Not much space if you're going on holiday with the family in a Renault Clio. This design fits into a 52cm toolbox with transmitter and all accessories.
Just thought I'll share my crash resistant design that has evolved through many drops and repairs. On impact it is now usually just a matter of replacing a rivet or a prop. The electronics and battery can quickly be removed for installation on another airframe.
The props are 15" RC timers and as shown I get about 23min flight time with a slightly damaged 5000mAh 4cell Lipo at 1500m above sea level, 25 deg C.
The difference in spacing between front and rear props doesn't have a noticable effect on stability and it flies waypoints very well.
I'll post basic plans if anyone is interested or if you want an airframe let me know.
Update: Plans for the airframe
Comments
Here is a picture of the GSM/GPRS/GPS Tracker I use. Costs around $100 locally. I secure the battery cover with duct tape so it keeps on working after a crash. Weighs about 50g.
I just did my back yard maiden...flew good. As others said, it is quiet. I've got one prop that isn't tracking right...I'll work on that. I also seem to get a little bit of a fluttering sound when moves around in flight some...almost like some slop in the bearings(?)...could be related to the non-tracking prop too though. Weather permitting I'll take it to the park tomorrow for some PID tuning. I have a vacation coming up in a few more weeks and would really like to have it going good with gimbal installed so I can do some FPVing with it.
@Murray, Thanks for the infomation.
@MDRM, Thanks for the CG location. I had calculated about 12mm forward of the rear plate...I'll readjust for ~20mm. I was also thinking of longer rear arms and reduced sweep to get closer to a 'square' arrangement. This would certainly aid with the c/g after adding a gimbal and camera up front.
FWIW, I had my bottom rear plate cut so it's straight across at the back, with the upper plate as designed. I did this to allow for a rearmost mounting surface for the battery. I almost wish I just made the upper plate the same way to aid in component placement (Rx, lipo alarm, etc). Maybe V2 (if I opt to doing another frame) might incorporate that.
I don't think my magnetometer is defect as it flew waypoints perfectly for the first 8min, but want to try an external compass soon to see if it solves the problem. There are other options as well to experiment with such as adjusting the "compass weight" values (how much it relies on compass for navigation). First I'll just redo all calibrations and compassmot and see if the problem is still there.
@Lee: Longer rear arms sounds like a good idea. It will also give you more space to mount the batteries further aft. If I remember correctly then it is the power cables going to the ESC's that cause most interference, so it might not help to move them out. If you don't plan autonomous missions then interference shouldn't be a problem.
@Chris: The Black Mantra mentioned earlier in the blog seems nice, but has some limitations. If you are not in a hurry, I can consider making an extra frame for you when I build the next version.
Daniel,
I thought about the noise issue. I'm not running APM 3.x yet. I thought about putting the ESCs out on the arms for some cooling and keep the center area a little more noise free. For now I left the motor wires long, and put the ESCs in the bottom of the center section.
I did my first c/g check last night. Oops...even with two 4S 2650mAh packs on the back frame it's still a little nose heavy based off the 'half way' balance point. That's with a GP sitting up front...but I'll be adding a little more weight with a gimbal too. I think the rear arms could actually be longer to help make it a little wider distance between the rear motors and put a little more weight a little further back to help with balance.
I'm thinking of some possible mods for a V2 version by using HK Talon Tricopter folding arm mounts, slightly wider frame, and longer arms. I'll get a good try out with the current version first to see if 'improvements' are worth a try or not.
I like the idea of mu-metal, but it will probably interfere with Earth's mag field. I think you're better off buying the $15 external mag module. Then consider having it on a boom above the frame.
@Murray: Is your Magnetometer defect, or is this a normal problem with these devices?
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