alternative tail servo question (update) 2 WITH TEMP READING

[larry1]

Well, after getting tons of help from Chris with my heli I finally got it in the air again.

Although I cannot get rid of the hot tail servo syndrome with the 9254 / 401 combo .

I was thinking of trying a futaba 9402 high torque and fast analog servo before I throw in the towel.

Any and all opinions with using this servo is appreciated.

[Alfred]

Can you tell us what you have tried?
As an example, have you adjusted the maximum throw on the gyro for the rudder servo?
It might be hitting the mechanicle stops and stalling.
I am obviously guessing here as I don't know your expeirience with helies/gyros.
I have three GY401's and the latest is using 105mm tailblades on a Stratus.
Not being a hardcore 3D guy, I am not pushing the gyro/servo to the limits the 3D guys do.
I have tried some hard piruoettes on the Stratus and it's piouretting rate and stopping power is just awsome. I was a lot more worried about the tail gears then the gyro/servo combo.

[flyinfool]

How hot is hot.
The 9254 does get rather warm in normal use.

Also check for; (in no particular order)
1. too high of gain.
2. binding in the linkages (new tight ball links?)
3. Improper end point adjustment.
4. too long of servo arm.
5. More than 5 volts to servo.

[larry1]

real hot, almost to the point where you cannot touch the servo.

I have tried low gain, high gain. I have set the tail per Chris's post on the other site.
no binding at all. Smooth as silk.
The only thing I could think of is the g26 engine may be out of tune. Although it runs great (at least I think it does) and is not erratic at all.

small servo wheel

the reason i ask about the 9402 analog servo is because i am not a hardcore 3d guy. I want reliability out of the tail.

I mean, all I can do now is hover for about 5 minutes and thats it. Servo is smoking hot by then.

[BobbySmith]

What servo wheel are you using?

[larry1]

the smallest wheel that came with the 9254

[Alfred]

That servo is cactus.
If it's pretty new, send it in for replacement/repair

[larry1]

servo is brand new. maybe a total of 10-15 minutes on it

[BobbySmith]

larry try the star looking arm and put it in the outer hole. it is 12mm off center and see what happens.Also reset all youre gains and endpoints

[larry1]

ok, i will try it and post back tomorrow evening

[Malorie]

Are there any shakes in the bird that may be causing the gyro to overwork the servo?

Just a thought,
Malorie

[larry1]

no shakes that are unordinary.

although i do see the rear vertical fin vibrate a slight tad at the bottom.

[larry1]

to my original question, has anyone tried a 9402 servo on the tail?

[ShawnK]

Not me.

But let's make sure that we're not overlooking anything before you just go out and buy another servo...

* What is your limit pot set to (on the gyro)?
* What is your delay set at?
* Is the DS switch on?
* What are the ATV/EPA settings on your radio?
* How much gain are you running? (And what radio are you using?)

More often than not, I see people running waaaay too much gain on their gyros. Many people (I'm not impying you here) crank their gyro gain up until the tail wags, then back it down until it just stops. That still beats the crap out of your servo. The way I would suggest you set it is to turn it down until it starts to drift, and then turn it back up just enough to stop the drifting. This will help prolong the life of your servo dramatically.


By way of example, I have a 601 in my bird, and it works best at around 36% gain. I would suggest that you lower your gain down to the 35-40% range, and retry.

But first things first... what do your numbers look like? And if you can get an exact temperature (like with an IR gun), that would be helpful as well.

[larry1]

ok my limit is set at around 100-120
gain is at 80% with a hitec eclipse 7 transmitter
epa is at 100% factory setting in radio. is that what it should be at?
delay is at 0
digital mode is on on gyro

i dont have a temp gun, although it is very hot to the touch. cant hold hand on for more then 5 seconds

i was going to try it again today. Although work came up :roll:

i will try the larger servo horn on tomorrow and try lowering the gain

[ShawnK]

Personally, I think your gain is about 40 points too high.

I'd leave your limit setting where it is, leave your EPAs on the radio where they are, and just turn down the gain.

Incidentally, the servo is going to get hot. It's just what they do. Keep in mind that the way your 401 gyro works in heading hold is buy constantly feeding signals to the servo in order to calculate it's positional drift, so it's not as if the gyro just sits there until the heli starts to move. It's being fed update information the entire time the radio system is on. As such, that little motor is wiggling back and forth quite a lot. Doing so generates heat.

As a matter of history, my 9253/4 on my EB used to run 110-120 degrees on every single flight, but it never gave me any signs that it wasn't able to handle it.

Someone will probably jump in here and disagree with me, but I'd say that you need to turn your gain down (as I described above), and just fly the helicopter until it gives you a serious reason to not fly it. A hot servo isn't necessarily a sign that something is wrong... for a tail servo, a certain amount of heat is just the Cost of Doing Business.

In other words, don't assume it's broken until it's actually broken. :mrgreen:

BTW, I highly recommend against using a longer servo wheel. Doing so will cause you to reduce your travel limits (they need to be around 100% or so on a 401 anyway), which will actually make your servo work harder because it doesn't have as much "wiggle room", and you'll actually decrease your torque to the tail rotor (if that doesn't make sense, PM me and I'll explain why that is). You're cramming too much work into too small a space to move. That tail servo needs to rotate, so don't choke it down by using a longer servo wheel.

[Alfred]

the 401 is not the 601.
But 80% gain is too high.
All three 401's of mine are at 55%-70% gain with 70% being the absolute upper limit used on a heli for FAI style flying and 95mm instead of 105mm tail blades on a 60 size.

[larry1]

well i had my gain at 35-40% and tail servo is still hot. I can only hold it for about 10-15 seconds before it gets very uncomfortable.

This was about 2 weeks ago when i last tried it. It was 90 degrees outside and very windy. Not sure if that would have anything to do with it.

[ShawnK]

Larry, I'd quit trying to fix it unless it's actually broken. Yes, the servo gets hot... it's going to!

A hot servo is not necessarily an indication of imminent failure. Unless it's giving you an actual, definitive demonstration of poor performance, I'd just stop worrying about it and go fly.

My .02... there's bound to be differing opinions.

[larry1]

update,

well, i flew 4 tanks today. First time its been flown in weeks.

Boy, this eb sure can roll, loop, and fly inverted nice.

Upun landin after 15 minute flights I noticed the tail servo is a bit cooler now that it isnt just hovered.

I am going to put a temp gauge to it tomorrow if possible.

QUESTION!! What is the normal operating temperature range for the servo?

Also, I just put the aluminum fancy carb spacer on and was wondering where I should set the needles. Back to 1 3/8 low and high?

I had Gary's dvd but for the life of me i cannot find it. I am not sure what i should be hearing and listening for with the motor. :roll:

Again, gassers are new to me. Excuse the ignorance.

thanks

larry

[larry1]

Here is my update.

outside temp . 85 degrees with 7 mph winds.

After two consecutive 10 minute flights I took many readings on the servo and engine with a ir gun. please review.

Servo temps were 93,97,85,102,108,112 degrees. depending where the reading was taken on the servo.

engine temp was 214, 235 next to the spark plug.

needles set at high end 1 3/8 approx and low end a screwdriver width leaner then 1 3/8

this is using 5oz oil per gallon fuel and running one of those cool aluminum carb spacers.

let me know what you think.

larry

[cbergen]

How did the engine sound? How did the power feel?

How did the tail work?

There are too many variables to try to guess on temp alone, unfortunately.

If one engine runs at 260 degrees, and runs fine, good power, no problems, and another engine runs at 230 degrees, runs fine, good power, no problems, then what's the difference?

I truthfully have no idea, nor care to know, what temp my engine is running. Mine may be different than yours and it is unnecessary to chase temps if the engine is tuned to run smooth with good power.

If the tail servo is working, holding the tail, doing what it is supposed to do, if it is a little warm, OK. If it's NOT working, and is blistering hot, then you need a new servo......

There is no set temperature that says, "OK this # is too high, do this to fix it".

[larry1]

Cool Chris.

Just paranoid here after loosing the last servo.
I never imagined how nice and responsive this bird would fly knowing the size of it.
I have a new favorite in the stable. Love it!

Power feels goodand sounds good. Tail holds just fine with no drift. On full punch out and hard manuvers it does bog a bit. I am not sure what that is telling me? maybe a hair to lean or rich?

Pitch range is 9 -9 with the 800mm blades.

[cbergen]

Oh, I understand about the paranoid part!! :D

Sounds like some slight tweaking of the throttle curves, and maybe some cyclic to throttle mixing to add a little throttle in hard cyclic moves will add some more zest!!

[Filmflyer]

Larry1
How much time do you have on your motor and what mixture. I ran into the same problems with the Observers. kept getting hot servo's on the tail. figured out that the motor although sounding great was still kicking a little and causing problems with the tail servo getting hot. What I do now is break the motor in without having the Gyro gain on at all. Juast set it to 0. if you tail is set up right it should hould a hover with out very much input at all. Just my 2 cents.