Pod Competition Final Design Package Technical Brief; LEHIGH HYPERLOOP (1)
1. Technical Brief and Overview
Lehigh Hyperloop
Team Captain: Correll French
Executive Summary
Faster transportation is key to the advancement and forward progress of civilization.
This report describes and evaluates the Lehigh Hyperloop Team’s design of a Pod for
the SpaceX Hyperloop transportation system. Aiming to create a smooth, durable,
and cost effective pod, each subsystem was uniquely designed and integrated into the
overall project. Aerodynamic drag was minimized to optimize speed and acceleration.
To promote stability and safety, systems were designed to respond at high speed and
automatically to constant sensor input. To keep the project affordable, several
systems were custom designed from raw materials and parts. To accommodate all
passengers, accessibility and safety have been a major factor of the design effort
including a Handicap Accessibility System. Focusing on a smooth and comfortable
ride, the design’s focus has been to create a unique and optimal ride for all end users.
2. 2
Contributors
Correll French*
IBE Finance and Electrical Engineer
Team Captain
Tech Tanasarnsopaporn*
Material Science
Lead Mechanical Engineer
Vincent Pileggi*
Mechanical Engineer
Levitation Lead
Devon Zeidler*
Electrical Engineer
Communications Lead
Andrew Culkin
Mechanical Engineer
Hull Sub-team
Evan Mehok*
IDEAS Mechanical Engineer
and Computer Science Engineer
Handicap Sub-team
Colin Bader*
Mechanical Engineer
Brakes Sub-team
David Brandt*
Electrical Engineer
Brakes Sub-team
Emily Porfiris
Mechanical Engineer
Hull Sub-team
Alex Ferencin
Physics
Fund-raising Committee
Kenny Edwards
Mechanical Engineer
Propulsion Sub-team
Seamus Cullinane*
Electrical Engineer
Lead Design Engineer
Christian Murphy*
Mechanical Engineer
Simulations Lead
Kyle Higgins
Physics
Outreach Lead
Kaity Hwang*
Mechanical Engineer
Propulsion Lead
Jacob Baer*
Civil Engineer
Propulsion Sub-team
Zhoujie Ji
IBE Mechanical Engineer
and Mechanical Engineer
Levitation Sub-team
Kyle Leonard
Electrical Engineer
Communications Sub-team
Joseph McDonough
IBE Electrical Engineer and Finance
Logistics Committee
Zack Fisher
Mechanical Engineer
Hull Sub-team
Peter Nguyen*
IDEAS Mechanical Engineer
and Product Design
Hull Sub-team
* - Denotes Technical Brief
and Overview Co-Authors
3. 3
Contents
1.0 Hull……………………………………………………………………………………….6
1.1 Geometry………………………………………………………………...………6
1.2 Chassis and Body Structure…………………………….……………………8
1.3 Materials…………………………………………………………….…………12
1.4 Mass of Subsystems……………………………………..……………………13
1.5 Pressure Cavity and Bypass System………………………………………13
1.5.1 Pressure Cavity……………………………………………………….14
1.5.2 Bypass System………………………………………………………...15
2.0 Energy………………………………………………………………………………….16
2.1 Power…………………………………………………………………...………16
3.0 Propulsion……………………………………………………………...………………20
3.1 Hover Engines…………………………………………………………………20
3.2 Principles of Hover Engine Design……………………...…………………21
3.3 Producing Thrust………………………………………..……………………21
3.4 Wheels…………………………………………………………….……………23
3.5 Work…………………………………………………………………….………24
3.6 Maintenance………………………………………………………...…………24
4.0 Braking…………………………………………………………………………………25
4.1 Introduction……………………………………………………………………25
4.2 High Powered Braking…………………………………………….…………25
4.3 Hydraulic Brake Pad…………………………………………………………26
4.4 Rear and Diffuser Gradient Altering………………………………………27
4.5 Reverse Thrust in Confined Space…………………………………………27
5.0 Levitation………………………………………………………………………………29
5.1 Overview……………………………………………………………….………29
5.2 Compressor…………………………………………………………….………29
5.3 Air Bearings……………………………………………………………...……30
5. 5
12.0 Logistics………………………………………………………………..………………55
12.1 Pod Construction………………………………………………...……………55
12.2 Production Schedule………………………………………….………………56
12.3 Pod Testing………………………………………………….…………………57
12.4 Functional Tests………………………………………………………………57
12.5 Ready Checklists……………………………...………………………………58
12.6 Transportation of Pod to California………………………………..………59
6. 6
Hull
Geometry
The external geometry of the Pod is undeniably the cornerstone in achieving
a system that maximizes speed and energy efficiency; the primary goals of the
Hyperloop Design Competition. As aerodynamic drag varies with the cube of
vehicle’s speed, the ability to reduce a small amount of drag coefficient may result
in a large difference in power consumption while increasing the maximum velocity
achievable.
The Pod is designed into three distinct sections: head, passenger
compartment, and tail. For scalability reasons, the passenger compartment section
is designed to be a straight cylindrical shape (see more in Scalability). Therefore,
the design of head and tail sections directly contributes to most of the aerodynamic
drag and downforce onto the system. Per the design criteria established by the
SpaceX Hyperloop Competition, the size of the tube (70.6” diameter) creates another
challenge to reducing the drag. As the size of the passenger compartment – largest
portion of the Pod – is set at 31.5 x 35.4 x 33.5 inches (Width x Length x Height),
the geometry of the prototype hull must meet this requirement to accommodate the
crash test dummy being provided. From there, to optimize the pressure drag of the
Pod, the head section is shaped into a smaller area. The frontal area is designed
based on a toroidal hybrid shape. This results in the ease of air flow along the side
of the Pod. The tail section is also concave to reduce detachment drag. Along the
side and bottom of the Pod, there are diffuser tracks which enable the control of air
flow along the Pod resulting inless turbulence. These designs were achieved
through various theoretical and numerical analyses, creating an optimum design.
7. 7
Diagram: 2-Dimensional design CFD velocity field
To avoid air choke at low travel speed due to the suction of the levitation
system, cost and energy effectiveness at high speed travel, the air intake area is
designed to cover approximately 40% of the total frontal area. This design also
allows an adequate portion of the air in the tube to flow to the side and above the
Pod reducing detachment drag at the rear. Furthermore, to prevent the effect on
overall aerodynamics due to the Kantrowitz Limit with the suction system and the
limitation of the plug fan, the gradient of the frontal area of the Pod is designed to
slope upward at the maximum allowable angle. This allows excess air to flow out to
the rear easily, raising the maximum travel speed.
Diagram: Exterior-front view Diagram: Exterior- back view
8. 8
The exterior of the Pod has the maximum dimension of 3.05 x 10.85 x 3.88 ft
(Width x Length x Height). The detailed dimension of the Pod is as follow:
Diagram: Pod exterior dimension (expressed in millimeters)
Chassis and Body structure
The chassis serves as a vehicle skeleton to support the Pod’s weight, frontal
air pressure while moving at high speed, and the forces due to high acceleration.
The chassis design is inspired by monocoque construction where the frame is built
as a single-shell structure. This provides a strong support to the Pod while reduces
the weight of the Pod as compared to other types of structures. (Note: For the
Prototype Build Lehigh Hyperloop will be creating the Pod’s space frame using
aluminum alloy beams and bent alloy sheets as materials for cost efficiency).
9. 9
Diagram: Chassis overview
Along with our unique safety features and emergency braking system,
several design concepts have been implemented to fulfill the extra structural
requirements for the Pod’s design. The design for the emergency braking system
has it attached to the lower floor of the Pod. When the braking system is deployed, a
great amount of force will act upon the parallel support structures. This will
prevent the collapse of the body frame while allowing the emergency braking
system to perform as needed. As modeled below, the chassis structure is well within
the transportation industry’s factor of safety.
Diagram: Emergency braking stress simulation
10. 10
Diagram: Emergency braking factor of safety
While the chassis maintains the core structure, the body frame design also
facilitates the distribution of forces upon crashes. For head-on impact, the use of
lower density materials – i.e. aluminum alloy pipes – will result in small
deformation of the structure throughout the body frame to alleviate the impact.
This technique is widely used in modern vehicles and has proven performance. As
seen in the simulation below, the majority of the stress is distributed along the
chassis, head and tail structures, and the lower part of body frame minimizing the
effects on the passenger compartment.
11. 11
Diagram:
Crash impact stress simulation (displacement scale exaggerated to aid view)
Diagram: Crash impact factor of safety
12. 12
Materials
The core structural material to be used in the chassis is Aluminum Alloy
6063-T6 I-beam, which will support the Pod’s weight and withstand impacts.
Stringers made of Aluminum Alloy 6061-T6 square pipes will connect the U-shaped
chassis as extra support structures. In body frames and crumple zones, Aluminum
2024 T-6 square pipes will be used. The material’s strength properties will maintain
the structure and withstand frontal pressure, and will allow for the adequate
distribution of force for safety. The frame structures will be welded; then, the body
metal sheets will be riveted onto the frame. While there are several components at
the lower part of the Pod, the diffusers are designed to be flat surface to reduce
aerodynamic drag. There are gaps designed between the floor and equipment such
as propulsion motors. These gaps are intentional allowing a certain degree of
movement to the equipment.
To allow easier mounting of equipment onto the interior structure, we will
use honeycomb carbon fiber and metal sheets to create flat surfaces inside the Pod.
The interior flooring will be attached on top of chassis stringer.
Diagram:
Interior carbon fiber flooring technology is widely used in aircraft industry
13. 13
Mass of subsystems
The total mass of the Pod is estimated at 1,250 kg. The table below shows the
breakdown of the sub-system weight. Sub-components are positioned in order to
distribute the weight of the Pod and center of gravity at the middle of the Pod and
8” from the Pod floor. This low center of mass minimizes the torque acting on the
system and prevents disturbance to the weight distribution system.
Team Mass (kg)
Hull 110
Propulsion (service) 120
Propulsion (operation) 70
Energy 400
Communications 5
Sensors 5
Levitation 300
Air pump 50
Total 1,060
Dummy Seat 20
Robotic Lift 100
Dummy 70
Total w/ extra 1,250
Table: Breakdown of subsystem weight
Pressure Cavity and Bypass System
While the hull exterior design minimizes the aerodynamic drag of the Pod,
the small ratio of cross-section tube and impact area creates a limitation for top
travel speed. In order to reduce the frontal pressure drag, a bypass system is
14. 14
created. Alongside the bypass system, a pressure cavity is designed to aid and be
integrated with the levitation system’s compressor air intake.
Pressure Cavity
On the front of the Pod is mounted a durable, high pressure and high flow
rate fan that induces differential pressure in the front cavity. Since the compressor
can only operate in certain pressure conditions, this cavity sets a suitable
environment for the compressor to work while lowering the pressure formed in front
of the Pod, resulting in less pressure drag. Within the pressure cavity, there is a
vent which acts as the pressure regulator. At low travel speed, there is low frontal
pressure in front of the Pod. The vent can be closed to allow the cavity pressure to
build up and create suitable conditions for the compressor. At higher speed, there is
higher frontal pressure and inlet flow than what the compressor requires, for which
the vent can be opened to relieve the high pressure and flow from the cavity.
Diagram: Pressure cavity and vent setup
15. 15
Bypass system
The excess flow from the pressure cavity and the remaining pressurized air
from the compressor will be released through the nozzle at the back of the Pod. As
the resulting air flow has high flow rate with higher pressure than the tube’s static
pressure, this will act as a secondary force to propel the Pod. Air flow from the vent
is induced by low pressure created by the two fans positioned at the back of the Pod.
The flow will be circulating through the internal system to provide convection
cooling and maintain temperature for the working conditions of the compressor and
other internal components.
For cost efficiency, a commercial plug fan of 128,000 cfm will be used as the
suction unit. This type of blower cannot account for all portions of frontal air flow
needed to be bypassed. Because of this limitation of the suction system at subsonic
speed, a considerable portion of the air flow is unaccountable. For large scale
production, more suitable alternatives to the plug fan are discussed in the
Scalability section.
16. 16
Energy:
Power
Subsystem Amperage Volts
Communications(Computer) <5A 120V
Communications(Embedded
Systems)
<1A 12V
Levitation 100A 240V
Propulsion
400A(40A per
motor)
12V
Total 122.5A 240V
Table: Estimated Energy Requirements
Due to high voltage and amperage requirements for levitation, lithium ion
batteries have been selected as the power source for the Pod design. While a
hydrogen fuel cell could provide a great amount of power, the size of a hydrogen fuel
cell large enough to release the required high amperage would be the size of the pod
itself and too large to be efficient. A gasoline powered engine/generator is not an
option due to sustainability and hazardous material usage. It has therefore been
determined, modeling a solution taken from the Tesla Model S battery, a large
battery using smaller commodity batteries would be used.
A 18650 battery size with 9800mAh's and 3.7V was found to be a cost
effective battery at only $1.32 per battery while also providing enough capacity and
normalized voltage. To reach the capacity and voltage needed, we will be using
battery modules that consist of 50 batteries in parallel. This produces a module that
has a capacity of 490Ah and a voltage of 3.7V. We will then combine seven modules
in series to produce larger modules of 490Ah and 22.2V. Eleven of these larger
modules are then wired in series to produce a battery of 490Ah and 244.2V
17. 17
achieving the desired energy system. This equates to 3,300 of the smaller
commodity batteries. With this setup, if the Pod draws current at .25C, it will be
able to achieve the full 122.5A required to run at full capacity. To organize the
batteries the Pod will be made using 18650 battery brackets as shown below. To
handle charging the team will utilize a power charging module (PCM) that is rated
at 150A, 22.2V and 6 cells. This was chosen for its amperage rating as well as its
cell rating. With large modules consisting of 6 smaller “cells” this has been
determined to be optimum for the Pod’s battery design. It has been designed to
balance the batteries while charging, providing system safety and protecting the
batteries from over drawing, over charging, and short circuits.
Part Link to Part Price per Unit(USD) Quantity
Total
cost(USD)
18650 Battery
http://goo.gl/Q2Cr1
N
$1.32 3000 $3,960.00
Battery Protection
circuit
http://goo.gl/7hhdc
q
$50.00 10 $500.00
Battery Spacers size
3(10 pack)
http://goo.gl/4nvdF
B
$3.00 132 $360.00
Battery Spacers size 2
(10 pack)
http://goo.gl/ws8V1
9
$2.00 132 $240.00
Table: Battery Module cost breakdown
20. 20
Propulsion
Hover Engines
Arx Pax announced early in the competition that they would be developing
and selling their hover engine to teams. The Lehigh Hyperloop team has
determined that levitation of the Pod is not feasible with the aforementioned hover
engines as it would require 25-30 of them.
The air levitation system designed by the team allows the Pod to move freely
with minimal friction as discussed further in the Levitation section. In conjunction
with the designed levitation system, custom designed and built hover engines will
be utilized to propel the pod. The Lehigh team has custom designed a hover engine
of larger diameter and magnetic power to produce the required propulsion. Utilizing
the custom design, the budgeted cost is $7,154.08 total for 10 hover engines.
Equivalent cost for 10 Arx Pax hover engines has been estimated to be $48,500.
Due to the significant cost savings, the team has elected to utilize custom designed
hover engines in their Pod’s design.
Custom Hover Engine Parts Cost/Part # of Parts Total Cost
Motors $27.99 10 $279.90
Magnets 1" $7.19 360 $2,588.40
Magnets .5" $1.14 1800 $2,052.00
Magnets .25" $0.22 1800 $396.00
Motor controllers $89.99 10 $899.90
Metal (Aluminum) $245.96 3 $737.88
Shipping (Metal) $200.00 1 $200.00
Total $7,154.08
Table: Hover motor cost breakdown
21. 21
Principles of Hover Engine Design
The foundation of the hover engine is Lenz's Law; by moving a magnet over a
conducting surface a repelling magnetic force is generated. Lenz’s Law may be
observed when a magnet is dropped down a copper tube; the magnet drops through
the tube slower than a non-magnetic material. While Lenz's Law does produce a
repelling force, it can be made greater by creating a stronger magnetic field. Thus, a
Halbach array, an arrangement of magnets which amplifies the magnetic field in a
unidirectional pattern, is utilized in the custom designed hover engine.
Picture: Halbach Array Comparison
Producing Thrust
The hover engines must be tilted to produce thrust, as shown in the Arx Pax
data sheet.
Picture: Arx Pax motor tilt diagram
22. 22
Two screws from the two stepped motors connect to the top plate on the
magnetic disk. One motor will be programmed to move the screw up +0.17633
inches, and the other will be programmed to move down -0.17633 inches. This
results in a 10 degree tilt for the spinning disk. The left side will raise 1.56 inches,
and the right side would dip 1.56 inches.
Diagram: Hover motor depiction
Left Side Right Side
Center of Tilt
23. 23
Diagram: Circular Halbach array
Wheels
The main function for wheels on this pod is to provide ease of mobility at low
speeds; a range from 0 to 100 mph. A total of six polyurethane coated wheels will
support the pod, cargo and passengers weight during the initial stage of
acceleration and the final stage of deceleration.
24. 24
Work
In addition to supplying Pod support at low speeds, the Pod’s wheels will be
required to steer and propel the Pod outside the tube system, to and from the
station. Since the Pod’s wheels main function is for use inside the tube, which will
be a near vacuum environment, a non-pneumatic tire was selected. The non-
pneumatic tires will provide greater support and less deflection and instability at
high rpm then the typically specified high speed roller coaster caster. Once the
wheels were selected, custom front and rear brackets were designed. The bracket
design of both systems utilizes trailing arm suspension principles, theoretically
limiting vibrations at high speed and increase stability. The front and middle
brackets will be mounted to a tapered roller bearing and then connected with a
bushing to a servo style motor. The steering is controlled in these motors, allowing
for high precision when needed. Additionally, in case of an emergency, the pod can
be decelerated by increasing the toe of the wheels and using the small rotor pad
system similar to that used in automobiles. The rear wheels will be hard mounted
to the deployment system on the Pod. They will not be free to rotate. Each wheel
will have a motor that will drive the pod forward and backward. The motor will be
permanently housed inside the Pod, the center of rotation for the deployment arm
will be in line with the motor shaft. A chain drive transmission will be used which
will lower gear ratio.
Road speed will be calculated to allow the motors to change speed when
cornering, preventing shutter and excessive wear.
Maintenance
Regular inspections of all the systems is crucial for the proper function and
safety associated to the Pod. Since these wheels will be driven on rough surfaces,
excessive wear will occur limiting the wheels lifetime and reliability requiring them
to be inspected frequently for repair, maintenance and replacement.
25. 25
Braking System
Introduction
On top of reverse propulsion to decelerate the Pod, the braking system uses a
set of brake pads which grip the aluminum rail to slow the Pod. The system consists
of twelve Twiflex T2 brake calipers mounted along the sides of the central T-beam.
The system is pneumatically powered and theoretically capable of delivering a
combined force of up to 4050 N or 2.025 ms-2 of deceleration.
Diagram: Twiflex T2 brake calipers; T-Beam will be inserted in place of Brake Disc
High powered braking
In the case of collision or malfunction in the tube, high powered braking must
be available to ensure the safety of the passengers. Although the maximum
magnitude of acceleration/deceleration recorded by NASA is 83g, this emergency
braking will be within the non-harmful range of deceleration for the human body of
5g or just under 50 ms-2. The table below shows different braking distance and time
at various travel speeds if only the hydraulic brakes are used.
Travel Speed (ms-1) Travel Speed (mph)
Brake distance
(m)
Brake period
(s)
10 22.3694 1 0.2
25 55.9235 6.25 0.5
26. 26
50 111.847 25 1
100 223.694 100 2
150 335.541 225 3
200 447.388 400 4
250 559.235 625 5
300 671.082 900 6
Table: Braking time and distance
Hydraulic Brake Pad
The emergency braking system consists of three sections: hydraulic brake
pads, rear flow manipulation, and reverse thrust.
First, the hydraulic brake pads are deployed while the levitation system
turned off. This will result in the normal force equal to the combination of weight
and downforce. As mentioned in body frame and chassis, the structure has been
designed to withstand this large amount of force without impacting the passenger
cabin. In order to avoid inducing excessive stress and heat onto the aluminum sub
track of the tube, the Pod uses ceramic brake pad as the braking material. Ceramic
brakes are proven to reduce wear on track and noise while maintaining durability
and power.
Diagram: Commercial ceramic brake pad
27. 27
Rear and diffuser gradient altering
As the Pod is setup within the tube, many flow manipulation techniques can
be applied. At the rear, the diffuser and back covers will be expanded. The small
change in diffuser gradient will result in large increase in detachment drag at the
rear.
Diagram:
Rear expanded and diffuser concaves into the pod can significantly change
detachment drag.
Reverse Thrust in Confined Space
Another important mechanism in flow manipulation lies in the concept of
reverse thrust at the side of the pod. While the levitation system is turned off, the
suction system and pressure cavity are still active at a lower rate. This allows the
Pod to produce pressurized air using the compressor; the 55 CFM output at 8 bar is
adequate for this application. The mechanism is composed of two layers of reverse
thrust nozzles installed at each side of the Pod. This mechanism allows for the
simulation of the abrupt change in the Kantrowitz Limit, and ultimately reduces
travel speed to levels significantly below subsonic speed. According to the
simulation, this mechanism increased total drag by at least three times the drag
without reverse thrust.
29. 29
Levitation
Overview
In order to eliminate friction between the Pod and the ground, the Pod must
levitate. To accomplish this, magnetic levitation, compressed air, or a combination
of the two must be utilized. The Lehigh Hyperloop design employs compressed air
as the main form of levitation; the main source of which is an Ingersoll-Rand rotary
screw compressor. Although the Pod will be equipped with hover motors that could
assist in levitation, they will be reserved mainly for propulsion. In order to produce
lift, the compressor will feed air to four air bearings provided by Airfloat, a division
of Align Production Systems.
Compressor
The compressor creates a continuous flow which allows the air bearings to
receive steady air flow without the need to store a tank of compressed air within the
Pod. Rotary screw compressors also offer advantages to a Pod of this size that are
not offered by other types of compressors, such as an axial compressor. Rotary screw
compressors are typically smaller and lighter than other continuous flow
compressors. This particular model is also entirely electrically powered. Since there
is no need for fuel, the entire Pod can be powered via lithium ion batteries.
Eliminating the need for fuel is also beneficial since there is no need for a fuel tank
which reduces the Pod’s overall weight and eliminates the risks associated with
combustible materials. The compressor’s internal assembly will be reverse
engineered, deconstructed and reassembled in a configuration that is more suitable
to the Pod’s design. The original assembly does not maximize the area it
encapsulates, leaving several large voids within the compressor. It also comes with
large side panels not necessary for this purpose. The new configuration should
effectively utilize the space available, allowing for the design of a more aerodynamic
30. 30
Pod. The compressor should also be cooled more efficiently with the air intake at the
front of the Pod.
Frequency
(Hz)
Rated
Pressure
(barg / psig)
Nominal
Power
(kW / hp)
Flow
(m3min /
cfm)
Length
(cm /
in)
Width
(cm / in)
Height
(cm / in)
Weight
(kg/ lbs)
60 8.5 / 125 11 / 15 1.55 / 55
104 /
41 73 / 29 91 / 36
295 /
650
Table: Compressor Specifications Ingersoll Rand Model: UP6 15c-125
Air Bearings
Air bearings, pictured below, were selected for converting the compressed air
into lift due to their reliability and efficiency. Air bearings are a highly reliable,
proven technology. They have been tested, modified, and improved through years of
research and development. In addition to providing an effective and reliable
product, purchasing air bearings is cost effective and time efficient as no man hours
are being put into the creation of an alternative method of utilizing the compressed
air.
Through the purchase of a controller, also supplied by Airfloat, the pressure
and air flow rate provided to each air bearing will be individually controlled by the
onboard processors to maintain stability. This will control the pitch, yawl, and tilt of
the Pod. The compressor’s output is higher in pressure and flow rate than required
by the air bearings, so the system does not need to be operated at full power. The
power capacity of the selected compressor is designed to maintain proper output as
the tube pressure is reduced to operating conditions. Having influence over each air
bearing ensures that Airfloat’s maximum recommended pressure and flow rate are
not exceeded. Additionally, the controller allows the net flow to be redistributed to
the air bearings in order to counteract an unequal weight distribution within the
Pod. Counteracting an unequal weight distribution allows for stable acceleration
through the tube. All excess air flow emitted by the compressor will be channeled
31. 31
outside of the Pod through a pipe system expanding from the controller. Being that
the payload capacity of the air bearings is approximately 4 times the weight of the
Pod, this system will adequately maintain suitable conditions for the air bearings
and allow the Pod, as well as its cargo, to move through the tube with minimal
resistance.
Picture: Airfloat Specifications
32. 32
Communications and Sensors
Sensors
The sensors, listed below, are the peripheral devices needed to control and
monitor the Pod. They have been selected for their ability to remain reliable at the
conditions the Pod is expected to experience and for their compatibility with
Arduino microcontrollers. The sensor network will consist of temperature,
accelerometer, pressure, and vibration sensors situated around the Pod to allow for
environment monitoring. These sensors will be connected to one of 5 regional
Arduino microcontrollers to allow for communication with other systems and with a
main Zotac Nano receiving terminal.
Table: Component Costs
Communications
Communication between the sensor systems and the main computer will be
done over Wi-Fi. The selected Arduino Yun microcontroller and Zotac Nano have
Wi-Fi built in and will act as transceiver and receiver. Sensors will be
systematically polled and interact with the regional microcontrollers to which they
are attached. The Arduino will then communicate with the main computer over Wi-
Fi. Once the data from the sensors is received, it will be displayed on a graphical
user interface, analyzed, stored, and relayed to the user.
33. 33
Navigation
Navigation will be handled by an Adafruit GPS and a NVIDIA video
processor. This GPS operates at a 10Hz updating rate, it will be efficient at keeping
track of the position of the Pod while it travels through the tube. The GPS will be
connected to an Arduino controller that will transmit the location over Wi-Fi to a
main external terminal. The NVIDIA video processor will analyze the external
features of the Pod determining how far the Pod has gone and how far it has to go.
The utilization of these two sensors will ensure that the Pod position can be
determined at any point in the tunnel, and will allow for the brakes to be activated
at the correct time.
Sensor Placement
The sensor placement diagram, shown below, illustrates the main areas of
the Pod that will need an Arduino microcontroller to connect sensors in that area.
The main sensor regions are the front, top, and rear of the Pod along with the cabin
and engine/compressor areas. These areas will have a regional Arduino that will
connect with the desired sensors for the area. The placement of these sensors will
allow for a view of the overall state of the Pod during operation. Sensor placement
will have to be taken into consideration during construction of the hull and during
placement of other subsystems to ensure accuracy and control.
35. 35
Safety
Safety Features
The Pod is designed to run on internally stored power, however, should power
dissipate spontaneously or the Pod loses power, the wheels will automatically
deploy preventing collision with the bottom of the tube. The wheels will also have
an independent back up power supply to run their motors so that the Pod may be
removed from the tube under its own controls. As the Pod hull is designed using the
same materials as airplanes, in addition to the hull not being pressurized
differently from the tube, the Pod will be able to withstand rapid pressure changes.
In addition, the hull has been designed with a skeletal layer and supported
internally to strengthen it from collapsing due to explosive pressurization.
The fault tolerance of the Pod has been refined with the use of redundancies
for each system. For braking, the first stage is reversal of the propulsion motors
from acceleration to deceleration which has been projected to be able to maintain
3G acceleration and deceleration. If the Pod reaches a speed above expectations, the
rail brake pads will automatically be activated to increase friction near the end of
the tube. Finally, if the Pod will not stop under normal braking procedure, the on
board processor and controls will activate the All-Stop Command. With levitation,
current calculations show that the rotary compressor can create enough lift for the
Pod with less than 60% of its overall potential at high speeds. Even at lower speeds,
it will be able to lift the Pod with its full power. However, in case it cannot, the
wheels will not retract until the Pod sensors detect sustained lift. In terms of
energy, the projected power consumption compared to storage will be two hours of
battery life assuming normal operating parameters.
If the Pod becomes immovable due to failure in the propulsion system, the
wheels will be deployed and controlled manually with their independent power
supply and receiver. This may also be used in case the Pod breaks away from the
center rail or becomes wedged in the tube.
36. 36
All-Stop Command
Using onboard sensors, the speed and energy storage will be tracked such
that if there is a power failure or the Pod cannot safely stop under regular means
the All-Stop command will activate. The wheels will automatically deploy during a
loss of power and the brake pads on the rail and wheels will be engaged to increase
friction. These can also be activated manually at the control console in case of
unforeseen circumstances. In terms of trajectory, the safety parameters will be set
that the computer will assume a standard 3G deceleration using the propulsion
motors. If the Pod cannot stop within the remaining distance under these
parameters, the Pod will activate additional braking systems up to the All-Stop
Command.
Stored Energy
The sources of stored energy in the Pod include Lithium Ion batteries for
electrical energy and air tanks for pneumatics. These will be discharged and
emptied before transporting the Pod and during maintenance.
Hazardous Materials
The hazardous materials in the design of Lehigh Hyperloop are Lithium Ion
batteries and pneumatics which will be maintained in proper containers and
environments. As the battery modules will be custom built, the individual batteries
will be ordered in bulk and stored carefully for travel and construction. During
construction of the prototype, the hazardous materials will include welding and
metal work for which several team members are trained and certified.
37. 37
Handicap Seat
Picture: Hull Cutaway to internal view
Application
As this Pod is being designed for mass public transit, by law and moral
standards, it is required to be handicap accessible. The Handicap Accessibility
System, as designed by Lehigh Hyperloop, allows for easy access into the Pod, by
any passenger, but especially by someone with a physical handicap or disability.
Design
This device utilizes a scissor lift, in combination with a linear-sliding tray on
guiderail tracks, to lift the floor up and out of the Pod so that it is level with the
38. 38
ground. Attached to the lift is a single seat, which the passenger can easily step
into, or be placed into, depending upon their physical needs and conditions.
Picture: Handicap Seat 3D rendering
Picture: Scissor Lift CAD model
The design of the scissor lift will be strong and compact, while allowing the
seat to be lifted to an easily accessible height. The four motors and gearboxes
utilize chains to provide power to lift the applied weight, while remaining efficient.
The tray rests on top of carts, which are locked onto guiderails. There are two
levels of guiderails to maximize the distance of linear motion. Parallel to the
39. 39
guiderail tracks are threaded rods. A single motor spins each rod, and the resulting
motion forces the threaded attachments on the carts to move the tray linearly to its
destination.
Picture: Guiderail CAD model
Parts and Cost (Estimated)
Item Price per Unit (USD) Quantity Total Cost (USD)
VersaPlanetary 1:1 Gearbox with 1/2" Hex Output $39.99 4 $159.96
VersaPLanetary 5:1 Gear Kit $14.99 4 $59.96
VersaPlanetary CIM Adaptor $4.99 4 $19.96
Bag Motor $24.99 4 $99.96
IVTAAN Linear Guide $73.22 4 $292.88
Aluminum Plate w/ 6061-T651 Mill Finish .5x28x48in $364.35 1 $364.35
1/2 in. x 10 ft. Threaded Electrical Support Rod $10.36 1 $10.36
Threaded Brackets around Cart $30.00 8 $240.00
VersaFrame 1" x 2" x 0.10" Pre-Drilled Tube Stock (59" length) $24.99 2 $49.98
Nuts $10.00 5 $50.00
Bolts $10.00 5 $50.00
WCP SS Gearbox
Base Options1 x WCP SS - Single Speed Base Kit
P/N: 217-3421 Gear Ratio Options1 x WCP SS - 50:24 Ratio Kit
P/N: 217-3624 Motor & Motor Controller Options3 x CIM Motor
P/N: 217-2000
Flanged Bearing - 13.75mm (1/2" ThunderHex) x 1.125" x 0.313" $3.99 50 $199.50
1/2" ThunderHex Stock (3 feet) $13.99 5 $69.95
Clamping Shaft Collar - 1/2" Hex ID $2.99 100 $299.00
8mm to 1/2" Hex Adapter $4.99 9 $44.91
2mm Key (5-pack) $2.99 3 $8.97
1/16" Acetal Spacer - 1/2" Hex (10-pack) $4.99 5 $24.95
1/8" Acetal Spacer - 1/2" Hex (10-pack) $4.99 5 $24.95
Power Distribution Panel $199.99 1 $199.99
Talon SRX $89.99 6 $539.94
#25 Roller Chain (10 feet) $9.99 2 $19.98
#25 Heavy Duty Master Link $2.49 5 $12.45
#25 Heavy Duty Half Link $2.49 5 $12.45
#25 Sprocket w/ Hub - 16t - 1/2" Round ID $6.99 6 $41.94
#25 Sprocket w/ Hub - 22t - 1/2" Hex ID $6.99 6 $41.94
VersaFrame 1" x 2" x 0.10" Pre-Drilled Tube Stock (59" length) $24.99 6 $149.94
VersaFrame 1" x 1" x 0.100" Pre-Drilled Tube Stock (59" length) $19.99 5 $99.95
Chair $300.00 1 $300.00
Total $4,561.86
$178.94 6 $1,073.64
Table: Handicap System cost breakdown
40. 40
Scalability
Extension of passenger compartments
Since the Pod is divided into three distinct sections (head, compartment, and
tail), our Pod design allows the compartments to be connected easily. To facilitate
movement during the turns, the pivot connectors can be placed after each segment
of the Hyperloop Pod. The choice of connector can be the modification of Scharf
coupler with additional buffer mounting as in the diagram below. This allows the
Pod to retain the strong chassis connection while absorbing and transferring forces
during braking. This type of coupler also has built-in electric coupler that allows
transmission between segments. The gap is estimated to take up less than 0.4 m in
length, and the connection has 100-160 degree of freedom. The space between each
segment will then be covered by smooth metal sheet cover to aid aerodynamics of
the Pod.
Note: The length of the segment can be varied from 3 meters or longer, and shall be
determined by the smallest turning radius of the path.
Diagram:
Siemen® Schwab coupling consists of coupling head, shock absorber and buffer
41. 41
Maintenance
One significant loss of revenue and time in all vehicle systems lies in their
maintenance. Since the Pod is designed in distinct sections with each part able to be
disassembled and replaced, the maintenance is localized per section that requires
fixing unlike cars or airplanes. Such sections can be easily replaced and enable us to
reuse the vehicle parts that are still functional. The tail can be removed for
recharging the batteries and storage of luggage while the passenger compartment is
boarded. The front compartment can be checked and maintained separately.
Cost of Production
The major cost of building the Pod is the chassis and body frame. For small
scale production – as in this Hyperloop competition – the Pod will use aluminum
tubes and welding to make a space-frame chassis. However, the Pod structure has
been designed to be easily converted and compatible with pressed metal panels as
used in large scale production in the transportation industry. In terms of energy
storage, the current design will operate for up to two hours on service propulsion
and up to one hour on operational propulsion. Since the largest power consumption
comes from the levitation system, and is identical when scaled up, the power scaling
is linearly based on the amount of propulsion needed.
Performance: Competition versus Actual Production
As tube diameter will be larger than the competition’s specification, this will
further reduce the ratio of the cross-sectional area between Pod and tube. By
effectively increasing the Kantrowitz Limit of the Pod system, a higher top travel
speed can be achieved. In addition, a longer tube length will allow longer periods of
acceleration, resulting in higher terminal velocity. Also, a longer period of
deceleration can be employed which increases the safety factor for the passenger.
The frontal suction unit is another important and costly component of the
Pod. For cost efficiency and dimension limitation, the Pod model for competition
42. 42
uses a plug fan with 128,000 CFM flow rate which cannot retrieve the total amount
of air required during subsonic flight. This causes high pressure drag at the front of
the Pod. However, in large scale production, the fan can be engineered and custom
made for a much higher flow rate with reduced size. This will increase the
operational range of the suction system; therefore the Pod will be able to achieve
higher top speed.
43. 43
Simulations
Design Criteria:
Tube length = 1 mile = 1609 m
Max Pod Acceleration = 3.2 g = 3.2*9.81 = 31.39m/s^2
Non-Emergency Pod Deceleration = -3.2 g = -3.2*9.81 = -31.39m/s^2
Pusher Acceleration = 1.5 g for 1000 kg
= 1.2 g for 1500 kg
~1.35g for 1250 kg =13.23m.s^2
Maximum Displacement of Pusher = 800 ft = 243.84 m
Air Pressure = 8960 Pa
Air Density = .1065 kg/m^3
Air Viscosity = 1.89e-5 kg/m-s
Temperature = 310 K
---------------------------------------------------------------------------------------------------------------------
Trajectory
Calculating Minimum Speed and Travel Time:
The minimum speed and travel time was calculated with the assumption the
pusher is the only acceleration force with the hover engines used to maintain
optimum travel speed. Using maximum displacement of the pusher at 234.84m and
an acceleration of 13.23 m/s^2, the pod will achieve a maximum velocity of 80m/s.
The pod will then maintain its speed to a distance of 243m from the end of the tube.
The pod will then decelerate at the rate it was accelerated. Acceleration and
deceleration are calculated to be 6 seconds/phase, with a cruise time of 14 seconds.
The total travel time is estimated to be ~26 seconds.
Calculating Maximum Speed and Travel Time:
Assuming that the hover engines will accelerate the Pod at a rate that will
allow the Pod to achieve max speed equal to half that of a full scale pod, it will be
required to accelerate at 31.39 m/s^2 until the Pod reaches the tube’s mid-point.
44. 44
The Pod will have reached its max speed of 224m/s at the half mile/tube mid-point.
Deceleration of the Pod will commence at the tube’s mid-point by applying the brake
systems and reversal of the hover engines output creating an equivalent
deceleration speed for travel to the tube’s terminus. Total travel time for the Lehigh
Hyperloop is calculated to be 14.28 seconds.
Graph: Trajectory Preditions
Aerodynamics
The simulation modeling performed by Lehigh Hyperloop revealed that at
224 m/s, the speed of the air flow would max out at 405.2 m/s (906.4 mph), passing
the speed of sound. It has been determined that achieving this air flow speed will
not generate significant problems with the Pod beyond slight instabilities. The Pod
itself will not travel at the speed of sound.
Table: ANSYS value Overview
45. 45
Diagram: Iso Streamline Velocity (224 m/s)
Diagram: Zoomed Iso Streamline Velocity (224 m/s)
Diagram: Side Streamline Velocity (224 m/s)
The design team utilized the computer program Fluent to simulate and
record the Pod’s drag and lift. Utilizing drag and lift magnitudes, the coefficients of
drag and lift were calculated to be .481, .069. These numbers were obtained using
the calculation at 224 m/s for Iso Static Pressure. In addition to this, Fluent was
able to find Static and Total Pressure along with Turbulent Intensity.
46. 46
Diagram: Iso Static Pressure (224 m/s)
Diagram: Iso Total Pressure (224 m/s)
Diagram: Iso Turbulent Intensity (224 m/s)
Thermal
Using the estimated top speed of 224 m/s and with lowered air pressure, the
flow of air does not pose a significant thermal threat to the Pod. However, the
California sun will have an effect on the thermal profile. Applying solar heat gains,
the tube will reach an approximate temperature of 310K. The thermal profile
47. 47
transfers heat to the Pod and the areas that are most affected by the heat gain (i.e.
the base of the Pod which is directly in contact with the tube). Other regions of the
Pod, such as the top, will not be as greatly affected since it is not in direct contact
with the tube. The thermal profile also allowed for the determination of where the
Pod dissipates heat from (heat flux).
Diagram: Iso Thermal Profile
Diagram: Front Thermal Profile
Diagram: Iso Heat Flux
48. 48
Random Vibration
A frequency of 320.24 Hz was selected to test the effects of random vibration
on the Pod. Using the Random Vibration analysis in ANSYS, the total X, Y, and Z-
Axis maximum and minimum deformation in meters was calculated. Along with
that, the stress and elastic strain on the Pod from that vibration were determined.
Deformation did not exceed more than 1.9353e-002 m in any direction positive or
negative.
Diagram: X-Axis Vibrations Deformation
Diagram: Y-Axis Vibrations Deformation
Diagram: Z-Axis Vibrations Deformation
49. 49
Vacuum Compatibility
Due to its structural properties, Aluminum 2024 t-6 has been selected as the
material for use within the Hyperloop’s vacuum. With the addition of belt frames
and stringers, Aluminum 2024 t-6 is projected to maintain its structural integrity in
the tube’s low pressure environment.
50. 50
Financial Analysis
Cost Breakdown
The costs have been categorized by team responsibilities. For the levitation
components, service wheels, air bearings, and rotary compressor, the team has
opted to use Commercial-Off-The-Shelf (COTS) components as they are more cost
and time effective, and they are modifiable after purchase. In addition, the team
currently does not have the skills, resources, or time to construct these from
scratch. These COTS components are designed to be molded to the project and can
be converted to our designs.
For custom builds, such as the Handicap Accessibility System (referred to as
Handicap Seat), the costs have been broken down further into a bill of materials
below. The custom builds were found to be more inexpensive to build from scratch
and fit the design better. The most noticeable cost saving came from the propulsion
motors which are almost 30% the price of buying the COTS. In the case of the
Handicap Seat, as this was an original idea, it has to be built from scratch and is
budgeted accordingly.
Table: Cost Breakdown
51. 51
Bill of Materials
By analyzing the costs of materials, the team has been able to plan ahead
and know the materials that will be needed to successfully complete the build.
Because not all fastening and mounting materials were included, the cost
breakdown totals have been adjusted to account for missing materials, shipping,
and taxes.
The team is currently seeking sponsors in manufacturing and production to
assist with specific part selection and purchasing. With additional sponsors, the
team feels confident in their ability to construct the full size prototype.
52. 52
Table: Bill of Materials
Total Cost
The calculated cost for build is $42,394.05 which includes some adjustments
for taxes and shipping. Including contingency for any design changes and material
cost inflation, we have calculated a budget cost of $45,000. An additional $15,000 of
53. 53
expenses is anticipated for equipment, tools, testing, and shipping the Pod to
California.
The total project budget is an estimated $60,000.
Fundraising
Costs not anticipated and/or covered by sponsors, the team has taken and
will continue to make efforts to raise additional funds through their own endeavors.
These currently include T-Shirt sales and a crowd funding site run through Lehigh
University (See pictures below).
To date, the team has raised approximately $3500 which has been allocated
to travel expenses and materials for the Design Weekend being held at Texas A&M.
The team is actively seeking corporate sponsors and have succeeded in being
sponsored by St. Onge Company from York, PA. Furthermore, talks with several
companies in the Bethlehem area are underway for additional corporate
sponsorships dependent on our performance at Design Weekend. After Design
Weekend, the team will obtain commitments from their corporate sponsors and
continue fundraising through Lehigh University and other sources to fully fund the
project.
Picture: Team T-Shirt
55. 55
Logistics
Pod Construction
The Lehigh Hyperloop team has been given permission to access the
university’s metal and wood shops, and warehouse space for the fabrication and
assembly of parts and systems for the Pod Construction. Facilities for the build are
located on the Lehigh Campus in Bethlehem, PA. Although spatially adequate for
the build, the shops and warehouses may not have the necessary tools and
equipment required for a successful build. The team is researching what tools and
equipment they will have to purchase to properly outfit the workspace being
supplied by the school.
The assembling of parts and components will be completed at the space
referred to as Mountaintop. It is a large warehouse style building, pictured below,
available for prototyping and construction projects. Usually used for summer
projects, the team has received permission to use the space for construction and
testing of the Hyperloop Pod. Several members of the team are certified auto-
mechanics, builders, or manufacturers who can train the rest of the team and
supervise construction of the project.
Photo: Mountaintop Space
56. 56
Production Schedule
Currently, the production schedule, shown below, uses the assumption that
materials will not be available until the first week of March. The time waiting for
shipments of materials will be utilized for coding, material prepping, and controls.
These task can be started immediately and certain materials should arrive quicker
than others. We feel using this later date of March 7th accounts for any
uncertainties in delivery and allows for more delays should they occur.
Additionally, without knowing which days will be available to work, the predictions
use a three workday per week schedule. With these assumptions, the estimated
finish date for construction would be April 16th approximately six weeks for build.
This allows for an additional six weeks of “extra” time should production run over
schedule with the goal of having the Pod construction completed by the last week of
May. With this buffer, there should be ample time as many of the systems will be
constructed simultaneously by our sub-teams.
57. 57
Diagram: Construction Gantt Chart
Pod Testing
Within the Mountaintop space, a test platform will be constructed to test the
levitation, service propulsion, and operational propulsion systems at slow speed.
For electrical systems and sensors, test environments will be arranged to confirm
the accuracy and frequency of measurements to further refine the fault tolerance of
the system. Although this does not allow for testing at full speed, it allows more
systems to be tested before the pod is transported to California for final testing and
build weekend.
Functional Tests
For Pod loading, the pod will be driven to the tube entrance under its own
service propulsion and enter by wheel if there is ramp access. If the platform is
58. 58
raised, it will be picked up by the crane supplied by SpaceX. The full power up will
run with a preprogrammed diagnostic to confirm 2-way communication. The
simulations and predictions for levitation currently show the Pod can levitate at
regular air pressure, so test A will be run by the control console. After entering the
tube, the second communications test will be performed by user input to the console.
Finally, at vacuum pressure, the final test can be performed, however, the wheels
will remain deployed in case the pod cannot levitate while stationary at reduced
pressure. Once the pod has levitated, the wheels will retract similar to an air plane.
These initial tests will be performed on internal battery charge. At the end of the
tube, the systems will be powered down and the wheels will be engaged by the
control console to remove the Pod from the tube. The end diagnostic will confirm
that the pneumatics are discharged, rotary compressor is off and discharged, and
the operational propulsion motors are disengaged. The Pod will then be driven out
and away if the platform is not raised. If it is, the crane will be used to place it on
the road or access path and driven back to storage.
Ready Checklists
Once 2-way communications have been confirmed, the subsystems will be
started one at a time to confirm they are operational while the rail brake is
engaged. The pod may be unable to hover at vacuum pressure and may need
wheels to remain engaged up to required speed. Confirm by sensor that the pusher
is in contact with the interface to prevent damage. Finally, once all systems are
confirmed, disengage the rail brake and prepare for launch.
At the end of the tube, pneumatics and the rotary compressor will be
discharged and disengaged while the Rail brake remains engaged. Wheels will be
confirmed to be locked and engaged for service propulsion before communications
confirms the all-clear. Finally, the rail brake will be disengaged and the Pod will be
free to drive out of the tube.
59. 59
Diagram: Ready checklists
Transportation of Pod to California
Within the Mountaintop space, there will be access to cranes and delivery
docks which will be used to load the Pod onto a truck if it cannot be driven on. The
wheels will be locked and strapped down to be transportated to California. Current
estimates have the cost of transportation being at $5,000. During transportation all
batteries and pneumatics will be empty if they must remain in the Pod and will be
trasported with care. Upon arrival, it will be driven or craned off the truck and
recharged for driving to the staging area.
