High School Project: My Entrance Into the Hobby

A Little Background:

It has taken me quite a long time to finally sit down and write an article for this project. With the formal completion of the project at the end of May 2014, the modifications and improvements made the following summer, and my entrance into college, I have not felt ready to conclude the project until now. The majority of the build embodied in this article took place during the month of May, the rest taking place over the summer. It includes thoughts and learning gained from the perspective of a first time multirotor flyer and scratch builder.

The purpose of this project was to fulfill my high school senior project. The senior project is an optional course only available to seniors in high school that allows you to investigate any idea you want as long as you present your results to a panel at the end. I took on my project after developing an obsession with multirotors, having no build experience, and having only a few hours of real life RC plane flying experience (hundreds more on a sim). As you will see, the project veered off course for a number of reasons. Despite this the project was wildly applauded by both teachers and school directors. Most importantly it sparked one of my biggest passions today.

Original Project Goals:

-Construct a basic quadcopter and learn to fly
-Contruct and calibrate a brushless camera gimbal
-Film aerial video of various locations with the gimbal
-Develop autonomous (waypoint) flight
-Test out other quadcopter abilities (flips, lifts, etc)

The Build:

In the months leading up to the project start I made designs in Sketchup and renderings in Kerkythea:

 Quadcopter Parts List:

- 4X DT750 Motor

- Q-Brain 4X ESC

- Multiwii Pro with GPS

- 915MHz telemetry

- Turnigy 9X TX/RX

- 2200 mAh Lipo

- 1045 and 1147 Props

Gimbal Parts List:

- 2804-210Kv Brushless Gimbal Motor

- 2206-140Kv Brushless Gimbal Motor

- 2-axis Brushless Camera Gimbal Controller

The frame is built out of ½” square poplar dowels from the hardware store and 1/8” plywood. It is based on the Hobbyking X666 frame with portability and style in mind. I designed the frame to have the smallest main plate area as possible, but to still be able to fold together. I settled on a 4.5" square plate in the middle and 12" arms. The landing gear was cut by hand out of plywood using templates made in Sketchup. For the paint job, I decided to paint two arms black and two white to aid orientation. I had enough wood for two extra arms which were painted red to signify if an arm was replaced. Two coats of paint with sanding in between and it the wood looked like aluminum or plastic.

After completing the frame the project started to go south. I had two orders of electronics from Hobbyking, one of which went missing after leaving Hong Kong, the other refusing to be shipped from the US. To make use of the time I began work on the camera gimbal. The gimbal is made out of wood and is designed to be adjustable along three points to allow for balancing. I tried to make it as small as possible while still being able to hold a point and shoot camera. The gimbal was ready for electronics now as well, but the shipments were no were to be found.

 After almost one and a half months of waiting and lost project time, my electronics from HK's US warehouse arrived, the international shipment still missing. I had lost more than half the time allowed for my senior project waiting for parts that should have been there day one. It was time to jump in head first.

I first spent a good amount of time navigating the learning curve that is the Multiwii Pro, but eventually I got it configured for flight. The international shipment finally arrived, crushed as if someone sat on it. Luckily everything inside was completely unharmed, providing me the final parts required to get my build in the air.

All the electronics where mounted to the frame and the quadcopter was ready for its maiden. The first few flights were very short and nerveracking. For reasons I still can’t explain, the battery heated up significantly and one of the cells died. It was clear that the copter required some PID tuning. Days past as I continued to tune flight PIDs, level PIDs, and position hold PIDs. At the same time the gimbal was built and tuned to an acceptable state. Finally the gimbal and quadcopter were ready to be united.

To mount the gimbal on the quad I built custom landing retracts for clearance. This made the copter incredibly heavy and difficult to take off, but it was possible. Here is where disaster struck. I brought the build to my school on the weekend in hopes of obtaining my first stabilized aerial footage. I was excited and did not realize the extent of the winds that day. After takeoff the legs retracted and the camera was running smoothly. Suddenly the wind picked up and my quadcopter was pushed back behind me. Either a rising column of air or some PID issues pulled the copter up 20ft higher. Despite my best efforts to land the quad, the whole set up crashed headfirst into the cement at a reasonable speed. The wreckage was disheartening, parts were strung about in places parts should not be, and all of this happening the day before the project due date.

Upon further inspection at home, the basic quadcopter was up and flying again in 10 minutes. The gimbal had broken along easily repaired glue joints and the legs required a new central plate. All together I had the whole system repaired for my big presentation the next day. I attribute all this to aspects Flite Test uses in their multirotors, such as break away motor mounts and easily replaced wooden parts.

After this ordeal my presentation went to plan and my high school was truly impressed by the work I had done. Unfortunately I did not achieve any autonomous flight or get any aerial footage. The reasons were painfully obvious, I was a fairly unskilled pilot, I did not have enough time considering my skills, and the quadcopter was overly complex.

 The new plan was to ditch the point and shoot size gimbal, remove the retractable landing gear, and move up to 1147 props. The new gimbal was constructed out of two ply plexiglass bent into ninety degree angles with a candle. It is designed to carry a light GoPro, saving as much weight is possible. It was mounted directly on the front of the main body and required no extra modification to the copter. The 1147 props required some tuning, but resulted in a smoother, more stable machine. It was this setup that I filmed this final video on, and it is this gimbal that would move on to be on my newest aerial platform.  

Conclusion:

Although it did not go entirely to plan, this project was an amazing experience. I took on the challenge as a school project and with my limited time I think I was able to achieve quite a bit. I was able to get aerial footage, albeit not very stable footage, and position hold working. Perhaps the biggest lesson is this. Entering the multirotor hobby through scratch building may be a tiring, frustrating, trial and error process, but it is worth it. The amount of information and skills I learned through my successes and failures is invaluable, and will surely benefit me more in future builds then buying a commercial product would have. My senior project may have concluded, but my participation in this hobby is just beginning.

If you read this or just looked at the pictures, thank you.

-Sam

Click here for the original build log