Something is wrong with my copter build

Thanks for putting all that together for me.
@ $56 these Arris motors stay in my budget.

Dont jump just quite yet! Look around! get comfortable reading the motor test data. You could probably find cheaper. That was just a quick google.

I like SunnySky motors. Try the “V” series or the “XS” series:


Or Dualsky motors. They have a new “HD” series that look promising:
http://shop.dualsky.com/c/hd-motor-for-multi-copter_0378

All of the above are high quality.

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I wonder if everyone suggesting too much power has actually tried flying copters w/ huge power to weight ratios? I’ve been flying 250mm and smaller copters for several years now which all hover at about .12-.15% throttle. They all perform great. Yes, there is an explosion of power above hover level, but that’s what I’m going for on these small copters. But, my point is, I fly auto missions w/ them, I fly in stab and loiter and various other modes. Powerful copters are definitely workable. It did take me a year of daily flying to train my thumbs and have very good control in stabilize. But no problems at all in alt-hold or auto missions…
I’d be looking for other issues, besides only having more power than necessary.

Did the OP every mention exactly what the issue is? I just see that “throttle is too hard to control”. What exactly is happening? Does it oscillate or not maintain altitude properly or what? And in what mode? Stab or alt-hold?

@wicked1 This is interesting, I would like to figure this out. I have several arducopter quads flying & used to fly 3d planes & copters so have no doubt about my skill on the tx. What happens in flight is zero altitude control. The 2 drops this copter had were level flights but I could not control the throttle. When I tried to stop the climbs the copter just fell. I was in stab mode & only let it go up 3-4 meters.
I am looking into my motors and esc’s as the issue.

A bit hard to pick anything consistent from a 2s flight.
But I was wondering why your parameters are so far from default?
eg: your ATC_RAT_PIT_FILT and ATC_RAT_RLL_FILT are set to 2.
I would have thought reducing them to 10 would have been sufficient.
Your motors just don’t run up together


Since posting this have you calibrated the ESC’s?
I would do that before anything, then look at restoring default parameters and doing slight adjustments in line with the new tuning page in the Wiki.

As @wicked1 points out, being massively overpowered is not always a limitation, it depends on the tune.
Here is an example and it flew very well https://www.youtube.com/watch?v=0BCkBj9tC88

Just a thought, have you tried reducing the amount of rocks in that bucket until it can just get off the ground?
It might give us a useable log file we draw some conclusions from.
I would however do the above recommendations first.

The motors aren’t spinning up together because the drone is strapped to a bucket and the I-terms are building up as it tries to stabilize. Need a log of a real flight to make any determinations.

You might want to enable motor interlock, too. That will keep the motors spinning and keep the copter somewhat stabilized even if you put the throttle to zero. Otherwise, it will completely stop spinning the motors, and with big props, it might not be able to spin them back up very quickly when you give it some throttle again.

And I agree w/ Mr Boland about your filters… Put them back up to 10. And his suggestion about lifting the bucket or adding a lot of weight to it another way might be a good way to be able to get a log. If you’re afraid of a flyaway, strap a brick to the copter to try to get a hover log, and still leave it tethered to the bucket in case it tries to fly away.

I have an old F330 frame that is basically a rocket. i cant remember since it is very old (like APM2.6 old - still flies great!), but it must have a thrust ratio of ~3.5.

However, a 250-350 size copter has much smaller props and a way smaller moment of inertia in every axis. Thrust to weight ratio has a smaller impact on on a smaller copter. We cant compare that to a 550, 600 size with 2x the propeller length.

Do you seriously believe that 15" props on 750kv motors and 6s is a reasonable power setup? for 2.2kg?!

I just went over your post where you mentioned a vertical flyaway.
The usual culprit is vibration.
looking at the short end clip of the last log (10.BIN) I notice your VIBES shot up to 90 with massive clipping.


I realise you are testing and it was not a real flight.
This is why getting it into the air so we can have a look at a hover log will help greatly.

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2019-06-26 17-34-45.bin (471.1 KB)
I found one of the flight logs.

Yes, this log is quite telling.

It flies away because it has too much power:

The motors are bottoming out, and the drone climbs even though its desired climb rate is negative. The throttle level is pegged at 0% (not shown).

One thing that is very important for overpowered copters is to tune your minimum throttle settings. By default, MOT_SPIN_ARM is 10% and MOT_SPIN_MIN is 15%. This means that your motors cannot go below 15% throttle in flight, which is clearly needed for your situation.

Tune these params by progressively lowering MOT_SPIN_ARM until you reach the lowest value where the motors reliably spin up every time. Then, you can set MOT_SPIN_MIN to the same value. This will free up some room on the motors’ bottom end.

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So the 700kV motors are not the best choice but wouldn’t a larger heavier 6S battery put a band-aid on the problem? I had a light weight quad of similar configuration with 3508 380kV motors and used a 6S 8000mah battery.

I have tried flying a larger over powered quad (1000+mm, 5010-350Kv, 1755CFs on 6S, and it was F’n dangerous. It hovered just a tad above 25% throttle, landings were a challenge, and AutoTune puked all over itself. I wised up. I shortened the arms to 660mm, dropped down to 1655 props, and hung a 3 axis gimbal w/a GoPro on it and now it is a real joy to fly.

I have 3 other aircraft with Pixkawks. One is a Tarot 680 Pro Hex with 4006-740Kv motors swinging 1355s on 4S, one is an H4 Alien 680mm Quad with 5010-530Kv motors swinging Tarot 1552 folding props on 4S, and the last one is a 500mm quad with 2814-710 Kv motors swinging Sail 1344 wood props on 4S. I have a 250 Nighthawk clone racer with an Omnibus F4 running iNav, a Tyro 79 3" racer running Betaflight, and a BoldClash B-03 BWhoop Pro. I also have 2 450 helis, so I think I know a thing or 12 about power systems.

The OP’s aircraft is SEVERLY OVER POWERED AND IT IS UNSAFE TO FLY.

The primary issue is running 700Kv motors swinging 15" props on 6S

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00000016.BIN (279.3 KB)
@mboland
I tried to fly the bucket as suggested. The TOW was 5KG. I lowered the props to 13x5.5"

The bucket flew away instantly after takeoff. I lowered the throttle to 0 and the bucket kept going up. I was in stab mode. Quite a sight actually. Lucky it just hit a house
Vibes with the bucket attached went very high & lots of clipping. I guess because of the prop overlapping the bucket hole. This probably caused the flyaway but could you confirm please.
I give up on these motors and will look into some of the motors @ekliptiko suggested. Lesson learned 3 bent frames and 1 busted F9P.
5010 -6s - 750 KV is not a good fit.

Are you sure you’re in stab? I can’t think of any situation where zero throttle wouldn’t stop the motors (or put them to mot_spin_min) in stab. Other than a bad transmitter calibration. All the issues w/ barometer and vibrations, etc, shouldn’t matter in Stabilize. (This comment is also for my own benefit… because if I’m wrong I’d love to hear why and am sure someone will tell us)
I’m not trying to discourage you from getting different motors and agree w/ everyone else they’re an issue.

A motor/prop pair that I love for 6S packs is the Hobbyking Multistar 4822-390 kV coupled with a 15x5.5 S800-style carbon prop. Granted, I have some very old motors, from the start of the Multistar sub-brand, and they actually looked like rebranded HengLi, but they, and the installed bearings, withstood the test of time, and give some serious performance for cheap.

Otherwise, if you can afford T-Motor, their MN4012-11 400 kV with either 15x5 or 16x5.4 are good combo.

[LE] @wicked1 if your bird is lighter then the thrust your drivetrain produces at MIN_THR, it will climb with RC throttle at zero.

Yes I was in stab I looked at my log.
My max throttle was raised only to 1150 then lowered.
The bucket as shown flew away & hit the neighbors (renters, thank a higher power) roof.
I had no intention of flying like this above liftoff.
see RCIN.C3

Well that’s true… His copter must be overpowered to a level I can’t quite comprehend :). And like I said earlier in the thread, my daily flyer hovers at .12%.
He can tune the related parameters… mot_spin_min, mot_spin_arm, thr_min, etc… All motors will have a level of moving the props but not producing any thrust.
But if he’s getting new motors, no need to go in to all of that.

It’s not so much the overpowered copter as the vibrations.
Massive vibrations which are inevitably going to cause uncontrolled vertical gain die to the stability overpowering the FC’s prime directive.

Although you are using a much larger range of output to the motors, you can see it is still bottoming out trying maintain stability through all that vibration.

1: Have you calibrated the ESC’s? As motor 4 seems to be more reactive than the others.
2: The vibration is the problem you are chasing.
How have you mounted the FC?
Source and quality of the CF tubes used?
Just how much flex does the frame have under load?

Looking at the desired to actual I note that the yaw goes in opposite directions but it doesn’t take long for the others to depart.

Aside from the vibration, I was just looking closely at your build, and assuming the orange anodised connectors are the front, I noticed your blades are reversed.
That won’t help.

Your desired to actual seem to go in opposite directions, so apart from the blades, is the FC mounted correctly and directions and offsets correct?

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Thanks for looking at that.
Orange is right gray left. Props are correctly rotating, it was assembled like this to make frame repairs. The same frame,FC & mounts flying very well on other builds and I can’t really make any vibration determination flying with a trash can. The vibe levels are much lower in the other log files.

The ESC’s are BLHELI_S I do not know if this is a problem. These are new to me and I have not tried them before. I ran through esc calibrations with each battery change 6s-4s. It seemed to react fine without props.