HardDeck

Hello all

I am enjoying H9 330L with ZDZ 80, but have concerns about aileron flutter in flight. Have JR 8611 single servo for each aileron, and can see flutter on low pass and when hovering. Set is by the book re throws, and all of the slop is in the servo gear train. The servo are new. I don't really think flight performance is issue, but I am worried about safety. I know H9 uses 2 aileron servos for each wing in later version (330S), but not sure why as 8611 have plenty of torque.
Interested in comments / suggestions.

Thanks
RJM

SydDythers

My Feedback: (5)

Did you seal your hinge gaps?

rmh

sealing gaps only acts as a movement damper
Use 6V- set servo such that it has maximum throw (150% on JR Radios) THEN set aileron linkage for max throw you will ever need and that should not be over 40 degrees each way.
- Max intended throw must be at max possible servo rotation.-max ATV
Do not use long arms -then cut back on servo rotation -this kills effective power. Badly.
If you use say -70 % expo-- the aileros can typically be left in high rate for all flying -then uses a switched setup for elevator and rudder for precise, non agressive 3D flying
The servo has gobs of power for this setup and one aileren servo per side -done with NO slop and bending is fine I used 8411's for same setup on some of these models we setup-- never a hitch
I never seal my hinge lines - just make em close to flush fit-
The new 8411A is almost 300 in ozs torque at 6V

as722

My Feedback: (1)

Flutter in a hover ?

Diablo-RCU

My Feedback: (1)

The 8411 and 8611 servos quite often develop major gear slop after little use. I've observed this flutter issue with them too in friends' planes. I hear this problem has been solved in the new version of this servo.....the "A" version.

jjamesrb

My Feedback: (39)

I sold all my 8611's because of the problem you are having with the gear slop.I had only 30 flights on my 40% carden and came by with a slow pass and the elevators were fluttering like a birds wings i landed immediately checked the servos and linkages and there were tons of gear slop.Sent them in to horizon and after 3 weeks i got them back, in the mean time i switched all the servos to hitecs 5955's titantium gears and have not had any slop yet in quite a few flights. I called Gene at troy built models were i bought the servos and he said , oh yea most guys that buy them have to send them in between 50 to 100 flights to have the gears replaced (which is free for 3 years with warranty) not for me i'm not going through that bs, and to think i would of missed 3 weeks this summer waiting for them to return them to me.The new 8611a isn't going to help the problem, they have more torque and improved cases(cases will help if the pin breaks the case housing) but still have the same gears (metal).After putting the hitecs in i had to raise the expo because the responsiveness was much greater because there wasn't any slop in the surfaces.I've had to dial down the expo because as the gears worn it wouldn't react near as fast.Try the new hitecs i think you'll be impressed, i know i am (plus there programmable and you don't need matchboxes).

thedak

My Feedback: (21)

Buy some real servos


HS-5955TG

3D ONdaEDGE

This is something new to me. I bought 8611A because I had only heard good things about the 8611. I read hundereds of flights with no slop. I do know that the 8411 were only good for less than 100 flights but not the 8611. Im intersted to see how everyone feels about this.

Josey Wales

My Feedback: (61)

I have over 100 flights with my 8611's with not a hint of a problem..I wouldnt put a Hitec servo on any plane I really cared about..but thats just me

PaulBK

the 330 is designed for two aileron servos per wing, with the slots already cut out in the wing...the ailerons are big..big enough that i doubt there is enough rigidity in the surface to be driven by a single servo. i don't think what you are seeing is servo slop, i think what you are seeing is the result of not properly supporting the aileron at more than one point.

Robotech

My Feedback: (9)

If memory serves me the original Extra initially was shipped with wings setup for one servo. I also believe H9 replaced them at no charge due to the flutter problem you are describing.

Tired Old Man

My Feedback: (1)

Hundreds of flights on 8611 servos, still no slop. Then again, My linkages are installed with extremely little to zero play at the connection points. Standard clevisis are never used, preventing a lot of play from day one.

Ronbo

My Feedback: (12)

i have over 75 flights with the 8611 on the original single aileron H9 330L. the aileron is quite rigid, sealed hinge gaps. John VH did a thread on his conversion of his cap to single servo with 8611's, and 3d the hell out of it. saw the video. there are even those that use it on the H9 Ultimate, 1 servo per surface. Im going to too on my Ultimate. My other extra has the dual servo wings, but i have 4721's and like almost 200 flights on that setup. these are non metal geared. they are sealed as well as good hardware.

HardDeck

Thanks everyone for comments. Didn't expect such a flurry of responses. I am certain that the problem is in the servo gear train as there is absolutely no play in the linkages. The gaps are sealed. I do have a lot of flights on the plane, and I am interested in the comments re relatively limited number of flights before need for rebuild of the 8611 (and 8411 which I have on elevators). I am not sure that what I see in flight is really "flutter" - rather may just be vibrational manifestation of the servo/gear play at neutral - that's why I see it in hover - but I am concerned that this play may develop resonant flutter at speed and bring the plane down.
I am going to send the servos in to JR for rebuild - maybe buy some 8611a in the mean time (or HS5595?)-- will JR up grade my 8611 to 8611a?? Can I expect better performance going forward? I guess these are questions for JR. By the way, this plane (H9 330L) was designed with one servo per aileron whereas newer H9 330S is designed with for two servos per aileron -- and since all of these new big servos have more than enough power to run an aileronon one servo (with reduction in complexity etc) --- I am wondering why Mike / H9 went with two in the newer model??
Incidentally we recently had a world class pilot visit here and I spoke with him while looking over his plane and noticed that none of the gaps were sealed -- said he never does that anymore -- just tight fit at hinge line!?

sillyness

My Feedback: (25)

Why not seal the gaps? Do it while watching the Simpsons... just doesn't make sense not to.

Has anyone actually heard of a case of a well set up plane with 8411s or 8611s developing no kidding flutter? We used to fly these planes with sloppy gears in regular old coreless servos... I can't believe the new 8611s are any worse!?!?! I like all of my 8611As and 8611s (new cases).

Ronbo

My Feedback: (12)

I believe part of the reason for 2 servos mod was liability. but perhaps the real reason is that at that time, only the 8411 torque range was available then. now we have servos in the 200-300 oz torque range that even do fine on 35% models, as a few have posted in the past here, single servo setup. The extra 330L is actually 30%. If you are worried about the servos, send them in. JR should replace and upgrade them to A version.

rmh

Sealed gaps - If it works for you do it - but it has nothing to do with flutter-other than acting as a movement damper.
The reason for the two servos on first H9- was that too many servo setups are simply put - horrible .
Long arms on servos that twist - servos with huge deadbands low voltage 4.8 setups on cheap servos etc..
So the BEST route is similar to full scale -- attach at two, widely spaced points.
If the aileron is stiff /and pretty much twist resistant, then one good servo setup is fine.
Tapered ailerons are more resistant also.
Horizon did replace some kits due to the single servo setup -
Frankly I think they bent waaaay over backwards to satisfy complaints from sources which could bust an anvil with a rubber mallet.

drbebob

"Flutter" while hovering is probably not FLUTTER. Have you ever held on to the TE of your ailerons while you slowly rev up from idle while still on the ground. That vibration is probably what you are seeing. I assume you are using a twin gas two stroke motor which are all simultaneous firing and have moderately low vibration. If you are using a big single that would probably be more suspect since they have larger rotational vibration amplitudes.
I previously posted about my 29% Katana with tail "flutter" which is more likely to be a rotational vibration caused by a large amount of turbulence from the wing roots and the inherent rotation vibration of a single cyl 50cc motor.

rmh

The twins have the SAME low speed vibrations -which aren't very strong unbalance problems- simply the reaction of prop being accelerated.
The worst are large single four strokes -the reaction and then acceleration of the prop creates some pretty strong airframe pulses.
Even loyal diehard fans of twins admitted , my large single cyl gasser actually was as smooth or smoother at idle -
However at 2700 3000 rpm the singles all have a "node" caused by the inherant unbalance The engineers select this spot (typically) as it has to happen somewhere and all in all best spot .
Some are worse than others -It takes a well matched ignition to get it right.

Steverin06

My Feedback: (25)

My 40% extra would do the exact same thing. During a hover or harrier, I would routinely see the elevators(2 8611s each) and rudder(3 8611a's) wiggle quickly as if they were fluttering. It's not fluttering, it's gear slop. After about 30 flights on the servos is when I really started seeing it happen. The gearing on these servos is crap.

drbebob

another thought for "sillyness". Don't forget to balance your prop. I imagine that vibration node that Dick is talking about is about at the rpm that most folks run when they are "3D-ing". I have been using JR servos for years and refuse to acknowledge any problem with their product (except for the 703 retract servo) especially their new digital servos, they are as solid as can be; which doesn't mean they aren't sucseptible to misuse. I have started running gas in the past year and have a pair of DA50's. I have been very impressed with their minimal vibration. Somebody did their counterbalance homework. I have not run a gas twin but have run a Saito 300 for a number of years and will say that the 4 stroke twin has almost no vibration while singles are notorious for shakin the shack. Dick, I still think that the gas twins have to run a bit smoother due to the cancellation of reciprocating movement of the two pistons. What large single are you running? If it has reasonable vibration levels I may need one. Nothing like the torque of a big single as most dirt trackers will attest to.

Bob

rmh

I run the ZDZ80-s and the typical best 3D propping is above the 3000 rpm -during hover stuff

Power absorbed by prop is not linear - by any means . I will tach mine on hover using the new ignition/tach setup.
I have to take off and fly lower power than hover -to dod this as the tach records max in air rpm.
It will do this easily tho as take off can be at very low rpm . H9 EDGE 22 lbs
In air level flight is 7200 to 7400 full speed on 26x12 ZM PROP. And that is waaaaay too fast for IMAC!
I am guessing at roughly 4000 rpm hover -which would be under 1/2 stick on the Tx
The transition vibe is low -I have no problems with servos
My servos on this plane ar 8411a on rudder (one is plenty) and 8411's elevator and 811 (4) on ailerons
Everyone poo poos the 811 but I have done a few 33% setups with these on ailerons and 6V- No problems and great -fast response - Not as fast as 8611's I did on one but really very good.

BHunn3

Wow,

for ages all I have been reading is crap about how Hitec digitals are the worse servo out there - go buy JR8611's. Now the JR's are crap and we are suppose to go buy Hitec. My, how the world does turn. so lets see, no Hitec, no Jr. Hummm doesn't leave us much does it. []

sillyness

My Feedback: (25)

Why is this thought for me? Me loves me 8611As!

Floater-RCU

"I have been using JR servos for years and refuse to acknowledge any problem with their product"

Gee Bob don't we go through life with an open mind.
Personaly I will use either Hitec or JR, but I've been around enough years to know that brand loyalty can make some people pretty blind.
Floater