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Author Topic: First Flight Today! Tuning Help?  (Read 1628 times)

Offline M.Schmavs

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First Flight Today! Tuning Help?
« on: September 14, 2019, 09:28:13 PM »
To start, I never thought taking my thumbs off the sticks on a maiden flight was a possibility. Sure, I could have just done it, but it only happened because I was immediately comfortable. The model was just holding there practically on it's own. First shot. Barely needed any correction as it left the ground. Wow.

Now, I digress, because that's probably what happens today with flybarless controllers. This is my first non-flybar experience so I don't know exactly where to give praise... The model, the controller, the settings? All of the above? Either way, I'm ecstatic about it.

With that said, pitch pumps were a bit laggy and "twitchy". Meaning, when descending and trying to pop back up, the model felt like it wanted to keep falling but with hesitation until finally catching and ascending. I'm trying to figure out if I should look at the governor or possibly the gyro settings for that. Forward flight acceleration and slowing showed no signs of lagginess.

Tail was rock solid no matter what I gave it.

Throttle curve is a flat 85% and cyclic gyro gain is 50%. Throttle was at 80% but I turned it up. Gyro was at 55% but I turned it down. Maybe I went the wrong way but cyclic does feel more connected at 50%.

This is also my first time trying to use a governor. I always set my flybared models up with linear throttle curves. I just didn't like the feel of governors ~12 years ago but I assume they are better performing these days.

I opted for a 1200KV motor with 16T main and 18T tail pinion. I want to keep my headspeed lower than what you pros are running while I relearn everything. This has me thinking I might want to increase the throttle percentage but I was under the impression to leave 15% headroom.

To sum it up, I guess I'm asking for generic tips on what to look at when the heli behaves certain ways during flight. Tuning Tips so-to-speak. Or maybe just link me to a useful site, haha. I've been searching with no luck.

If it matters, my ESC is a HW 120a Platinum and gyro is CGY760R.

Thanks in advance for any help!

Offline Wolf51

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Re: First Flight Today! Tuning Help?
« Reply #1 on: September 15, 2019, 04:49:32 PM »
The 516 won't disappoint, its a great model.

About the pitch pump hesitation:
according to my headspead calculator with 1200kv motor, 16t pinion and 85% throttle you'll be around 2150 headspeed. The heli will perform fine at that, but higher headspeed would help to sharpen the response in that situation.

The hobbywing esc has an excellent governor, but your setup and battery charge at startup can make a difference. Can you tell us what governor settings you're using.

Cheers

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Offline M.Schmavs

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Re: First Flight Today! Tuning Help?
« Reply #2 on: September 15, 2019, 05:37:51 PM »
I wouldn't mind more head speed if need be... Is it advisable to go above 85%?

I left the governor parameters at their default settings. Looking at the manual, Parameter P is set to 4 and Parameter I is set to 5. To be honest, based on the descriptions, I don't even know what those parameters do haha.

I did change the Governor type to Store mode.

Offline Wolf51

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Re: First Flight Today! Tuning Help?
« Reply #3 on: September 15, 2019, 07:43:46 PM »
Governor store mode is best for consistent governor performance.
There is a basic procedure to do when you first set it up to optimise governor operation. If you haven't done that have a look at this video by Kyle Stacey
https://www.facebook.com/KyleStacyRC/videos/583050965441244/

As for increased headspeed, I'd suggest using the std 18t pinion which should give about 2400 rpm at 85% throttle setting with your motor.
You could increase your throttle to 90% with existing gearing but that will only get you 2200 but reducing the governor headroom at the same time.


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« Last Edit: September 15, 2019, 07:47:05 PM by Wolf51 »

Offline M.Schmavs

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Re: First Flight Today! Tuning Help?
« Reply #4 on: September 15, 2019, 08:06:17 PM »
Super Helpful Video! Thank you! I'm glad I watched that before wasting my time messing around with the parameters.

18T it is! Placing an order now. With that said, should I put the stock 20T tail gear back on when making that change?


Offline Wolf51

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Re: First Flight Today! Tuning Help?
« Reply #5 on: September 15, 2019, 08:52:34 PM »
There is an 18t pinion in the kit, assuming you built from new?

I would instal the std 20t tail gear at the same time

I fly a lot at about 2450rpm and the tail is solid with the std 20t gear

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Offline M.Schmavs

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Re: First Flight Today! Tuning Help?
« Reply #6 on: September 15, 2019, 09:19:18 PM »
Well, I feel silly... I completely forgot about the kit supplied pinion. I did build from new so that also means I just wasted $20 - Hopefully I can call and cancel in the morning. Total face palm.

On the bright side, I can make the changes tomorrow since I don't have to wait for it to arrive - HA!

Thank you again, so much for your help! You guys are awesome on this forum.

Offline Wolf51

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Re: First Flight Today! Tuning Help?
« Reply #7 on: September 15, 2019, 10:41:11 PM »
Hold on, theres a bit more to governor store mode that isn't covered in the video.
I thought it was. The rpm standardisation only happens the first time you spool up in gov store mode.

Have a look at this document from hobbywing. It explains the governor setup in detail.
https://www.google.com/url?sa=t&source=web&rct=j&url=http://www.hobbywing.com/products/pdf/PlatinumV4.pdf&ved=2ahUKEwj1qemntdTkAhXDgeYKHdsWDTkQFjAGegQIARAB&usg=AOvVaw1GwfuxVyw01cXbenJgYigm

It takes some reading but should answer your questions

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Offline M.Schmavs

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Re: First Flight Today! Tuning Help?
« Reply #8 on: September 16, 2019, 10:46:28 AM »
It looks like I'm all set with standardization, calibration, and pitch-pump-performance!

After re-gearing with STOCK gears everything is just about perfect! Piro rate is better, cyclic is better - Just everything! It didn't occur to me the only change I should have made in relation to slowing the head speed was just the motor Kv. I overlooked the fact that most people using the 16T are running 1350Kv motors so my research was a bit skewed.

One final issue I found when tail tracking is my pitch rod is too long. I have the links pretty much bottomed out and it's still not enough pitch. The AVCS is carrying the tail in that aspect. Maybe some hydraulic lock formed when installing the threaded ends and an air pocket formed from the epoxy. I don't know. Thinking about buying a new rod and ends to fix that.


Offline Wolf51

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Re: First Flight Today! Tuning Help?
« Reply #9 on: September 16, 2019, 06:14:11 PM »
Good to hear the gearing changes have improved performance for you.

About tail control and travel limits, go back and check you've assembled according to the manual.
-tail belt only twisted 1/4 turn
- tail belt tensioner at 90°
-tail control rod length adjusted so servo arm and tail bell crank are both at 90°

Now check tail travel limits and adjust in the appropriate section of your cgy760 setup (I can't help there as I fly vbar).

For reference, the tail control rod on my 516 is approx 569mm between ball link centres, leaving about 4 turns of thread visible at each ball link, yours may vary.

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Offline M.Schmavs

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Re: First Flight Today! Tuning Help?
« Reply #10 on: September 16, 2019, 07:25:52 PM »
Yessir, thanks to all the help, things are much better. I even calculated the head speed from the HobbyWing data and it's running at 2,348 RPM... I'm also getting 10 minutes with my back-to-basics flying.

Mechanically, everything looks good on the tail. Just confirmed the belt only has 1/4 twist, tension arm is at 90 and the boom is flush with the forward edge of the forward frame clamp. I just can't get both the bell crank and servo at 90. Also just measured my tail rod and center to center is only 4mm longer than yours at 273mm. My visible thread is 1 on each end. I might get a full turn on each end.

Oh - and I reset the travel after I put the 20T gear on this morning.