Problem/Opportunity: Provide the outdoor nitro powered RC(Radio Controlled) car enthusiast a better experience and greater rate of success by increasing the efficiency of the engine by means of integrating a temperature control system to automatically adjust the carburetor on the cars engine.
Goal: Integrate an engine temperature control/carburetor adjustment to a nitro powered RC vehicle.
Objectives: We would like to propose a marketable product that will increase the performance of nitro powered RC cars. The engine temperature control/ carburetor adjustment will be composed of a parallax microcontroller that will work in conjunction with an RC servo and thermocouples. As a whole the system will be able to automatically correct the engine’s optimum performance by adjusting the fuel mixture through the temperature sensor output measurement: Thereby increasing the performance of the engine and the experience of the hobbyist.
Success Criteria: To be considered successful, this project should provide us with a high degree of difficulty that will demand the use of knowledge acquired from our studies at UCF. It will also be a success if the project produces a marketable product that satisfies the current needs of the RC industry.
Assumptions, Risks, Obstacles: Like in many projects, there are issues that must be considered. We must not assume that a project will be completed without first acknowledging the possible risks and obstacles that could be faced.
A risk we are willing to take by accepting this challenge, is the possibility of failing to comply with the needs of the intended market. Another possible risk is not being able to complete the project by it’s intended due date and also the possibilities of missing a patent to unknown competitors.
Senior Design Project Proposal
Request for Approval
Bernie Rosario, Chris Mountain, & Jorge Fontanez
Introduction:
We are asking to design a temperature controlled automated carburetor control for a nitro powered radio controlled (RC) vehicle. The purpose of this device is to offer RC enthusiasts greater reliability, power, and ease of use out of their nitro vehicle. Our product will be based on the demands of the RC industry, such demands include, light weight, low power consumption, and rugged durability all within a very small package. Our design team will be mentored by our faculty advisor, Dr. Ducharme who is an expert in the field of electronics and a nitro RC hobbyist as well.
Background:
A nitro RC is powered by a miniature two stroke engine generally ranging in displacement from 2cc to 9cc. These engines use a mixture nitro-methane, methanol, and oil, this fuel is commonly referred to as “nitro”. The two-stroke engine design allows for large amount of power to be made compared to a 4-stroke engine of the same size. A RC nitro engine will generally give between 1 and 3 horsepower and reach speeds past 40,000 rpm. The relatively small size compared to horsepower makes these engines ideal for RC vehicle power plants.
To make these engines run at peak performance proper adjustment of the engine’s carburetors is needed. The carburetor’s main function is to meter the amount of fuel going into an engine relative to the amount of air that is also entering the engine. In a nitro RC vehicle, adjustable needle valves are used to meter how much fuel is used at idle/low engine speed, and high engine speed. Generally when the idle/low speed of carburetors are set they can be left unadjusted for the rest of the day, whereas the high speed carburetor needs to be adjusted depending on many variables throughout the day. An engine makes its peak torque while running at an air to fuel ratio just below the stoichiometric mixture or the ratio of air to fuel that combines all fuel with the available oxygen within a combustion chamber. A carburetor can be adjusted to add more or less fuel at a given point; this is called leaning, or richening the air/fuel mixture. When a mixture is lean, this means that there is more air than fuel compared to the nitro fuel's stoichiometric mixture, when a mixture is rich, this means there is more fuel than air compared to the nitro fuel's stoichiometric mixture. An air fuel mixture that is too rich will cause the vehicle to bog and lack power and acceleration. An air fuel mixture that is too lean will cause the engine to run hot, causing reduced oiling, and may reduce the life of the engine.
RC vehicle enthusiasts use many tools to optimize their carburetor to provide a high level of performance. The current standard is to take a measure of the cylinder head temperature while the vehicle is stopped after the motor has been warmed up. Hobbyists then adjust their high speed carburetor leaner or richer, depending on how hot the motor is running. If the motor is running too hot (over 220F), a richer mixture will cool the motor down, if the motor is too cool (under 200F) leaning the carb. will increase the head temperature. This method of adjustment is not reliable for a number of reasons, ambient temperature, relative humidity, and barometric pressure can change from run to run. Also, when checking an engines temperature the vehicle must be stopped, this allows the engine to cool significantly between runs. These problems make it difficult to properly fine tune an engines carburetor to its peak performance.
Project Timeline:
Task Descriptions:
Research:
A detailed and extensive research on the project topic should be completed for the beginning phases of the senior design project. During the research phase a list of references, specifications of equipment, and a review of current literature should be included. Our main focus will be on the Parallax propeller chip, operation of the R/C Nitro/ 2-stroke Engines, servos, and temperature sensors.
Project Proposal:
Prepare a thorough proposal of the selected senior design project. The proposal should include the scope of the project (ex: problem/opportunity, goals, objectives, etc.), a timeline, specifications, review of current literature, and list of references.
Order Parts & Accessories:
Order and purchase the necessary parts or accessories needed for the senior design project to be created. Some of the necessary equipments that will be needed are: Parallax Propeller Demo Board, R/C Nitro 2-Stroke Engine, temperature sensors, Analog-to-Digital Converter, and any required parts that are needed for the project to function correctly.
Project Design & Construction:
Create a flowchart or blueprint to be used as a step-by-step manual for the assembly of the project design. Brainstorm and map out several different prototypes before the final project design is chosen. Once the final design is chosen begin construction/assembly of the project.
Lab Testing & Troubleshooting:
All test runs, data recordings, and test analyzing should be performed in this phase of the project. Any percentage errors, miscalculations, and malfunctions of the project should be corrected for the finalization of the project.
Finalize Product:
In this phase, any final modifications and adjustments should be made on the design product to be presentable ready for the Project Oral Presentation
Written Report:
A complete and detailed project report should be written according to the format and guidelines specified in the Senior Design Project syllabus.
Prepare Project Oral Presentation:
All materials and documents should be ready to present for the day of the Project Oral Presentation (ex. PowerPoint presentations and videos). The final product should be complete and be ready for display. Rehearsal of the full presentation should be demonstrated with the group for better preparation.
Project Oral Presentation:
An oral presentation will be presented openly to the public. Business attire is mandatory during the oral presentation. The time limit for formal talk is 15 minutes. Questions and demonstration is limited to 10 minutes.
Engineering Specification:
Parallax Propeller Demo Board
This microcontroller is jam-packed with various capabilities and applications that are compacted into a circuit board. This amazing microcontroller comes with several features such as a VGA & TV output, USB-to-serial interface, mouse & keyboard inputs, Stereo output, microphone input, a breadboard to practice designing your own custom circuits , eight available I/O pins, and many more. Required additional equipment is provided below in the chart.
Review of Current Literature
[1] Carburetor 101, by Eric Perez provides a good explanation of the carburetor used in a 2 cycle (stroke) RC engine. He provides a step by step instructional document, on how the reader can optimize the performance of the carburetor.
The author provides many clear and easy to understand diagrams such as an engine tear down, a detailed carburetor, and a two needle carburetor assembly drawing.
[2] The article by Digital Nemesis titled How R.C. Servo Motors Work focuses on the functionality of the R.C. Servo.
The author breaks the article into many sections. Some sections explain the components that make up the servo and the rest of the sections are dedicated to the controlling of the servo via Microcontrollers.
A block diagram is included within the article to provide a visual of the circuitry that composes an R.C. Servo.
[3] Thermocouples is a document fully dedicated to this electrical temperature reading component. The article mainly explains how a thermocouple operates, defines its color codes, and describes recommended use limits and thermocouple standards.
Although the article did not provide any diagrams, graphs or flow charts; it did include a vast amount of links and references to navigate and learn more about the subject.
[4] In Measure High, Measure Low by Jon Williams, who describes himself as a temperature enthusiast, provides a concise history regarding the origin of thermocouple.
Williams also directs his audience attention to the DS2760, a chip that its central function is to monitor lithium-ion batteries, but can be used effectively as a thermocouple.
The rest of the article is dedicated to the interfacing of the DS2760. Throughout this portion Williams provides many useful elements, such as printed screens and schematics to further increase the knowledge of his audience.
List of References
[1] James Cox, Fundamentals of Linear Electronics: Integrated and Discrete, 2nd ed.
[2] James A. Gray and Richard W. Barrow, Small Gas Engines, 2nd ed.
[3] John B. Heywood and Eran Sher, The Two-Stroke Engine: its development, operation,
and design.
[4] Jeff Martin, Propeller Manual.
[5] Norman S. Nise, Control Systems Engineering, 5th ed.
Justin Rosario
N.M.E Design Team
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