Trex 700 heli shaking

The Heli is flying sideways as-well. Camera is aimed to the Region Of Interest. You can set that up (ROI) in a mission with Mission Planner.

Bill, I totally agree with you regarding PSC_VELXY_D to have that not at 0.
I use on my 700 =0.28 and on my 600 =0.25.
Now both are doing a perfect Loiter what both did not do with the value 0.

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Well that is very kind of you. I hope you guys figure it out.

ok the verdict is … maybe. So i took my zip tie that was holding the v3x to the jello plate off and put it around the entire jello plate. so that removes that from the equation. I took my pitch gauge leveled the main shaft. the checked the blades. i rotated them as i was checking the servo to swash level. both blades are the same pitch all the way around. maybe .1 pitch variation total. i lost light to do a hover to check tracking. still had minor vibration on spool up. I noticed the radio say sensor lost when spooling up. i dont know if that was bad timing or the vibe caused a problem. the radio says that from time to time. i have read other peoples have the same issue. The flight took of fine. looked like it could have been going 22 mph thats where i had it set at .the flight was mostly smooth not drunken like before. on second pass back the it looked like it slowed down. i set all spline waypoints. it was done with the flight when it finally said 3 across the radio. so still a lag from something. when i armed the heli the yaapu said 25.1 volts after take off and switching into auto the radio said 23.3 volts and never changed during the flight. i took out of auto to loiter and flew it a 100 feet. it shook on forward flight for a moment. then it smoothed out. when i landed it in stabilize batterys were below 23 volt radio still said 23.3 volt. only after i disarmed did the radio correct the voltage. I had the ground control radio unhooked after setting the flight path.
No Wind to speak of mabey a breeze tail and head wind at 70 ft.
With no ground control i have no tlog

Other changes i raised the yaw input from 15 to 40. and the rate stops i zeroed out.
I did a full calibration of gps and accelerometer and level horizion.

could these old servos on the swash cause some of this if they are not responding like they should or if a vibration is causing them to react wrong. when i was adjusting servo 2 the servo did not respond one time i touched it and it worked fine after. ???

My radio ground control was purchased from these guys. In Texas. Hope that helps.

https://www.helibatics.com/pilot-500mw-telemetry-transceiver-for-pixhawk-apm-ardupilot-mega-multiwii-aio-915mhz/

Looks like servo 1 was still dancing. Now servo 1 is a different servo from the other 2. We burnt a servo we placed blame on the blade holder being on when the heli got plugged in but that was servo 3 so we took servo 1 and put it in 3. Then I found the specs speed and pressure and found a servo that was as just as fast but stronger. That one went in servo 1. The signal from rc out is from the v3x right or does it have to get some info from the servo. I am under the understanding the v3x sends signal down the line. That happens few months ago.

Also I see it went into failsafe landing when I was in loiter. Radio did not say a thing. Good thing I was already in the process of landing it.

It’s registering a little higher vibration now with the mount tied down. But nothing drastic and no clipping at all. Definite improvement in the position controller. Looks like it tracked the GPS course pretty much dead on this time.

Are you gonna plug in that radio and try it again?

It was actually at ~10kts, not 20. But it looks like the turn from 2 to 3 is pretty sharp. And it must be only about 200 feet from 3 to 4. Due to the way the nav controller works it might not get going much faster than that so it can make the corners within the accel limits. You’d have to give it bit more room like maybe 400-500 feet to see if it gets to 20kts in auto. But as weak as the battery is in that helicopter that might not be a good idea because it doesn’t look like it’s going to go very far until you put bigger fuel tanks on it.

Yeah, servo1 is still bouncing around but bounces opposite servo 2 when everything is fairly static as far as attitude

image

And now, can actually see what the frame is doing. You have slightly higher vibes in Y-axis than X

image

But the y-axis is a bit excessive and that is the axis that rotor balance and tracking issues show up on. Checking the blade pitch static on the bench for tracking is a good setup practice. But they rarely fly that way when they’re producing lift. Seeing that knife edge on the rotor disc in static hover is good but doesn’t always yield the best vibration characteristics. This is where the DynaVibe comes in handy. We’ll some track the rotor on Jet Rangers so one blade is sometimes flying higher than the other to get lowest vibration in static hover. Then take it out and cruise it at 100kts and see what we get. Sometimes have to adjust the pitch links for cruise to lower the vibration in cruise flight after adjusting it in static hover. But the DynaVibe has a strobe and the blades are numbered so we know exactly which blade is causing the problem.

Your RC heli is no different. And the controller has a sort of DynaVibe built into it with the IMU vibration measurement. You were hiding this from yourself with that jello plate. Now you can see it. So what I do when I can’t wangle the DynaVibe is mark one blade holder with a marker so you always adjust the same one. Hover it and look in your ground station at the vibe messages. Land it and turn the pitch link on that marked blade one way or the other. Re-hover it and observe the disc tracking visually, as well as what it says on the GCS. If it gets worse, turn the pitch link the other way and try it again. Before I found out we could use the DynaVibe on RC heli’s I have spent 6 hours before tuning and tracking the rotor on my RC heli’s to get both x and y below 8-10.

Another source is the transmission gears. Check the backlash all the way around on the main gear and see how much radial and axial runout it has. Align is horrible for this because of the way that gear mounts on their very poor autorotation clutch. So sometimes it’s just about impossible to get rid of that geartrain vibration in an Align without replacing all the parts from a higher-quality helicopter that has a brass bushed over-running clutch.

Sure, you can try to filter it all out and adjust the tuning to match. But fixing it mechanically yields the best results. Keep in mind these things are mass-produced for 3D pilots who crash 'em and rebuild 'em several times a season. So the quality is “good enough”.

As far as the servos, the controller only sends a signal to it. The servo has an internal pot or hall effect that tells the servo’s controller what the position of the output shaft is. So that dancing on servo1 is not from the servo, it’s because the frame is shaking side to side.

Doesn’t that helicopter have a FBL unit tray in the front? Why didn’t you put the controller on that? IMO that would be a better location for it.

Edit: This is the plot of the x and y vibes with that jello plate in there. It doesn’t tell you anything about what the frame is doing. It would be like let’s mount the DynaVibe transducers on the Jet Ranger with some rubber pads and see if we can still balance the rotor. Fly it, cyclic shakes, all the needles in the panel shake, your passengers in the back got their coffee vibrated right out on their lap, but the DynaVibe says it’s all good.

This is what you want to get your vibration plot to look like. This is from one of my piston machines flying a survey flight. This machine has a perfectly balanced and tracked rotor using the DynaVibe to tune it. Notice the amplitude of the vibration peaks on y-axis. The higher amplitude on x is due to the engine and the vibration from the acceleration of the piston and crankcase and what gets transferred to the frame. When the mix in the cylinder lights and the piston goes down, the crankcase goes the other way. It is balanced with reciprocating weight in the piston and rod, as well as the counterweights on the crank. But it still vibrates.

Your electric in its current configuration is not as smooth as my piston gasser.

My y axis has always been a lot higher from the the other 2. I never asked which one is was which I guessed y was like a yaw vibration. Wrong.
Ya I’m charging the batteries again. To do a fliggt with the radio. But with the battery on the radio frozen and no warnings. I’m scared to go to far. I messed with the heli on as in servos and controller for 40 min before I flew it. I know it said 25.1 volt but think that was ghost voltage. It normally goes down evenly not a huge drop like that. I have more battery showing up today with a dual charger. So I don’t have to plan battery charges days in advance. Current charger takes 3 hours per batt.
Now if they are getting weaker if I put the new batterys in parallel should I put diodes in to make sure their is no canabilism. Or will they “use up” evenly. I only have the 25 volt sensor. I was looking at buying the 50 volt sensor for the series.

Looking at weather it might have had 10 mph tail and head wind. So forward could have been faster than return. I never found spec on ground speed in log. Only in tlog. But no tlog this time.

Another question. My motor has 3 wires but under it are 2 tiny wires they were connected to something on The original 3gx or a some thing. Those wires could not be producing an rf wave somehow causing problems?

Thinking of running longer wires on the radio and putting it on the tail. For a test after I run it again normally.
In the crash my ESC to a mild hit and broke the plastic off the ESC and a piece of the nose. Glad I had controller where it is.

More info came to my brain. When hooking up the craft and theory cable for telemetry I hooked it to serial port 4/5 and followed wiki. It did not work I think I had to set the setting to 6 to get it to work. Don’t know if that would have caused the delay I can look toniggt yo see what I actually set the param at.

Y is side to side, X is front and back, Z is up and down. A tail vibration can definitely cause high Y-axis vibration.

Parallel batteries will discharge together and remain even on voltage. You can even put two different sized ones in parallel, the smaller one will deliver less current than the larger one. If they are in series, then they both have to be matched because the same current will flow in both batteries, regardless of their size, it will over-discharge the smaller one (or one with less capacity) and damage it.

Look in the GPS tab in the log. It shows the GPS speed, which is usually pretty accurate.

I doubt it as radio frequency interference from a 10 pole motor would be somewhere in the AM radio broadcast band and cause an annoying alternator whine in your AM radio. What would those wires be for? Maybe rpm telemetry or a governor? If in doubt, and they’re not being used, twist them into a tight twisted pair and terminate them properly so they don’t short out on anything.

IMO the FBL unit tray is the best location. But I think I have seen photos where some people that have put their controller on the top of the plastic tail mount too. It appears you have yours in the battery bay, which is where the batteries should be. The Z-axis CG of the helicopter should be somewhere around the main transmission gear and I think they design the location of the FBL unit tray so it is approximately inline with that Z-axis CG for proper roll sensing.

The plan what to hang batteries on the landing gear for easier changes and more batteries. I didn’t know if I’d need 6 batteries for a 20 min flight. 2series 3 parallel. I hung the copter by a string centered on the main shaft. To see what the cg was. As long as it is all vertical weight and I’m not doing eratic flying couldn’t see the harm. Might make heli react slower but under the belly is gonna be the gimbal I am designing for my odd shaped sensor we spoke of before.
Me being a noon and everyone saying its gonna crash. And as the motor cycle saying goes it’s not if but when. So I put it in the battery hold to protect it. I ran all high voltage to the nose I nfrong of the motor to get away from rf. I put radios on the back and below to get distance from rf. Had to plan on the worst case because I had no clue how sensitive a these sensors were.

On another note. Iv had 3 close calls and 1 crash due to battery voltage telemetry. I know the yaapu has lots of neat features. I think the auto rotate rpm would be cool I bought an align hall effect sensor. But looks like I need to buy the gas suite to make it work. Also the last GPS coordinates for a crashed heli. But on a battery machine battery knowledge is king. If I can’t figure that out I’m going to have to get a Bluetooth ear bud to listen to the computer warnings since radio will be in my hand but way behind

I’ve had a set of 500mw radios before and they caused havoc with my servos. I could make the tail servo go nuts by moving the antenna around.

I recommend this set:

Or if you really need the longer range:
http://store.jdrones.com/jD_RD900Plus_Telemetry_Bundle_p/rf900set02.htm

It looks like the battery failsafe went off at 22.9 volts, which is 3.8VPC with a 6-cell battery? And that’s under load.

I am certainly not well-versed in setting up this battery stuff, but is that what people use? I thought 3.85VPC at rest is storage voltage, and about 50% capacity for LiPo batteries?

So when you shut down it looks like it immediately recovered to 23.5V, which is 3.91VPC, which is only very lightly discharged (I think). Are you sure you have this battery stuff set up right?

Seems to me back when I flew electric helicopters if they came in at 3.5 VPC after a flight and they had rested for awhile, I was not too concerned about it, and they seemed to last about 200 cycles. Although some of them would develop a bad cell after only 60-70 cycles and that’s what I didn’t like about the expense of flying electric aircraft.

I think I had the low battery cutoff at 3.0VPC in the ESC, which would be 18.0V for a 6-cell. If it got to 36 volts (12S power) then it would cut the power and start cycling it and had to autorotate the heli (although still under power). But even those recovered back to at least maybe 3.2VPC if I ran them to the limit. Which was not good for the battery, but I only did that a few times. I never set any failsafes on the battery because if it was still running and not home yet I would fly it and ruin the battery before I’d lose power and have to autorotate it.

Maybe somebody that knows more about these batteries can point you in the right direction on that. I only tried electric one year after I seized up my O.S. 105HZ nitro engine for the third time and didn’t have time to put another sleeve and piston it because I had flights to fly. So I bought a Trex 600 electric and flew that, it seemed to work pretty good. Then I bought a Synergy 626 electric and flew that for a year. The care and feeding of those batteries was more than I wanted to deal with. Nitro fuel was $35/gallon. $150 bucks a crack for piston, sleeve and bearings in the 105 and overhaul that every 50-60 hours. Carey Shurley developed the piston gas conversion for the Synergy 766, I’ve never looked back. Just dump gas in it and fly it 10 hours a day and it comes back for more. 411.7 hours on the first one and the engine has never been out of the frame since new. Only problem I’ve had with those is the fuel pump. I put the new stainless steel fuel pump diaphragm from Walbro in them, even that’s not a problem anymore.

So, unfortunately, I forgot most of what I learned about electrics. But I do know I ran the batteries a lot more aggressive than you are.

I have disabled the cut-off on the ESC on mines. I’d rather ruin the battery.
Lipos can be run down to 3.3v/cell. Hit 3.0v/cell and you start doing real damage. 3.8v/cell is ~50% full.

Jacob there is these new settings for sag compensated voltage, etc… I don’t know much about that, or how it works. Alan is not measuring current so I don’t think he can use that anyway. But doesn’t experience flying it, and then see what the battery recovers to after it rests, tell you what the voltage sag is under load anyway? Are those figures you gave under load? Or after the battery rests and recovers?

Sorry, yes…apart from the 3.8v/cell = 50%, the numbers are under load.

Huh, so there is
Sory, http://ardupilot.org/copter/docs/parameters.html#batt-fs-voltsrc-failsafe-voltage-source

I cannot find how it calculates the sag?.
Sag will vary greatly depending on battery type and load.

I set up my failsafes based on under load values. If you go below 3.3v/cell, under load, you will wear down the cell quickly, below 3v/cell, you can kill it.

First few flights, I rarely use more than 50% of estimated usuable capacity. I then go home, look at the discharge curve, vs expected and then go 75% next flight.

As a general rule of thumb, I expect usable capacity to be ~80% of rated capacity. Some batteries, like the Multistars, you were lucky to get 50%, even if you stayed well under the batteries claimed C-rating. (The “cheaper” tattus weren’t much better).

You also have to anticipate that as voltage goes down, current goes up and the battery will discharge faster.

I now run li-ion, so my values are quite different, but as a starting rule for lipo, I would have 3.7v/cell as my first failsafe (RTL if you don’t trust the telemetry!). and 3.4v as Land.
Then adjust as needed.

Cool, thanks. That sounds about right. I probably over-worked my batteries when I flew electric because I remember when I hooked them to the charger if it said 3.5V on all the cells I was pretty happy. When a cell went bad I’d start finding one at 3.3, and as it got worse one day that battery would come with the cell at 2.9. And then the charger would refuse to charge it. So I “cheated” by setting the charger for lead-acid and boost that cell above 3, then switch to LiPo and it would charge it. Then I marked that battery as “bad” and used it for short flights.

I did NOT enjoy dealing with batteries. Some of these guys got elaborate balance boards and stuff to mass-charge batteries, and they’re running Honda generators at the RC field to charge their batteries. It’s like dude, just put the gas in the helicopter instead of the generator and get rid of all that :neutral_face:

Well, as you know I’m leaning heavily that direction (Gas), however the li-ion pack has proven quite practical so far. I’m still running it conservatively, but I still gain more flight time than I did with a similar weight Lipo. It’s got an onboard BMS, that I can plug into a PC and check the heath and charging is just plugging it in and forget about it. (Well, you wont forget, as the fan on the charger sounds like a jet engine, but anyways).

However, due to the severe voltage sag, li-ion will be limited to low-to-medium power operations. S, perfect for surveys.

I’m not a fan of batteries but what I can afford to play with for now and crash! I looked into li- ion batteries cannot find a dealer in USA. I suppose I could make my own if i bought spot welding equipment. Iv been looking at 2170 batteries. From Tesla cars or Samsung. The more I have troubles, some of my own doing, and some cuz I don’t know enough yet. Buying a ready built and TUNED heli is looking like I might mortgage the house and get a heli that flies good so I know what that looks like lol.

Early in this thread I posted a log that had hard auto in the title. During that flight. Batteries reached 22.5 volts and dropped straight down below 18 volts. The heli looked sluggish. I had soft cut off on the ice 2. I was 50 ft up. I said here comes my first auto rotate. I dropped collective. I let it come down to 10 ft flared way to early. I watched the blades dam near stop and it dropped 8 ft. Good thing I just put my tall landing gear on cuz it bent and took the blow. So that the reason for the voltage Failsafe’s. When I went into the tree. Voltage was at 22.9 and I was trying to auto it in. Not what the ESC did that time. But heli blades were slow and unresponsive.

I have looked at Milwaukee batteries but voltages are to low for amps unless I could run 60 volt instead of 50 max charge.

We are buying cheap lipo’s. Floureon they seem to work but I don’t know anything about adjusting the kV on the motor for more efficiency or if running the ESC at 70 percent is efficient. We only pull 20 amp at 12 s and max I have seen is 30 amp. My idea was if I put a few more in parallel that will lower the amp draw per battery and be able to run them longer

Yeah, I built my own li-ion pack. It still costs a fair bit and I only did it after I had the heli working as intended on lipos.