ODU Formula SAE
MAE 435 - Spring 2013
Midterm Report
Chris Caulkins
Andrew Rowe
Andrew Myers
Thomas Guglielmo
Aaron Hopkins
Stephen Christiansen
Charles Pearson
Kamod Gautam
Kevin Kelly
Abstract
The ODU Formula SAE team is well on its way to completing the 2013 vehicle. Significant progress has been made in getting the team and vehicle ready for competition in May. The main portions of the vehicle, such as frame, engine, suspension, and other hardware are in place. In parallel with fabricating the new vehicle, the team has improved driving skills using the 2012 vehicle. The combination of a well-designed vehicle and skilled drivers are important for success in competition.
A large portion of the vehicle was designed by the previous semester’s team, and approved by SAE early this year. After approval was given, the designs of the frame, suspension, and control systems were constructed in the Motorsports Lab. In addition, other critical components began to be added to the vehicle. Such tasks as creating a way to securely mount the differential off of the rear of the frame were anecdote via a cantilevered bracket mounting system. Conversely, the pedal layout was altered to allow for the addition of a clutch pedal, to allow for a more intuitive driver experience. Both the front and rear rockers were machined out of aluminum in order to save on weight but still maintain strength.
The engine mounting and positioning is particularly critical because of the large amount of weight it adds. The engine mounting setup was designed in order to achieve the lowest center of gravity as possible. A custom oil pan was fabricated which lowered the engine and therefore created a low center of gravity. This greatly benefits the drivability and handling of the vehicle. Engine performance testing was conducted using the 2012 vehicle because it contains an identical engine. This provided a baseline which will be transferred to the new vehicle that will require minimal changes due to different air intake setup.
Aero team's contributions are nearly complete as body panels, nose-cones, side-pods, and rear diffusers are in the manufacturing process. Flat body panels were made from a light but stiff 4 layer vacuum bagged fiberglass. The underbody tray required a stiffer construction so 10 layers of fiberglass was used. The nose-cone, side-pods, and rear diffuser required additional support so foam reinforcements were used between 8 layers of fiberglass. Minimal body work will be required due to the use of female molds in the fabrication process. Aero team's other responsibilities include fabrication of the seat, seat mounting, safety harness, and driver ergonomics.
Table of Contents
Abstract ...... 2
Table of Contents...... 3
List of Figures...... 4
Introduction ...... 5
Background ...... 6
Methods...... 8
1.1 Powertrain...... 8
1.2 Aerodynamics...... 10
1.3 Chassis...... 12
1.4 Suspension/Brakes...... 12
1.5 Controls...... 12
Results...... 14
Conclusion...... 15
Discussion...... 15
Appendices...... 16
List of Figures
Figure 1: Page 109 from 2013 FSAE Rule Book...... 7
Figure 2: Page 139 from 2013 FSAE Rule Book...... 7
Figure 3: Dyno curve for 2012 ODU FSAE vehicle...... 8
Figure 4: Baseline fuel map transferred from old ECU...... 9
Figure 5: Side-pod mold being vacuum bagged...... 10
Figure 6: A near perfectly smooth panel due to the use of female molds...... 10
Figure 7: A heat lamp was used to cure the resin overnight; the surface temperature was maintained at 90 Deg while atmospheric temperature was close to 40 deg...... 11
Figure 8: Baseline compared to updated fuel map...... 14
Figure 9: A smooth “showroom” finish is a byproduct of using female molds and vacuum bagging technique...... 14
Appendix
Figure A 1: Project Gantt chart...... 16
Figure A 2: Aero body budget...... 17
Figure A 3: Aero safety budget...... 17
Figure A 4: Aero team shop supplies budget...... 17
Figure A5: Powertrain Budget...... 18
Introduction
Formula SAE is a worldwide competition between engineering schools to compare and challenge each other. Each school is required to design, build, and drive a formula style vehicle. Each team is then judged on certain criteria such as design application and skill, cost efficiency, and overall performance. This gives the students experience applying the theories learned in class to a real world situation.
The project begins by creating a preliminary design and a budget proposal to whomever may be funding the project. Once a budget is settled, the team can begin designing the vehicle in great detail. The designs are subject to rules stated by SAE that allow the team to be creative in engineering design, but still maintain safety to the driver.
Background
Formula SAE is a race vehicle design competition for students attending universities around the world. The first competition was held in 1978 and the longest running competition is held annually in Michigan, which is where the Old Dominion Formula team will compete in May 2013. The teams are run primarily by engineering students with some faculty guidance to complete their projects. Each vehicle is designed and manufactured from the ground up and it is each team’s responsibility to create a project plan in order stay under budget and produce a final product for competition. The participating teams must produce a new vehicle for each competition year.
There are currently 120 teams registered for the May 2013 Michigan competition that ODU will compete against directly. The event is safety orientated, considering most team members are amateurs, and the vehicles must pass several safety tests before being allowed to compete. These include a rollover stability test, in which the tallest driver will sit in the vehicle as it is tilted sixty degrees to determine if the vehicle has a tendency to rollover, a breaking test, in which the vehicle’s brakes will be checked by testing if all four tires can be simultaneously locked. Additionally, there is a noise test to determine if the vehicle is operating at a safe noise level, 110 decibels.
The competition has several judging aspects: design, performance, and endurance. The design aspect consists of the judges giving scores for how well they believe the vehicle was designed and built. They will be taking everything into account, including cost and making sure the team did not break any of the design rules.
There are two types of events, static and dynamic. The static events are a design report and a cost report given to the officials, experts from the automotive industry, before the actual vehicle is tested. The design report explains the effort that went into the vehicle and what engineering solutions were decided on to produce a functioning vehicle. The cost report is a discussion on manufacturing the vehicle and it explains how much it would cost to put the vehicle in large scale production. The presentation given to the officials will be based off the design and cost reports. The goal is to prove to the officials that the team has a comprehensive understanding of why the vehicle was decided in the way it was and how it can be cost effective for large scale manufacturing.
The dynamic events include an acceleration test, skid pad test, autocross test, and efficiency test. In these dynamic events, points will be awarded based on performance and compared to the other teams in the competition. The endurance event is the main event where the most possible points can be earned. The endurance event consists of a twenty-two kilometer race to test the vehicles’ durability under long term conditions.
The point scale is as follows:
Figure 1
Page 109 from 2013 FSAE Rule Book [1]
Figure 2
Page 139 from 2013 FSAE Rule Book [1]
Methods
1.1 Powertrain
The Powertrain team has the responsibility to design and fabricate the heart of the vehicle. The engine selected for this year’s vehicle is a 2006 GSX-R 600cc motorcycle engine and transmission. This engine/transmission combination is used because of the reliability, availability, and usability of components that have been designed from year to year. Since we are running 93 octane “pump” gas a 20mm diameter intake restrictor is designed per FSAE rules. The 2012 vehicle has the exact same engine, and from this we will dyno test to get baseline data which can be closely correlated to the 2013 vehicle. This includes parameters such as power output, torque output, speed and fuel/ECU mapping. Below is data taken using facilities at TCC using the 2012 vehicle:
Figure 3
Dyno curve for 2012 ODU FSAE vehicle
This graph still has issues which have been fixed since this test was performed. Between 5,000 and 7,000 RPM the performance is very poor. The fuel map on the ECU was modified to produce better performance and a much smoother curve. A more in depth fuel map is shown below:
Figure 4
Baseline fuel map transferred from old ECU
Transmitting the output of the engine to the ground is another key factor of performance. The final gear drive ratio is found using the following:
drive ratio = Ndiff/Neng =53/15 = 3.533 [2] (1)
This will give a significant amount of torque transfer to the rear wheels. This must be transferred through a differential. A torsional differential is used to accomplish this while maintaining good handling and drivability.
Another hurdle to overcome in the design phase is engine cooling. A properly designed cooling system will allow the engine to run under heavy loads and not overheat. The objective of this system is to maintain a constant optimum operating temperature in the engine. Furthermore, the cooling system must be reliable and light while mounted on our vehicle’s frame. The calculations and design criteria were completed in a previous semester and concluded that a factory Hayabusa radiator should be used. This was justified in that the cooling capacity in known to be sufficient and being readily available for purchase with minimal cost as opposed to a custom radiator.
The air intake manifold is another important factor in engine performance. This was designed and validated in a previous semester and will not be included in this report. Since this is a sequential port injection style engine fuel injectors are being used. The specific calibration and flow calculations were provided by Synerject, LLC.
1.2 Aerodynamics
The aerodynamics team has been tasked the responsibility of designing and fabricating the body panels, side-pods, nose cone, and rear teardrop. The aero team has also been tasked with safety design and fabrication. Over spring break flat body panels were created using an advanced vacuum bagging technique as opposed to a traditional hand lay fiber glassing technique.
A traditional method to laying fiberglass has several different ways for human error to affect the outcome of the piece. Environmental factors such as dust or moisture could create flaws in the fiberglass which could lead to issues later on in the fabrication. Laying the glass by hand could also lead to the glass having issues with varying thicknesses or air bubbles inside the finished product. That is why the vacuum bagging technique was chosen.
Figure 5
Side-pod mold being vacuum bagged
The vacuum bagging technique eliminates many of the issues that can be found in the more traditional methods. Since the parts being fabricated for the vehicle are all relatively small, this makes it ideal for the use of vacuum bagging. What vacuum bagging does is remove the air from a mold and allow the epoxy to be distributed evenly between the mold and the vacuum bag. This also creates a relatively smooth surface on both sides of the body panels that normally would be tougher to achieve if laid by hand.
Figure 6
A near perfectly smooth panel due to the use of female molds
Vacuum bagging is a fairly simple process that can be done quickly and efficiently. The first step is to set up the mold and vacuum bag it so that there is a smooth surface to begin laying the glass. For a flat body panel, a 24” X 48” acrylic sheet was used to create not only a nonstick surface but also a perfectly flat surface for the glass to mold to. After the mold has been prepared a release agent cloth can be placed across the mold followed by the desired layers of glass and then finally topped off with bleeder cloth across the entire mold. Once all of the layers have been put down, the mold can be outlined using butyl tape. After the tape has been laid out a tube with a spiral cut pattern can be draped across one end of the breather tape so that the epoxy can be distributed across the glass. A second tube with the spiral cut pattern will be covered in shop towels and placed across the other end of the mold. From here the vacuum bag can be placed and secured over the mold and checked to see how well the seal is holding. Once the seal has been properly tested the epoxy can be mixed and drawn through the tube without the shop towels so that it covers the entirety of the glass. The tubes can then be clamped and the whole mold placed under a heat lamp so that the epoxy can dry. Twenty four hours later, heated by the heat lamp, the epoxy has cured enough for the mold to be delaminated and the fiberglass to be removed from the vacuum bag.
Figure 7
A heat lamp was used to cure the resin overnight; the surface temperature was maintained at 90 Deg while atmospheric temperature was close to 40 Deg
The safety components that the aero team has been given responsibility of are the seat, harnesses, and roll bar padding. The seat has been purchased online from Jegs due to time constraints. It will also be mounted at about a 37 degree angle which according to page 50 sections T5.1 of the FSAE rulebook is considered a reclined position and requires a six point harness which has also been purchased online from Jegs. The rulebook also states on page 53-54 section T5.6-5.7 that padding must be placed anywhere on the frame where the driver’s helmet may come in contact with it so 0.5” roll bar padding and padding for a head restraint have been purchased from Jegs.