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100 Class Electric Helicopters 100 Class Electric Helicopters manufactured by Align, Tarot, SYMA, Airhog, Chaos, HK and similar.


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Old 08-31-2020, 01:35 AM   #1 (permalink)
gfx
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Default XK K110 mechanical setup

I bought the XK K110 helicopter ready to fly. Looked perfect upon first inspection. On my maiden flight I noticed it flew really well except it rolled to the left. I then noticed it requires full right trim to get it to fly more level but not even full right trim fixed the situation. Upon further inspection, I noticed it was evident that whoever set up the helicopter compensated for the roll discrepancy by installing the left servo higher than the right such that the horizontal rod that holds the canopy in place could only be installed at an angle, causing the canopy to go on lopsided. So as to not bore you further there were some other discrepancies and I decided to reinstall the servos correctly and change the length of the linkage rods. Big mistake. I change the mechanics and now the helicopter doesn’t even have enough pitch to takeoff. Can someone please guide me on how to set up the servos and linkage rods correctly so that the swash is level and whatever? Isn’t pitch supposed to be zero at mid stick or do I have that wrong? It’s been a long time since I’ve flown helicopters and done all this. Now things come ready to fly and are usually set up a lot better than this. Plus I have no experience with these tiny little helicopters or mechanically setting up a flybarless helicopter. The radio seems to be set up nicely. Before I mess with it pitch pumps really powerful and fast. Hard to believe my relatively few adjustments made it so that it doesn’t have enough bitch to even get off the ground! I left “bitch” in for fun. Haha! 😜

Any help would be very much appreciated. I love this little heli! Tons of power and flies rock solid. Just hated the hard left roll and the crooked canopy. I really just should’ve left it alone!
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Old 08-31-2020, 07:42 AM   #2 (permalink)
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Default Push the main gear back on

Regarding the "insufficient collective pitch to take off" problem (which is very common)...
The K110 has a "feature" in that its main gear takes the brunt of most crashes. What happens is that the main gear will typically slide down the shaft (or even fly off completely).

To fix it, simply push the main gear back on snug against the lower main bearing. (There should be zero vertical play in the main shaft).

Regarding your other setup questions, you'll need to do some research on your own. Also, there is a very active K110 thread over on RCGroups where you will get a very quick response here.

Hope this helps!
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Old 08-31-2020, 04:57 PM   #3 (permalink)
gfx
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Default

Quote:
Originally Posted by ridge-runner View Post
Regarding the "insufficient collective pitch to take off" problem (which is very common)...
The K110 has a "feature" in that its main gear takes the brunt of most crashes. What happens is that the main gear will typically slide down the shaft (or even fly off completely).

To fix it, simply push the main gear back on snug against the lower main bearing. (There should be zero vertical play in the main shaft).

Regarding your other setup questions, you'll need to do some research on your own. Also, there is a very active K110 thread over on RCGroups where you will get a very quick response here.

Hope this helps! [IMG class=inlineimg]https://www.helifreak.com/images/smilies/icon_biggrin.gif[/IMG]
Thanks for your help and link. I’ve never crashed or even landed hard. The gear is in place. I will try that link and look out for suggestions. Thanks so much!
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Old 09-03-2020, 03:44 AM   #4 (permalink)
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Quote:
Originally Posted by gfx View Post
I decided to reinstall the servos correctly and change the length of the linkage rods.
Personally I do it for the K110 like I did on the NanoCPX:
I first fix the servo arms (90 degree to the swashplate links) and then I go for the three links to make the swashplate perfectly level.

I don't do any mechanical nick/roll (in the air) tuning by changing again the links afterwards if there is any drift.
I use another technique...


Quote:
Originally Posted by gfx View Post
Big mistake. I change the mechanics and now the helicopter doesn’t even have enough pitch to takeoff.
This probably just means that your mid point is not set correctly.

The swashplate shall be around the middle of the main shaft when you measure the back pin so you can have equal positive and negative pitch.

If it isn't, but the swashplate is level yet, you just have to equally move the three links all CW or CCW (all the same amount); start with just 1 or 2 turns depending now how you are off.


Quote:
Originally Posted by gfx View Post
Can someone please guide me on how to set up the servos and linkage rods correctly so that the swash is level and whatever?
It is VERY IMPORTANT to only do this in the 3G mode!


Quote:
Originally Posted by gfx View Post
Isn’t pitch supposed to be ZEROat mid stick or do I have that wrong?
Yes, collective pitch shall be ZERO at mid stick in 3G mode.
Ideally with no subtrim on the collective pitch channel (AUX1).

This comes later for fine-tuning (when you got the mechanical part correct and only a few mm are missing to match the both main blades perfectly).

Interestingly, I get two different results when I fold the two main blades to one side or to the other side of the plastic main holders.

If I turn the head (blade holders) for 180 degree and check again the alignment of the two main blades always on the back side I also get two different (slightly) different ZERO blade measurements and suddenly they do not match anymore like before.

https://www.helifreak.com/showthread.php?t=861273

So I always make sure that I find the "correct side" which I had done the tweaking for if I ever have to touch it again (after crashes).


Quote:
Originally Posted by gfx View Post
Plus I have no experience with these tiny little helicopters or mechanically setting up a flybarless helicopter.
The radio seems to be set up nicely. Before I mess with it pitch pumps really powerful and fast.
Hard to believe my relatively few adjustments made it so that....
Normally the K110 seems to come with uneven ail (roll) connector length.
And often the servo arm is differently setup on both AIL (left vs right roll) sides out of the box.

So if you have a different servo arm placement not going for 90 degree on any of the two roll sides, then the swashplate won't be level even if you have the same length.

And if you then try to fix the two servo arms for the correct middle position on the spline output shaft (for the best 90 degree you can get to the swashplate linkage) and you may also measure two roll linkages with the calliper gauge to have exactly the same length, then:

- the swashplate won't be perfectly level as the spline has small differences on two servo gears:
I had to move my ELEV front servo back and use it on the right roll side to make it similiar to the left roll side.
I wanted that the servo horns look almost identical on both roll sides...maybe you have to try 3-4 servos to find a good match.

- once you turn one of the roll linkages to make the swashplate level mechanically (after fixing your 2 roll + 1 nick servo arms for 90 degree):
Surprise, surprise!
Your swashplate may look now to be perfectly level even with a special swashplate leveler tool I got from the V120d02s (it is too short) or a zip tie, but the K110 might slightly drift on roll and/or nick in the air!

..(...)..

- What you probably get with a RTF:

A) They don't care for perfect 90 degree servo horns to be looking at the same mid height on both sides
B) connector lengths may be the same or not
C) if it really was test flown: Then the roll link lengths might be different because of "in-the-air roll drift compensation" (to give one side 1-2 further turns against the drift)


- If the links are different and you want to make them equal:
Then your swashplate might not be level mechanically anymore.
Forget about the same link lengths when the FBL does not allow you to properly tune the servo arms for 90 degree; there will be some difference, even if it is minor

- if you have touched the two roll links:
Then you might lose what the technican has done at the factory checking if there is any roll drift (in the air for basic hovering) and trying to compensate this with by turning one linkage

- you will have the same issue with the front elev servo:
Servo arm 90 degree (in 3G mode), getting the linkage length correct by first fitting it to the two roll linkage length, then checking if the swashplate is level and first fixing this if it is not by turning the elev rod CW or CCW.
But this does not necessarily mean that you will not experience any more or less nick drifts in flight / on hover!!

-----------------------------------------------------

If it is not the main gear:

Your touching of the three rods means that you might have moved the swashplate out of the mid position of the main shaft, as explained above.
But then you should not get ZERO pitch at mid stick.

----------------------------------------

Before you do anything:

Make sure that your pitch curve is set to 0-25-50-75-100
The "50" mid point is VERY important.

Some Normal pitch curves do use 60 or other values for the 3rd number.
Is your Hold pitch curve also set to 0-25-50-75-100?

Normally it is required to properly adjust the min/max servo travel adjust for the collective pitch channel (aux1).
You want to limit the max positive pitch to 11-13 degree by setting some distance on main blades between each other when you fold them back (like 34mm vs 40mm vs 44mm).
I can't remember right now what the correct distance values are, but they had been posted on the V977 forum once.
And there is a little trick to do some math to get the right pitch for the main blade length.

Hard to guess what is the main factor now which limits now your positive pitch (not getting enough for take off):

- if you already have tweaked for ZERO pitch and the two main blades match
- with the correct Hold + Normal + Idle Up 1/2 pitch curves (50 at the 3rd mid point)
- correctly doing it 3G mode (the biggest mistake is to do this in 6G mode - ask me how I know this )

How do your 2-3 servos arms look like? Are they now 90 degree at mid stick?
Personally I think it is better to correctly start from the bottom as this takes a longer time on this little K110 (took me more than a few hours spread over several days) with the required dismounts and factory does not seem to have the time or to get it right.....and not to start with the initial with a head / linkage setup as long as one (roll) arm is already off.

On my three K110 helis I also have done the whole head setup from scratch (starting at the servos, dismounting the servos, refitting the servo arms, remounting them+servo holder, readjusting the three link length, making the swashplate level, moving the swashplate to the mid of the main shaft to get ZERO pitch, etc.).

For any "in flight" nick/roll drift tuning there are two solutions and I will post my own solution later (I can link my comment in another thread) without you having to ever touch the push rods again after your swashplate is perfectly level.
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Last edited by Thomas.Heiss; 09-03-2020 at 04:33 AM..
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Old 09-12-2020, 12:38 AM   #5 (permalink)
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Excellent post!

There’s a ton of really good set up videos on youtube to walk you thru the heli setup and their radio setup, or a Futaba radio, calibration of the sensors and trim flight.
The lousy single page of paper they give you for instructions are pretty difficult to cypher and I love their tiny print.

Big issue I had when I got mine was the plastic head/Swash just has too much play. Good news, $20 gets you a pretty decent metal setup and without the slop she becomes very precise in the air for such a small heli. And, they crash very well.

It’s a good little mild 3D flyer, and in stability mode she’s perfect to learn to fly.

My suggestion, start out in stability mode but transition to collective as soon as possible. Newb’s have an issue sometimes of relying on stability too much and it becomes a crutch.
Just be ready to flick the switch back into stability if you get confused, and you will at first.
It’s not that hard to get used to, in normal mode your already just using the top half of the collective stick to fly. That muscle memory should be well on its way to cementing itself into your subconscious. Once it does, loose the crutch.
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