Lepton/airtronics opinion/experience?

[lockheed]

My problem is with those airtronics servos 94761Z, and before I invest in a different brand I want to know if in your case you are satisfied. If I put my radio on, swash plate mid stick, 2 of them, elevator and pitch, have a play of about 1.5 mm. which translate into an unstable hovering. It seems that those arm or the gear inside will stretch and develop this loose setting. I did replace one gear set even tough thet look normal, but it lasted about two flights and it came back!
Your experience with those servos could help me,

Regards

Mike

[lockheed]

Just talked with a fellow member here, and same problem with is lepton, hovering is not really a relaxing story, but once flying ok.
Went back and inspected my heli and I noticed that the radius block is kind of loose on the mainshaft. I did swap with a brand new one and it's the same...
Anyway I would like to hear of lepton flyers that have a rock solid feel on their machine...My experience with T-rex 450 on 4 S and .90 Freya is nothing to compare..

Regards
Mike :arggg:

[tday]

what is the radius block---is that the slide block in the washout assembly? Anyway, I'm not sure what you're referring to.

And when you describe play---you mean you're able to move the swash plate 1.5mm at the elevator link and the blade grips have slop of 1.5mm? That's probably not the servo, do you think---but a first step is to isolate where the slop is.

Mine has no servo slop at all and none at the swash plate---rock solid. The washout isn't as solid as the rest with the control arms having a little side to side play that leads to a little play at the blades but surely not 1.5mm. I've replaced some links after being a little aggressive with the jr servo link ball tool with a few of the first ones. I haven't seen even a little bit of instability flying, though---unbelievably steady and hovering in a gusty wind is very steady too.

Tom

[avatar71]

tday, what is your hardware config?

[tday]

I have a very nice 4s set-up: hyperion z3025 10 815kv motor, an align esc (does the job but the gov function isn't up to the task---so I use throttle curves and mixes), medusa 3a/6v bec, airtronics 94761Z servos, logictech 6100t gyro/tail servo with 68mm hard plastic tail blades, and mah 425mm lepton cf blades. My radio is the dx7--fast response and small receiver.

I was thinking about the elevator play---and I had some play when I was going through my first few flights and getting things set-up. The elevator front lever is tightened to a flat spot on the lever shaft (right word?). I wiggled the lever as I tightened it to the flatspot---but didn't get it set just right at first. A few hard maneuvers and it suddenly had play at the flat spot and was hard to control. I re-set it and voila---beautiful from then on. Perhaps that's an issue with lockhead's bird?

[TMoore]

Are y'all running the arms that come with the servos? The only thing we've noticed on the Leptons is that radius block is sloppy that's why my friend tnbulldog machined up a couple to replace the stock one with. So far it hasn't made a huge impact on the hover stability.

What we have noticed is that the ball links are tight on the machine right out of the box and have systematically gone through the system and after about 30 flights started sizing key links to remove any stick slip from the control system. This is NOP for me anyway as I don't size links right out of the gate.

These servos are typically tight right out of the chute.

TM

[tday]

good point---I do my sizing up front and I did notice that the little ones on the head are *very* tight. Missed one on my first pass of sizing and things were sticky for sure!

[toyturbo]

Definetly make sure that all the links are nice and free with no binding. I got all my links like that and this bird hovers silky smooth!

[lockheed]

Yes Tday, it is the slide block. To make it clearer with my airtronics servos, I have two of them that have a play, meaning I can move the servo arm about 1mm play, but the motor inside the servo is not moving, hence a slop...I think this is why I am getting instable hovering....

[tday]

Yes, absolutely---there is no play at the servo horn. It's possible that the servo horn you're using is for a futaba servo (saw that watchout on finless' build videos). I'm told they fit, but are a little big/loose and that would cause some slop. I happen to use airtronics servo arms---found some nice, light nylon airtronics horns at Tower and there is no movement of the servo horn on the servo...and no movement or play in the servo gears.

If you have a question on this and you're using something other than airtronics specific horns---perhaps you could put one of the servo horns that came with the servo to see if they wiggle as well---if not, then it's the horn. If it still has play---it will be in the gears or someplace else within the servos. At that point I'd send them back, presuming they've not been crashed.

Tom

[avatar71]

i am using the aritronics horns and also have a bit of movement as well. Servos are essentially brand new and have only had one real flight on them.

what gyro gain is everyone using???

[Finless]

Yes, absolutely---there is no play at the servo horn. It's possible that the servo horn you're using is for a futaba servo (saw that watchout on finless' build videos). I'm told they fit, but are a little big/loose and that would cause some slop.


I have since replaced those arms FYI... I do have a trick to keep the hitech arms tight on the futaba splines but if not done right... well.. thats why I dont share the trick. Anyway I have since replaced mine with proper arms and drilled my own wheels.

Bob

[TMoore]

Yes Tday, it is the slide block. To make it clearer with my airtronics servos, I have two of them that have a play, meaning I can move the servo arm about 1mm play, but the motor inside the servo is not moving, hence a slop...I think this is why I am getting instable hovering....


Is the radio system powered up and running when you feel this slop you are talking about?

TM

[lockheed]

Just to confirm they are the airtronics arms, and I also have new one in stock, and they also have a play when installed, on two out of three servos!! :dontknow

So I opened the one with the most slop and....and....and the main gear the one actually where the arms goes in has some not broken, but bent teeths, and they are metal hence that slop. Now it has not been crashed, and removing all 3 of them, the swash and everything else is smooth as silk so no binding here. They are on their way to airtronics, suppose to be on warranty.
I run medusa BEC on 6V, using the last hole on the servo arm in order to be parallel with the pushpull lever. Now I wonder if I should not use the middle hole in order to give those gear a little rest :idea:
Anyway most of you don't seem to have any problem with those servos, so I guess it should be ok when they come back.

Let me know what you think of using the middle hole on the arm, any of you set up that way?

Thanks

Mike

[lockheed]

To Tmoore: on or off the play was there.

[TMoore]

I just checked 10 of the 761's that I have and they are all tight.

If you are seeing this much slop there is something seriously wrong. These servos use a 3 pole standard motor so you really can't even move them by hand like you can with a coreless motor servo. They utilize an aluminum output gear that is a gear sector so it's not machined all the way around like some other output gears. The rest of the gear train is a combination of plastic and metal gears.

Try using a JR servo arm and see if the slop goes away. JR arms are the same spline as ATX.

TM

[tday]

Mike---you can't change the geometry when using push/pull like eCCPM uses. Everything needs to be exactly symetric. But beyond that, moving to a hole closer to the spline requires more servo torque not less and stresses the servo more anyway. Gears can wear out but regular use doesn't bend them like you're seeing. Something else happened. Tom

[lockheed]

Ok Tom for the geometry, but for the stress I have to disagree... :lol:
The furher away on the arm, the harder for the servo.
Example, imagine a one foot long arm, and you hold it at the far end with your finger and have someone activate the servo, you will be able to resist the servo and probably prevent it for moving at all. On the contrary hold it at the beginning of the arm and do the same...it will require lot more strenght to stop it, at least that is the way I see it;

further equals more movement for same arc travel meaning faster, and closer less movement hence slower, but more torque :idea:

[tday]

Oops, what *was* I thinking?