Safety Cars

1. Safety Cars Project #5 Introduction to Transportation

2. Objectives After completing this activity, students will be able to: • Review the effects of gravity and friction on vehicles • Review all the support systems vehicles have • Research air bags and how safety has advanced throughout the years. • State the processes involved in creating a Safety Car, Bumper Design, and Roll Cage

3. Objectives • Create a vehicle that will support a roll cage made out of a copper rod that will protect an egg from breaking when rolled down stairs • Create a Safety car and add a front bumper using two springs and your design of a bumper. Run the car down the ramp and into a wall being sure the egg doesn’t break • Create a Safety Car that is capable of traveling down a ramp carrying an egg while an opposing vehicle doing the same is coming down the other ramp. • Using the Wind Tunnel, test your vehicles drag and lift

4. Content We have all either been in or have seen accidents before. This project is meant to inform you and educate you about vehicular safety and how you can protect yourself. It is also a chance for you to come up with a way for your vehicle to survive an impact from another car without breaking an egg.

5. Content Also, you will be constructing a roll cage and rolling your car down stairs with an egg to see if it survives. Finally, you will be constructing a bumper using springs and dowel rods and rolling the cars down the ramp into a wall with an egg aboard to see if the egg survives your different bumper ideas.

6. Effects of Gravity and Friction • What role does Gravity play on your vehicle? Answer: Gravity is a pulling force, pulling everything towards the center of the earth. When it comes to vehicles you can’t get rid of gravity. Car manufacturers know it is there and are forced to work around it.

7. Effects of Gravity and Friction What role does Friction play on a vehicle? Answer: Friction on a vehicle can be good and bad. When it is raining or snowing out, we want a lot of friction to make sure we don’t slip all over the place. Also, when going around sharp corners we want to make sure our momentum is not greater than friction causing us to spin out of control. We don’t want

8. a lot of friction when cruising down the highway because it reduces our gas mileage. Lets compare a drag car to a standard car. What is making so much friction? Answer: The tires are playing a huge role in how much friction we have. At the drag strip the tires are slicks and are usually very wide allowing the tires to bite the pavement with minimal slip. In this case we want a lot of friction at the beginning. On a regular car it makes no sense

9. to have slicks because of the weather. If a regular car had slicks on a rainy day it would slide all over the place. Instead the tires have treads of varying patterns to help bite the pavement. The width of the tire is usually proportional to the amount of horsepower a vehicle has as well. The more horsepower the wider you want your tires to be. So we have gravity pulling down on our vehicles causing friction between the tires and the pavement. We use the engines torque to help overcome the friction giving us momentum.

10. Vehicle Support Systems According to the book “Exploring Transportation” by Stephen R. Johnson, one of the most obvious support systems for land vehicles is the road and highway network. Without the system of paved roads, vehicle travel would be uncomfortable and unsafe. Vehicles would not be able to travel at the speeds they do now.

11. Vehicle Support Systems Support systems for vehicles can be divided into five categories: • Related Construction- the structures on which vehicles travel (roads, highways, bridges, tunnels) • Passenger Facilities- the buildings and facilities that provide comfort and services to passengers (hotels, motels). • Cargo facilities- the buildings and facilities that provide loading, unloading, and storage for various types of cargo. • Vehicle maintenance- those facilities designed to maintain and repair vehicular systems (mechanics garages) • Other support systems- any other system that is needed for safe transportation

12. Safety through Air Bags Air bags have been around for a long time. They are a very important life saving device that is required to be installed in every vehicle. What is an Air Bag? Answer: They are gas-inflated cushions built into the steering wheel, dashboard, door, roof, or seat of your car that use a crash sensor to trigger a rapid expansion to protect you from the impact of an accident.

13. Safety through Air Bags According to the web site: http://inventors.about.com/od/astartinventions/a/air_bags.htm • In 1971, the Ford car company built an experimental airbag fleet. General Motors tested airbags on the 1973 model Chevrolet automobile that were only sold for government use. The 1973, Oldsmobile Toronado was the first car with a passenger air bag intended for sale to the public. General Motors later offered an option to the general public of driver side airbags in full-sized Oldsmobile's and Buick's in 1975 and 1976 respectively. Cadillacs were available with driver and passenger airbags options during those same years. Sponsored Links • Early airbags system had design issues resulting in fatalities caused solely by the airbags. Airbags were offered once again as an option on the 1984 Ford Tempo automobile. By 1988, Chrysler became the first company to offer air bag restraint systems as standard equipment. In 1994, TRW began production of the first gas-inflated airbag. They are now mandatory in all cars since 1998.

14. Safety through Air Bags Types of Airbags There are two types of airbags; frontal and the various types of side-impact airbags. Advanced frontal air bag systems automatically determine if and with what level of power the driver frontal air bag and the passenger frontal air bag will inflate. The appropriate level of power is based upon sensor inputs that can typically detect: 1) occupant size, 2) seat position, 3) seat belt use of the occupant, and 4) crash severity. Side-impact air bags (SABs) are inflatable devices that are designed to help protect your head and/or chest in the event of a serious crash involving the side of your vehicle. There are three main types of SABs: chest (or torso) SABs, head SABs and head/chest combination (or "combo") SABs.

15. Safety through Air Bags Allen Breed - History of the Airbag Allen Breed was holding the patent to the only crash sensing technology available at the birth of the airbag industry. Breed invented a "sensor and safety system" in 1968, the world's first electromechanical automotive airbag system. However, rudimental patents for airbags go back to the 1950s. Patent applications were submitted by German Walter Linderer and American John W. Hedrik as early as 1953

16. What does a Wind Tunnel do? A Wind Tunnel is used to measure the amount of LIFT and DRAG that your vehicle has as it passes through the air. Drag is resistance holding the car back, while Lift is how high the car lifts off the ground. We want to try to minimize both Lift and Drag on your vehicles to improve the speed your vehicle has. Wind is blown over your vehicle using a large fan. Your vehicle is attached to a threaded rod and when the wind blows over your vehicle, it pushes your car backwards. If your vehicle is aerodynamic then the wind will blow over your

17. What does a Wind Tunnel do? vehicle with little resistance. Sanding your project smooth and taking care to use vinyl or light paint with help your project out.

18. Seat Belts What is a Seat Belt? Answer: According to the web page: http://www.crash-worthiness.com/injury/seat-belt.htmlSeat belt injuries can occur when a defective seat belt fails to adequately protect a vehicle passenger in the “second collision” phase of an automobile accident. There are thought to be two collisions in an auto accident. The first collision is the vehicle's impact with another vehicle or object. The second collision is the passenger's impact with the interior of the vehicle, or in cases of ejection, impact outside the vehicle.

19. Seat Belts The purpose of a seat belt is to minimize the injuries and damage caused in a second collision by reducing or eliminating injurious occupant contact with the vehicle's interior. Seat belt injuries often occur when there is a seat belt design, production, or installation defect. The National Highway Traffic Safety Administration estimates that more than 2.9 million people suffered seat belt injuries in 2002. In that same year almost 43,000 people died as a result of seat belt injuries. The percentage of passengers who wear seat belts is at a record high in our nation at 79 percent. The number of people wearing their seat belt who suffer from serious seat injuries indicates that seat belt defectiveness is often the cause of damage in these accidents. In twenty percent of all rollover accidents seat belt failure is a main contributory factor to serious injury.

20. Seat Belts Although seat belts do save a lot of lives there are a few times when they didn’t work properly as you just heard. Restraint is important to minimize the injury caused by the second impact. For this project, we will be using eggs to represent humans and you will be devising your own seat belt to restrain the egg to the pine frame. You may use string, wire, elastics, other types of strapping material. You cannot cover the egg with fabric to hold it down, the egg must be exposed showing the seat belt. Don’t tape the egg down either as the tape might rip the shell off when you take it out to show me if it survived.

21. Seat Belts Your vehicle with the egg on it restrained by your seat belt will be sent down a ramp into a wall. If your seat belt works you egg will stay in the vehicle and not break. You must also make a body for your vehicle out of cardboard. It doesn’t have to look like a specific vehicle but rather a general type. The top of your vehicle has to be open so you can get your egg out and back in without having to take the body off. Cardboard needs to be along all four sides but not the top.

22. Roll Cage and Roll Bars What is a Roll Cage? Answer: The next stage in stiffening the chassis is usually adding a roll cage. Though primarily a safety feature, roll cages are welded or bolted to the chassis in several places which adds to the chassis' resistance to twisting. There are numerous styles of roll bars and roll cages.

23. Roll Cage and Roll Bars What is the difference between a Roll Cage and Roll Bars? Answer: The difference between a roll bar and cage is the complexity of the structure, and its scope of protection. Generally, the roll bar's purpose is only to provide a crush resistant structure above the driver's head. This is usually a single bar with support bars to have four points of contact with the car chassis for strength (a two-point roll bar is useless for racing). A roll cage is a more complete structure designed to protect the driver from all sides. Obviously, the latter is safer, but may be impractical for the dual purpose street car as it will require significant modification to the car's interior panels.

24. Roll Cage and Roll Bars For this project you will be starting with your block of pine and creating a custom roll cage to protect your egg. You already have a seat belt design that will need to be modified if it didn’t work. You will then get a three foot long piece of 1/8” copper rod that you will use to solder together your custom roll cage. Your roll cage must be attached to your block of wood. You may also attach your roll cage to the body of your vehicle. The roll cage must be up at least a ¼” above your cardboard body. This is done to prevent you from using your cardboard body instead of the roll cage to protect the egg.

25. Bumpers What is a Bumper? Answer: A bumper is a shield made of steel, aluminum, rubber, or plastic that is mounted on the front and rear of a passenger car. When a low speed collision occurs, the bumper system absorbs the shock to prevent or reduce damage to the car. Some bumpers use energy absorbers or brackets and others are made with a foam cushioning material

26. Bumpers What is the purpose of a bumper? Answer: The car bumper is designed to prevent or reduce physical damage to the front and rear ends of passenger motor vehicles in low-speed collisions. Automobile bumpers are not typically designed to be structural components that would significantly contribute to vehicle crashworthiness or occupant protection during front or rear collisions.

27. Bumpers It is not a safety feature intended to prevent or mitigate injury severity to occupants in the passenger cars. Bumpers are designed to protect the hood, trunk, grille, fuel, exhaust and cooling system as well as safety related equipment such as parking lights, headlamps and taillights in low speed collisions

28. Bumpers What are Federal Regulations for bumpers? Answer: 49 CFR Part 581, "The bumper standard," prescribes performance requirements for passenger cars in low-speed front and rear collisions. It applies to front and rear bumpers on passenger cars to prevent the damage to the car body and safety related equipment at barrier impact speeds of 2½ mph across the full width and 1½ mph on the corners.

29. Bumpers This is equivalent to a 5 mph crash into a parked vehicle of the same weight. The standard requires protection in the region 16 to 20 inches above the road surface, and the manufacturer can provide the protection by any means it wants. For example, some vehicles do not have a solid bumper across the vehicle, but meet the standard by strategically placed bumper guards and corner guards. Information from the web site: http://www.nhtsa.dot.gov/cars/problems/studies/Bumper/Index.html

30. Bumpers The third stage of your project consists of your vehicle having a bumper attached to it. You will be cutting dowel rods, attaching small springs to them and putting them into holes drilled in the front of your vehicle. You will then attach a custom bumper of your design to the dowels. We will send these vehicles down a ramp and into another vehicle coming down an opposing ramp. If your bumper, roll cage, and seat belt do their jobs your egg should survive the impacts.

31. Materials • Scrap wood • Pine • Metal Rod 1/8” diameter OR ¼” Dowel Rod • Wood Glue/ Hot Glue • Supplies from trays • Machines and tools

32. Challenge Each student working on their own will design, sketch, and construct their own Safety Vehicle using various materials and equipment in the Construction Lab. The Sketches are random ideas of your thoughts but there should be a minimum of 4. From those 4 sketches select 1, draw it in detail using a ruler and straight lines (no freehand drawing). Be sure to include dimensions on your Initial Drawings. When the project is complete you will be required to complete the evaluation form and do a Final Drawing. The Final Drawing compares what your Safety Vehicle ended up looking like (again, no freehand drawing, use rulers) to what you drew for your Initial Drawing. Your grade is broken down into 6 parts be sure to see the Evaluation part for further explanation.

33. Challenge Your grade for part 1 depends on how close to your Initial Drawing you constructed your Safety Vehicle. The closer it resembles your Initial Drawing, the better your grade will be. The more changes you make or extra pieces you add the lower your grade will be. The safety vehicle is a 12” piece of pine wood that you will drill two holes in for axles. You will then cut cardboard in the shape of your vehicle attaching it to the wood. Your vehicle must resemble a car, truck, or SUV. You cannot just make up a vehicle. It does not have to be as detailed as the Accuracy Cars but it has to look like a car, truck or SUV.

34. Challenge There are many different tests that will be conducted on your vehicle and you will have ample time to complete each before we test. Your grade for part 2 depends on your project being tested for a seat belt. You will cut a piece of wood 12” long x 4” wide. You will then drill two holes through the piece for your axle to fit through. Next you will drill a hole in the middle of your board being sure not to go all the way through it. It should be large enough to hold an egg crate in. Your egg will sit inside the egg crate which is in your board. Next you will be using up to 5 elastic bands to hold down your egg. The elastics are acting like a seat belt. The way you wrap them around your egg determines whether it will survive or not. We will then be rolling your project down a ramp and into the wall and see how your car does. Will it be too top heavy, front heavy, or side heavy causing your vehicle to flip over breaking the egg. Will your elastics hold the egg in safely or will it just pop out at impact.

35. Challenge For your Part 3 you will again sketch and draw an Initial Drawing with dimensions of a bumper design. You will have to create a bumper for the same vehicle. You will be drilling two 3/8” holes in the front of your vehicles being sure to make them only 4 inches deep. You will then insert two springs provided by me into the holes. You will then attach two dowel rods to the springs. Next you will be fabricating your own bumper design that you feel is the safest design.Your bumper must wrap around the front of the vehicle. Your bumper is not a plow or a spike or point. Finally your bumper must attach to the two spring loaded dowel rods.

36. Challenge When ready we put the egg in the crate holder again securing it with up to 5 elastic bands and send it down the ramp and into a wall in the hallway. The idea is to test different bumper ideas and prevent the egg from breaking. Your bumper must wrap around the front of the vehicle. Your bumper is not a plow or a spike or point. Finally your bumper must attach to the two spring loaded dowel rods. Once this part is completed you will have to do Final Drawing of your bumper plus the evaluation worksheet. For Part 4 is to sketch and draw a roll cage on a piece of paper being sure to include dimensions and details.

37. Challenge When you have created your safety vehicle you will be given a copper rod that is 3 feet long and 1/8” thick to create your roll cage. You will be bending and soldering this rod together and attaching it to your vehicle being sure to use up all 3 feet of the rod. Try not to cut it too many times to ensure you get all the strength. Also the cardboard sides cannot be higher than the roll cage. The roll cage must be at least a 1/4” above the cardboard body. We will then place an egg inside your roll cage and roll your vehicle down the stairs leading to the library. Your vehicle must travel the full distance of the stairs to receive credit. If it stops half way you must push it a little to keep it rolling. The idea is to prevent the egg from breaking and learning about stress points on a roll cage. Your egg will rest on a single egg crate holder. The holder is screwed to the vehicle and egg is held in with elastic bands, up to 5 if needed. When this part is completed you will have to do a Final Drawing of your roll cage and complete the evaluation worksheet.

38. Challenge At this point you will have a roll cage and a bumper on your vehicle. It is time to test your vehicles designs against the rest of the class and this is part 5. You are responsible for that egg at all times. The egg is considered broken if there is fluid from the inside of the egg on the outside of the shell or your project. If there is a crack in the egg but no fluid then you are still in. When ready we put the egg in the crate holder again securing it with up to 5 elastic bands and send it down the ramp and into a classmates project that is coming down the other ramp. You must however be able to take your egg out and put it back in every time you test your vehicle.

39. Challenge If you break your egg putting it in or taking it out of your vehicle it is counted as a broken egg and you are done in the competition, even if you won your match. This part of the project is going to focus only on the structural support of your vehicle. Your project also cannot weigh more than 1 pound with the egg in it. Remember to drill your axle holes first to ensure straight holes and evenly balance your car to ensure a straight run.There are no partners on this project; each student must make their own vehicle.

40. Challenge Your grade for part 6 is the vehicles when done cannot be smaller than 12” long x 4 ½” wide x 8” tall or larger than 12” long x 4 ½” wide x 10” tall. You will be automatically disqualified and receive a zero if it is smaller or larger in any or all of these dimensions.Be creative on this project and a nice design and creative effort will only increase your grade. You must do all work in class unless I give you permission to take it home. Good luck

41. Procedures • Select the your favorite vehicle that isn’t too challenging to make • Research it on the computer finding pictures • Print off 2 copies of each: front view, side view, rear view, top view • Cut your pine wood, wood glue it together • Construct your vehicle • Practice your vehicle as often as possible making any changes needed

42. Evaluation • Sketches and Initial Drawings are a separate grade worth 100 points • There is a final drawing and an reflective worksheet that counts as a separate grade of 100 points • See Attached Rubric • Remember that there is no fooling around in the lab • Always wear your safety glasses or you will be removed from class

43. Evaluation 100 Points • Project stayed within the required dimensions • Project survived seat belt phase • Project survived the bumper phase • Project survived the roll cage phase • Project survived more than 2 rounds against classmates • Project looks like initial drawings with minimal changes • Student shows above average effort • Student shows above average safety skills

44. Evaluation • Project stayed within the required dimensions • Project survived 2 out of 3 tests (roll cage, bumper, or seat belt) • Project made it more than 2 rounds against classmates • Project looks like initial drawing with moderate changes (noticeable) • Student shows average effort • Student shows average safety skills 75 points

45. Evaluation • Project stayed within the required dimensions • Project survived 1 out of 3 tests (roll cage, bumper, seat belt) • Project made it at least 1 round against classmates • Project doesn’t look like initial drawings with very noticeable changes • Student shows little effort • Student not allowed in class if not demonstrating proper safety skills 50 points