Gate 4 - Product Explanation (Group 18)

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Revision as of 14:26, 30 November 2012

Gate 4: Product Explanation

Purpose

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

Tools Used

- 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.

**Table 1: Difficulty Scale**
Difficulty #	Description
1	These simple tasks require very little effort. It is easy to see what to do for these kinds of steps and is simple to carry out.
2	For these kinds of steps it may be necessary to screw components into place, requiring the use of a screwdriver. These steps may also require some tricky adjustments of the parts to get them into the proper location.
3	More than two parts are usually involved in these steps. Often there are intermediate stages where parts must be held until another part is placed over top. Once both parts are placed they can then be screwed down at the same time. This step requires a great deal of effort to carry out.

Product Reassembly

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.

**Table 2: Helicopter Reassembly**
Step #	Parts	Procedure	Difficulty
1	Main frame Inner shaft with lower grip set	To begin the reassembly, we attached the lower grip set with the inner shaft. We started here because the shaft is the center piece of the helicopter and was one of the hardest parts to disassemble during the disassembly process. We then placed the inner shaft with the lower grip set into the main frame. We did not attach the blades to it yet because it would only make our reassembly process harder.	2
2	Gears with die steel set limit Triangle limit	The next step was to attach all the gears which is located right at the bottom of the shaft. Putting the gears together was a hard task because it could not securely balance itself without the triangle limit and the fact that it took two of the group members to help put it together showed it was in fact a hard task. After attaching triangle limit where the gears fitted well in it, we had to secure it by screwing in the die steel set limit to ensure the gears would not fall off.	3
3	Landing skids Battery case	There were two landing skids which were attached to the battery case which not only holds the battery but also holds the circuit board and acts as the bottom half of the interior body.	1
4	Top blades Top blade grip set	We attached the top blades to its grip set.	1
5	Motor A Motor B	We added the motors at this stage because reattaching the gears was a tough job and after that was accomplished, reattaching both the motors to it's holders and it's gears the other gears was an easy task.	1
6	Circuit board On/Off switch Left lower aluminum set	We then attached the circuit board to the battery case and joined both the main body and battery case together. We then connected the wiring together which included the On/Off switch which was already connected to the left lower aluminum set but we did not attach the left lower aluminum set to the main body yet.	1
7	Motor coolers Motor decoration Upper aluminum set	We then just slipped on the motor coolers around each motor and attached the motor decoration above the motors. Then we screwed in both the upper aluminum pieces.	2
8	LED lights	Then we attached the LED lights to both sides of the lower aluminum pieces. Once that was accomplished we connected the wiring of the lights to the circuit board and then screwed both the lower aluminum pieces to the main body.	2
9	Tail motor set Tail decorations	We reassembled the tail motor set then we placed the wiring in the main boom which will then be connected to main circuit board. Then once that is done we screw in the tail decorations.	3
10	Tail support	Then we attached the main boom with the tail components attached to it, to the main body. The two tail supports were then screwed to main body and the tail's main boom.	1
11	Balance bar	Attached the balance bar with screws above the top main blades.	1
12	Bottom main blades	We attached both the blades to the bottom grip set.	1
13	Head cover	Finally we attach the head cover to the main body.	1

Mechanisms

Flight mechanism

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:

Lift=A*σ*V²

A = area covered by blades while in motion σ = density of air V = velocity of blades

Gear mechanism

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=Win/Wout

R = Radius of gear Win = Work in Wout - Work out

Design Revisions

Electrical wiring

blades system

Gate 4 - Product Explanation (Group 18)

Revision as of 14:26, 30 November 2012