JNohsey

My Feedback: (28)

Have been having a problem trimming an couple of my fun fly planes. One of the pattern flyer's in our club said it could be the servos not re centering.

He has an board with an servo tray on one end and an ruler about 10 inch. out on the other. We put 1 of my servos in it. He put an servo arm with an piece of wire on it. We started working the servo to the left and right with the tx. and marked the positions on the ruler. It didn't go to the same spot when move to the left or right and let the stick go back to center. Some of the differences where up to 3/8 of an inch.

And yes I know fun-fly planes aren't suppose to fly straight and level, but would like to be able to trim them, where the surfaces would recenter

da king

My Feedback: (5)

sounds good but what is the ?.

JNohsey

My Feedback: (28)

No question, just want to let some know that if they have an untrimable plane they may want to look at the servos.

WreckRman2

My Feedback: (5)

What servos are you using?

JNohsey

My Feedback: (28)

Was using Hitec 425. We have check several of the Hitec that I have. 605, 525, 545 and 77. Some of the old ones I had center ok, but none of the new ones would recenter. I have just about come to the decision that I not going to be using any more on control surfaces of my planes.

WreckRman2

My Feedback: (5)

No comment... You seem to have found your problem...

Texas 3D

My Feedback: (16)

that might have been the problem with my extreme 330 ! I doubt it though because it was flying nice at the beginning and then all of the sudden would fly like crap, and I could not get it into trim anymore. I changed servos, and it remained the same. I was using Hitecs though 225's and 625's
Doesn't matter, because I threw the Extreme 330 in the trash just an hour ago. I stomped and jumped on it because it deserved no better

YNOT

We could have had a better time burning it Ulf.

Thats the same problem I ran into with regular servos on helis. One of the biggest advantages to the corless servos, better centering.

ChuckAuger

My Feedback: (12)

I was just on the verge of citing your 225 woes when Wrecker made his comment. I had a buddy who bought an Aeroworks 60/90 Edge ARF, so I read the whole 1200 (or whatever) post thread. One of the recurring themes seemed to be the centering issues with the 225's. I won't bash Hitecs, 'cause I own very few of them. But again, I own very few of them. I tried to talk Wrecker out of his purchase prior to the demise of his DP Extra...to no avail. And we know how that turned out.

I hope and wish that everybody buys Hitec servos and has great luck and long life from them, please write to me and tell me how it goes.

JNohsey

My Feedback: (28)

Wreckrman2, how you seen this or heard this before?

WreckRman2

My Feedback: (5)

Hitec 5625 held position off center on the 5th flight... here is the result:

rcman-RCU

My Feedback: (31)

All servos have "dead bands" around the center position. The servo can stop anywhere in this dead. Generally, the more expensive the servo, the smaller the dead band. You can minimize the affect of the dead band by doing two things:

1. Make sure your servo rotates the servo arm full range, usually as much as 50-60 degrees each way, for full control surface deflection. Your radio's travel adjustment and dual rate percentages should be near maximum for full control surface movement. This causes the dead band to have the least affect on the control surface.

2. Make sure your linkages have as close as possible to zero slop. Ball links on the servo arms help. Don't use worn out clevises or control horns.

3. Setup your linkages for less control surface deflection. Do this by adjusting the linkages, not reducing the travel settings on the radio!

A good share of centering problems are caused by not following these rules. If you want great centering and large control throws, you will probably have to spend more on servos.

heliplane

My Feedback: (2)

I would agree that more expensive servos are better, but if you use standard servos I think that Futaba S148's are the best....as a matter of fact one of the major R/C publications either RCM/Model airplane news or Model Aviation did a servo test and the S148's beat even Futaba's own high $ servos......I put Hitec standards on the aelerons on a Freestyle that I built for my Dad and they centered terrible.......Another thing that I have noticed is that last couple times I have had servos go bad the centering is the first thing that goes....My rudder servo on my EXT 330 which I took out of another plane went bad and it appeared to work fine but when it came back to center it would go past center then come past center the other way and then stop at center and yes my plane flew really weird when this was happening....just my 2 cents

Billy Hell

My Feedback: (2)

Now I feel concerned about my brand new Hitec flight pac with 425BBs. I haven't had any troubles listed above but all my planes run 425BBs so maybe they are the exception to the rule. I hope so.
Are there any positve Hitec servo experiences out there to help balance this thread?

heliplane

My Feedback: (2)

I don't mean to dog Hitec servos....I think that the 605's are pretty good...they don't center as good as Futaba's high dollar servos like the 9202's but are a lot faster and cheaper.....maybe to get the good centering and quick transit time you have to go digital...I wanted to try the Hitec digitals but have seen some pretty scary posts on those...I think they got the problems ironed out.....I hope so because I think that faster servos would be really helpful on 3D especially hovering...Part of the centering problem with Hitec standards might be because of the slop without a bearing so maybe the BB standards will be OK...I use the ball bearing conversions that Tower sells for my 148's and it seems to take a lot of slop out....

rcman-RCU

My Feedback: (31)

Servo wear can also increase centering problems. In general, ball bearing servos with nylon gears hold up the best. Some of the metal gear servos develop a lot of play in the gear train, which accounts for some of the centering variation.

I think faster servos will also have worse centering than slow servos. Slow servos have a longer gear train (more slop), but this is more than offset because the servo motor stopping error has less effect due to the long gear train.

I also wonder how good the centering is on those Futaba 148s after 10 hours of hard use?

GaryB-RCU

My Feedback: (3)

...yep, i saw that servo test, too - the Futaba 148's actually beat their own much more expensive servos on centering...of course, the problem is, the 148's aren't the fastest...

...to me, you can observe the Hitec 605's on the huge rudder on my Knife and tell that there is a centering problem - IMO, the Futaba 9402 centers better...but is much slower - .26 vs. .16 second response time - also, the 9402 costs almost twice as much - to get good centering AND high speed with Futaba costs $99.99 a pop - too rich for my blood - especially on a fun fly plane...

...so i use 605's on the rudder and elevator on my Knife - they're pretty fast and nothing stripped after 97 flights - on the rudder i try to split the difference on the slop - in other words, when i give full right rudder and release to neutral, there is still a little right in my rudder; when i give full left rudder and release to neutral, there is still a little left in my rudder...they work ok and the fast (.16 transit time) seems to really help out with hovering...they seem to be precise enough for my fun fly...

ChuckAuger

My Feedback: (12)

Or you can get a .14 speed/90 in oz digital Futaba (that does about .10 speed/110in oz on 6v) for $75.

Texas 3D

My Feedback: (16)

I used to buy nothing but Hitecs for a while, but have not been doing this for a couple of months now, due to all the bad comments I read on RCU . I asked myself if it justify's to save $20 for a servo and then risk a $1000 plane with them ? I buy nothing but JR's now !
All Hitec users should ask themselves the same question.
After the experience with my Extreme 330 and reading through this thread, I will definitely sell all my Hitec's now ! New and used ones !

Tony, I promise that we will burn the next one !

GaryB-RCU

My Feedback: (3)

...i observed the centering slop on Hitec 605's when installing them new in my Knife - after close to 100 flights the slop is not noticeably worse...

...maybe Futaba digitals @ $75/ea. is the way to go on rudder & elevator on the Knife - still seems a little high to me for fun fly servos - but if i was convinced it would make hovering easier i might give 'em a try...

Funtan Man

Which Futaba is that for $75? I'm putting together the 80" OHM Edge right now and that may be good for ailerons and elevators.
Thanks.

GaryB-RCU

My Feedback: (3)

...yeah, i'm curious which Futaba digital that is for $75 - i checked @ Tower's site - to get as much torque as a Hitec 605 ($29.99) it looks like you would need to get an S9250, 76.2 oz./in.; .11 transit time...Tower's price $106.99...

SMALLFLY-

My Feedback: (19)

Here we go again. Hitec 425 servos are probably the most reliable inexpensive servo's I have owned and I have owned a bunch of them (probably 25 or so) Every plane I have has hitec servos from 422's to 645's and the only problem I have had is 2 hs 77 servos burning out motors because I use them outrageously on FF rudders where they really dont belong and a few stripped gearsets from banging around in my truck. yes 300 series are crappy and the 605's never centered very well but these are many years old servo designs. the 625's and 645's center much better(although not as good as a coreless) and the 525's and the 545's center almost as good as a coreless. My futaba 3001's have given me more problems and I like my 9202 and 9102 but they are slow for the price. Any servo can go bad at any time. It is a mechanical device powered by an electrical device. The more complexity the more that can go wrong. hence the reason I shy away from digital servos holding power or not

ChuckAuger

My Feedback: (12)

The 9252 is $75, but you can't get it for that from Tower..

http://www.helihut.com/

GaryB-RCU

My Feedback: (3)

...for practicing hovering, the 645 appears to be a little slow? (.24 sec.) for elev. and rudder...the 625 is faster (.18 sec.), still not as fast as the 605 (.16 sec.) - the 625 might be a good choice...

...thanks for the Helihut link - it is now in my favorites - good price on Futaba digitals...