By Tuan Vo, Project Manager

Material of aircraft:
To build the body of the aircraft, we have decided to go with plastic foam.  A 12”diameter X 4”high wheel of foam weighs in at 98grams.  We will cut the foam to mount the fans and components using a hot knife. In this project, one of the basic and most important requirement is to make the aircraft look like a UFO.  Foam would be ideal when considering cost, weight, and level of skill during fabrication. 
 

 
The outside shell will have to be lightweight yet rigid enough to protect the aircraft.  There are two materials we can use that has the two characteristics: fiberglass and carbon fiber.  Both materials will have to be molded with a resin and hardener chemical reaction. 
 
Below is a qualitative comparison between fiberglass and carbon fiber, taken from Fibre Glast Company.
 
The legend is as follows: P=Poor, F=Fair, G=Good, E=Excellent.
 

 
Although the cost of production for carbon fiber is higher than fiberglass, the stiffness to weight ration of carbon fiber is superior.  Weight reduction is what we need, and the cost to produce the parts for this aircraft is not too big and within budget.
 
The carbon fiber we are using is 2×2 twill woven with thickness of .012 inch thickness. One sheet of CF should be able to provide the rigidity we need.  However, we will be using two layers just to ensure
 

By Tuan Vo, Program Manager

Introduction:
Weight is the number one factor when determining our components that will be used on our aircraft. As stated in the Preliminary Design Document, we decided to use the fans and speed controllers given to us.

Purpose: To identify and expatiate on the equipment and materials selected for the aircraft.

1. Microprocessor:

We had a choice of several microprocessors that are lightweight enough and can provide the processing functionality required for flight. The last team to work on this project utilized the TinyDuino which is produced by tiny-circuits.com.  The TinyDuino processor board was used in conjunction with a USB and ICP shield and protoshield.  All together this set up costs 40$.  The processing is the specification provided by tiny-circuits.com.

• Atmega328P processor (same as is used on the Arduino Uno)
• Reset switch
• Status LED
• 8MHz ceramic resonator
• Optional battery connector for CR1612-CR1632 coin cell batteries
• External power supported with a 0.1″ power connection holes
• Supports automatic switching between +5V and VBATT (if +5V is present, it will be used instead of the battery)

This TinyDuino setup was provided to us by the customer because it was utilized by the last group to take on the vertical take-off and landing aircraft.  However, the last group could not power the TinyDuino using USB alone.  There appears to be hardware damage when we received the stack of boards.  It constantly need a coin cell battery in there just to be able to power on.  Power was not the main factor that inhibited this team from recycling the TinyDuino for this build, it was the fact that we could not program with it.  No one in the company knew how to communicate with the TinyDuino, and we have tried asking tiny-circuits.com for support to no avail.  The last team to use it also documented significant difficulty while programming it, although they left us no help on how to establish a connection in the first place.  One problem could be that the TinyDuino was structurally compromised, and we could buy a new one to find out if it’s an isolated case.  However, the cost of the whole setup is $40 dollars, so we decided to explore other options. 

The Arduino Uno is a good board to use; it uses the same ATmega328P that the TinyDuino uses.  However, we cannot use this reliable board because at 28 grams it is too big and heavy. The Arduino Pro Mini and Mini series are smaller versions of Arduino Unos, weigh only 4 grams and are much, much smaller in size.  However, the consensus on quadcopter forums is that the Pro Mini and Mini are troublesome to work with and have a reputation of failing more frequently.  

The final board we have decided on is the Arduino Nano.  The Nano is very similar to the Uno and Pro Mini, weighs in at 4 grams, and has been proven reliable in the past.  In fact, one of our team member has used the Nano in his EE444 class where it was used on a robotic rover.  The Nano runs off of 5V battery source which could be provided by the onboard Battery Eliminator Circuit (BEC) of one of the speed controller. Below is the provided specification for the Arduino Nano.  It has 14 I/O pins which is more than enough control outputs for PWM purpose.  At $10 dollars each, the Nano is a good choice.

By Tuan Vo, Project Manager

The weight of the aircraft must be of proportion to the amount of thrust the propulsion components can support.  This resource reports defines resource as all components, power, and mass requirements related to the aircraft.

Study by Juan Montano on components and mass provides us with total mass when powered by 4 fans.  Note the structure mass is estimated based on a previous model hexacopter using all the same components except the Tinyduino controller and number of fans. Also at the time of writing this document, the two batteries are being shipped. 

Power resource: 

* The Arduino Nano, XBee, and IMU operates under 50mAh which is negligible considering the current draw of the fans is many thousand times larger.

Task Description 

• Receive parts from customer.
• Evaluate parts for functionality. Make lists of parts needed.
• Determine system requirements from mission objectives obtained from the customer.
• Establish model of the aircraft using 3D modelling.  Create major components needed such as fans, microcontroller, and power source.
• Write a Preliminary Design Document to give to customer to obtain funding.
• Purchase parts.  Work with programming the microcontroller and wireless communication device, XBee, while waiting for parts to arrive.
• Build a remote control device to receive user input and transmit via XBee to the microcontroller.
• Build the body of the aircraft.  Cut the foam for the middle section and mold carbon fiber for the top and bottom piece.  Cut out as necessary.
• Do systems tests that can be done without mounting the fans onto the body.
• Mount fans onto the body and carry out the rest of the system tests.
• Final adjustments to programming and structure based on tests.
• Final presentation to the customer.

Level 1 Requirements – By: Tuan Vo and Elaine Doan

1. The VTOL will be designed with a flat conical frustum base and a dome (semi-sphere) attached at the top center of the conical frustum to model after the UFO from the movie, The Day the Earth Stood Still.
   1. Compare the 3D drawing created by team to a picture of the UFO, approved by the customer.
2. The VTOL will fly once around the ECS 317 room (The room is measured to be 30 ft. wide and 23 ft. long. Assuming an oval flight path, distance to be travelled is 86.75 ft.)
   1. Test: Erect a perimeter with the same square dimension as room ECS 317.  Fly the VTOL aircraft around the inside perimeter one time.
3. For safety and to avoid contact with people, the VTOL aircraft will fly at minimum elevation of 8ft from the ground.
   1. Test: Use measuring tape to indicate on the wall where 8ft is. Achieve vertical takeoff and hover the machine at 8ft, indicated on the wall.  Control and move the VTOL aircraft around and make sure that the elevation remains at 8ft with deviation of 0.5 ft. or less for the duration of flight.
4. The VTOL will be controlled wirelessly from the minimum range 40 ft. (the distance from one wall to the opposite wall of the ECS 317 room).
   1. Test: Stand at one end of the ECS 317 classroom and wirelessly control the VTOL across the room to the opposite wall.