I have built balsa R/C planes back as far as the 1960’s. But did not get interested in MultiRotor UAVs until just a few months ago. Looking at my options, I decided to purchase a 3D ROBOTICS QUAD KIT. The 3DR QUAD KIT seemed to be the best airborne platform for the remote data acquisition and the teaching of flight kinematics that will be part of a DRONE 101 course I am developing.
With some fear and trepidation, I began to assemble my “BIRD” ( which I named DERVA ). As the build progressed I made some observations and made a few changes to make DERVA my own. The following is a set of comments on these efforts. I am submitting them to solicit comments from other 3DR QUAD builders. As of mid-October 2015 I have not installed my SPEKTRUM AR9020 receiver, telemetry, flight log modules and the solderless breadboard I plan to use for prototyping. One last comment about my AR-9020 concerns its antenna placement. I plan on using a spiral plastic book binding comb to keep the antenna vertical.
Nylon-centered stop nuts ( NYLOCKS ) were NOT included. I bought these from my local hardware store.
Why do the nuts have a black phosphate finish while the screws / bolts do not ? You should also consider replacing the PHILLIPS SCREWS / BOLTS with ALLEN-HEAD SCREWS / BOLTS.
The DEANS CONNECTORS were already soldered in place so no soldering was necessary. These connectors had slightly bent pins so I had to pry things a bit to get them to plug in to the POWER DISTRIBUTION BOARD.
Before attaching the motors to the carbon fiber plate that is secured to the arms, the screw immediately under the place where the three wires exit the motor case should be inserted. Putting this particular screw “in” is difficult once the motor is attached to the arm.
PAGE 9 shows three VELCRO strips, but the words talk about only TWO.
PAGE 10 has the BLUE ARMS shown on the “stubby” side of the frame plate and the BLACK ARMS on the “elongated” side; which is correct. However, the second sketch showing motor rotation has the BLUE ARMS on the “elongated” side and the BLACK ARMS on the “stubby” side !!
I don't like the fact that the POWER DISTRIBUTION BOARD is just laid in place ! It should be insulated AND secured somehow.
Mounting the GPS mast is a bit confusing. There is talk of the “SHORT SIDE”. Why not just talk of the side that has the notch for the connectors on the GPS ?
The MICRO SD card came pre-installed into the PIXHAWK.
I added 6.5mm BRASS STANDOFFS to raise the ACCESSORY PLATE a bit higher to make it easier to add or remove connectors after the kit build is completed.
I moved the legs out farther on the arms ( all the way to the motors ) to give the QUAD a wider stance and hence a bit more stability.
PAGE 21 talks about and has a link called Y6-KIT. I thought I was building a QUAD ? This page should also have links to the software to be downloaded.
I found that two of the four propellers supplied were unbalanced. You should include information and instructions on propeller balancing.
PAGE 22 shows a reversed orientation of the arms on the main frame; AGAIN.
Replies
Regarding the supplied hardware & instructions... Well Drone kit manufacturers don't hold a candle to R/C airplane kit manufacturers, not by a mile.
I bought the previous version of the quad kit several years ago & it came with no paperwork. oh i did get a sticker :D
I see that the centre plates have been greatly improved, the one that I had was horribly cramped.
If the legs are still made out of fibre glass plate then beware, they can easily break. I doubled-up the legs on mine and added thicker spacers between the legs at every hole.
The R/C RX: I have a spektrum AR9020 & I don't think it has a PPM output, in fact I've been waiting for years for Spektrum to make one with PPM output.
The Pixhawk requires a R/C receiver with PPM or SBUS output or one can connect a spektum satelite RX. [make sure to bind the satelite while attached to the 9020 RX with the TX before connecting it to the Pixhawk]
The square arm-tubes will deform easily from over tightening, I had use internal spacers... a real PIA that was. Maybe the arm 'fixturing' has improved.
On the quad I had , the motor wires exited the arm-tubes at the very end and they were prone to being damaged, I used four layers of adhesive lined heat-shrink tube for safety. Hopefully this too has been improved.
Do read the online Arducopter manual . It's loaded with information, and just about everyone on this site will be more than willing to help with any questions that you may have.
Regards
chris