The University of Arizona Hyperloop team designed an air bearing and suspension system for a Hyperloop pod. Their design included pushrod suspension and wheels to support the pod below 100 mph, with air bearings and hydraulic suspension taking over above 100 mph. A two-stage compressor was used to pressurize air for the bearings. Risks addressed included loss of air pressure and complete compressor failure, with backup systems like an emergency air tank. The estimated 11,000 lb pod design met requirements for speed, power usage, and tube interface.

1. The University of Arizona
Air Bearings & Suspension Hyperloop
Pod Subsystem Design
Namrah Habib, John Mangels, Irene Moreno, Corey Colbert, Jacob Pavek
on behalf of
The University of Arizona Hyperloop Competition Team

2. DLN 8/24/15
System Level Requirements
Type Description
Verification Method
Analysis Inspection Success
Pod Constraint Pod mass shall not exceed 11,000 lbm X X Meets
Test Track Interface Pod shall shall fit within the cross-sectional area of the test track X X Meets
Operational Pod shall be moveable at low speeds when not in operation X Exceeds
Test Track Interface Pod shall utilize Operational Propulsion Interface X Meets
Operational Pod shall be able to come to a complete stop by use of a braking system X Meets
Operational
Pod shall travel along the track in a smooth motion without colliding into
the center rail
X Exceeds
Operational Pod shall be able to travel at Mach 0.3 without inducing a Kantrowitz effect X X Meets
Operational
Pod shall be able to levitate using air bearings between the end of the
acceleration phase and the beginning of the braking maneuver
X X Exceeds
Pod Constraint Pod shall be powered by an onboard power system X Meets
Operational
Pod shall be able to operate with an ambient tube pressure between
0.02 - 14.7 psi
X X Meets
Power Constraint
Compressor and bearing support subsystems shall not exceed 1082.82
HP of onboard power
X X Exceeds
2

3. DLN 8/24/15
Subsystem Level Requirements
Subsystem Description
Verification Method
Analysis Inspection Success
Bearings
Air bearing system shall interface with the test track according to the
Hyperloop Tube Specification Document
X Exceeds
Bearings
Air bearings shall levitate the pod before the completion of 800 ft
acceleration phase
X Meets
Bearings Wheels shall support the pod during initial acceleration X X Exceeds
Bearings Bearings subsystem weight shall not exceed 3700 lbm X Meets
Bearings
Pod shall smoothly transition between wheeled bearings and air bearings
during acceleration and deceleration phases
X Exceeds
Compressor Compressor shall intake air moving between 0 and 334 ft/s X Meets
Compressor
Compressor shall supply air pressurized to 3.2 psi for the air bearing
subsystem
X X Meets
Compressor Pod diameter shall not exceed 70% of tube diameter X Meets
Compressor Compressor subsystem weight shall not exceed 4700 lbm X Meets
3
*Demonstrations and test verification methods were not considered because no physical pod is being built

4. Hyperloop Pod Structure
1
22
3
4 5
(1)Nose (2)Hydraulic Actuators (3)Pod (4)Air Bearing Platform (5)Wheel (6)Tube Track
4
6
1
Below 100 MPH
Above 100 MPH

5. Air Bearings & Suspension Structure
5

6. Compressor
Wheels
Air Tank
Air Bearing
Platform
Legend
Mechanical
Connection
Pushrod
Suspension
Pod
Frame
Hydraulic
Suspension
6
Concept Architecture

7. Air Bearing System Overview
7

8. Air Bearing System Overview
8

9. Design Concept
Pushrod Suspension
Wheel
Air Bearing Pad
Hydraulic Actuators
Operation Below 100 MPH
•Pod weight is supported by wheels and pushrod suspension
•1 Wheel and pushrod suspension per air bearing pad
•2 Hydraulic Actuators per air bearing pad
9

10. Design Concept
Operation Above 100 MPH
•Pod weight is supported by air bearings and hydraulic suspension
•Minimum 1 inch gap between wheels and tube surface
Pushrod Suspension
Wheel
Air Bearing Pad
Hydraulic Actuators
10

11. Design Concept Safety Feature
Condition
Nominal operation above 100 MPH
• Hydraulic actuators pressurized
• Air bearings are extended
• Wheels float
• Pod levitated according to air bearing
requirements
Condition
Compressor failure
● Air bearings fed from reserve air tank
● Pod slows to safe wheel speed
● Air bearings retract
● Pod levitated according to wheel requirements
11

12. Hydraulics System
12

13. Hydraulic System Components
13
Air bearing to damper
attachment point
Pod to damper attachment point
Air bearing to damper
attachment point
Spring
Piston guide cylinder
(hydraulic fluid contained
here)
Damper piston
Damper piston guide
Hydraulic fluid line
connections

14. Hydraulic System Components
14
Component Description Material
Hydraulic Spring Spring used in bearing platform suspension 6150 Chromium-Vanadium Steel
Upper/Lower Piston Pistons used in hydraulic suspension 6061 Aluminum

15. 15
Pushrod Suspension

16. 16
Pushrod Suspension

17. 17
Pushrod Suspension
Mass 21.6 lbm
Material Normalized 4130 Steel
● Used during nominal acceleration and deceleration of the pod

18. Air Bearing Platform
18

19. Air Bearing Platform
19
Mass 131.86 lbm
Material 6061 Aluminium Alloy
Load Capacity 2750 lbf

20. Air Bearing Platform
Pad Geometry
Length 75.0 in
Width 15.0 in
Thickness 1.25 in
Air Bearing Geometry
Cavity Radius 7.25 in
Cavity Depth 0.02 in
Nominal Gap Height 0.03-0.06 in
Nominal Bearing Angle 0.05°
20

21. • Orifice Control Flow:
• Length < Diameter
• DOrifice = 0.4(DTubing)
• High bearing stiffness
• Easily maintained
• Rowe Valve:
• Provides constant flow of air
• Fast response
• Larger bearing tolerance
• Greater load capacities
Air Flow Control Schematics
21
Hydrostatic and Hybrid Bearing Design

22. Compressor
22

23. Power
Tubing
Compressor Architecture Diagram
Legend
Data
Bridged
Power
Mechanical
Connection
Axial
Compressor 1
Low Pressure
Axial
Compressor 2
High Pressure
Motor 1 Motor 2
Control
System
Processor
Storage Tank
Air
Bearings
Suspension
Thrust
Power
23

24. Power
Tubing
Compressor Architecture Diagram
Legend
Data
Bridged
Power
Mechanical
Connection
Axial
Compressor 1
Low Pressure
Axial
Compressor 2
High Pressure
Motor 1 Motor 2
Control
System
Processor
Storage Tank
Air
Bearings
Suspension
Thrust
Power
24

25. Power
Tubing
Compressor Architecture Diagram
Legend
Data
Bridged
Power
Mechanical
Connection
Axial
Compressor 1
Low Pressure
Axial
Compressor 2
High Pressure
Motor 1 Motor 2
Control
System
Processor
Storage Tank
Air
Bearings
Suspension
Thrust
Power
25

26. Power
Tubing
Compressor Architecture Diagram
Legend
Data
Bridged
Power
Mechanical
Connection
Axial
Compressor 1
Low Pressure
Axial
Compressor 2
High Pressure
Motor 1 Motor 2
Control
System
Processor
Storage Tank
Air
Bearings
Suspension
Thrust
Power
26

27. Power
Tubing
Compressor Architecture Diagram
Legend
Data
Bridged
Power
Mechanical
Connection
Axial
Compressor 1
Low Pressure
Axial
Compressor 2
High Pressure
Motor 1 Motor 2
Control
System
Processor
Storage Tank
Air
Bearings
Suspension
Thrust
Power
27

28. Compressor Modeling
28
• Compressor is split into two stages
• Low compression stage operating at 8000 rpm
• High compression stage operating at 11000 rpm
• Ambient air enters compressor at Mach 0.3
• Air is initially at 0.116 psi and is compressed to 3.19 psi

29. 29
Compressor Modeling
Component Material
Stator Blades & Shell Titanium Alloy
Rotor Blades & Shaft Nickel Based Superalloy

30. Air Flow Control
30
Air Flow to
Passenger
Compartment

31. Compressed Air Tank
31
Pressure Required
for Air Bearings
1.60 psi
Mass Flow Rate
From the Tank
0.44 lb/s
Air Density 6.85 x10-3
lb/ft3
Air Temperature 700 K
Diameter of Tubing 3.0 in

32. Emergency Air Tank
32

33. Air Bearing System Overview
33

34. Sensor Placement for Compressor
34
Legend
T - Temperature Sensor
P - Pressure Sensor
A - Accelerometer
RM - Rotary Motion
T1
P1
A1
RM1
T2
P2
A2
RM2
• Temperature and pressure sensors monitor compressor conditions
• Accelerometer and rotary motion sensors detect when system
approaches critical speeds
• Anti-vibration mounts reduce destructive vibrational effects

35. Sensor Placement for Air Bearings
35
P1
P2
Legend
P - Proximity Sensor
• Proximity Sensors ensure nominal ride height

36. Estimated Design Parameters
Tube Pressure 0.11 psi
Pod Cross-Sectional Area 8.61 ft2
Compressor Mass-Flow Rate 1.87 lbf/s
Mass Estimate of Compressor 2627 lbm
Item No. Description Quantity Total Mass (lbm)
1 Air Bearing Platform 4 527.44
2 Hydraulic System 8 165.04
3 Wheel System 4 176.88
Air Bearings / Suspension:
Compressor/Pod Design:
36
Power Requirement Estimate 885 hp
Max Pod Velocity 0.322 Mach
Estimated Minimum Pod Mass 8135 lbm

37. 37
R5
R7
R8
R9
R1R3
R6 R4
R17
R2
R15
R10
R11
R12
R16
R13
R14
37
Likelihood

38. 38
Addressing Major Risks
• Risk 11: Complete Loss of Air Bearing Pressure
• Bearings coated with low friction coefficient material
• Pod can safely coast on bearings without catastrophic damage
• Risk 12: Complete Compressor Failure
• Unique emergency air tank design provides sufficient air to
bearings for pod velocity to decrease to wheel-safe speeds

39. Cost Estimate Analysis
Materials Cost Estimate
Materials Cost
($/kg)
Amount
Material (kg)
Standard Cost
Titanium Alloy Cost 30 268.4 $8,052.00
Nickel Based
Superalloy Cost
50 942.8 $47,140.00
1060 Al Alloy 2.2 15.059 $33.13
6061 AL Alloy 3.5 394.96 $1,382.36
Normalized AISI
4130 Steel
4.5 80.231 $361.04
Total Material Cost $59,968.53
**Material cost estimate based on average values per kg from multiple suppliers
39
Manufacturing Cost Estimate
Compressor $10,000
Air Bearing Platform $860.16 x 4 = $3,440.64
Wheel System $3,750 x 4 = $15,000
Hydraulic System $2,500 x 8 = $20,000

40. Cost Estimate Analysis
Sensors Cost Estimate
Accelerometer $100
Rotary Motion Sensor $40
Temperature Sensor $60 x 2 = $120
Pressure Sensor $90 x 2 = $180
Displacement Sensor $50 x 8 = $400
40
Air Tank Components
Mass Flow Controller $2200
Pressure Regulator $350
Secondary Tank $250
Main Tank $200
Other Design Costs
Motor to Power
Compressors
$500
Tubing 15.75 $/ft x 200 ft = $3150
Control System $2,000
Total Cost $84,599.17

41. Scalability
• Air Bearings & Pushrod/Wheel Assembly:
• Scaling based on increase in weight
• Hydraulic Suspension:
• Adjust scale of spring to weight requirements
• Air Storage:
• Scaled according to back-up safety requirements in the case of
catastrophic compressor failure
• Compressor:
• Scaling is complicated due to complexity of blade design
• Material composition should remain the same, assuming constant
operating conditions between test-scale and full-scale pods
41

42. 42
Questions?

43. Team Description & Objective
The University of Arizona Hyperloop Team is a motivated group of three graduate and twenty
undergraduate students who have an interest in the Hyperloop concept. Our team represents an
engineering club on campus whose aim is to allow the students to develop research, design, technical
skills.
Our team’s objective is to study and optimize the air bearings and suspension system for a Hyperloop pod
design. We plan on presenting our design at design weekend but we do not intend to compete with a full
pod design.
Team Members:
Namrah Habib, John Mangels, Irene Moreno, Corey Allen Colbert, Jacob Pavek, Philip Ciuffetelli, Jacob
Grendahl, Kevin Sherwood, Mark Ernst, Rohan Mehta, Tristan Roberts, Aaron Kilgallon, Jeremy
Harrington, Mandy Olmut, Ryan Jensen, James Nguyen, Patrick Portier, Harshad Kalyankar, Ryan
Petronella, Jonathan Heinkel, Joel Mueting, Sean Gellenbeck, Ben Kaufman
Faculty Advisor:
Dr. Cho Lik Chan
Aerospace and Mechanical Engineering
43

44. DLN 8/24/15
System Level Requirements
Type Description
Verification Method
Analysis Inspection Success
Pod Constraint Pod mass shall not exceed 11,000 lbm X X Meets
Test Track Interface Pod shall shall fit within the cross-sectional area of the test track X X Meets
Operational Pod shall be moveable at low speeds when not in operation X Exceeds
Test Track Interface Pod shall utilize Operational Propulsion Interface X Meets
Operational Pod shall be able to come to a complete stop by use of a braking system X Meets
Operational
Pod shall travel along the track in a smooth motion without colliding into
the center rail.
X Exceeds
Operational Pod shall be able to travel at Mach 0.3 without inducing a syringe effect X X Meets
Operational
Pod shall be able to levitate using air bearings between the end of the
acceleration phase and the beginning of the braking maneuver
X X Exceeds
Pod Constraint Pod shall be powered by an onboard power system X Meets
Operational
Pod shall be able to operate with an ambient tube pressure between
0.02 - 14.7 psi
X X Meets
Power Constraint
Compressor and bearing support subsystems shall not exceed 1082.82
HP of onboard power
X X Exceeds
44

45. DLN 8/24/15
Subsystem Level Requirements
Subsystem Description
Verification Method
Analysis Inspection Success
Bearings
Air bearing system shall interface with the test track according to the
Hyperloop Tube Specification Document
X Exceeds
Bearings
Air bearings shall levitate the pod before the completion of 800 ft
acceleration phase
X Meets
Bearings Wheels shall support the pod during initial acceleration X X Exceeds
Bearings Bearings subsystem weight shall not exceed 3700 lbm. X Meets
Bearings
Pod shall smoothly transition from wheeled bearings to air bearings during
acceleration phase
X Exceeds
Compressor Compressor shall intake air moving between 0 and 334 ft/s X Meets
Compressor
Compressor shall supply air pressurized to 3.2 psi for the air bearing
subsystem
X X Meets
Compressor Compressor diameter shall not exceed 70% of tube diameter X Meets
Compressor Compressor subsystem weight shall not exceed 4700 lbm X Meets
45
*Demonstrations and test verification methods were not considered because no physical pod is being built

46. Risks Identified (R1-R6)
46
Label System Failure Possible Solution(s) Risk Matrix Rating
R1
Hydraulic
Suspension
Suspension won't come
down/jammed upon reaching
reasonable speeds for air
bearings.
Recall the pod for inspection.
Minor/Moderate &
Rare
R2
Suspension locked in the
"down" position.
Slow the pod down using braking mechanism and have the
pod attempt to slow down enough to where it can safely glide
on the air bearings with little to no damage to the parts. Fix
upon arrival.
Moderate & Rare
R3
Wheels & Wheel
Suspension
Broken spring, rocker,
damper, torsion bar, etc.
General maintenance inspections Insignificant & Rare
R4
Broken spring, rocker,
damper, torsion bar etc.
during transit
There should be multiple wheels so not much concern during
transit. If this occurs during the beginning of the trip recall the
pod and fix. At the end of the trip, decelerate to slower speeds
than what would be normal to pull the air bearings up and
gently rest the pod on the remaining wheels. Fix at the end of
trip. Make sure that max weight isn't reached.
Minor & Rare
R5
Wheels/tires worn during
transit
Decelerate to slower speeds. Minor and Unlikely
R6 Wheels/tires worn General maintenance inspections Insignificant & Rare
46

47. Risks Identified (R13-R17)
47
No use of hazardous materials in design
Label System Failure Possible Solution(s) Risk Matrix Rating
R13
Compressor
Complete rotor failure
Regular metallographic examinations
Compressor Braking mechanism
Minor & Unlikely
R14 Duct to storage tank failure
Auxiliary duct system.
High strength/reliability ducts
Regular inspection of ductwork
Insignificant & Unlikely
R15
Material Failure:
• Low/High cycle and thermal fatigue
• Environmental exposure and foreign
object debris
• Excessive tensile load on blade tip
Regular inspection of high stress parts
High performance materials Moderate & Rare
R16
Blade Failure
• High centripetal forces
• Gas flow induced steady state stress
• Foreign object debris
• Thermal stress e.g.: nonuniform
temperature distribution
Highly accurate, symmetrical blade design
High performance material composition
Regular blade inspection
Performance inconsistencies require inspection
Moderate & Unlikely
R17 Entire Pod Weight Overload Check weight before takeoff.
Insignificant/Minor &
Rare

48. Risks Identified (R7-R12)
48
Label System Failure Possible Solution(s) Risk Matrix Rating
R7
Wheel Motor(s)
Motor(s) failure (won't work, turn on, etc.)
General maintenance inspections. Before take off,
if not working, delay the schedule to fix.
Minor & Unlikely
R8 Motor(s) failure during transit
Slow pod down enough to where the weight can
be put on wheels without them being
turned/rotated beforehand.
Minor & Unlikely
R9
Air Bearings
Damage to air bearings during transit
Maintenance/repair/replacement after pod comes
to a stop at the end.
Moderate & Unlikely
R10
Loss of pressure to one or multiple bearings
in transit (duct failure or clogged orifice)
Decelerate to slower speeds, retract air bearings
to have pod on wheels to reduce damage to the
bearings. Try and figure out issue, otherwise roll
on wheels to end of trip.
Moderate & Unlikely
R11 Loss of pressure to all bearings
Pod falls on bearings; bearings will be coated with
material with a low coefficient of friction; this will
allow the pod to slide without causing catastrophic
damage
Major & Rare
R12 Compressor Complete compressor failure
Compressed air tank will supply to the bearings
with air until the pod can be slowed to acceptable
wheel deployment speed
Major & Rare