Gate 4 - Product Explanation (Group 18)
Gate 4: Product Explanation
In Gate 3, we produced a detailed analysis of each individual component that made up our RC helicopter. In this Gate 4, we are required to reassemble our product back to its initial form. We will need to provide a detailed step by step process describing how the product was reassembled, identify mechanisms in our product, and provide design revisions that would make our product function better.
This gate contains the Project Management: Critical Project Review - Cause for Corrective Action and the Product Archaeology: Product Explanation - Product Reassembly, Mechanisms, and Design Revisions.
Project Management: Critical Project Review
Cause for Corrective Action
As we have anticipated in Gate 3, the main challenge we faced during the duration of this gate is the time constraints due to the Thanksgiving holiday. Some of our members returned home for the holidays, therefore the workload for this gate could not be divided among us until the break was over.
We did however start off reassembling our helicopter early, just before the Thanksgiving holiday, therefore we managed to complete the reassembly process relatively fast.
Overall, the group members still work well with one another and we communicate frequently.
Product Archaeology: Product Explanation
- 2 x 1.5mm Philips Screwdriver
- 1 x 2.0mm Philips Screwdriver
- Hex Wrench 2.5mm
Ease of Reassembly
In order to assign a level of difficulty to each step of our reassembly, we created the following scale.
To complete this reassembly we did everything by hand, along with the use of a screwdriver. During our disassembly we started did it from inside out.
The flight mechanism of the RC helicopter is the most important mechanism of the helicopter. The flight mechanism is what allows the helicopter to take off and fly into the air. This mechanism is made up of the upper blades, lower blades, and tail blades.
When the motor is turned on and energy is transmitted through the shaft, all the blades spin in a circular motion, deflecting air downwards. This airflow, called the induced flow, is directed downwards towards the ground. This situation generates lift and the helicopter begins to hover off the ground. As more energy is transmitted to the blades, the faster it spins thus increasing the speed of the helicopter. The amount of lift generated is determined by the pitch angle of the blades and its speed as it moves through the air. The amount of lift generated can be calculated using the following formula:
A = area covered by blades while in motion
σ = density of air
V = velocity of blades
The gearing mechanism of the helicopter plays an extremely important role in transferring multiplying the energy produced by the motors to the blades. The gearing mechanism is made up of four gears in total, the lower blade gear, the upper blade gear and two transition gears. Our RC helicopter uses spur gears. These are a very common type of gears and can be found in almost all mechanical objects. These gears have straight teeth that transmit and multiply energy when it is rotating. The gears in our helicopter are mounted on shafts at the bottom of the body of the helicopter and are connected to the motors. When the motor is turned on, it spins the whole gear mechanism, which in turn produces torque and spins the main shaft of the helicopter. This torque is what causes the blades to spin in a circular motion.
The amount of work transferred by each gear depends on its radius. The following equation shows the relationship between the radius of the gear and the work transferred:
R = Radius of gear
Win = Work in
Wout - Work out
One of the main design revisions that may be made at the system level is a change to the flight mechanism, specifically the size of the tail blades. The tail blades of the Syma S033G RC Helicopter are quite small for its large size. The decision for the designers to make it small was probably due to the fact that it would have a lower production cost. However, if the size of the tail blades was doubled, the thrust produced by its motion would increase by approximately 50%. This will significantly increase the overall speed of the helicopter as the tail blades would contribute more power to the whole flight mechanism. The helicopter may also become more stable due to this change.
From a social factor, this redesign will have a positive impact as its higher speed will encourage veteran flyers to buy this helicopter for use in competitions while beginners who are learning how to fly the RC helicopter can fly it at faster speeds and have better control of it.
From an economic factor, the redesign will have a negative impact since more material would be needed to produce the tail blades, thus increasing its manufacturing costs and also the overall price of the helicopter. The cost to fix or replace a damaged tail blade would also increase.
Another design revision is improving the power transmission system by using magnets rather than mechanical gears. Using magnets in the place of gears has several advantages such as reduced maintenance, increased reliability, lower sound pollution and higher efficiency. The current use of gears needs to be carefully maintained by lubricating them frequently. Also, when the motor is spinning the gears, a loud noise is produced. Magnets on the other hand overcome all those problems and also make the helicopter fly better by maximizing the torque transmission.
From an economic factor, this redesign might produce a negative effect from the manufacturing point of view as magnets cost more to make compared to the gears but for the user, the maintenance cost would be lower.
From an environmental factor, a positive outcome can be achieved from this redesign as the noise pollution would be greatly lowered if the magnets are used.
Finally, the aerodynamic system of the helicopter can also be redesigned. The design of the head cover and the body decorations can be redesigned to make the helicopter more aerodynamic. For example, the head cover can be redesigned so that it helps direct the induced air flow downward, making it easier for the helicopter to lift off. Also, the body decorations can be redesign to allow the helicopter fly faster and enable the user to control it better.
From a social factor, a new sleek redesign of the aerodynamic system of the helicopter will attract RC helicopter enthusiasts to fly this helicopter. It may also encourage younger children to get involved into this hobby.