2016 SOR2 Design Report

hℐp://go.asme.org/HPVC
Vehicle Description Form                                      (Form 6)

Updated 12/3/13
Human Powered Vehicle Challenge
Competition Location:  Santa Clara Valley ASME Section
San Jose, CA
Competition Date:  April 22 24, 2016

This required document for  all  teams is to be incorporated into your Design Report.   Please Observe
Your Due Dates ; see the ASME HPVC for due dates.

Vehicle Description
School name:   California Polytechnic University Pomona
Vehicle name:  Spirit of Randy 2
Vehicle number: 23

Vehicle configuration:
Upright Semirecumbent
Prone Other (specify)
Frame material:  4130 steel
Fairing material(s)
Number of wheels:  2
Vehicle Dimensions  (please use in, in 3
, lbf)
Length   104.3 in             Width 21.75 in
Height   47.1 in             Wheelbase        47.27 in
Weight Distribution
Front       2.66 lb Rear     7.04  lb Total Weight     9.7 lb
Wheel Size
Front 700c Rear 700c
Frontal area    584in 2

Steering
Front Rear
Braking
Front Rear Both
Estimated Cd   0.2746

Vehicle history (e.g., has it competed before?  where?  when?)
No vehicle history

California State Polytechnic University, Pomona
2015 ASME HPVC Challenge

The Cal Poly Pomona Human Powered Vehicle Team
Presents

The Spirit of Randy 2

Team Officers
Jordan Jarnagin
Andrew Simpson

Team Members

Jordan Jarnagin
Andrew Simpson
Josh Diaz
Melanie Bailey
Bruno Hasebart
Robert Diaz
Khadijat Salami

Spirit of Randy 2; 3View Drawing

Abstract

Cal Poly Pomona Human Powered Vehicle for the first time successfully competed in the
ASME HPVC West Competition last year in 2015, and this year has set the goal for continuing to
build the program as well as improve on our design and manufacture processes. The first of our
two proposed vehicles for this year’s competition, the Spirit of Randy 2 (SOR2), is of the same
type of vehicle submitted last year, but completely redesigned.
The main objectives this year were to introduce standardization in to our operations; design,
manufacture and project management. In this effort, our organization has more than doubled the
amount of industry partners it had the previous year and has been able to start work on
aerodynamics for the first time. In terms of manufacture, our team had previously relied almost
exclusively on hand cutting and building in order to fabricate vehicles. This year, we have
introduced laser cutting in order to increase reliability and lower manufacture time.
Our first vehicle this year, the SOR2 is a semifaired front wheel drive recumbent that is
designed to be lightweight and fast.

Table of Contents

1. Design
1.1. Background
1.2. Objectives
1.3. Prior Work
1.4. Design Specifications
1.5. Concept Development and Evaluation of Alternatives
1.6. Innovation
1.7. Final Design
1.7.1. Ergonomics
1.7.2. Frame
1.7.3. Drivetrain

2. Analysis
2.1. Roll Protection System
2.2. Material Selection
2.2.1. Carbon Fiber
2.2.2. 4130 Chromoly Steel
2.2.3. Acrylic
2.3. Stress Analysis
2.4. Aerodynamics
2.5. Cost Analysis

3. Safety
3.1. Design for Safety
3.2. Safety Harness
3.3. Safety Accessories
3.4. Safety in Manufacturing

4. Conclusions
4.1. Evaluations
4.2. Recommendations
4.3. Conclusion

5. References

Appendix A

1. Design

1.1. Background

Mission Statement:
The CPP Human Powered Vehicle Team strives to create an environment that allows its members
to gain valuable experience in engineering design, project management, industry relations,
manufacturing, business, and performance testing.

1.2. Objectives

Long Term Objective:
To design, fabricate, and compete with human powered vehicles collegiately on an annual basis.

Short Term Objective:
To improve the quality of design and fabrication within the organization and create a documentation
protocol for future generations


Figure 1 : 2016 Gantt Chart

1.3. Prior Work

The SOR2 is the second iteration of the front wheel drive recumbent that we have produced. While
it is true that our organization has made a similar device in the past, the only things used from last
year were the same decision matrixes for choosing the type of recumbent and headtube angle.
Everything else is of new design.

1.4. Design Specifications

The goals of our design this year were to build a vehicle conducive to the specifications
outlined in the 2015 HPVC rules. these are:
● 15 ft minimum vehicle turning radius
● Vehicle braking from 15 to 0 mph in less than 20 ft
● Vehicle cargo area large enough to accommodate parcels of dimension 15x13x8 inches
● Rider safety harness
● Roll protection system that can support a 600 lbf top load with deflection of less than 2
inches
● Roll protection system that can support a 300 lbf side load with elastic deflection of less
than 1.5 inches

In addition to this, the personal goals of the team relative to last year’s design were to:
● Create a lighter vehicle
● Lower the vehicle center of gravity
● Incorporate aerodynamics into the design

1.5. Concept Development and Evaluation of Alternatives

As stated before, the concept for the SOR2 was based on its predecessor, the SOR1, and so no
other alternatives were considered. Because the main goal of last year’s design was to make it to
competition, this year the focus was aimed much more at concept optimization. Pictured below is
the decision matrix for the SOR1 which still holds as reasoning for the concept for the SOR2.

Tricycle
Bicycle Delta Tadpole
Category
Rear Wheel
Drive
Front Wheel
Drive
Rear Wheel
Drive
Front Wheel
Drive
Rear Wheel
Drive
Time
Allotment
Design 3 1 2 3 4
Fabrication 2 2 3 3 3
Design/
Fabrication
Stability 3 3 2 2 2
Drivetrain 3 1 3 4 4
Ergonomics 2 2 3 3 3
Frame 2 2 3 3 4
Steering 3 4 2 4 3
Total 18 15 18 22 23
Figure 2: Decision Matrix

1.6. Innovation

In our efforts to design an effective vehicle, innovation surfaced in two main areas; design and
manufacture. In design, the concept of the frame profile was to have the smallest front facing area
while being easy to maneuver. The result of this design intent was a frame that is more than ten
centimeters lower than its predecessor, less than half the weight, and one that is semifaired.

Figure 3:   SOR2 Assembly Apparatus

In terms of manufacture, last years design utilized a single large assembly apparatus for the
fabrication of the frame that proved to be ineffective in stabilizing precise geometries for welding.
This assembly apparatus was time consuming to make and the end result had to be refitted
numerous times in order to build the SOR1. This year, the approach to the assembly was taken in
pieces, focusing on each tube joint separately and assembling pieces of the frame to be fitted
together at the end. This style of assembly apparati employed a number of panels to be adhered to
specific parts of the frame and ultimately create the entire structure. Because the apparatus is made
exclusively of panels, the design was able to be done quickly on the preexisting SOR2 frame
model in CAD, and then subsequently laser cut to ensure accuracy. This process not only
eliminated apparatus building error, but also drastically reduced the time needed for design and
utilization of an assembly apparatus.

1.7. Final Design

Our final design is an semifaired front wheel drive recumbent bicycle with a moving
bottom bracket (drivetrain turns with handlebars). As mentioned before, the drivetrain setup is
essentially that of a conventional bicycle, but with modified orientation and cable routing . The roll
protection system completely surrounds our tallest rider to prevent injury in the case of a crash.
The rear of the vehicle is faired in order to reduce flow separation and improve aerodynamics.

1.7.1. Ergonomics

Since the majority of the male and female competitors riding the SOR2 in the 2016 ASME west
Competition are of the same height and body shape, the design was focused on the basic
dimensions of a 5’10” 150 pound person. One of the main design focuses of this year’s vehicle
was performance and speed. While last year’s vehicle was made to be useful for both racing and
recreation, the design of the SOR2 focused on racing. Because of this, the frame design was made
as low as possible by both lowering the center of gravity of the vehicle and putting the rider in a
more reclined position to lower frontal facing area relative to the SOR1. The SOR2 center of
gravity is five inches lower than its predecessor and its seat angle has been reclined an additional
ten degrees.

Figure 4 : SOR2 Ergonomic Design

Shown is a sketch of the SOR2 Frame Geometry with a rider’s geometry superimposed on top to
simulate the fit of a human inside of the SOR2. This style of ergonomic analysis was useful for
multiple reasons; first, it allowed the team to assess the visibility of the rider. Second the leg
elongation was easily assessed using this model by constraining the frame and allowing the sketch
of the superimposed rider to freely pedal around the bottom bracket. Lastly, this model was useful
in determining the height of the vehicle that would provide adequate protection for the rider. This
simple yet effective method of ergonomic analysis proved invaluable to the team in the design of
the SOR2

1.7.2. Frame

The frame was designed to incorporate two structures (a front portion and a rear portion)
which pivot about a point just in front of the rider’s seat. As previously stated, this design was
chosen for its feasibility.

During the design process, the commercially available Cruzbike Vendetta was used for
inspiration (Figure 6). This recumbent design relies on turning the bike primarily by leaning into
the turns as opposed to turning the front wheel. This aspect is crucial since turning the front wheel
sharply is difficult due to the rider's legs operating in the plane of the front wheel. Riders operate
the Vendetta in nearfully reclined position which  maximizes their power output due to the fully
extended pedalling motion. This rider configuration is well suited for fast rides with wide turns,
but proves disadvantageous when maneuverability in tight spaces is desired. This issue was
addressed in the Spirit of Randy’s design.

Figure 5:  Cruzbike Vendetta V20
(courtesy of cruzbike.com)

In designing the frame the main concerns were simplicity and strength. The front triangle
pivots about a standard 1⅛” threadless, non tapered head tube. This is the common point between
the front and rear of the frame. The front triangle of our vehicle can be thought of simply as the
rear triangle of a conventional bike transposed about the seat stays (with the seat stays changed to a
fork). To accommodate the cassette on our front wheel, we selected a straight bladed track fork
with a hub spacing of 100mm for modification. Using a heat treated bending process, the 100mm
spacing was enlarged to accommodate the 130mm rear wheel spacing desired. Because the fork
used was made out of 4130 Chromoly Steel, after bending it was subjected to a tempering process
to recrystallize the material at the bent sites in order to relieve internal stresses. The front fork
assembly is shown below.

Figure 6 : Front Triangle Assembly

In order to maximize the efficiency of the vehicle, the front fork was made rigid by making the
bottom bracket support boom attach directly to the fork rather than via a pin connection in previous
designs. This will ensure a more reliable and stable vehicle.

The rear portion of the frame comprises the bulk of the vehicle’s weight. It consists of
roughly 22 feet of 1 inch outer diameter, 0.035 inch thick, 4130 steel tubing. Aside from the head
tube and dropouts the entirety of the rear frame was made in house. Since the tubes were relatively
thin walled the initial plans were to tig weld the frame which would have produced clean weld
joints. In the end the frame was mig welded due to an inability to gain access to tig welding. Care
was taken to ensure the joints were solid while minimizing excessive creation of heat affected
zones. The machined, 1018 steel dropouts were purchased from Paragon machine works and
welded directly onto the ends of the two rearmost tubes. The total calculated weight of the rear
frame is 7 lbs.

1.7.3. Drivetrain

The drivetrain of the Spirit of Randy 2 utilized a traditional road bicycle setup, but in a
modified orientation. because of the standard setup, it was unnecessary to custom design or
fabricate parts. The components used (Listed in Appendix A), are all in a standard road bicycle
configuration except for the cable routing throughout the vehicle. due to the change in frame
geometry from a traditional road bicycle, the routing of the cables for braking and gear shifting had
to be placed in a way that allowed full functionality while not inhibiting rider experience or
performance. because the Spirit of Randy is a moving bottom bracket type vehicle, the possibility
of a rider hitting a brake or shifting cable with their legs while riding can cause unwanted braking
or shifting and therefore is a major concern when determining a proper cable routing scheme. The
Spirit of Randy’s cable routing is as minimalist as possible in order to avoid unwanted rider cable
contact.
When choosing components for the Spirit of Randy’s drivetrain, the following was
considered.
FSA Gossamer cranksets offer good strength for a relatively low price. The chainrings are
50/34t, also known as a compact crankset. This allows a wider gear range needed to accelerate a
heavy recumbent bicycle and still have high enough gears for higher speeds. Its 24mm axle fits the
threaded bottom bracket that is specified. The driven 1128t cassette has durable steel cogs riveted
to an aluminum spider to reduce rotating weight. This gear combination allows a wider gear range
needed to accelerate a heavy recumbent bicycle and still have high enough gears for higher speeds.
Connecting the two is a KMC X10.93 chain. It is 10 speed compatible, and shifts well due to the
shaping and chamfers on each link. The crankset spins on a standard BSA threaded bottom bracket
because of the ease of maintenance and availability. It measures 68mm wide to fit standard road
cranksets, and has a 1.370”24 thread with the right side being left hand thread.
Shimano’s Tiagra rear derailleur is 10 speed compatible and can shift up to a 30t cog on the
cassette. The cage is also long enough to accept the wide tooth difference from the front chainrings.
The Shimano 105 band clamp front derailleur because it is easy to mount to a round tube and
doesn’t require any complex hardware. Shimano 105 components are cost effective and reliable.
Shimano 105 brake and shifter hoods control the brakes and shifting. Although the right shifter is
made for 11 speed drivetrains, it will work with 10 speed rear derailleurs because the pull ratio is
the same. They have indexing for easy and reliable gear changes, and also has trims for the front
derailleur. Connecting the shifters to the derailleurs is shimano SP41 4mm shifter housing and
cables. These are standard bike cables that are very smooth and dependable with little friction. The
inner cables are stainless steel to prevent corrosion
Tektro dual pivot brakes were chosen because they offer more power than conventional
single pivot brakes. The extra power will help decelerate the heavier recumbent bike in a controlled
and acceptable manner. Msystem 5mm brake housing connects the brakes to the hoods.

The Frame this year utilized a modified Origin8 1⅛” Del Pasado fork for the front half of
the frame.
The first priority for the wheelset is strength. This bike will weigh more than typical bikes
and will have to withstand uneven surfaces in the endurance competition. Typical strong wheelsets
have 32 spokes with a three cross lacing. Mavic rims laced with straight gauge spokes in a three
cross pattern offer tons of strength. Shimano hubs are very reliable and roll on rebuildable cup and
cone bearings. Bontrager T1 25c tires have an all weather tread pattern and the slightly larger
volume absorbs more road imperfections than skinnier tires.
Recumbent bikes don’t need drop bars because there is no advantage in changing hand
positions. Pursuit handlebars offer good ergonomics, accept road brake and shifter levers, and are
available at bicycle retailers.

2. Analysis

2.1. Roll Protection System

The roll protection system was designed to protect the rider in the event of a crash,
ensuring that the rider would not contact the ground if the vehicle were to completely rollover. The
design parameters were those stated in section 1.4 (Design Specifications) and are reproduced
here.

● Roll protection system that can support a 2670 Newton top load with deflection of less than
2 inches
● Roll protection system that can support a 1330 Newton side load with elastic deflection of
less than 1.5 inches

Figure 7 : Top Top Load Displacement, Bottom Top Load Stress

Theoretical stress analysis was performed using SolidWorks Finite Element Analysis
(FEA) tools. Solidworks allowed the team to quickly and easily analyze the frame under multiple
production situations by applying custom weldment profiles that reflected commercially available

tubing. The selection of the fixed geometry to be used during the stress analysis was based on the
ASME HPVC west challenge criteria as well as how the frame would be tested in real life. The
rear dropouts and the bottom of the front part of the RPS were constrained During the FEA
analysis, as seen by the green arrows in figures 9 and 10. The material studied was AISI 4130
normalized Chromoly Steel which was the selected frame material. A 2670 N load was applied to
the top of the roll protection system at an angle of 12 degrees with respect to the vertical. A 300 lbf
load was also distributed across the seat rails in order to simulate the pressure induced by the
operator during operation. Under this static condition, with the effects of gravity considered, the
maximum induced stress was found to be along the axis of applied load, causing a maximum load
on the tube of 4.4477e+008 N/m^2.

Figure 8: Side Load deformation

Figure 9 : Side Load Stress

A 1330 N side load was applied to the two member joint of the roll protection system, which is
approximately shoulder high of the operator, as seen above in figure 10. Again taking into account
the effects of the riders distributed load (300 lbf) and the effects of gravity, the maximum induced
stress was found in the midsection of the frame with a magnitude of approximately 4.4e+008
N/m^2   and the maximum deflection was found to be at the top of the roll protection system with a
magnitude of approximately 10 mm (~0.39 inches) as seen in Figure 8.

According to MatWeb, the tensile yield strength of AISI 4130 is 435 Mpa in which case
the stress produced from FEA is well within the safe range with a maximum theoretical factor of
safety with respect to yielding of 1.32. Throughout the FEA analysis the Spirit of Randy never
showed signs of plastic deformation and was determined to have a maximum factor of safety with
respect to allowable elastic deflection of  3.75.  One inch outer diameter tubing with wall thickness
of .035” was used to construct the frame.

2.2. Material Selection

Carbon fiber will be used to create the box for the parcel pick up and drop off in the
endurance event. The frame will be made out of chromoly steel. The nose cone will be made out of
acrylic.

2.2.1. Carbon Fiber

We investigated the possibility of using carbon fiber in order to make an aerodynamic
fairing.  Unfortunately we were not able to obtain the necessary sponsors or funds in order to
make our dreams and designs come to fruition, but we were able to get enough material to make a
carbon fiber basket.  By exploring the world of carbon fiber, we are getting one step closer to
producing a full body fairing.  This will be our goal for the following year.
We began our exploration into the world of carbon fiber by manufacturing small four inch
by four inch squares out of unilateral prepreg carbon fiber.  This carbon fiber was difficult to
work with so we began using two by two cross twill dry fabric and used a room temperature
curing epoxy resin in order to make four by four test samples Figure 10.  Utilizing this form of
carbon fiber, we were able to manufacture test samples that we were happy with.  We began using
this new found knowledge to manufacture our carbon fiber basket.
By practicing with the carbon fiber, we were able to get a basic process down in order to
make carbon parts in the future.  We have begun testing and experimenting with different
thicknesses of test samples (different numbers of plies) in order to see how each combination
would react.  We found that for our basket, that a three ply thickness of two by two cross twill
fabric would give use the flex and stability we need.
After getting a grasp on what it takes to manufacture carbon fiber parts, we began
constructing more geometrically complex test samples.  Once these tests proved successful we
realized that a complex aerodynamic fairing is possible for next year's bike.  We are continuing to
expand our knowledge on composite mold design and manufacturing in order to make our dreams
for innovation to come true.

Figure 10 : Left Investigation of hand layup/ pressure molding techniques, Right First radiused hand layup

2.2.2. 4130 Chromoly Steel

For the vehicle frame we went with the same material as we used last year. The reason we
chose this material again was its versatility. When choosing the frame material we made sure that
we could cut, bend and weld the material in our shop. Also the material needed to follow the
standards outlined in the ASME rules. The biggest detriment we had was the inability to get access
to tig welding. This is how we came to look at steels for their weldability. When welding steel it
not as difficult as some other metals such as aluminum or titanium. From the website of our steel
source (TW Metals), we found the yield strength to be 80,000 psi (min), the tensile strength to be
90,000 psi (min), and the hardness 95 HRB. This year we are testing these material properties in
our shop to learn how to do it and to validate the manufacturer's given material data.

2.2.3. Acrylic

The fairing this year will be made out of acrylic. Acrylic was chosen because it is perfectly
clear, abrasion resistant, and depending on the grade can have good impact properties.
The mold will be made out of wood and the acrylic will be vacuum formed over the mold.

2.4. Aerodynamics

This is the first year that our team has set out to create a fairing to reduce drag. The design
of the bike doesn’t allow for a fully faired recumbent because of the nature of how it steers.
Initially a tail fairing was considered but after analysis it wasn’t proving to help reduce drag on its
own. A nose cone was then added and seemed to help. The nose cone on its own along with a
small aerodynamic box which would have a removeable lid for parcel pickup during the endurance
event turned out to be the best combination. All of the fairing iterations were tested using

Solidworks Flow Simulation. The tests were run at 528 in/s which is 30 mph which would be an
improvement over SOR1’s top speed which with the nose cone and lighter and lower frame should
be attainable. Figure 11 and 12 below show a relative pressure surface plot and velocity flow
trajectory respectively. The drag force at 30 mph was found to be 2.5lb. Using this and other
values the drag coefficient can be determined. The calculated drag coefficient is 0.2746.

Figure 11 : Relative Pressure Surface Plot

Figure 12 : Velocity Flow Trajectory

2.5. Cost Analysis

The cost analysis compares the SOR2 as a prototype, the cost to produce ten vehicles in
one month, and the production cost to produce ten per month for three years.

Category
The Spirit of Randy
as presented
Monthly Production
Run (10 per month)
Three Year
Production Run
Capital
Investment $0.00 $3,800.00 $136,800.00
Tooling $35.00 $35.00 $1,260.00
Parts and
Materials $1,523.81 $14,375.00 $517,500.00
Labor $0.00 $2,000.00 $72,000.00
Overhead $0.00 $1,728.47 $62,224.92
Total $1,558.81 $21,938.47 $789,784.92
Figure 13:  Cost Analysis Summary

This summary only includes the costs associated with fabricating the vehicle. Capital
investment along with labor and tooling are noted as $0 due to the fact that shop space was
provided for free and student labor was unpaid. A more detailed breakdown of the cost analysis
can be found in appendix A.

3. Safety

3.1. Design for Safety

The SOR2 incorporates a roll protection system, 4point harness, reflectors, Brakes, and a
padded seat (for long rides).

3.2. Safety Harness

The Spec D Tuning  JDM Style four point universal racing harness seat belt  was selected as
the vehicle's primary and only safety harness. Weighing in around three and a half pounds this
harness will minimize the overall weight of the vehicle. The Spec D Tuning harness features 2 inch
nylon webbing straps with 80 inches of arm strap, a quick release buckle and extra wide pads
located at the waist. The four point seat belt design applies pressure to the rider's chest and waist
securely harnessing them to the seat. When applied correctly the Spec D Tuning harness will keep
the rider's torso secure and in place allowing their legs and arms to move freely. In the event that

the rider should put the vehicle through a complete rollover, the Spec D Tuning harness will keep
the rider safely inside the vehicle. This component couples nicely with the Spirit of Randy’s roll
protection system. The 2 inch width of the strap allows more tension to be produced and adds to
the durability of the strap increasing its lifetime. The quick release buckle makes entry and exit
quick and simple for riders of various discipline and age. The extra wide pads increase rider
comfort by distributing the pressure across a larger area of the rider's body. These reasons make
the selected harness a safe and long lasting component of the vehicle.

3.3. Safety Accessories

The Spirit of Randy is equipped with front lights, rear lights, and reflective stickers to
increase visibility during all hours of operation. The rider will not be encased in a vehicle shell and
therefore standard hand turn signals are to be used in the event of traffic maneuvers. The SOR2
will come equipped with mirrors and a bell as well.

3.4. Safety in Manufacturing

Safety was a top priority during the manufacturing process of the frame assembly
apparatus, the frame, and during vehicle assembly. The two shops used both required their own
separate safety certifications that were completed by each individual team member. While working
in the shop the team wore safety glasses, noted proper emergency procedures and filed the MSDS
paperwork for all chemical products used.

4. Conclusions

4.1. Evaluations

In its second year as a competition organization, the Cal Poly Pomona Human Powered
Vehicle Team was able to successfully continue the HPVC project and create an optimized version
of its first entry vehicle the Spirit of Randy. During the design phase of the SOR2 the team was
able to increase its industry contact pool, work on design optimization, and preform design in
aerodynamics. The team is much further along than it has been in the past, and continues to
improve and innovate.

4.2. Recommendations

Recommendations for next year would be to begin aerodynamic design earlier, what
seemed an easy task in the beginning turned out to be a process that took much more time than
anticipated.

4.3. Conclusion

At this point in the SOR2’s development, the team has been successful in achieving its
main goal of design optimization, and is well on its way to competition. As the design process
progresses, the team continues to learn new things in various areas such as design practice,
manufacturing, business relations, and most importantly, slack and lead times. As the competition
approaches the team is confident it will perform well at its second competition.

6. References

Wilson, David Gordon, Jim Papadopoulos, and Frank Rowland. Whitt. Bicycling Science.
Cambridge, MA: MIT, 2004. Print.

"MatWeb The Online Materials Information Resource." MatWeb The Online Materials
Information Resource. N.p., n.d. Web. 01 Apr. 2015.

2016 SOR2 Design Report

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