TEAM 3 - web1.eng.famu.fsu.edu

TEAM 3

16 APRIL 2003

EML 4552/4553 SENIOR DESIGN

Addendum to Final Design Report

“A Reflection on the 2003 SAE Mini Baja East Competition”

Spring 2003

Blunt, Michelle

Brinson, Thomas Coldwell, Brian

English, Ned

TABLE OF CONTENTS ADDENDUM ...................................................................................................................... I

Competition...................................................................................................................... I The Good.......................................................................................................................... I The Bad......................................................................................................................... IV The Ugly ....................................................................................................................... VI

2003 SAE Mini-Baja East Overall Results .....................................................................VIII Lessons and Reflections................................................................................................ IX

Mini Baja Team ADDENDUM

I

ADDENDUM

Competition The University of Central Florida hosted the SAE Mini Baja ® East competition in Orlando, FL during the first weekend of April 2003. Details of the competition events and results may by found at the official SAE Mini Baja East website, http://www.minibajaeast.com. The FAMU-FSU College of Engineering baja car #42 placed 42nd (unintended irony) at the 2003 SAE Mini Baja ® East competition. The following is a breakdown of the team’s observations categorized as the good, the bad, and the ugly.

The Good The powertrain was considered to be a partial success because the car still moves. Some components of the powertrain did fail such as the open differential (which the customer was advised against) and a lose sprocket that was quickly tightened. Aside from the powertrain, a major success of the vehicle was its floatation. The floatation design proved to be among the elite. One of the judges commented that the team’s floatation was the best he’d seen all day. Another team wanted to borrow our detachable floatation for their vehicle. During the floatation test, our car (with driver) quickly recovered from the 30-degree tilting test. This was a suspenseful event considering the rear floatation addition had not been tested. The floatation test was on Saturday and if any team failed the test, that team could not compete on Sunday in the 400 point – 4 hour Endurance Race. Our team was elated to see the vehicle float. It was the first highlight of the competition. The second highlight of the competition came at the end of the endurance race when we completed our first and only lap. The judges didn’t count the lap because time had expired; however the team counted the lap. Throughout the rigorous course, the car had some failures (see “The Bad” section), but none that could not be fixed, and we were determined to complete a lap.


II

Figure 1 – Endurance course map

Figure 2 - After a long day, car #42 perseveres and emerges from the woods


III

Under normal conditions, the car would come out of the woods (by the white sign, see Figure 2) and proceed with the race (through the yellow caution tape, see Figure 2). Time had expired so the judge directed the car off course. This was a disappointment, but it was quickly overshadowed by our perseverance and the fact the car still worked.

Figure 3 - Victory through determination and perseverance

Figure 4 - A sense of accomplishment


IV

Figure 5 - The team and the car on its "victory" lap to be washed down

The Bad POWERTRAIN Open Differential Do not use an open differential for an off road terrain event such as the Mini Baja ® East competition. An open differential is the cheapest and least complicated (functionality wise) of any other type. It allows for the two rear wheels to rotate at different angular velocities, which is great for steering. It fails to accommodate for when one wheel is slipping (which may occur in a small mud puddle) and the other wheel has traction. Under this condition, the open differential will cause the tire that is slipping to continue slipping because this type of diff wasn’t design for off road driving. A limited slip differential or even no differential, just on solid rear axle would have been better than an open differential. A limited slip differential transfers power to the tire with least traction, so in the event that one tire is slipping, all the power is transferred to the tire with the most traction and the vehicle moves.


V

In summary, the team advised against using an open differential, but the customer mandated it. Its original plan was to be optimized with independent rear brakes for water maneuverability; however, it failed under mud and slippery conditions because all the power is transmitted to the tire with least traction. The Engine The big mistake made with the engine happened while in Tallahassee. The customer set the governor on the engine to 3800 rpm. What’s the big deal, you ask? Well, the competition rules state that all engines will be governed at 3600 rpm before competing. The vehicle’s performance observed by the team in Tallahassee (at 3800 rpm) was not an accurate prediction of how the vehicle would perform in Orlando (at 3600 rpm). The customer was told that the governor should be set (at most) to 3600 rpm during testing, but he stated that setting the governor to 3800 rpm was close enough. This was definitely not the case. While in Tallahassee, operating at 3800 rpm, the vehicle reached a max speed of 27 mph; however while in Orlando, operating at 3600 rpm, the vehicle couldn’t get past 15 mph. Our towing ability decreased analogously with our speed. What a difference 200 rpm makes! If the governor would have been set to 3600 rpm while in Tallahassee, then the team would have been able to observe the vehicle’s performance at that frequency and made any necessary changes improve its output. Note* The team understands that the mini-baja competition was a first for everyone and it is not our objective to point the blame at anyone. This was definitely a learning experience for us all. The CVT The CVT unquestionably needs to be covered in a sealed case. Belts and clutches don’t operate well when they’re wet. Furthermore, the high ratio of 1:1 was never reached in the CVT, which suggests that the spring and weight combination should be reconsidered. The way the CVT works is as the engine output shaft speeds up (which is rigid with the drive clutch of the CVT), so does the centrifugal force. The force swings the internal weights of the clutch out (against the resistance of a spring), which causes the plate to move. The heavier the spring, the harder it is for the weights to move the plate. A lighter spring would probably resulted in a 1:1 high ratio. OVERALL VEHICLE Steering Every mechanical failure during the endurance event was directly related to the steering other than a lose sprocket. The rod ends and linkages were old and not intended for the abuse they experience. The group spent 90% of its down time (time spent not racing) during the endurance event, trying to fix the steering. Components were replaced, worked on, and broken parts were welded.


VI

The steering configuration and all of its components should be revisited. This system of the vehicle should be made of preferably new parts, which are very strong and durable. Suspension Independent rear suspension would have been great for the Mini Baja ® East Competition; however, the rear suspension we had was sufficient. The problem was with the front suspension. It was entirely too weak. The system needs to be replaced with stiffer springs or maybe the current springs can be repositioned to improve their response, either way the front suspension needs great improvement. The addition of bump stops is also recommended. The bump stops would limit the compressibility of the front springs. The goal is for the springs to compress, but not as easily as they do. The improvement of the front suspension will help the steering last longer, because impact forces will be absorbed by the suspension and not transferred to the steering. Braking – “Cutting Brakes” Originally, the cutting brakes (or the independent rear braking system) were designed to function with the open differential for water maneuverability. For example, whenever the car would be in the water and there was a need to turn, the driver would apply a brake to one of the rear wheels causing the vehicle to somewhat pivot about that wheel. This was a great idea, however they never functioned properly. In fact, they were adjusted too tight and caused friction between the brake discs and calipers. The entire rear braking setup had to be disconnected during the competition. The team recommends eliminating the cutting brakes and use the front tires as steering. Adding rear fenders will improve water maneuverability through propulsion. Tires The vehicle’s 22-inch rear tires with 10-inch rims should be reconsidered. We recommend that the vehicle use at least 30-inch rear tires with the smallest possible rims. The current rear tires may be moved to the front of the vehicle. This will obviously assist in the floatation department and it will also improve land control because of the greater traction-ground contact area. The increased diameter of the tires would also increase the much needed ground clearance, which is mandatory for such rough terrain.

The Ugly Student Customer For future references, the team does not recommend a student being a customer of any senior design project. For the SAE Mini-Baja purposes, we would recommend Dr. Hollis as the sole customer, and prefer the faculty’s approval and strong presence during decision-making or even decision considerations.


VII

It is our belief, that a faculty member would have been more open to some of our ideas than a student. The individual we are referring to was a great worker, but he was just difficult to work with. This was probably due to the fact that the individual had a vision already embedded in his mind, and he wasn’t open to many other ideas. The student was a great team member as far as work ethic is considered, but a poor customer as far as leadership, responsibility, and tolerance. Team Dynamics The pictures shown in this addendum only show 3 of the 4 senior design team members, and not because the 4th member was behind the camera. The fourth team member didn’t contribute much to the team. This wasn’t more evident than during the final race of the competition, the endurance race. When asked where he or she was during the 4-5 hour race, they replied, “I was in the shade”. This comment probably would not have been as bad coming from a student who put in an adequate amount of work on the project throughout the year, but it didn’t. The team feels that the student had been “carried” throughout the year and the exclamation point was added with the comment that was made about being in the shade. Furthermore, even if the individual didn’t lend a hand in the endurance race, it would have been somewhat better to see the team member present and clapping as the car emerge from the woods. But the individual wasn’t present, and that’s exactly why there are only three team members in the photo…there wasn’t 4th member around to be placed in the picture. It just seemed as if the desire to achieve and to see the vehicle perform well was missing from that team member. This illustrates the importance of not allowing team members to ‘slack off’ so that bitterness does not build up over time. All team issues should be discussed professionally and quickly so that no unforeseen issues arise at the closure of the project.


VIII

2003 SAE Mini-Baja East Overall Results

# School Total Overall Points Rank

3 Ecole de Technologie Superieure 979.78 1

25 Bucknell University 967.92 2

1 Tennessee Tech. University 902.05 3

12 College of New Jersey #2 891.57 4

32 University of Rhode Island 865.54 5

9 Northeastern University 845.05 6

8 Universite Du Quebec a Trois-Rivieres 820.95 7

22 Virginia Tech 2 800.61 8

14 Rochester Institute of Technology 1 784.75 9

26 University of Michigan - Dearborn 762.45 10

4 Auburn University 709.05 11

41 Universite Laval 708.29 12

11 University of Tennesee - Martin 702.26 13

6 University of Central Fl. #1 682.88 14

5 Clarkson University 674.91 15

2 College of New Jersey #1 650.19 16

15 Rochester Institute of Technology 2 620.92 17

30 Boston University 617.81 18

21 Virginia Tech 1 593.80 19

13 Auburn University Lady Tigers 554.01 20

45 University of South Florida 520.27 21

16 Vanderbilt University 492.65 22

18 Georgia Institute of Technology 2 458.63 23

28 University of New Hampshire 433.53 24

47 University of New Orleans 432.31 25

29 North Carolina A&T State University 424.48 26

43 Queen's University of Ontario Canada 411.40 27

34 Binghamton University 401.69 28

17 Georgia Institute of Technology 1 398.84 29

39 West Virginia University 397.86 30

24 Florida Atlantic University 378.95 31

27 Villanova University 343.68 32

19 Tulane University Men 341.11 33

23 Louisiana State University 340.28 34

49 Instituto Tecnologico De Aguascalienties 331.71 35

38 US Military Academy - B Team 259.49 36

20 Tulane University Women 238.87 37

44 Georgia Southern University 224.44 38

40 West Virgina Institute of Technology 202.72 39

37 US Military Academy - A Team 201.39 40

36 Widener University 190.71 41

42 Florida A&M University / Florida State University 100.35 42

7 University of Central Fl. #2 62.00 43

31 Syracuse University 59.00 44

33 Polytechnic University - Brooklyn 48.00 45

35 Cooper Union 40.00 46

46 Southern University A&M College 40.00 46

48 Princeton University 0.00 48

50 Florida International University 0.00 48


IX

Lessons and Reflections One important lesson that the team took away from this experience was to never give up and always persevere. Even though the team didn’t place as high as we would have liked, we understand that is was our first time and there are plenty of areas to improve. However, whether it was our first time or not, we did not want to give up. Always fight to the end! For future teams, always compete in every event. For every event that we did not compete in, we lost points. Actually, we didn’t lose any point, but we didn’t gain any either. As shown on the scoring sheet, we only had 100.35 points. There were 400 points worth of events that we didn’t even attempt to compete in. If we had gained half of those possible 400 points, we would have jumped six teams to be in 36th place. Furthermore, every event (other than the endurance race) is held on either Friday or Saturday, which is done purposely to prepare teams for the endurance event. By competing in the steering and suspension event, we could have confronted our steering problems early and have performed better in the endurance race. Participating in the mud -bogging event would have foreshadowed any problems had with ground clearance. The following is the point breakdown:

• Endurance Race 400 pts • Steering and Suspension 100 pts • Sled pull 100 pts • Mud bog 100 pts • Land maneuverability 100 pts • Top speed 50 pts • Acceleration 50 pts • Water maneuverability 100 pts • Design 250 pts

o Report 50 pts o Evaluation 100 pts o Safety 50 pts o Cost Report 50 pts

The team did not participate in steering and suspension, mud bog, water maneuverability, or the design evaluation event. The reason for the team’s lack of participation goes back to student-customer issue. No one student should be “in control” or feel as if they’re superior due to their position as the customer; therefore, his or her decision for the team to work on the car verses competing in every event possible would have been overridden. Field communication is also very important. Every team member should be stationed throughout the course (see figure 1), and should have some form of communicating with each other. Most teams at the competition had walkie-talkies. This was excellent for locating their vehicle whenever a component failed and repair was needed.


X

On field maintenance was also an issue. Following the lead of more experienced schools and observing our need during the events. It would be advantageous to the team to bring as much possible equipment as possible to the event that would be pertinent in the repair of the vehicle. This equipment would also need necessary portable power sources that could be transported to competition. These factors should be kept in mind during the fundraising phase of the project. Not only is it necessary for the team to purchase necessary parts and materials focused solely on building the vehicle, but other expenses such as equipment needed for repair and funds necessary to pay for hotel and travel accommodations. All stencil/silhouette numbers, powertrain guards, and other nonstructural components should be made from lighter material and should be as small as possible. This will reduce the weight of the vehicle, and thus the load of the 10 hp engine. This year’s baja was the first for FAMU-FSU COE in about a decade. It was built completely from scratch, and most of the schools that perform well compete year after year with small iterations on their already successful designs. The team recommends that next year’s baja team use this car as a test car and template of what and what not to do. In fact, improvements should be made on this car to compete side by side with a new baja car for next year or 2005 competition (schools are allowed two cars). Scrapping of this year’s car is what shouldn’t happen. It is a learning tool, and can be improved to be a successful mini-baja car. Future baja teams of FAMU-FSU COE should register for more than one baja competition. Some of the successful teams compete in the Baja East, Mid-West, and West competition. Back to the old cliché, practice makes perfect.

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