bump, bump, bumpin along

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atpfilms

Member
I've been trying to dial in my new build - rctimer x650 clone, rctimer 30A escs (simonK), 2814 motors, flysky, NAZA, 5000Mah 4S, and am having an issue. Here is the list of things I've done already - balanced multirotor, balanced props, reinforced crappy rctimer booms, calibrated ESC's to radio, used remote gains to try to find sweet spot.
Here is the issue I've been having. No matter what the gains are at, I get a bit of an erratic jump every half second to a second or so. If I set the gains higher, it seems to get worse. Its not like gain oscillation, but jumpier and more erratic. I'm beginning to suspect the ESC's as I've heard of others with problems with the RCTimer ESC's. Also felt the ESC's today after flying and they felt pretty hot. Anyone have any thoughts on this problem? I'd love to get this thing flying smoothly!
 

gtranquilla

gtranquilla

RadioActive
Need more info to answer your question..... What is your AUW - all up weight? Did you run your design thru eCalc for Multicopters? Motor startup current can be up to 200% of the normal running current..... eCalc will tell you if your ESCs are overloaded...... QUOTE=atpfilms;114227]I've been trying to dial in my new build - rctimer x650 clone, rctimer 30A escs (simonK), 2814 motors, flysky, NAZA, 5000Mah 4S, and am having an issue. Here is the list of things I've done already - balanced multirotor, balanced props, reinforced crappy rctimer booms, calibrated ESC's to radio, used remote gains to try to find sweet spot.
Here is the issue I've been having. No matter what the gains are at, I get a bit of an erratic jump every half second to a second or so. If I set the gains higher, it seems to get worse. Its not like gain oscillation, but jumpier and more erratic. I'm beginning to suspect the ESC's as I've heard of others with problems with the RCTimer ESC's. Also felt the ESC's today after flying and they felt pretty hot. Anyone have any thoughts on this problem? I'd love to get this thing flying smoothly![/QUOTE]
 

A

atpfilms

Member
Tranquilla - thanks for your response. I don't currently have a scale to weigh my copter, but based on the parts, I'm looking at around 1100 grams I think. The parts I came up with were similar to someone else's build. Thanks for the ecalc suggestion - I tried running the build through ecalc. It doesn't have my exact motors listed, so I did the best I could with the settings. Ecalc said the max power was over the max power limit of the motor based on the manufacturer's suggestion, but I'm not sure I had all of the settings right. re: the hot ESC's, I was doing a lot of gain adjusting, so I was starting and stopping the copter quite a bit. This could have worked the ESC's pretty hard. FYI, these are the motor's I've got...

http://www.rctimer.com/index.php?gOo=goods_details.dwt&goodsid=858&productname=
 

kloner

kloner

Aerial DP
the motors gotta be smooth, props dead on for everything to work right. a vibe will drag a motor rpm down and naza will feel it and show as a drop, can range froma dip to an iminent encounter with the ground. when you fly it, feel around just after for heat, that'll be the culprit. Sometimes you can see it in the prop, looks like theres two blades when it should all look like one. other times it's just a crappy bearing in a motor. Can be new and still suck
 

gtranquilla

gtranquilla

RadioActive
The more powerful the motor and the larger the prop.... the more any remaining vibes affect IMU sensors, electronics etc. (angular momentum). The motors needed to be balanced with the motor/prop adapters installed. I use ISeisomometer app for IPhone with gravity force enabled then focus attention on the x and y axis almost ignoring the downward z axis. Minimum vibe is when you can only see a stable low amplitude wave representing the bearing +- tolerance. More recently I eliminate the prop/motor adapter and mount the new carbon fiber props with the three holes directly on to the motor.... In the case of the Turnigy Multistar 420KV http://www.hobbyking.com/hobbyking/..._4830_420Kv_22Pole_Multi_Rotor_Outrunner.html they were so smooth I had nothing to balance....
 



gtranquilla

gtranquilla

RadioActive
Just watched the vid..... At first I thought those blue objects were two very large batteries!!!... but they are foam..... Most of your prop lift comes from the outer 3rd of the diameter and those foam blocks could contribute to inefficiencies etc. And there is a hill nearby.... You will get turbulence if flying on the lee side if there is much wind on the upwind side. Your control system is only as good as the sensors..... if baro sensor gets spoofed..... the controller will make decisions based on bad input data. The rest depends on other factors including PID loop tuning of the vertical baro control specifically.....
atpfilms said:
Thanks Kloner and Tranquilla. I'll look into the motors. Sounds like that's the most likely culprit. Took some video of what's going on...

http://youtu.be/YjvYnAfvSzM
Click to expand...
 

kloner

kloner

Aerial DP
it definately has a or a few vibrations going on. get a decent prop balancer and educate yourself on how to make them perfect, get some motors. if you crash, you can get sent back to this stage, willl want to learn how to recover and get it back, usually it involves money......
 

A

atpfilms

Member
Yeah, sorry, I came down a bit hard one time and broke one of my landing gear - waiting on a new one, hence the blue foam. I can confirm though, that the quad flew the same way with stock landing gear. I think part of the problem may be that I went with bigger motors and they didn't fit the mounts correctly, so I had to drill some holes. The holes are pretty darn close, but not exactly perfectly square on the mounts. The motors are solid on the mounts, however. I would assume this could cause the vibration? Basically, I didn't want to spend the $ to upgrade to sigma mounts (http://www.cnchelicopter.com/servlet/the-2276/xaircraft-x650-special-upgrade/Detail). Do you have a good recommendation for some different motors to try that would work for an rctimer x650 clone?
 

A

atpfilms

Member
Also, on a related note, in your opinions, how important is quality of ESC for smooth flying? I was a bit worried going with RCTimer parts.
 


A

atpfilms

Member
Benjamin Kenobi said:
How important is it for your craft to not fall out of the sky? I believe quality parts are worth it.
Click to expand...

Definitely agree; however, I was doing this build to learn to do a build, and now that I'm actually flying, I may want to upgrade parts if it will make it a smoother flight. Just curious as to what components are most important in smooth flight or is it really all more about balance and vibration?
 

gtranquilla

gtranquilla

RadioActive
I buy almost exclusively from Hong Kong and Singapore and have not been disappointed yet..... Motors, ESCs and batteries I buy from HobbyKing. Carbon fiber props and brushless gimbal systems I buy from RCTimer and from Germany. No real issues yet..... as far as I am concerned. Maybe be cautious with some of RCTimers parts and from GoodLuckBuy etc. Typically the DIY guys are risk takers and Asian parts help to keep the cost of your man cave spare parts and misordered parts cost down to a minimum. In some cases you can use and resell without taking as much of a hit as compared to buying from NA sources and Hobby shops.
atpfilms said:
Also, on a related note, in your opinions, how important is quality of ESC for smooth flying? I was a bit worried going with RCTimer parts.
Click to expand...
 

Benjamin Kenobi

Benjamin Kenobi

Easy? You call that easy?
In that case, vibration and balance are key. I've seen guys flying broomsticks with motors on perfectly because they balanced everything just right. I use DJI stuff so can't really take the high horse on quality (although I've found the quality great, others haven't).
 

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