Wrong Motor Help?

[M.Schmavs]

Here I am again with another problem!

So my history goes like this - I bought a 1200kV motor to slow the head speed down on the 516. After some help from another member, I'm using the stock 18T pinion and 20T tail gear. (I had the 16T pinion on and it wasn't performing very well.)

Fast forward to today, I realized my motor is 8 Pole so I recalculated my head speed from the HobbyWing data. It came out to 2,935! I put a digital tach on it and it was reading somewhere around 2,800. I backed my throttle down to 80% (from 85) and it's reading just over 2,700 on the tach.

So all concern aside, it flys great! But this might be a little too much for my skill level. I'm putting back-to-back 6-8 minute flights on it, temperature is steady at 91F. I'm putting average 3300mAh back in the packs after a charge. They're 5000mAh if that matters.

I definitely want to slow this thing down without lowering the throttle % in the radio too much more.

What should I do? Just get the recommended 1350kV motor and put the 16T back on?

Try the 17T pinion? Why would the 16T make it so sluggish? Could I be wrong with my numbers?

[Wolf51]

Hi,

Are you still using the hobbywing governor?
If so, did you redo the esc governor standardisation after you changed from 16 to 18T pinion? (That would mean changing to another governor mode, saving, then reset to governor store mode and redo the 50% throttle runup) Otherwise the hobbywing data may not be correct for the changed gearing.

Using MrMels headspeed calculator the headspeed should be around 2367 at 80% throttle.

What is the rpm number you see in the hobbywing data?


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[M.Schmavs]

Yessir, still using the HobbyWing Governor.

...and, after I replaced gears, I did re-standardize the ESC but suppose it wouldn't hurt to do it again. I don't doubt I could have incorrectly retried it.

The ESC is showing 118x1000. I was originally dividing with a 10 pole which came out to 2,348RPM but after realizing it's an 8 pole, it went up drastically. Maybe I'm doing that all wrong too?

I definitely think I should retry the standardization. Thanks for reminding me that exists!

Any other suggestions?

[mikelansford]

Definitely redo the standardization on the hobbywing. Running that gearing and motor wolf is correct with what head speed you should see.


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[Wolf51]

Lets see,

this gets a bit tech, but its only so we can be happy and fly our helis

Using your hobbywing data of 118000 rpm max
the formula: Maxm headspeed at 100% throttle = Max RPM / (motor poles / 2) / (Gear ratio)

Headspeed @100% throttle for 10 pole motor = 118000 / (10 / 2) / (181 / 18)  = 2347
Headspeed @100% throttle for  8 pole motor = 118000 / (8 / 2) / (181 / 18)  = 2933
So we're both getting the same answer to the calcs, close enough.  I hope thats a good thing

At 100% = 2933 , 80%  = 2346 which is also very close to the MrMel calc, again a good comparison.

If the blades have been turning at around 2800 the heli would be very sensitive, I would say aggressive, on the sticks compared to the headspeed you had with the 16T pinion. Unless you also tamed down your FBL settings.

Raises these questions for me:
Did you do throttle endpoints so the esc knows what to expect for throttle signal range from the transmitter?
Is the digital tach reliable/accurate?

Edit: Thanks Mike Lansford, sometimes more heads is better

[M.Schmavs]

No worries about the tech stuff! I'm into it and it's definitely a factor I love about the hobby. I'm just not as sharp as I used to be, haha.

"Definitely redo the standardization on the hobbywing. Running that gearing and motor wolf is correct with what head speed you should see. "
I agree. I think that's the ticket! Batteries are on the charger now for tomorrow's session.

"At 100% = 2933 , 80%  = 2346 which is also very close to the MrMel calc, again a good comparison."
Does this mean I am actually where I want to be? I was running 85% so that's 2,493? I didn't account so much that the final calculation was for 100% throttle but makes perfect sense.


"Did you do throttle endpoints so the esc knows what to expect for throttle signal range from the transmitter?"
Yessir, I did.

"Is the digital tach reliable/accurate?"
Beats me! haha It's a Hangar 9 micro tach, brand new.

As far as sensitivity goes, I would also expect it to be much more sensitive and aggressive feeling. I haven't touched any settings, dual rates, expo, nothing in the radio or the FBL unit. It flies just perfect for my beginner style.

I may have created another thread where I'm just overthinking again...

[Wolf51]

On the back of all that, as you say:

- Redo the esc gov standardization
- Set throttle in the 70-90% range to get the headspeed that delivers your desired feel/performance from the heli.
- enjoy

Oh, and maybe check that tach on something that has a known reference rpm.

Cheers

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[M.Schmavs]

Thank you both so very much! I will report back once I check and recheck everything tomorrow.

[M.Schmavs]

Update:

The new "magic number" is 111.
At 85% throttle, I'm getting 2,347 RPM - Sound right?
I did forget to put the tach on it.

The first thing I noticed is how quiet it is now. The second, obviously, it's more tame and smoother. Much more suited to my style of flying. Although, I admit, the higher speed was pretty awesome too.

Something that just clicked with me is when I got my radio back from warranty, I noticed the helicopter was "louder" but didn't think much of it. I just kept flying. In hindsight, I should have redone the endpoints and standardization the day it came back. After all, they did replace the throttle stick potentiometer.

Thanks, yet again, to this forum and all you good people willing to help a new guy out!

[mikelansford]

Glad you got it sorted and flying good. I love my 516


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[Wolf51]

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[M.Schmavs]

"Glad you got it sorted and flying good. I love my 516"

Thank you and me too! It's a great machine. I like it even more than my old Miniature Aircraft 600 model.

Another great benefit from having it setup correctly (duh) is, at the expense of a few degrees on the motor and ESC, the batteries are a lot happier. They come down cooler and only 2500mAh going back in, effectively cutting 15 minutes off the charge time. I can still fly back-to-back without worry of heating things up. Just. Awesome.

[woodscra]

Schmavs,
What did you end up with for motor kV and Pinion?

[M.Schmavs]

Luckily, I didn't have to change anything mechanically. Just a software issue with this one... Staying with the 1200kV motor and stock 18T pinion.

[earlybird0513]

Here I am again with another problem!

So my history goes like this - I bought a 1200kV motor to slow the head speed down on the 516. After some help from another member, I'm using the stock 18T pinion and 20T tail gear. (I had the 16T pinion on and it wasn't performing very well.)

Fast forward to today, I realized my motor is 8 Pole so I recalculated my head speed from the HobbyWing data. It came out to 2,935! I put a digital tach on it and it was reading somewhere around 2,800. I backed my throttle down to 80% (from 85) and it's reading just over 2,700 on the tach.

So all concern aside, it flys great! But this might be a little too much for my skill level. I'm putting back-to-back 6-8 minute flights on it, temperature is steady at 91F. I'm putting average 3300mAh back in the packs after a charge. They're 5000mAh if that matters.

I definitely want to slow this thing down without lowering the throttle % in the radio too much more.

What should I do? Just get the recommended 1350kV motor and put the 16T back on?

Try the 17T pinion? Why would the 16T make it so sluggish? Could I be wrong with my numbers?

If you put a 16t pinion in for lower HS you should have put a 18t pulley on the tail to increase the tail speed. Your tail probably couldn’t keep up with the low HS. I did this on my 516s HS were 2150, 2200, 2300. It flew perfectly fine with 5min flights no problem.


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