450 How hot does your tail servo get?

[Mda1701d]

Hello again all,
I've been flying the blade 400 a bit once more, just limited to hover practice in the garden, but now with no training gear!
Question is this.........
A while back, had a close call at the field when the tail servo bailed out at the end of the third and last battery pack. Servo was red hot. After a few tests, I fitted a new servo, Align DS425M metal gears. The esc is fairly new, a JPEG energ pro, and the Align gyro is GP 750.
I have the gyro set for digital servo, and small heli, and limits set. There doesn't appear to be any mechanical binding on the tail mechanism, and with 67% on the gain, only a very slight wag. Not bad for a very used heli!
The servo gets quite hot after a five minute continuous hover, after landing, I can bear my finger on it, but any hotter and it would be uncomfortable! The instructions state the max temp for the servo is 60 degrees, but how hot does the tail servo get on other peoples models please? I would like to know if I still have a problem before it ends up in a heap again!
Thanks all.

 

[murankar]

If your servo is getting that hot its probably a setup issue or something electrical. Something is working that servo to death. Is your setup correct on the correct on the gyro (I.e. hrz, deadband, pwm)? On the mechanical since its a new servo then is the tail control system butter smooth with zero resistance? This includes the tail hub pitch slider and the linkages.

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[Admiral]

The tail servos on my B400 only get mildly warm, the only thing you haven't mentioned with your GP750 is the Servo Pulse Length which should be 1520 for the DS425M, a slight wag will means that the servo is working constantly while you flying I would start by trying to dial that out.

 

[murankar]

Oh yeah the wag is a setup issue for sure and yes the servo is doing double work since the gyro continues to correct the tail.

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[Mda1701d]

Thanks for the replies!
Been through the heli again tonight, disconnected the servo, took the blades off, and checked the tail mech with motor running. All was nice and smooth, with no binding. Only thing found was the ball link was touching the servo body on the end point one way, not much, but corrected by swapping the ball to the outside.
The other thing I found was after a minute or so of simulating tail wag and making the servo work rapidly, it did start to get warm.
I think the next step will be to dial out the slight tail wag, even though I wasn't worried about it, as it's only a practice heli!

 

[murankar]

the slow wag is one of two things. Either the gain is to low (which is real easy to check), adjust the gain up till it is gone. If it does not go away then its the mechanical gain of the tail control system. All you would need to do is move the ball link on the servo horn one or two holes closer to center. Tail blade size can make a difference also but not that much.

 

[Mda1701d]

Thanks for the reply again muranker!
I've been messing around with the gain on the tx to try and dial out the wag, about 67% seems to fly the best, but still not quite there. Also, running the ball link on the closest hole to centre makes it better. That's when it started touching the servo body lol. Swapped back to the outside to cure that one. Now the rod is just not quite as straight as before.
Hopefully the weather will be ok tomorrow, and I won't be too late from work, then I can get a volunteer to shoot a vid of the skoda hovering so you can see how it's reacting. Might be better now without the slight bind.
Thanks again,
Mark.

 

[murankar]

Then maybe look at the size of the tail blades. Go to a 58 or 59mm tail blade. I am not sure if there is anything else to adjust at this point.

Your tail pitch slider is it the standard 450 pro style with a single ball link at the bottom or is it the same as the Dominator tha'ts an over under setup?

 

[Mda1701d]

It's got the std single ball link, and 56mm blades from what I can see. All stock blade 400. Perhaps some better tail blades would help! Not tried it again yet, too much work tonight!

 

[murankar]

I know that carbon fiber would give some results, not sure which way though (I.e. better vs worse). I know the length of the blade will have some affect also, longer blades will move more air =less gain. I wish I knew more about that 790 gyro.

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[Stambo]

I personally don't see what your problem is.
There is absolutely nothing wrong with a bit of hot tail.

 

[murankar]

That's funny. Never thought about it like that. Yes that would be a good thing.

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[Mda1701d]

Finally got the time and weather to do a quick test flight. After this short hover, servo was quite warm to the touch. Repeated the same thing, hover, land, check servo three times with this lipo, and the servo ended up as hot as the heat sink on the esc. Comments please!
The heli was bobbing around a bit due to the breeze, oh yes, and my poor flying lol!
Thanks!

Blade 400 hover - YouTube

 

[murankar]

Is it me or is there a small wag in tail?

 

[Mda1701d]

Lol stambo, I can remember the days when hot tail was available..........
In the air it does seam that there is a slight wag, the tail is very direct, but is it enough to make the servo get hot? I bought my multi meter home to see what voltage is being delivered by the esc. Will post with results. Thanks!

 

[Graham Lawrie]

There looks like tail wag and possibly an issue with cyclic? hard to tell in the video