Mousetrap Car Project - Report Example

Your team identification name Your Workshop day Date The recipient’s company name The recipient’s address Dear (Client name) Our company was approached by the FunTime Toy Company to design and development of a speed- trap racer to be marketed as a racing toy for children above the age of eight (8). The mousetrap car was required to achieve the highest speed so as to cover a distance of five (5) meters in the shortest possible time, starting from a standing position. A standard mousetrap provided by the customer was the only form of propulsion to be installed in the car, with no physical alterations allowed on the mousetrap, except the holes drilled to mount it on the wheel frame. This report entails the various design alterations that were made on a standard mouse trap (provided by the customer) in a bid to achieve the best performance. The adjustments done to the racer were restricted to a budget of $50, so that the final product would not have an exorbitant production cost. The details of the mousetrap car developed to meet the aforementioned objectives are set out in this engineering report. Yours Sincerely Your name Author: xxxx Tutor: xxxx Date: xxxx Table of Contents 1.Introduction 3 2.Design Descriptions 4 3.Engineering Drawing 6 4.Technical Information 6 4.1Components, Price and Weights 6 4.2Torque and Friction 6 4.3Theoretical Speed and Distance 7 4.4.Actual Speed and Distance 7 5. Discussion 8 5.1 Performance Comparison and Analysis 8 5.2 Design for Manufacture 8 5.3 Recommendations 8 6. Conclusion 9 References 9 Appendix 10 Appendix 1: Raw Test Data 10 Appendix 2: Calculations 13 Appendix 3: Speed Test Results 13 Appendix 4: Instruction Manual 13 1. Introduction The design of a mousetrap car purposed for high performance depends on various design elements, which dictate its operation. The most significant design elements to be considered include the dimensions, weight and material used to make the mousetrap wheels, the dimensions and properties of the axle linking the various sets of wheels, among others. The purpose for which the mousetrap car is designed dictates how these design elements are harmonized for maximum performance. However, blatantly increasing the aforementioned aspects does not guarantee the mousetrap car’s highest performance. One may find that exaggeration of one of the factors causes a reduction in another, reducing the overall performance of the vehicle. Despite there being no specific formula to achieving the highest performing mousetrap car, maintaining the perfect balance between these design elements goes a long way to improving the level of performance obtained. There are generally two purposes for which mousetrap cars are designed, either to achieve the highest speed or travel the longest distance. Mousetraps designed to travel over a long distance (referred to as distance- trap racers) have large drive wheels, small driving axles and long lever arms. Conversely, mousetraps designed to achieve the highest speed (referred to as speed- trap racers) have smaller drive wheels, larger driving axles and shorter lever arms when compared to the distance- trap racers. Other additional design aspects are fitted to the respective mousetrap cars to further improve their performance. Adaptations added to speed- trap cars can be broadly categorized as adaptations to increase acceleration or reducing resistance [Wik16]. This exercise focussed on the design and development of a speed- trap racer for the FunTime Toy Company, to be marketed as a racing toy for children above the age of eight (8). The mousetrap car was required to achieve the highest speed so as to cover a distance of five (5) meters in the shortest possible time, starting from a standing position. A standard mousetrap provided by the customer was the only form of propulsion to be installed in the car, with no physical alterations allowed on the mousetrap, except the holes drilled to mount it on the wheel frame. 2. Design Descriptions To design a speed- trap racer with the highest performance, the alterations to be done fall in either of the following categories. However, it should be noted that these alterations will not increase the maximum speed the mousetrap car will achieve, but rather increase the acceleration of the car towards that maximum speed. Furthermore, increasing the acceleration comes at the expense of distance travelled, which is a minor concern if the speed developed by the mousetrap is adequate to cover 5 metres. A. Increasing Acceleration The acceleration of the speed- trap racer can be increased by either of the following design alterations [Wik16];- 1. Shorten the lever arm – Longer lever arms extend the time during which the axle is pulled. This has the effect of increasing the distance covered by the car before it achieves the maximum speed, making the car slow. Therefore, shortening the lever arm achieves maximum speed faster. 2. Use smaller wheels – Reducing the size of the wheels reduces the amount of torque necessary to begin a rotation, meaning the car takes longer to reach maximum speed 3. Increase the size of the axle – Increasing the ration of the axle diameter to wheel diameter reduces the force necessary to accelerate the car. A large axle- small wheel combination increases the car’s acceleration 4. Increase traction – Increased traction increases the pressure the wheel exerts against the ground, allowing it to pick up speed. A material with rough texture is glued to the wheels to increase acceleration B. Reducing Resistance The resistance of the speed- trap racer can be reduced by either of the following alterations;- 1. Reduce weight – Smaller weights reduce the rolling friction on the ground, reducing the drag on the mousetrap, allowing the car to gain maximum speed faster 2. Reduce number of pulleys and gears – A complicated system of pulleys and gears increases the friction between the components, reducing the net force acting on the wheels. Connecting the lever directly to the axle provides the maximum force, thus giving greatest acceleration 3. Limit air resistance – As speed increases, so does the air resistance on the speed- trap racer. Reducing the air resistance allows the car to reach maximum speed faster and maintain that speed 4. Eliminate friction between the axle and frame – Friction between the axle and frame causes major losses in the force required to drive the wheels. Proper lubrication allows most of the energy generated by the mousetrap to be used to turn the wheels 3. Engineering Drawing (Attach) 4. Technical Information 4.1 Components, Price and Weights The table below gives the components of the final model of the speed- trap racer;- Part Mass (g) Weight (N) Radius (mm) Price (AUD) Mousetrap 31.21 3.06 - Chassis 27.98 2.74 - Rear Axle 6.30 0.62 2.3 Rear Wheel 29.40 2.88 60 Front Axle 6.30 0.62 2.3 Front Wheel 29.40 0.59 35 Screws 12.15 1.19 - TOTAL 119.36 11.70 - It should be noted that the price of the final model lies well within the approved budget for the mousetrap racer. 4.2 Torque and Friction The table below gives the torque developed by the operation of the speed- trap racer;- Degrees Force Radians Torque 0 0 0 0 30 2.40 0.52 0.96 60 4.00 1.05 1.60 90 4.80 1.57 1.92 120 7.80 2.09 3.12 150 8.50 2.62 3.40 180 10.30 3.14 4.12 The coefficient of friction for the operation of the racer was determined to be;- Coefficient of Friction: Drive: 0.919 Front: 0.356 4.3 Theoretical Speed and Distance The theoretical speed achieved by the racer when all the spring energy has been released is given by the following equation;- where is the spring energy, is the mass of the car and the maximum velocity attainable. The maximum velocity in the equation is constant regardless of the how fast the car gains speed. The time taken to reach this velocity depends on how fast the spring energy is released. In the case of the speed- trap racer, the design intends to release the energy as fast as possible to achieve maximum speed faster, thus covering the required distance in a slower time. 4.4. Actual Speed and Distance Equation 1 above assumes the car is a rigid body that does not have friction losses, which is does not represent the real life scenario. The racer is made up of various components, whose interaction causes a loss in the final spring energy to reach the drive wheels. The friction between the moving parts of the racer and the rolling ground friction also reduce the spring energy used to propel the car. Accounting for these losses reduces the maximum attainable velocity and the distance travelled by the racer. This means that it takes longer to cover the 5 metre distance. 5. Discussion 5.1 Performance Comparison and Analysis The final iteration of the speed- trap racer was able to cover the required 5 metre distance in a relatively good time period. The adjustments made to the mousetrap racer improved in overall performance in terms of speed. However, the maximum speed achieved during the exercise was lower than the theoretical (calculated) maximum speed, due to the losses caused by friction between the moving parts and the interaction of the components of the speed- trap racer. 5.2 Design for Manufacture The initial model could not travel the required distance (5 metres) due to its significant weight. In a bid to reduce the weight, we removed the sides of the model and replaced them with hooks to hold the front and rear axles, with a zip tie added to the rear axle. This model was able to travel the required distance. However, the speed was too low and the racer did not cover the distance in a straight line. In Model 3, balloons were glued to the surface of the rear wheels to increase friction and prevent slippage. The body of the speed- trap racer was replaced by balsa wood, which is lighter and longer to prevent the vehicle from veering off course. This model performed significantly better than the previous ones. In Model 4, the wheels were also replaced by balsa wood (light weight and with smaller radii). The axle lengths for both wheels was also narrowed to reduce the weight of the car and the force needed to start its motion. These adjustments improved the whole performance of the speed- trap racer, reducing the time it took to cover the 5 metre distance. 5.3 Recommendations The following adjustments can be made to the speed- trap racer to improve its performance;- A. Shortening the lever arm Shortening the lever arm achieves the maximum acceleration. However, over-shortening the lever arm will cause the car to spin out, thus the most optimum length must be determined through trial and error experiments. B. Further reduction in weight The weight of the wheels, axles and frame of the speed- trap racer can be reduced by using even lighter materials, reducing the resistance to achieving the maximum speed. 6. Conclusion The final model of the speed trap racer was able to achieve the objectives set out for the exercise by the customer. The maximum speed developed by the mousetrap car is subject to the friction losses between the car’s moving parts and the rolling friction with the ground. Shortening the lever arm increases the speed at which the spring energy is released, which increases the acceleration of the mousetrap car, allowing it to reach maximum velocity faster. References Wik16: , (WikiHow, 2016), Appendix Appendix 1: Raw Test Data CAR VERSION 1         mouseTrap Arm Length (mm): 40 EXPERIMENT 1 RESULTS       Degrees Force Radians Torque 0 0 0 0 30 2.40 0.52 0.96 60 4.00 1.05 1.60 90 4.80 1.57 1.92 120 7.80 2.09 3.12 150 8.50 2.62 3.40 180 10.30 3.14 4.12 EXPERIMENT 2 RESULTS       Part Mass (g) Weight (N) Radius (mm) MouseTrap 31.21 3.06 - Chassis 257.90 25.27 - Rear Axle 6.30 0.62 2.3 Rear Wheel 29.40 2.88 60 Front Axle 6.30 0.62 2.3 Front Wheel 29.40 2.88 60 Screws 24.29 2.38 - TOTAL 384.80 37.71 - Mass (g) Weight (N) Rolling Angle Weight (Drive) (N): 193.60 18.97 Deg 0.5 Weight (Front) (N): 191.20 18.74 Rad 0.01 Coefficient of Friction: Drive: 0.279 Front: 0.280 EXPERIMENT 3 RESULTS       Ftract Weight Uf Drive 0.75 18.97 0.04 Front 0.75 18.74 0.04 CAR VERSION 2 and 3 "lighter"       mouseTrap Arm Length (mm): 40 EXPERIMENT 1 RESULTS       Degrees Force Radians Torque 0 0 0 0 30 2.40 0.52 0.96 60 4.00 1.05 1.60 90 4.80 1.57 1.92 120 7.80 2.09 3.12 150 8.50 2.62 3.40 180 10.30 3.14 4.12 EXPERIMENT 2 RESULTS       Part Mass (g) Weight (N) Radius (mm) MouseTrap 31.21 3.06 - Chassis 47.59 4.66 - Rear Axle 6.30 0.62 2.3 Rear Wheel 29.40 2.88 60 Front Axle 6.30 0.62 2.3 Front Wheel 29.40 2.88 35 Screws 12.15 1.19 - TOTAL 162.35 15.91 - Mass (g) Weight (N) Rolling Angle Weight (Drive) (N): 80.96 7.93 Deg 0.7 Weight (Front) (N): 81.39 7.98 Rad 0.01 Coefficient of Friction: Drive: 0.570 Front: 0.331 EXPERIMENT 3 RESULTS       Ftract Weight Uf Drive 0.5 7.93 0.06 Front 0.5 7.98 0.06 CAR VERSION 4         mouseTrap Arm Length (mm): 40 EXPERIMENT 1 RESULTS       Degrees Force Radians Torque 0 0 0 0 30 2.40 0.52 0.96 60 4.00 1.05 1.60 90 4.80 1.57 1.92 120 7.80 2.09 3.12 150 8.50 2.62 3.40 180 10.30 3.14 4.12 EXPERIMENT 2 RESULTS       Part Mass (g) Weight (N) Radius (mm) MouseTrap 31.21 3.06 - Chassis 4.61 0.45 - Rear Axle 6.30 0.62 2.3 Rear Wheel 29.40 2.88 60 Front Axle 6.30 0.62 2.3 Front Wheel 29.40 2.88 35 Screws 12.15 1.19 - TOTAL 119.36 11.70 - Mass (g) Weight (N) Rolling Angle Weight (Drive) (N): 70.75 6.93 Deg 1 Weight (Front) (N): 48.51 4.75 Rad 0.02 Coefficient of Friction: Drive: 0.919 Front: 1.006 EXPERIMENT 3 RESULTS       Ftract Weight Uf Drive 0.1 6.93 0.01 Front 0.1 4.75 0.02 Appendix 2: Calculations Appendix 3: Speed Test Results Appendix 4: Instruction Manual Read More