Finally got the time to finish my quad and (attempt to) fly it! It's my first quad. and I went a little different with the setup (see specs below) to try and see if I could push the propulsive efficiency up a bit and have more power on tap for heavier payloads down the line. My static tests indicated that this is the case, but we'll see if it was worth the effort after some more flying :)
Setup:
APM 2.0
3DR Frame
DT750kv motors
Turnigy 25amp Plush ESCs
12x3.8 SF APC props
Turnigy 4000mah 3s 30-40c
Hitec Aurora 9
TOGW = 1420 grams
See current tuning:
Video of best flight (i.e. didn't flip over or hit a tree)
Positives:
1) It flew!
2) Somewhat stable..
3) No damage besides mostly superficial prop scuffing and small chip at one prop tip. 3DR frame seems pretty darn solid. I tried to take it easy
Issues:
1) Even though i triple checked the wiring (albeit, I did not do the complete pre-flight check.. shame on me) I seem to have motors reversed. It rolls the way I expect it to - Left stick = left, right stick = right; but it pitches opposite - Fwd stick = reverse flight, Backwards stick = forward flight. Can this simply be fixed by reversing my throttle command on my transmitter? My first though it that this will work with the stablized mode, but any other mode will not be corrected. Or is this the standard way to fly a quad?
Note: just checked PBD wiring again and it's correct according to these instructions. Still not sure why it pitches opposite of what i am expecting.
2) As you can see in the videos the quad tends to drift (all of my flying was done in "stable mode") in various directions. I also see some oscillations. Tuning advice?
3) On a few occasions after a hard landing, the quad would flip it's and max throttle the motors attempting to right itself for a few seconds (hence the prop scuffing). Is this common? Gentler landings did not seem to cause this problem.
One note: besides some R/C planes and one of those small, stabilized RC helis I have not flown anything like this. I am sure that some of the issues are pilot error which will only improve with more time.
I am going to attempt to fly it again tomorrow, but will probably try to find a bigger area.. with grass.
Thanks!
Jonathan
Comments
Update:
After some frustrating issues that I troubleshooted with help from a few of the guys at 3DR, I got a bit more flying/tuning time in with my quad.
**** SIDEBAR ****
The guys are 3DR rock! Alan gave me a quick tour and showed me some of the new products they are working on (looking forward to 2012!). Jordi helped my troubleshoot my APM, which turns out may have been a battery or soldering issue on the PDB (my fault). Great visit and I get to add one more reason why I love living in San Diego :)
**** END SIDEBAR****
I have tried a few different prop combinations since my first effort, and I believe that I have settled (at least for now) on 12x3.8 SF props "chopped" to 11" with the thought of unloading the motors a bit. I will most likely go back to 12x3.8 once i break my current setup.
I also added some foam to the bottom of the APM to damp some of the vibes. Not really sure if it's helping at the moment.
Lowered the roll and pitch rates, which definitely seemed to ride some of the wobbles. Still have wobbles in descent (up the Stab Pitch I term?)
Didn't get to try much of alt hold, but when I did use it, it seemed to work for a little while then would start to oscillate up and down.
Also, my quad tends to drift in stabilize mode, and it seems as if I am always trying to provide corrections. Any suggestions to improve this or is this the norm? You can kind of see this exhibited in the video.
(Don't mind the kids.. I corrected them earlier when they thought it was a plane :))
I have had a few more tests since with varying success. Quad has completely flipped while trying to pitch or roll. I think this was a combo of bent motor mounts from previous crashes. Spent a few hours fixing and modifying after this including chopping my props to 11" to test the difference out. Quad flies well like this with some wobbles because of funky I believe. Last flight tested alt hold which works well and tried to tune pitch rate with ch6. This quad definitely like low values because as I incremented up the quad became unstable and flipped. Broke a prop and some spacers. Need to get more prior to my next test
What's new? Have you managed woobling?
Hi Jonathan!!
About those flips after hard landings, I also have experienced something like that and damaged some motor shafts :\ I am also a noob in this quad flying stuff :D but I am learning..
I talked with a friend and he told me to not use the ESC's 5V, instead use a 5V BEC and to check my trim values. It worked for me!
How are you powering your APM?
Regards AS
I have hexa with same motors.http://www.rcalbum.com/index.php?action=dtl&amode=&id=6313 First I used 10x4.7APC props with good results. A also flew with 12x3.8 APC and I had same problem with wobbling, I think these props are too heavy and there is problem with fast reaction.One this prop is cca 17g heavy, instead of 11g for 10x4.7. My fried has on DT750 these props http://www.mejzlik.eu/multicopter-propellers/, he is very satisfied.
Thanks for the suggestions guys. I will first try reversing the channel and seeing what happens.
I probably will try smaller props if I can't tune out the wobble, but I lose my efficiency and T/W advantages if I do.
Will report back tomorrow :)
I second Alan's suggestion. Your PDB sounds fine or else it would be rolling constantly. Just reverse the RC channel and it will fly as you expect.
Safe crashing ... Er, I mean flying :).
Hey Jon! Glad to see you got it flying. About the reversed pitch, I usually have to flip both my pitch and yaw in the stock settings for my spektrum radio. So if you flip the pitch you should be all good. Instructions for the PDB should not have changed, but ill look them over.
It seems that its doing some agressive recovering, tuning can help but not sure if maybe it was pilot error like you said and you were correcting strongly. Flying the quad is all tiny smooth inputs.
About it flipping, I have never had anything like that happen on hard landings. But if you bring it by when you come visit we can take it for a spin. A tip for tomorrow when youre flying over grass, careful when the quad bounces on the ground (if it does), the legs sometimes get caught in the grass and will flip over the quad. If you feel that happening, just kill the throttle. Good luck tomorrow :)
I think the boards have changed since those instructions. Might be worth trying to swap the front and back motors. I've pinged the 3DR team to see if the instructions need to be updated.