Final Product Air Raid Siren:
Success Criteria:
- Complete the project within the time limit following the schedule ✅
- The siren creates an air raid siren whistle sound at least 80 decibels from 1m away ❌
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Most of the people agree that the siren is visually appealing ✅
How Does the Device Operate?
The batteries transfer electrical energy to the motor. The motor spins, spinning the specially configurated turbine clockwise direction. The turbine consisted of small wedged triangular shapes. The bottom layer compromises 6 openings (ports), and the top layer compromises 5 ports. The turbine spins clockwise, sucking air from outside, and spitting it out from the ports. The case around the turbine has the same number of ports (5/6 ports). Thus, as the turbine spin, it lines up and then doesn’t line up to the case gaps causing pulsating airflow and creating sound. The high pitch, which is 6 ports, and the low pitch, which is 5 ports creates two different pulsating air flow making the air raid siren dual tone.
Reflections on success criteria:
I was able to follow the plan that I made ahead of time in the Develop and Plan section of this project. Every day, I followed the schedule and kept in mind the checkpoints that I need to hit. I knew the schedule would be important because I missed two classes.
The decibels were rather hard to achieve. My siren, as you can hear from the video, does create a whistling sound. However, when testing at a 55 decibels quiet room, it only reaches 65 decibels. Although after the peer feedback, I tried to fix the sound issue, and to some degree, it helped. However, the decibel is still significantly lower than 80 decibels. After analyzing, the reason why it’s not as loud could be the motor speed, the size of the siren, and the inaccurate measurement of the turbine case. Next time, I should plan ahead of time and do more research (to buy a better turbine), and make sure to consider every aspect of a project (wobbling of the turbine).
All the people that gave peer feedback stated that the turbine is visually appealing because the red and white creates a strong contrast.
Reflections, points I’m proud of:
The original design of the color for this siren was red, and grey as it resembles the WW2 Carter’s siren. However, the school doesn’t have grey as a 3D printing color, so I changed it to white. Still, it’s very visually appealing.
Changing the siren’s height from 2cm to 4cm worked very well because the motor was still able to spin at its max speed at a height of 4cm, which resulted in a louder sound
The suggestion from Mr. Michie, “drilling a circular hole for the motor” worked really well because it’s able to stabilize the entire motor
Rather than sanding down the small turbine case, changing the size of the case and re-3D printing worked better
The ‘cardboard trick’ worked exquisitely well because it directs more air to exit the turbine, resulting in a louder sound compared to the without the cardboard case
Using tape to secure the motor worked nearly flawlessly as it was able to stabilize the motor
Reflections, points I can improve:
Making the turbine case too small or too big. Next time, consider all aspects of the project. In this case, the wobbling turbine suggests it needs a larger case.
(See more points I can improve, check out the success criteria reflections)
Potential Clients:
This could be used for educational purposes for all ages. Especially teens because many people might think that an air raid siren is from a speaker, but actually it’s from a turbine.
Impacts of My Product:
Most of the air raid sirens around the world are made from metal, which is heavy. Especially building a large one, might require different welding tools. On the other hand, this 3D-printed air raid siren is made from plastic, which is light and portable. As 3D printing technology is becoming more prominent and being used in various industries, my project proves that it could replace the conventional metal air raid sirens.