Hi, just been testing my Y6 with it's new 6000mah 4S pack and noticed the motors are getting hot. This is affecting the bottom motors more where if you touch them on the base, non rotating part, they are too hot to touch for more than a few seconds. The rest of the motor is hot but can be held without issue.
To check I did another flight with a 3S 4400mah setup and the motors were again getting hot, not as hot but the flight time was 5 mins vs 13 mins.
It's also worth noting with the 4S setup the ESCs were also getting hot, again after a 13 min test flight.
The flight itself basically consisted of a 13 minute hover in loiter mode, I was testing battery times, and consumed 5000mah. The weather for the UK was hot, 25 deg C. The Y6 is a new 2014 B version weighing 1900 grams or so, std config plus 600 gram pack, with std 10 inch props and 850 blue motors.
And finally to the question, is this normal of does something sound wrong?
The only thing I can think I haven't done is balance the props, guide for this would be handy, but I have no vibration issues looking at the data log.
Replies
If I were trying to insult you, I could have gone off on a rant about you personally,the attitude I perceive from my own interpretation of your posts, etc. I did none of those. I have no way of knowing how well versed you are in any particular topic. As such, I can make general recommendations on where anyone can find information. If you already have that information, then that's great. If you have followed the recommendations in that information, even better. The goal is to give someone leads they might need, knowing many of those leads can be ignored as not applicable. The alternative is to withhold potentially useful information. That fails to help anyone.
As far as ecalc results rom various users, you have as much access to them as I do. The claim I was responding to was a complaint that we were barely within spec. I don't see the basis for a complaint that we almost have a problem. Either there is a problem, or there isn't.
Look, man, I don't have your resume in front of me, and I don't mean to speak beneath you. That is a waste of time for both of us. However, this forum has many on it who are experts, and many who try to get away with not knowing what they were doing. I was just as guilty of that on my first few flights as many, and I am far from expert still. I see people showing off quads they have flown for months that have obviously poor basic build details. I've seen full scale pilots and UAV'ers alike try to get away with flying damaged and unreliable parts. I can only conclude from that that the basics are worth repeating.
If I ever come here to get a diagnosis of a big problem, I fully expect someone will tell me to make sure my ESC's are calibrated, my props are on the right direction, etc. They have no way of knowing I know that! and in all fairness, didn't once. I can hardly blame them for trying to help.
So far here is what I've logged with CF discs on top and bottom of my Y6. With these plates the lower motors running at 50-65% throttle produced on average 130F degree (54C) temps according to my laser thermometer. The upper ones ran around 95F (35C) degrees. The ambient temperature during these measurement was indoors at approx 77-79F (25-26C) degrees. This was observed on 3x autonomous flights with the same amount of time and throttle. Althought he temps do not seem excessive, I'm not convinced that my laser thermometer is telling me the truth. Although the readings seem consistent, the temps are in my opinion not telling me the truth as I cannot grap and hold the lower motors for any longer than a second or two. I also smell a electrical/plasic smell from lower motors which indicate they are very hot and close to melting the insulation. I'm venturing to believe my touch is right and the temps should be up in the high 100's F if not lower 200 F degree range. Does anyone out there have more accurate temps?
With that being said, I do believe the lower motors will benefit from less restrictive and more conductive mounting plates which will help dissapate heat via conduction and convective cooling.
UPDATE 9-18-2014:
I pulled the CF mounting discs off and performed 3 more flight tests. The results were inconclusive as far as allowing air from the upper propeller to wash over the lower motors. The temperature readings were nearly identical to earlier reporting. One thing I did see was the time it took for the lower motors to cool down after each flight. Due to the motors mounted to "+" mounting plate which is touching the aluminum arm, I did see a quicker cool down on the lower motors.
However, I still feel that after 8 minutes of running the Y6, that I'm beginning to see a loss of thrust when I swap out batteries and go back up for a second flight. I suspect that the lower motors are not performing as well as they did when at ambient temperatures. I'm planning to conduct one more flight and submit logs for DEVs to review. Like to get there opinion on whether the lower motors are lossing power when they are over heating.
On a seperate note, I finally received my pancake style Sunnysky 690kv motors and plan to swap motors on lower side to test. Has anyone tested different motors configurations? I'm thinking of keeping 850kv on top but run the 690kv on the lowers for testing. What will be the problem if I try to fly with this configuration?
Your guess is as good as mine; not enough experience with this hobby.
I'm going to use KDE 2814-515 with 13" props (not SF), so not pancakes, waiting for one more item before completing the project and should be ready to try it by the end of next week. T-Motor props are too much payola for my flying skills :) The motors seem like overkill, but not really after crunching all the numbers if one is looking for significantly longer flight times. I want reliability too. They also will allow the use of the new Multistar 10c 10A battery without worry which weighs 800g; just received it, ~60g heavier than the RMRC 8A 45c.
After looking at close to every Y6 frame out there, for $65, albeit heavy, the 3DR Y6 frame is a good deal and solid as a rock. The last (and first) bad crash convinced me of that. However I'm also convinced the stock motor/prop is right at the outer limits of their design intent. According to ECalc, it's over.
For my 2.4kg Y6 copter it needs ~400g thrust per motor at 50% throttle to hover. Here's the data sheet for APC 10x4.7 SF props. http://www.apcprop.com/v/downloads/PERFILES_WEB/PER3_10x47SF.dat
With the claimed efficiency losses of co-axial vs axial configurations at 10-15%, those performance numbers will be lower.
Consider APC's RPM formula for SF props: Maximum RPM=65,000/prop diameter (inches) So for a 10" prop, that's 6500 max. I have the test equipment at work to check just about anything, but haven't measured the RPM. Has anyone? Add another 500g and the drivetrain is really stressing. IMO adding any significant extra weight to the stock Y6 is asking for trouble.
I was looking at Vulcan frames but not willing to drop $500 on one, at least this year. The 3DR frame will work for now, It should be fun. Building/racing drag cars for 20 years has nothing on these copters.
It figures the motors I originally wanted but were out of stock for weeks are now available as of today:
http://www.buddyrc.com/sunnysky-v2216-15-650kv-ii-brushless-motor.html
I have checked my bottom motors with an ambient outside temperature of 95 degrees loaded with a gopro and gimbal. Elevation here is 4280 feet. I had 10" props on top and 11" on the bottom. It hovers at half throttle, and for the 8 minute flight I was just hovering. I measured the bottom motors at 160 degrees (hottest part of the motor) and the top motors were 10 to 15 degrees cooler on average. I have since switched to 10" props all the way around and I have not measured the temps yet (couldn't find my temp gauge when I moved my shop) the bottom motors are still hot but do not feel as hot as before. Now that I have found my gauge i will measure on the next flight and let you know. Also I measured the ESC's at 120 degrees.
I'd be interested in knowing the temps with 10 inch on lower motors. The issue is that the 11 or higher inch propellers on the lower running the 850kv motors will put a strain on them causing the ESC and motors to heat up. It's a demand thing. I check eCalc site and it not recommended for either upper or lower motors to run anything larger than 10 inch props. With that being said I wonder if 3DR knew that when building the Y6 vehicle and used what they thought was the large props and kept it within power/lift limits.
For what it's worth I did pull my CF discs off and connected the "plus" motor mounts to my Y6B. I did get it up for a test flight but for whatever reason my Radio freaked out (buzzed) while copter was in a hover (POSHOLD)about 100ft up. Since I didn't have throttle failsafe enabled, I decided to switch it off and back on. Radio reset and what happened next freaked me out. The copter flipped and started coming down. I switched to stabilized and gave it command to right itself. Unfortunately I did not have enough power or height to come out of it completely. Three broke props and a crack in carbon fiber plate. So now I need to do some minor repair work and I should be airborne in the next couple of days and continue the temperature convection/conduction testing.
My advice to you is stay with 10 inch props on lower motors. Heck since the upper motors are running cooler, have you tried running 11 inch on top?
I feel your pain, as I can relate to many mishaps problems and general failures, yes I agree with you for the smaller props for the lower motors, I although did not seem to have the problems noted as for heat generation I changed my setup after a talk Rob L. did based on disk loading and the theories on rotor dynamics.
I think your calc is correct and from what I find is a hold over for using 3s batteries, maybe? not really sure, As you know I have been customizing my Y6 extensively, and have a new CF centerbody in production that should be allot lighter and stronger, although it will be backwards compatible it is a completely new design . Same for the landing gear, the design is much more resilient while still being CF. I should have pictures to share this week.
I did test out other motors, but quickly I hit other limitations such at the max amps for the PDB, and want to stick with the Y6, and with as many parts as possible, just changing the ones I could make from raw material.
The new setup will be over 60% lighter than the replaced components while stronger in every way. I did not use any flat CF plate in the design, the main body assembly, the arms and gear...
hope it works as well as I think it can... will be happy if its just better though
I like the 10" tops with 9" tri blades on the bottom best with the oem setup
Trearig, Do you have any videos of the prop configuration you mentioned? I'd like to review it and see how it performs inflight.
Also like you idea of building lighter but stronger centerbody. Be interested to see pics of your modifications when you're done.
Lastly, please provide me URL where you purchased your tri-bladed props. Thanks.
Once the updates are complete to our Y6 I will do a extensive blog post with pictures and videos of the operation.
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