The Crossfire 2 is here. Everything you loved about the original but simpler, stronger and easier to build. The original Crossfire has been out in the wild and flying for about a year now and I couldn't be more happy with the interest in this project. Special thanks are in order to all those who printed, tested, flew and remixed this thing. The open source community is incredible and I am proud to share the Crossfire 2 with you. As always please print, fly and enjoy. Feedback, makes and remixes are always appreciated. If you like my designs a small donation is greatly appreciated, it allows me to keep posting cool things!
Check out this video for some motivation. https://vimeo.com/79370836
So what is new with the Crossfire 2? In general, a lot! It looks like the same ol' Crossfire but its not. I took a lot of feedback on improving the design and I believe I have addressed the major ones.
-The Arms: The arms landing gear on the old crossfire was weak. I designed it to be light but it ended up being too brittle. The new arms have been beefed up and strengthened in the weakest areas. It is still very light and I believe it now to be the perfect mix of strength to weight. Also the arms have been designed to have M3 lock nuts press fit in. This standardizes the hardware for the quadcopter and allows easy attachment of the arms. It also allows to top or bottom plates to be easily removed allowing access to the center of the frame.
-The frame: As mentioned above the Crossfire 2 has been standardized to M3 hardware. The frame has also been modified to receive any type of flight controller. The standard flight controllers (KK Blackboard, KK2.1) can now be mounted directly to the frame in either 45 deg. or orthogonal orientation. On top of that the Crossfire is designed to be optimized for the APM controller by mounting to the frame via vibration dampening bushings. Using this setup, without any balancing of the props whatsoever give more than adequate vibration dampening. See attached graph, vibrations are roughly half of what 3DR says are tolerances. The frame has been standardized to the vibration dampening camera mount system. Everyone is mounting cameras to their quads these days even if they are not FPV and this is definitely the best way to go to get clean video. Lastly I have added extra holes in the frame to accommodate easier wire routing depending on your setup. Also there are new standoff holes to mount the top cover.
-The Top Cover: The top cover has been modified to mount the APM 2.6's GPS/Compass module.
Update 2/23/14: I have uploaded the .SKP files for those who want to remix the design.
Update 2/13/14: I have added links in the instructions for an explanation on motor kv and a calculator to help run some numbers on motor and prop combinations. A lot of people have been asking about this, and its still a bit of a mystery to me even after building a bunch of multicopters. I hope this helps.
Update 2/1/14: I have added batter strap slots to the Bottom Plate for battery straps. If you are not planning on having a camera or vibration dampening battery tray you can now strap your battery directly to the Bottom Plate.
See the attached PDF for a build log and instructions.
At the infill settings I've published the frame weighs 400 grams with everything. Thats the 4 arms, the hardware, the Top and Bottom Plates, the Top Cover and the Battery Tray along with the vibration dampening bushings. The arms weigh 38 grams, so thats about 12 grams lighter than the DJI arms. The whole frame together weighs 400 which is 120 grams heavier than the DJI Flamewheel but they don't take into account the hardware weight to put everything together. Those numbers along with the weight of all your equipment will decide what motors, props and ESCs you go with. The one pictured weighs 1700 grams (GoPro3, gimbal, brushless motors, props, FPV equipment, APM and a 4000 may battery.
Arms: So far there are two arms uploaded.
ArmTall3H - Standard re-enforced arm with a tall leg and 3 hole mounts for the motor.
ArmTall4H - Standard re-enforced arm with a tall leg and 4 hole (16x19mm) mounts for motor.
For the Vibration Dampening Battery Trays see thing here, there are 4 different options to suit your needs. http://www.thingiverse.com/thing:239594
Here are a couple links that explain motor kv and a calculator to help with choosing the right electronics and prop combinations.