As mentioned earlier I laid down the money for the Cinestar 3 axis gimbal from Freefly. I bought it from www.quadrocopter.com. The customer service was awesome and the shipping was scary fast. I ordered on a Monday morning and had the gimbal in my hand Thursday with USPS Priority Mail. I have been working with carbon fiber for the better part of 10 years, and I must say that the Cinestar gimbal is a work of art. The servos feel very smooth. I have yet to power them. The gimbal came separated in two boxes. One for the pan axis and the other box contained the roll / tilt axis. Assembling the two halves was very simple. www.freeflysystems.com has very good tutorial videos to guide the new Cinestar owner through all of the setup and assembly. So with that said I have not used the gimbal yet. In fact I just got around to making the parts I needed to complete it.
Today I cut the legs for the Cinestar Gimbal. At $210 for a set of landing gear I decided to build my own for much cheaper. After all I do know a guy who machines carbon all day.. I purchased some 25mm boom blocks from www.quadframe.us and began designing my new Cinestar landing legs. I had to have some sort of style in them so I opted for the WBD logo and gave them a bit of a curve. I tied them together at the bottom like the original Cinestar legs. See the pictures below for more details.
For a gimbal controller I decided to step out on a limb and try a multiwii based controller which is actually one of my Quadrino Zoom boards. At one time I had noticed in the multiwii code that there was an option to declare a gimbal. After some research about what exactly to edit in the code to get the desired effect I was after it was decided to test the board on my basic gopro gimbal I built a while back. If any of you are interested in the multiwii gimbal controller or would like me to post what I did exactly let me know. email@example.com . Anyways, I needed a way to properly mount the board to the frame and I also needed a battery tray for the main power battery. So the design for the combo fc mounting plate / battery tray was born. See the pictures below for more details.
Long ago my wife and I were going to do some aerial photography and due to FAA & FCC restrictions we were grounded. I had purchased a Canon A640 for that project after learning about the different controllers one could purchase to control most of the aspects of the camera such as zoom, shutter, video start/stop, etc. all from an RC radio. That camera has lasted me a very long time and I still use it. My A640 has been dropped, crashed, broken, repaired and is still kicking, taking great pictures. It was a no brainer for me on this project to choose a Canon DSLR. I chose the T2i for numerous reason. The two main being weight and price. I happened on this one for a very good price and could not pass it up. The T2i was used on one vacation then put back in the box then on a shelf. The camera is basically new.
For a radio to control the gimbal with I decided to stick with a Turnigy 9x modded like my current flight radio that has been solid as a rock since day one. Turnigy 9x / frsky DIY 2.4ghz module / smartie parts pogo board / ER9x firmware. Sounds like a ton of stuff but with all of that the radio is still under $100 and performs just as good as any of the other radio I have ever owned. The receivers use diversity and there is a wide variety of types. Telemetry via the receiver is also an option with the frsky system. ER9x is an open source firmware replacement for the 9X giving it much more flexibility.
By this point you have probably figured out the MonsterHex will be a two person operation. One pilot and one camera operator. The camera operator will have his/her own screen. The video will be transmitted to the camera operator via a 900mhz signal. More to come on that as the project continues. Check out the pictures below.
Last weekend was my first real time to fly the hex fpv. The wind was blowing very hard. If I had to guess I would say up to 25+ at times. However determination kicked in and I fpv’d the hex which to my surprise didn’t mind the wind too much. The video looked horrible but the machine was flyable. In preparation for the fpv I cut a new sonar mount, fpv camera mount system in the front and a simple battery tray for the rear. All but the battery tray is shown in the pics below, still need to take a picture of that. The fpv camera mount is home to the video transmitter, OSD (underneath) and the fpv camera. I wanted the unit easily removable and as a unit. The camera is my trusty Pixim Seawolf 690tvl camera. The best fpv camera I have used yet. It is a bit heavy but the picture is really good and it will shrink the sun when looking directly into the light. As for the Sonar I tried to keep in mind that it needed to be 3+ inches away from the main body. The wire that I have seen most people use was a standard servo type 3-wire cable. After some research on getting the most from my Sonar I leaned that the Sonar is very sensitive to emf interaction either to the Sonar itself or the cable carrying the data to the flight controller. I located a piece of shielded cable in the shop which is surplus from another project and used it for my Sonar. I soldered in a right angle header to the sonar board for a neat clean wiring job. For what its worth the sonar is absolutely rock solid and I couldn’t be happier with it. Using shielded cable is highly recommended. One other notable point is I checked the balance on my Graupner 14″ props. The Graupners are quickly becoming my favorite props but the set that I have definitely needed balancing. One of the six only needed balancing tape on the blade. All the rest needed quite a bit of work on the hubs and the blades. I did manage to get some more of the jello out of the video. The battery cables were vibrating off the back of the gopro case so I’m not real sure how much I eliminated. Next major change to the hex is a relocation of the power wires. Then I can get a better measurement on the removal of jello since nothing will be rattling around.
My buddy Drew and I flew yesterday for a while (video below) and I went back out today to do some more setup work on the hex. It was good yesterday but initiating rtl or loiter was quite a shaky affair. After some PID tuning last night today was a little better. Good enough to perform a ‘return to launch’ and then ‘auto land’. Both of which make me very nervous. As seen in the video below there is still some oscillations in loiter mode. However, in the flight controllers defense, the wind was blowing up to about 15mph at times and then down to nothing. I am going to edit the settings again in an attempt to achieve a shake free loiter. One thing I did learn was that there is a slight delay from when you invoke loiter to when the flight controller actually takes over. Once the switch is flipped, continue to hold position for a 3 count and your set. Before that I would flip the switch and the hex would wander away about 20′ then go back to the original location. After the three count procedure it never leaves the original location.
My minimosd really helped me feel more at ease on the auto land and return to launch today. Once I flipped the switch to return to launch and let go of the sticks (but still held the radio tight.. lol) and rode along via fpv keeping a close eye on the angle meter and altitude. The hex rose a little to meet the minimum altitude for RTL, promptly flew to the spot where I armed the flight controller and began to auto land. It did overshoot the target by about 20′. The PID’s need to be adjusted to slow it down a bit. When RTL kicked in the hex rose quickly and wasted no time going to the target. When it came time to auto land I watched the altitude slowly click off. The hex was descending nice and calm. I will admit about 3″ off the ground I jumped the gun and turned it off. The stick throttle stick was up just a touch which is why it popped back up. No harm no foul. Now I can set my fail safe to return to launch and know everything should be ok.
Pictures AJ Goin took of the hex last weekend.
Video 1. Stock PID’s for loiter, rtl and auto land.
“Video starts at 1:23. First attempt at loiter with stock PID settings 2:00-2:14. There is some wobble but its not too bad. The wind was blowing some. Return to launch starts at 3:05. The hex overshoots home at 3:22 and then is on the ground via auto land at 3:40. I turned the switch off upon landing but didn’t pull the stick down. At that point the hex jumped a little. Other than that the APM performed great. I did manage to tune the PID some more in a second video (which I will post in a bit) and got more of the wobbles out.”
Video 2. I edited the PID’s for a little better Loiter and did some hands off floating. lol
Ever since I built the Monster Hex I have only had it away from the shop once. I have never really flown it (as stated in a previous post) simply because it was too big for me to feasibly transport. Recently I made the decision to shorten the legs to make the diameter 32″ (center – center). That is approximately 10″ smaller in diameter.
Initial flights around the shop were good. I could feel a good improvement on overall feel of the hex. The craft didn’t seem as “floaty” as before. The feeling I got was that the hex wanted to be flown rather than floated. At that point I knew I had made the right decision and was anxious to get it to the field.
Flying the hex out in the open felt good. This thing needs room. The wind was blowing but not too bad. Gusts were up to 15mph so nothing too major. In the videos below where I was just floating, I was testing the position hold in the wind. From watching the video it looked as though the hex didn’t really move at all. That made me very happy. After all the initial payoff to the hex project is to be a full time camera ship. Steadiness like that in moderate gusts, with no flight controller tuning yet means that there is much potential in the monster hex. Tapping the throttle to between 1/2 and 3/4 throttle resulted in a very abrupt shot upward. This project just keeps getting better. Now that I can transport it, the hex will only continue to improve. Flying a hex is a very similar feel to a quad. For me the biggest difference was the wind handling and the overall smoothness of flight.
In the videos below there is some shaking. I decided the night before to fab a carbon fiber battery and video transmitter mount as well as a camera mount for the horyzon cam. I had full intentions of fpv’ing the hex. I also mounted the go pro directly above the horyzon. Admittedly there is a little vibration in the hex that I need to get to but nothing too bad. However, my awesome mounting idea resulted in the gopro mount and the top of the horyzon cam to vibrate off one another. The gopro vibrated some and produced the videos below. The video from the horyzon cam was not an option. I took off fpv, went 2 feet and landed.. So that will be fixed before the next flights for sure.
I was just trying to get the feel for the hex so I was taking it a bit cautious.
I felt a little more confident on this flight. Tried to fly with a little more altitude and let the hex stretch its legs a little. One thing that became apparent is that this hex has a lot of power and can eat up area very quick. At no point did I get over 3/4 throttle and anything close to 3/4 throttle was only there for a split second. The main reason for this was I have never stressed this airframe before and want to go thru everything to make sure all is good. Next videos will be FPV!
It has been a while since I posted an update on the hex project. I just haven’t flown it because I couldn’t transport it. At over 40″ diameter I couldn’t safely transport it in my truck. So I decided to trim it up a bit. The Monster Hex now sits at 32″ diameter center motor to center motor. The result was a much better flying and more agile machine. At the larger diameter it floated well but that was about it. Plus I was concerned about arm flex at that length. I plan on definitely flying it at the field this weekend and if things go well fpv’ing it. There should be some good video after this weekend if the weather / wind holds out. Click the image below for a bigger view then click that image for an even bigger view!