pump Analysis
Specifications
 Free Air Displacement – 6.25 CFM @ 60Hz
 Horse Power – 1/2 HP
 RPM – 3440 @ 60Hz
 Ultimate Vacuum – 15 microns (2 Pa)
 Intake Ports (male flare) – 1/4", 3/8" SAE Male & 1/2"
ACME Male
 Oil Capacity – 15 oz./450 ml
 Dimensions – 13.7'' x 5.6'' x 10.4''
 Shipping Weight – 25.4lb/11.5kg
Evacuation Time
 Equivalent Length, Le, based on pipe losses
 Effective Pump Speed based on pipe geometry and flow regime
 Evacuation Time based on Volume, Pump Speed and flow regime
Main Pipe
Secondary Pipe
Combination of Pipes
Evacuation Time
Total Le (ft.)
60.0
3.9
Conductance (cfm)
Viscous
Transitional Molecular
4268347.2
315.4
49.0
16135.4
2.4
1.5
Sp
(cfm)
6.25
Effective Pump Speed (cfm)
Viscous
Transitional Molecular
6.25
1.70
1.17
4.74
1.38
 Total Evacuation Time (no leaks): 6.12 mins
N/A
Connection Port Analysis
Cable Feed Through
•
•
•
•
•
•
By recommendation of Dr. Robert Pearson and a
price vs. effectiveness research. The use of potting
compound is preferable for our application
Apiezon Sealing compound Q is an economic option
to seal a leak in a vacuum system. It is sufficiently
firm at room temperature to remain in position, yet
soft enough to be molded by hand and is readily
removed
Some Properties:
temperature range, °C: -10 to + 30
Vapor pressure @ 20°C, in torr: 1x10-4
Packaging: 1 kg
Cable
Polycarbonate Plate
Shrink Tubing
Sealing Compound
Pipe Connection - Bottom
 Connection allows for vacuum hose to be
Brewer’s Hardware
- P/N WLFM12F12
-Weldless Bulkhead
- 1/2" MPT X 1/2" FPT
connected though the bottom
polycarbonate cap
 Seals against each side via gasket
 Allows for pipe to be screwed on inside
drop tower to pass by polystyrene beam
bag
Pipe Fitting
Analysis
Pipe End Cap Fittings
Top
Bottom
Tower Fittings
Pressure Gauge Analysis
Digital Vacuum Gauge
Specifications
 Range
 Atmospheric to 0 microns
 Max Working pressure 400 PSIG
 Accuracy
 +/- 10%
 Powered By
 9V Battery
 Operating Temp. Range
 32° - 120° F (Compensated)
 -22° - 158° F (Non-Compensated)
 Mechanical Connection
 Standard 1/4” female SAE refrigerant
hose type with core depressor
Labview / Matlab Code
Vacuum Conditions
 Calculating Gravity within a vacuum
 Base chamber pressure will be considered as the optimal vacuum condition (Goal = 2Pa or 15
microns)
2(𝑥 𝑥0 )
𝑔=
(𝑡 𝑡0 )2
𝛥𝑔 =
𝜕𝑔
∗ 𝛥𝑥
𝜕𝑥
2
𝜕𝑔
+
∗ 𝛥𝑥0
𝜕𝑥0
2
𝜕𝑔
+
∗ 𝛥𝑡
𝜕𝑡
Note: Pressure threshold between Vacuum and Non-vacuum will be
determined through tested
2
𝜕𝑔
+
∗ 𝛥𝑡0
𝜕𝑡0
2
Atmospheric Condition
 Calculating Gravity with Drag
 Pressure range: Atmospheric Pressure – Vacuum Pressure Threshold
𝑚𝑎 = 𝐹𝐷
𝑚𝑔
𝑑𝑉 𝜌𝐶𝐷 𝑉 2 𝐴
=
𝑑𝑡
2𝑚
𝑔
(𝑥−𝑥0 )𝜌𝐶𝐷 𝐴
2𝑚
2𝑚
𝑔=
∗ 𝑖𝑛𝑣𝑐𝑜𝑠ℎ 𝑒
2
𝜌𝐶𝐷 𝐴(𝑡 𝑡0 )
𝛥𝑔 =
𝜕𝑔
∗ 𝛥𝑥
𝜕𝑥0
2
𝜕𝑔
+
∗ 𝛥𝑥0
𝜕𝑥0
2
𝜕𝑔
+
∗ 𝛥𝑡
𝜕𝑡
2
𝜕𝑔
+
∗ 𝛥𝑡0
𝜕𝑡0
2
𝜕𝑔
+
∗ 𝛥𝑚
𝜕𝑚
2
𝜕𝑔
+
∗ 𝛥𝐴
𝜕𝐴
2
2
𝜕𝑔
+
∗ 𝛥𝜌
𝜕𝜌
2
𝜕𝑔
+
∗ 𝛥𝐶𝐷
𝜕𝐶𝐷
2
Uncertainty in Measurements
 Position (x, x0), where x0=0m
 +/- 0.0025m from laser
 +/- 0.0005m from first measurement timing
 Time (t, t0) ), where t0=0s
 +/- 0.0001s from DAQ (10,000 samples per second)
 Mass (m)
 +/- 0.0001kg from scale
 Projected Area (A)
 +/- 0.0001 m^2 from measurement device
 Pressure (P)
 +/- 10% from pressure gauge
 Temperature (T)
 +/- 1 degree C from thermometer
 Drag Coefficient (Cd)
 +/- 0.1 from estimation (maybe better if calculated first)
Example #1 – Gravity in Vacuum
 1” Steel Ball





P=2;
t=0.782062;
t0=0;
x=3.0;
x0=0;
𝑚
𝑔 = 9.81 ± 0.0143 2
𝑠
 Relative Error: 0.15%
 Percent Difference: 0.00%
Example #2 – Gravity in Atmosphere
 1” Steel Ball








m=0.067278 kg
P=101325 Pa
A=0.000507 m^2
t=0.782895 s
t0=0 s
x=3.0 m
x0=0 m
Cd=0.47
𝑚
𝑔 = 9.81 ± 0.0157 2
𝑠
 Relative Error: 0.16%
 Percent Difference: 0.00%
Labview Front Panel
Matlab Code
 Drag Coefficient, 𝐶𝐷
 Cannot solve directly for 𝐶𝐷
𝑥𝜌𝐶𝐷 𝐴
2𝑚
2𝑚
𝑔=
∗
𝑖𝑛𝑣𝑐𝑜𝑠ℎ
𝑒
𝜌𝐶𝐷 𝐴𝑡 2
2
 Use root finding method to solve for 𝐶𝐷
 Secant Method (or other)
 Must assume value for gravity (9.81 m/s^2)
 Import Position and Time Data from Labview
 Experiment will require numerical methods and physics
knowledge
Subsystem Test Plan
#
Main Component
Description
Status
1
Catching System
Dissipate Objects Energy from Falling
Open
2
Release Mechanism
Quick Release w/ No Horizontal Motion
Open
3
Tower Frame
Test Tower Stability During Operation
Open
4
Laser Sensor
Best Position to Track Objects Fall
Open
5
DAQ Device
Appropriate Signal is Programmed and Functional
Open
6
Labview Program
Compare Results to Analytical Predictions
Open
7
Pressure Gauge
Calibrate and Test Entire Pressure Range
Open
8
Vacuum Pump
Vacuum Tube
& Fittings
Attach Pressure Gauge Directly to Pump
Open
Test Ultimate Pressure
Open
9
Fully Integrated System Test Plan
#
Main Component
Description
Status
1
Object Fall Time
Vacuum vs. Atmospheric Condition
Open
2
Gravity - Vacuum
Calculating Gravity through Labview
Open
3
Gravity - Atmosphere
Calculating Gravity through Labview
Open
4
Drag Coefficient
Calculating Drag Coefficient in Matlab
Open
5
Drag vs. Pressure
Stationary Platform &
Objects
Calculated Fall Velocity over Pressure Range
Open
Observe Behavior of Objects in Vacuum
Open
6
High Leak Rate
Importance
1
Risk Item
Severity
ID
Likelihood
Risk Assessment – High Risk Items Only
3
2
6
• Improper sensor alignment
• Sensor range inadequate
• Power loss
2
3
6
Effect
•
•
•
Loss of Vacuum
Noisy
Increased depressurize time
Cause
•
•
•
Bad Sealant
Gaps in o-rings
Surface impurities
2
Laser Sensor Looses • Loss of data
Item
(position and time)
3
Unsuccessful
Release of Objects
•
•
•
Items does not fall
Horizontal motion occurs
Unsynchronized release
•
•
•
Mechanism doesn’t open
Release timing off
Loss of power
2
2
4
4
Pipe Implodes
•
•
Safety Hazard
Project ruined
•
•
Pipe wall thickness
Material
1
3
3
Tower Falls Over
•
•
•
Safety Hazard
Damages to Surroundings
Project Ruined
•
•
•
Poorly supported
Earthquake
Weak structure
1
3
3
5
MSD II Schedule – Part 1
MSD II Schedule – Part 1
Bill of Materials
Bill of Materials Continued
Bill of Materials Continued
Bill of Materials Continued
Questions?