Gate 4 - Product Explanation (Group 18)

Revision as of 01:49, 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.

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	Images
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

Gear mechanism

Gear mechanism is a mechanism for transmitting motion for some purpose. In the R.C. Helicopter, gear is the most important part. It is located at the bottom of the helicopter. It is the bridge to connect rotor with main shaft. They provide a gear reduction in motorized equipment. This is key because, often, a small motor spinning very fast can provide enough power for a device, but not enough torque. There are many different kind of gears, but in our R.C. Helicopter we use spur gears. Spur gears are the most common type of gears. They have straight teeth and are mounted on parallel shafts. As we can see in the following picture, the rotor's gear which on the top of rotor connect with the small gear and transmit the motion. Meanwhile, the small gear deliver the motion to the larger gear by the teeth on them. Finally, because the larger gear was fixed at the main shaft, it brings the shaft turning with it. The gear ratio equation is:

R=Win/Wout

Blades mechanism

The blades system applied lift on the R.C. Helicopter to make it fly by deflecting air downward and benefiting from the equal and opposite reaction that results. The amount of lift generated is determined by the pitch angle and speed of each rotor blade as it moves through the air. Also, the blade can control the direction of motion which are downward, upward and forward. The amount of lift can be calculate by using the circular area swept by rotor blades multiply by the density of air multiply the square of velocity of air existing disk( Lift=A*σ*V²). When the blade is rotating it will bring the air flows around it. This flow of air is called an induced flow point to downward. It is most predominant at a hover under still wind conditions. Because the rotor system circulates the airflow down through the rotor disk, the rotational relative wind is modified by the induced flow.

Design Revisions