Calling All Experienced Multirotorists, beginner in need of some advice.

AndrewRussellHayes

Junior Member
I have built a tricopter and I think i have not properly matched my major components.

I will start by admitting that I don't really know what I am doing. I finally put together a working machine and flew (crashed repeatedly) for a few minutes.

I was experiencing a lot of problems getting a hover but my gut tells me it had to do with unbalanced props, out of tune APM settings and too much wind for a beginners first flight.

The real problem happened when one of my motors emitted a bunch of smoke. The motor would still run with throttle but I decided to go ahead and cut power and do a little research before I broke something more expensive.

My gut tells me, perhaps, I have overloaded the motor or something along those lines. I want your input. Do I have the proper setup? Do i need to switch a major component? Before I list what I have, my goal is a moderately high-powered tri that is capable of fast flight and some basic acrobatics when I become more skilled. Is my setup wrong? Do I need to change something? What is the best setup i can use for my goals? I'm willing to scrap a lot of my setup if i need but I'd like to keep using the APM and the battery and transmitter since they are the more expensive parts of my setup.

Here is what I have:

Motors: Turnigy Park300 Brushless Outrunner 1380kv (http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=14398)

ESCs: Turnigy Multistar 15 amp multi-rotor brushless esc 2-3S (http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=25363)

ESC Settings:
- Cut-off voltage: low
- cut-off type: slow
- startup: medium
- timing: auto
- brake: off
- battery type: Nixx (i was told this was best to stop low voltage cutoffs in flight)

Props: 8045 SF (http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=25812)

Battery: Turnigy 3000mah 4S 40C Lipo Pack (http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=10299)

Transmitter/Receiver Turnigy 9X 9Ch (http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=8992)

Controller: APM 2.5 (http://store.3drobotics.com/products/apm-2-5-kit)

servo: BMS-385DMAX Digital Servo (metal gear) (http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=8761)

I appreciate any input!

Also, side note question. When deciding wether or not to use one counter rotating prop is there a reason to, or not to, use one?
 

Johan

Senior Member
Hi,

I think you might want to try http://www.ecalc.ch/xcoptercalc.htm?ecalc&lang=en

You can use it to calculate limitations / mismatches in your setup.

You''l probably find that using a 4S with those motors will draw more current than they can handle.

On your counter rotating prop question:

If all props run in the same direction, the body of the tri will try to turn in the opposite direction (physics, momentum etc).
You can make it less by having one counter rotating prop.
What David did with his original tri was to have all three in the same direction and have the tail yaw mechanism slightly tilted to counteract that tendency.

Good luck!
 

xuzme720

Dedicated foam bender
Mentor
Too much battery and too much prop for those motors. They are rated for 3S cells and for a 8x3.8 prop on 2S...

Those motors are only rated for a max of 7A and my guess is the smoke you saw was the insulating varnish burning off the coil wire as it overloaded.

Everything else seems to be fine if you change the motors to something that can take 4S and 8x4.5 props.

maybe something like this? http://www.hobbyking.com/hobbyking/...s_28_30S_900kv_270w_short_shaft_version_.html
 

Cyberdactyl

Misfit Multirotor Monkey
Yes, if you had used a 3 cell battery you may have been ok. The motors may have just run warm, especially if it was just the frame you were lifting. But now that you have toasted the motors, I wouldn't trust them on lifting anything expensive, like your FC for one.
 

Gremlo

Member
Also another thing i noticed, your ESC's are only rated for 2-3S and you are using a 4S, That wont work either. I have run a tri with the exact motor/prop setup on 3S and everything runs nice, warm to the touch but that's fine.
 

cranialrectosis

Faster than a speeding face plant!
Mentor
Good luck on that link to ecalc.

Has anyone EVER used products that were listed in ecalc?

I think everyone goes in, types in whatever they can find on the manufacturers web page for whatever electronics they have and make wild unsubstantiated guesses about the rest and come up with totally irrelevant and worthless answers.

Because really, does anyone have any of the products listed in ecalc?
 

xuzme720

Dedicated foam bender
Mentor
You are really having a bad day, huh? I heard about your FT 3D...Sorry, man!

I can usually get pretty close to actual numbers with eCalc and have found stuff I run in there, too, once or twice. Surprised the hell out of me when I did...
 

Johan

Senior Member
I agree that using ecalc is not an exact science.

But the components in the OP either were in ecalc or something close enough was (using common sense).
If ecalc indicates a current usage more than twice the motors rating using those components, something is not balanced in the setup.
That was my point, not to fully rely on ecalc.

Sorry about your FT 3D!
 

cranialrectosis

Faster than a speeding face plant!
Mentor
I think the issue with ecalc is that getting close enough using common sense is beyond anyone who is new enough to the hobby to need a tool like ecalc.

Nothing against Andrew here but he bought a 15A esc for 2S and 3S and bought a 4S battery. What are the chances he is gonna get anything from ecalc?

I would LOVE to see a simpler solution. I understand the problem isn't simple. But most problems can be broken down into manageable sections. I would be surprised if thrust math cannot be also.

Ecalc is just too complex for a newbie in my opinion. It sure as heck is too complicated for me. Then again, so was the 3D...
 
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Johan

Senior Member
I think the issue with ecalc is that getting close enough using common sense is beyond anyone who is new enough to the hobby to need a tool like ecalc.

Yeah, I guess you're right now you put it like that.

Indeed I remember when starting out I was quite intimidated by all those entry fields whose meaning was still kind of vague to me.
Just when you need it the most, there is no 'guided' tool....

That would be great to have: A 'wizard' that starts out with some questions, refining / eliminating further questions / options based on choices you make.
 

xuzme720

Dedicated foam bender
Mentor
Yeah, I guess you're right now you put it like that.

Indeed I remember when starting out I was quite intimidated by all those entry fields whose meaning was still kind of vague to me.
Just when you need it the most, there is no 'guided' tool....

That would be great to have: A 'wizard' that starts out with some questions, refining / eliminating further questions / options based on choices you make.
Or one that has choices for components we actually use...
I usually don't bother with it since I can almost never find motors in it I'm planning on using, and the motors I have, well...I can just test those myself.
 

cranialrectosis

Faster than a speeding face plant!
Mentor
I guess my thinking here is this.

The purchase of the wrong components costs manufacturers or their retailers money in restocking and customer frustration. It also makes the build more challenging, which is not always a bad thing, but in this case it costs money and may prevent some people from trying the hobby out.

IMO, manually updating tools such as ecalc is the problem with current tools such as ecalc.

The retailer has the current components, is in direct contact with the manufacturer, and is charged with interfacing with consumers.

The best tool has intimate knowledge of the current components the retailer is selling without requiring manual updates. It would need backend access to the retailer's db.

Since it is the retailer who gets saddled with the overhead, and it is the retailer who has the data, isn't it the retailer's best interest as well as the hobby in general, to develop a tool that works within their own web site and helps you choose the proper components?

Can you imagine what it would do for the site/hobby to have a Newegg style, menu driven tool (see their RAM tools) that guaranteed the proper component match on Hobby King's website?

Or am I just being stupid here?
 

Tritium

Amateur Extra Class K5TWM
Quote: "The purchase of the wrong components costs manufacturers or their retailers money in restocking and customer frustration."

Not a problem for Hobby King. It is nearly impossible to return an item to them and not have a negative gain in the pocketbook!

Thurmond
 

xuzme720

Dedicated foam bender
Mentor
Heads up has tested prop sizes along with draw for their motors. And they ship fast and cheap. two things the HK doesn't do.
 

Cyberdactyl

Misfit Multirotor Monkey
Quote: "The purchase of the wrong components costs manufacturers or their retailers money in restocking and customer frustration."

Not a problem for Hobby King. It is nearly impossible to return an item to them and not have a negative gain in the pocketbook!

Thurmond

That's the sweet and sour ordering from China. The price points are SO low for items... and if you can get it for free shipping, like at Rctimer, Dealextreme, etc., you come out way ahead.

However, if it's not what you ordered, want or it's DOA, you're pretty much out of luck. That's why I am very nervous ordering single high priced items (>$100) from China.
 

xuzme720

Dedicated foam bender
Mentor
That's very true. I know some have had issues getting the wrong items from Hobbyking, but that is the one thing I can say they do right. In 20+ orders from them, I have only had one mistake, and it was in the last order of covering. I ordered 5 rolls, all different colors, and I got 2 rolls of yellow instead of an orange roll. All the other colors were what I ordered...
But it seems like they are having growing pains or something lately as service has dropped WAY off, takes even longer to pack...
 

Johan

Senior Member
I guess my thinking here is this.

The purchase of the wrong components costs manufacturers or their retailers money in restocking and customer frustration. It also makes the build more challenging, which is not always a bad thing, but in this case it costs money and may prevent some people from trying the hobby out.

IMO, manually updating tools such as ecalc is the problem with current tools such as ecalc.

The retailer has the current components, is in direct contact with the manufacturer, and is charged with interfacing with consumers.

The best tool has intimate knowledge of the current components the retailer is selling without requiring manual updates. It would need backend access to the retailer's db.

Since it is the retailer who gets saddled with the overhead, and it is the retailer who has the data, isn't it the retailer's best interest as well as the hobby in general, to develop a tool that works within their own web site and helps you choose the proper components?

Can you imagine what it would do for the site/hobby to have a Newegg style, menu driven tool (see their RAM tools) that guaranteed the proper component match on Hobby King's website?

Or am I just being stupid here?

It would be ideal if all retailers had a kind of standardized (XML) output with all components and specs.
Developers (like the people behind ecalc) could then use/match/filter to get the best matching set.

There is however one difficult point I think: I guess one of the starting points would be how much weight you'd want to lift.
This depends on the frame you want to build and the extra (FPV/Telemetry/OSD/Gimbal/Gopro/Volage alarm) payload.
Those are things you can measure, but there are also the power chain elements: motors, ESC's, battery.
The choices made also influence the weight. That is for the tool to incorporate into the equation.

There must be uncertain factors as well: efficiency that may be estimated by manufacturer, others might have measured it in practice.

But indeed unless you have all the information available electronically in a uniform format, the ultimate tool won't become a reality.