The Mangonel Project

Welcome to our exciting project guide on building your very own Mangonel, a medieval siege weapon! This instructable is perfect for students, hobbyists, and anyone passionate about historical engineering marvels. Whether you're a teacher looking to bring a dynamic hands-on experience into your classroom or a DIY enthusiast eager to tackle a new challenge, this guide is for you. I am a Highschool Teacher in San-Francisco California

Our project, "The Mighty Roman Mangonel," is more than just a step-by-step building exercise. It's an immersive journey into the world of medieval siege engineering, blending historical insights with modern scientific principles. This guide will lead you through the intricacies of designing and assembling a functioning Mangonel, providing a unique opportunity to delve into various engineering domains such as materials science, dynamics, and mechanical design.

What You'll Learn:

• The fundamentals of Mangonel design, including key components like the throwing arm, skein, and missile holder.
• Practical engineering skills, as you'll be making informed decisions about the length of the throwing arm, the number of skein loops, and the winching angle.
• The importance of teamwork and scientific thinking in engineering projects.

Supplies

Supplies for Educators:

Note: Educators will use CAD designs (provided below) to create pre-made parts for the student kits.

Manufacturing and Preparation:

1. CAD Designs: For all wooden components and mechanical parts.
2. Woodworking Tools: Saws, drills, sanders for shaping and finishing wooden components.
3. Metalworking Tools: For shaping and finishing the steel bar, trigger hook, and other metal components.
4. Measuring and Marking Tools: For precise cutting and assembly.
5. Safety Equipment: Goggles, gloves, hearing protection for manufacturing.

Materials for Kit Components:

1. Hardwood: For base beam, braces, vertical beam, strike bar, anchor block, throwing bar.
2. Steel Bar: For structural support.
3. Dowels: Various diameters for assembly.
4. Metal Rings, Hooks, and Washers: For mechanical assembly.

Packaging for Kits:

1. Boxes or Bags: To package individual kits.
2. Labels and Instructions: For easy identification and assembly guidance.

Supplies for Students:

Note: Students will receive a kit with pre-made parts and will focus on assembly, testing, and learning.

Wooden Components:

1. Base Beam: Hardwood, as per the provided drawing.
2. Front Brace: Hardwood, following the specific design.
3. Square Brace: Hardwood, according to the design.
4. Feet: Hardwood, as outlined in the drawing.
5. Angle Struts: Hardwood, following the design.
6. Vertical Beam: Hardwood, as per the drawing.
7. Strike Bar: Hardwood, designed as specified.
8. Anchor Block: Hardwood, in accordance with the drawing.
9. Throwing Bar: Hardwood, as detailed in the design.
10. Winch Dowel: A 28mm diameter dowel.
11. Wooden Dowel (1): A 20.5mm diameter dowel.
12. Wooden Dowel (2): A 9mm diameter dowel.
13. Steel Bar: As provided in the kit.
14. Trigger Hook: Included in the kit.
15. Wooden Spoon: Part of the kit.
16. Large Washers: Included.
17. D-shaped Metal Ring: Provided.
18. Split Rings: Part of the kit.
19. Nylon Cord: 4mm thick and 4.5m long
20. Nails (10mm)
21. Wood Screws(5X50mm Black Jappaned)

Tools and Miscellaneous:

1. Hammer: For nails and dowels.
2. Screwdriver or Drill: For screws.
3. Saw (if necessary): To modify any wooden parts.
4. Measuring Tape: For precise measurements.
5. Safety Goggles: Essential for eye protection.
6. Gloves: To protect hands during assembly.
7. Matches/Lighter
8. 90 Degree set-square
9. A length of wire to make a hook (coathanger)
10. Fine/Medium sandpaper
11. Craftknife

Optional:

1. Paint or Stain: For finishing the wooden parts.
2. Decorative Elements: To add a historical or personal touch.

Remember, safety is paramount, especially when working with tools and mechanical components. Ensure all participants are briefed on safety protocols before beginning the project.

This list covers the essential materials and tools needed for the Mangonel project, ensuring a smooth building process from start to finish. Feel free to customize the list based on the specific requirements of your kit or design modifications.

Step 1: Assessment Criteria

Please find below Assessment criteria:

Step 2: Simulating the Dynamics

Through the following assignments, students not only gain theoretical knowledge but also practical skills in dynamics, structural engineering, and material science. These skills are directly transferable to the design, construction, and optimization of a Mangonel, ensuring its effective operation, structural integrity, and safety.

mec1.pdf: Dynamics for the Mangonel-No Drag​​

• Understanding Projectile Dynamics: Learn about the effects of launch angle and velocity on the trajectory of a projectile without air resistance.
• Data Analysis and Presentation: Develop skills in creating and interpreting Excel graphs to analyze projectile trajectories.
• Application: This knowledge is crucial for optimizing the Mangonel's design to achieve desired range and accuracy.

mec2.pdf: Dynamics for the Mangonel-With Drag​​

• Incorporating Air Resistance: Understand how air resistance (drag) impacts the trajectory and range of a projectile.
• Comparative Analysis: Gain insight into the differences between trajectories with and without drag, important for realistic modeling of Mangonel launches.
• Practical Implications: Apply this understanding to fine-tune the Mangonel's design for real-world conditions where air resistance plays a role.

mec3.pdf: Structural Engineering Component Design Against Failure Under Static Actions​​

• Structural Integrity Analysis: Learn to calculate the strength and failure loads of materials under static conditions.
• Material Selection and Sizing: Develop skills in selecting appropriate materials and dimensions for structural components to prevent failure.
• Mangonel Arm Design: Directly applicable to choosing the right materials and dimensions for the Mangonel's throwing arm to ensure it withstands static loads without failing.

mec4.pdf: Structural Engineering Component Design Against Failure Under Dynamic Actions​​

• Dynamic Load Analysis: Understand how dynamic forces affect structural integrity, especially in motion.
• Safety and Reliability: Learn to predict and prevent failure under dynamic conditions, essential for ensuring the Mangonel's safety and reliability during operation.
• Optimizing Mangonel Arm Design: Use dynamic analysis to ensure the Mangonel's arm can withstand the stresses of rapid motion and impact without breaking.

Step 3: Unpacking and Preparing the Kit

Objective: Become familiar with the components and prepare for assembly.

1. Unpack the Kit: Open the kit provided by educators. Carefully lay out all components on a clean, flat surface. This step is crucial for inventory and organization.
2. Identify and Sort Parts: Use the provided instructions to identify each component. This will include various wooden beams (base beam, braces, vertical beam, etc.), metal parts (steel bar, trigger hook), assembly hardware (dowels, screws, nails), and the winch system.
3. Organize Your Workspace: Choose a spacious and well-lit area for assembly. Place your tools (hammer, screwdriver, drill) and safety gear (goggles, gloves) within easy reach. Organizing your space and tools beforehand will streamline the assembly process.

Step 4: Assemble the Wooden Frame

Assembly Steps for Wooden Frame and Lever Mechanism

1. Prepare Your Workspace: Clear the area to ensure ample space for assembly. Place the two long wooden pieces (side beams) parallel to each other on a flat surface, with the grooves facing inward and the holes aligned at one end.
2. Position the Crossbeam: Take the shorter wooden block (crossbeam) and position it perpendicular to the side beams at the end opposite the holes. This block will likely serve as a support or fulcrum for the lever mechanism.
3. Secure the Crossbeam: If screws or dowels are provided, use them to secure the crossbeam to the side beams. If not, ensure the crossbeam fits snugly against the side beams and is stable.
4. Assemble the Lever Mechanism: Take the rod with the handle and hook (likely a winch or lever arm) and position it between the side beams. Align the holes at the end of the side beams with the ends of the rod.
5. Insert the Axle: If the rod is intended to rotate or act as a winch, insert it through the holes in the side beams. Ensure that it moves freely without too much wobble.
6. Test the Lever: Rotate the handle to test the lever mechanism. If there is any resistance or misalignment, adjust the position of the side beams or the crossbeam to ensure smooth operation.

Step 5: Attaching Arms and Supports

1. Attaching the Upright Arm: Locate the central hole on the crossbeam where the upright arm will be mounted. Insert the bottom end of the upright arm into this hole, ensuring it stands perpendicular to the base. The upright arm should be sandwiched tightly between the angled supports, which are already attached to the base. Use dowels or screws through the corresponding holes to lock the arm in place.
2. Attach Struts to Side Supports: Align the holes at one end of each strut with the holes on the notched ends of the side supports. Insert dowels or screws through these holes to secure the struts to the side supports. If the fit is not tight, you may want to use wood glue for additional stability.

Step 6: The Winch System

1. Insert the Winch Dowel:
2. Slide the dowel through the holes at the back of the frame.
3. In case of tightness due to humidity causing dowel swelling, you may need to file the holes slightly for a better fit.
4. Lubricate for Smooth Operation:
5. If the winch dowel is difficult to turn, use a pencil to rub graphite on the contact surfaces. Graphite is an effective dry lubricant and has been used for this purpose historically.
6. Position the 6mm Pegs:
7. Slide the 6mm pegs through the holes on the winch dowel that are located outside the frame. These pegs will help in the operation of the winch.
8. Install the 9mm Peg:
9. Insert a 9mm peg into the holes in the frame adjacent to the winch.
10. Ensure this peg can slide in and out easily for functionality and do not glue it in place. Apply graphite to this peg as well to enhance its sliding capability.

Step 7: Assembling the Throwing Arm

1.Prepare the Throwing Arm:

• Inspect the arm to ensure it's the correct piece with a round cross-section and minor cutouts for proper orientation within the rope skein.

2.Position the D-ring:

• Super glue the D-ring onto the arm's side, aligning it longitudinally with the pre-marked line.
• Ensure the top of the D-ring is precisely 100mm from the arm's top.

3.Secure the D-ring with Wrapping:

• Start by making a loop with the cord about 12mm below the D-ring's intended position on the arm.
• Wrap the cord tightly around the arm and over the loop, maintaining tension.
• Thread the loose end of the cord through the loop and pull tight to secure the wrapping.
• If using nylon cord, tie the loose ends together over the wrapping to prevent slipping.
• Continue wrapping up to at least 12mm above the D-ring, passing the cord through the ring with each wrap.

4.Attach the Projectile Holder:

• Position the spoon on the arm below the D-ring, ensuring it is correctly oriented to launch missiles perpendicular to the skein's axis.
• Secure the spoon by wrapping the cord along its length, similar to the D-ring attachment process.

Step 8: Setting Up the Skein

1. Prepare the Skein Anchor Blocks:
2. Insert two 9mm pegs into the skein anchor blocks. If the pegs fit loosely due to size variations, you may need to secure them more tightly.
3. Install Metal Washers:
4. Place metal washers over the large holes in the anchor blocks and position these assemblies on the outside of the frame.
5. Position the Capstans:
6. Lay the capstans (6mm metal rods) over the washers, centered over the holes in the anchor blocks.
7. Begin Wrapping the Skein:
8. Tie one end of the nylon rope to a stable point, like a vertical beam, and pass it through the skein hole from the outside of the frame.
9. Thread it the same way on both capstans: from the bottom-to-bottom and then top-to-top, ensuring consistency.
10. Insert the Throwing Arm:
11. After a couple of wraps, insert the throwing arm into the skein, keeping the bottom wraps separate from the top wraps for each loop.
12. Complete the Wraps:
13. Continue wrapping until you have approximately 7 loops on top and 7 loops on the bottom of the arm.
14. Secure the Skein:
15. Once all loops are in place, untie the rope from the vertical beam and tie the ends together over the capstan with a secure square knot. Fuse the ends to prevent slipping.
16. Adjust the Throwing Arm:
17. Slide the throwing arm to set it at the desired length, ensuring it does not touch the ground and is correctly oriented with the D-ring at the back and the spoon facing front.
18. Tension the Skein:
19. To add tension, turn the anchor blocks towards the vertical beams, making only a quarter turn at a time.
20. An assistant may be needed to hold the throwing arm upright until enough holding torque is achieved.
21. Finalize Tension:
22. Determine the number of turns based on the required torque and the number of loops. At least one full turn is usually enough, but more can be added if necessary.
23. Be careful not to over-tighten as this can deform the frame or damage the components.

Step 9: Attaching Strike Pads and Beams

1. Prepare the Strike Pads:
2. Attach leather or leatherette strips to both strike bars using tacks. Be careful not to place any tacks on the face of the pad to avoid damaging the throwing arm.
3. Install the First Strike Beam:
4. Pull back the throwing arm, having someone hold the base if necessary for stability.
5. Position one strike beam between the throwing arm and the vertical beams, aligning the holes in the strike beam with the 'screw guide' holes at the top of the vertical beams.
6. Use the tension of the pulled-back arm to keep the beam in place and fasten it with screws.
7. Attach the Second Strike Beam:
8. Place the second strike beam below the first, ensuring it is exactly 100mm apart from the top of the first beam.
9. Secure it with screws as you did with the first beam.

Step 10: Setting Up the Winch Mechanism

1. Prepare the Winch Cord:
2. Cut a length of the yellow cord that seems reasonable for the winch mechanism.
3. Create a Double Loop:
4. Make a double loop with the yellow cord.
5. Thread the Double Loop:
6. Thread the double loop through one of the inner holes of the winch dowel.
7. Secure the Cord:
8. Feed the ends of the cord back through the loop and pull tight to secure the cord onto the dowel.
9. Attach the Split Rings:
10. Install two split rings onto the cord for added strength.
11. Tie-off the Cord:
12. Tie off the cord’s free ends through the other inner hole in the dowel.
13. Hook the Trigger:
14. Attach the trigger mechanism onto the split rings.
15. Attach the Firing String:
16. Tie a yellow string, at least 1.75 meters long, to the top loop of the trigger. This string will be used to release the winch and fire the Mangonel.

Step 11: Electronics Part

the following assignments provide students with a strong foundation in electronics, from understanding basic components to implementing complex systems using arduino, all of which are essential for the successful integration of electronics in a Mangonel project. This knowledge will enable students to design and construct efficient, reliable, and sophisticated electronics for the Mangonel, enhancing its functionality and performance.

Step 12: Assignment 1

Exercise 1 (A) – Blink

Objective: Blink an LED with an Arduino for a time based on your Roll number and then turn it off for 2 seconds.

Supplies Needed:

• Arduino Board
• Breadboard
• LEDs
• 100-ohm Resistors

Instructions:

1. Circuit Setup:

• Attach a 100-ohm resistor to one leg of the LED.
• Connect the cathode (negative leg, usually the shorter one or the side with a flat edge on the LED body) to the ground on the breadboard.
• Connect the anode (positive leg) to pin 13 on the Arduino.

1. Programming the Arduino:

• Write a sketch (code) where the LED blinks on for the number of seconds equal to the sum of the last two digits of your Roll number, then turns off for 2 seconds.
• Upload the code to your Arduino board using the Arduino development environment on your computer.

1. Testing:

• Verify that the LED blinks according to the specified timings.

Reflections:

After completing the circuit and programming, make observations about the process, any issues encountered, and how they were resolved.

Exercise 1 (B) – Push Button

Objective: Use a pushbutton to control the built-in LED on the Arduino.

Supplies Needed:

• Arduino Board
• Momentary button or switch
• 10K ohm resistor
• Breadboard
• Hook-up wire

Instructions:

1. Circuit Setup:

• Connect the red and black wires to the power and ground buses on the breadboard, respectively.
• Connect one wire from digital pin 10 to one leg of the pushbutton.
• Attach a 10K ohm pull-down resistor to the same leg of the button and connect the other end to ground.
• Connect the opposite leg of the button to the power bus (5 volts).

1. Behavior Understanding:

• With the pushbutton open (not pressed), the pin reads LOW because it's connected to ground through the resistor.
• When pressed, the button closes the circuit, connecting the pin to 5 volts, and it reads HIGH.
• Optionally, you can reverse this logic using a pull-up resistor.

1. Testing:

• Press the button and observe the built-in LED on the Arduino. It should light up when the button is pressed and turn off when released.
• Ensure the LED does not blink erratically, which could happen if the pin is left floating without a pull-up or pull-down resistor.

Reflections:

Reflect on the pushbutton behavior and how the use of resistors influences the circuit.

By following these instructions, you will complete the assignments involving blinking an LED and using a pushbutton to control an LED on an Arduino board

Step 13: Assignment 2

Exercise 2A – Study of ICs

Objective: Verify the function tables of CD4027 and CD4081 ICs.

Supplies Needed:

• Breadboard
• CD4027 IC
• CD4081 IC
• Single core connecting wires

Instructions:

1. Understand the ICs:

• Refer to the datasheets provided for both CD4027 and CD4081 ICs to understand their pin configurations and functional truth tables.

1. Set Up the Circuit:

• Insert the ICs into the breadboard according to the pin diagrams.
• Use connecting wires to make the necessary connections as per the function tables.

1. Test the ICs:

• Apply the input combinations as per the function tables.
• Observe and record the outputs, verifying them against the expected results from the datasheets.

Reflections:

After completing the circuit setup and testing, reflect on the accuracy of the function tables and any discrepancies observed.

Exercise 2B – IR Sensor

Objective: Demonstrate the working of IR sensors and receivers, displaying output using an LED.

Supplies Needed:

• Breadboard Power supply
• Resistors
• LEDs
• IR transmitter and Receiver (Photodiode)
• Single core connecting wires

Instructions:

1. Understand the IR Sensor Pair:

• Familiarize yourself with the operation of the IR LED and photodiode.

1. Set Up the Circuit:

• Connect the IR LED to the breadboard, ensuring it is powered correctly.
• Place the photodiode in a position to receive light from the IR LED.
• Connect a resistor and LED in series with the photodiode to indicate the output.

1. Test the Sensor:

• Power the circuit and observe the LED; it should be on, indicating high voltage across the photodiode when the IR light is received.
• Block the IR light path; the LED should turn off, indicating a low voltage across the photodiode.

1. Combine Sensor Outputs:

• If you have two pairs of IR sensors, combine their outputs into a single signal by logically connecting the outputs using an AND or OR gate, depending on the desired behavior.

Reflections:

Reflect on the working of the IR sensors, the conditions under which the LED turns on and off, and the effectiveness of combining sensor outputs.

Additional Assignment Task:

• Use Tinkercad to illustrate the pin configuration and verify the truth table of IC 74HC08 and IC 74H73.

For each step, ensure you are following safety protocols and handling all electronic components with care to prevent damage. After completing the exercises, each student should submit a separate sheet for reflections, including any conclusions or learnings from the assignment

Step 14: Assignment 3

Exercise 1 – Verify the Functional Table of CD4543

Objective: Test and confirm the function table of the CD4543 decoder using a seven-segment display.

Supplies Needed:

• Decoder (CD4543)
• Seven Segment Display
• Single core connecting wires
• Tinkercad Software tool (available at Tinkercad)

Instructions:

1. Circuit Setup:

• Place the CD4543 decoder and the seven-segment display on the breadboard.
• Connect the decoder to the seven-segment display according to the pin diagram.
• Use single-core wires to make connections as per the schematic provided.

1. Testing the Decoder:

• Input 4-bit binary values ranging from 0000 to 1001 into the CD4543.
• Observe the corresponding decimal level output on the seven-segment display.
• Ensure the output matches the expected results from the function table.

Reflections:

Document your observations and confirm the accuracy of the CD4543's function table.

Exercise 2 – BCD to 7 Segment Display Conversion

Objective: Use the CD4543 decoder to convert BCD inputs into outputs displayed on a seven-segment display.

Supplies Needed:

• Same as Exercise 1
• Arduino Uno

Instructions:

1. Connect the Arduino:

• Use the Arduino Uno to provide BCD input to the decoder.
• Make sure the decoder's latch signal is connected to the 5V (via a 10Kohm resistor) to allow for current binary input decoding.

1. Testing the Conversion:

• Use Tinkercad to set up and simulate the BCD to seven-segment display conversion.
• Test various BCD inputs and verify the output on the display.

Reflections:

Reflect on the conversion process and the operation of the CD4543 decoder.

Exercise 3 – Up Counter with Arduino

Objective: Program an Arduino to count from 0 to 9 indefinitely and display each digit on a seven-segment display.

Supplies Needed:

• Same as Exercise 2

Instructions:

1. Write the Arduino Sketch:

• Code an up counter that iterates from 0 to 9 and repeats indefinitely.
• Use BCD code to represent each number on the seven-segment display.

1. Test the Counter:

• Upload the sketch to the Arduino Uno.
• Verify that the seven-segment display shows a correct count from 0 to 9 in a loop.

Reflections:

Evaluate the functioning of the up counter and the accuracy of the seven-segment display output.

Assignment Tasks:

• Display Roll Number Digit:Redesign Exercise 2 in Tinkercad to display the last digit of your Roll Number on the seven-segment display.
• Infinite Up Counter in Tinkercad:Write an Arduino sketch using Tinkercad to create an infinite up counter that counts from 0 to 9 and verify its operation.

For each exercise, make sure to understand the theory behind the operation of the components and reflect on your learning outcomes and any challenges faced during the exercises​

Step 15: Final Project

Exercise 1 – Timing Circuit Construction for Mangonel

Objective: Build a circuit to measure and display the time taken by the Mangonel's throwing arm to pass between sensors.

Hardware Required:

• CD4027, CD4081, CD4543 ICs
• Arduino Uno
• Seven-Segment Display
• Single core connecting wires
• Digital Trainer Kit

Instructions:

1. Circuit Setup:

• On the breadboard, set up the CD4027, CD4081, CD4543 ICs, and the seven-segment display.
• Connect the two sensors from the Mangonel to the input of the circuit.
• Use connecting wires to make appropriate connections as per the schematic diagram provided in the assignment document.

1. Combining Sensor Signals:

• Combine the two separate sensor signals into one using AND or NAND logic gates.
• Ensure that the output preserves the signals from each sensor while combining them into a single output.

1. Converting Pulses:

• Convert the two short pulses from the combined signal into one long pulse using a J-K flip-flop.
• Set up the J-K flip-flop to change state with each pulse, creating a long pulse that spans from the start of the first to the end of the second pulse.

1. Connect to Arduino:

• Feed the long pulse into the relevant input on the Arduino board.
• Use the Arduino to measure the length of the pulse and to display the timing on the seven-segment display.

1. Software Implementation:

• Write and upload the Arduino sketch to interpret the input signal from the J-K flip-flop and to control the seven-segment display accordingly.

Reflections:

After completing the hardware setup and software programming, reflect on the functionality of the circuit and the accuracy of the time measurement.

Assignment Tasks:

1. Logic Gate Application:

• Use at least two different logic gates to obtain the signal required for the Arduino, as shown in the figure provided in the document.
• Explain the waveform behavior at each step using Tinkercad simulations.

1. Tinkercad Micro-Projects:

• Design sensor-based projects in Tinkercad that:
• a. Detect the motion of an object.
• b. Measure the distance between an object and the sensor.
• Discuss potential applications of these projects in terms of designing a precision Mangonel.

This instructable outlines the steps to create a timing mechanism for a Mangonel using digital logic and microcontroller programming. The key learning outcomes include understanding combinational logic, flip-flop operation, and interfacing with Arduino for real-world applications​