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Old Apr 02, 2012, 07:18 PM
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Originally Posted by v8truckin View Post
speaking of your fixed wing, did you ever receive a new 1 from your vendor (not gonna mention name)?
Big, long, yellow fruit that grows on trees?
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Old Apr 02, 2012, 07:27 PM
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Australia, VIC, Melbourne
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Hmmm, "Shipped direct to CN Airport" must not have detailed the sub-info about "Using a lame-ass donkey for that 55km trip" !! My Su-35 just actually flew out of HK yesterday afternoon - err, in a box, not on its own. Many days after the original "Shipped direct to CN Airport" message.

Whilst it was good to see another Su get into the air... Xsample's... and bravely on a seemingly bit of a windy day too(!).... it sounded terrible. Twin out of balance leaf blowers.... lol. I found that a bit dis-heartening.
This thing is going to need CS10's in it.
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Old Apr 02, 2012, 07:32 PM
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United States, CA, Sunnyvale
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Maybe jittering is a bad way to describe it. It certainly doesn't move without any input from the radio. I've had Futaba and JR digital servos behave like this on some of my planes. It flys fine in the air, servos center well but seems twitchy on the bench.

Quote:
Originally Posted by Sockrat View Post
I don't think jittering is normal for any servo, especially digital. I had don't know how many different brands and the only thing i find acceptable is "singing" under load. If it jitters or sings without load all it means it can't center - either potentiometer or circuit are low quality.
Sometimes, however even high quality servos start to interfere with each other when different brands are mixed on one wire. What I saw on BH Pete's video IMHO is either a crappy servo or a very bad interference. I had a few cheapest servos (f.ex. HK orange ones) that behave that way.
Looks like Freewing couldn't go with 12g plastic servos on elevators and replaced them with 17g metal gear digital for the same price...
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Old Apr 02, 2012, 07:33 PM
Should've, Would've, Could've
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Originally Posted by xviper View Post
Big, long, yellow fruit that grows on trees?
Theres a vendor with the name Plantain ?
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Old Apr 02, 2012, 07:56 PM
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Originally Posted by v8truckin View Post
Theres a vendor with the name Plantain ?
Good one. Aren't plantains usually green when you eat them? I was talking about a zuchini. Oh, wait! That's a vegetable.
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Old Apr 02, 2012, 08:24 PM
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So far mine are fine, at least from the standpoint of twitching or making noise... I will probably replacement mine with metal Hightecs...
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Old Apr 02, 2012, 08:33 PM
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Originally Posted by v8truckin View Post
Theres a vendor with the name Plantain ?
When you need customer service it's BOHICA. Bend Over here it comes again. Ordered from them again and got lucky with the B17.
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Old Apr 02, 2012, 09:12 PM
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Starting to venture into vendor-bashing territory
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Old Apr 02, 2012, 09:13 PM
Should've, Would've, Could've
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Originally Posted by fredmdbud View Post
Starting to venture into vendor-bashing territory
knew I shouldn't have asked...lol!
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Old Apr 02, 2012, 09:17 PM
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Saying where the plane came from isn't a big deal, and the "wordplay" was OK, but BOHICA - well, that's kind of hard to miss! lol
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Old Apr 02, 2012, 09:19 PM
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Quote:
Originally Posted by Sockrat View Post
I don't think jittering is normal for any servo, especially digital. I had don't know how many different brands and the only thing i find acceptable is "singing" under load. If it jitters or sings without load all it means it can't center - either potentiometer or circuit are low quality.
Sometimes, however even high quality servos start to interfere with each other when different brands are mixed on one wire. What I saw on BH Pete's video IMHO is either a crappy servo or a very bad interference. I had a few cheapest servos (f.ex. HK orange ones) that behave that way.
Looks like Freewing couldn't go with 12g plastic servos on elevators and replaced them with 17g metal gear digital for the same price...
Turns out we are all right and it can depend on the source of the issue.
More common though has been load.

A quick scan of the Freds source, Flighing Giants, Hitec and others come back with;
Efficiency and Noise
Due to noise and control circuitry requirements, servos are less efficient than DC motors uncontrolled. To begin with, the control circuitry typically drains 5-8mA just on idle. Secondly, noise can more than triple current draw during a holding position (not moving), and almost double current during rotation.
Noise is often a major source of servo inefficiency and therefore should be avoided. Ever notice your servo jitter or vibrate? This is because your servo is rapidly jumping between two different angles due to interference. What causes this interference? Well the signal wire is no different than a long antennae, capable of accepting unwanted foreign signals and sending them straight to your servo as a command. A common interference source is usually from other nearby servos and/or servo wiring. How to prevent this problem? Keep your signal wire short, meaning do not add say 3+ feet of extension cables to your servo. If you have many servo wires going through one area, and it isn't feasible to keep them apart, then twist them together. Supposedly this reduces cross interference and I've heard it works, although I cannot really tell for sure myself. You can also buy something called a servo booster extension which buffers and amplifies the signal.

Digital servos use a high frequency amplifier that updates the servo motor position 300 times a second or at 300Hz. By updating the motor position more often, the digital servo can deliver full torque from the beginning of movement and increases the holding power of the servo. The quick refresh also allows the digital servo to have a tighter deadband.

Hitec
Q. My digital servos jitter when they are at the end of their throw.
A. One cause of this phenomenon is having a Futaba or JR transmitter with the end points set beyond 120%. Try reducing the EPA below 120% and see if this cures the issue, otherwise call or e-mail our service department.
Q. What do I do if my Servo jitters while idling at center or through its travel?
A. This may be a dirty potentiometer. Open the case and remove the gears. Spray a zero-residue tuner cleaner into and around the "pot" and work it in. Once the cleaner has dried, re-install the gears and close up the case.



HS-20100520 HS-79XX Series Servo Minimal Load Jitter
#HS-20100520 HS-79XX Series Servo Minimal Load Jitter
Applies to HS-7965/7985/7955/7954/7940/7950 servos
Customers have noticed that these high resolution servos have a tendency to jitter when using 7.4 volt power packs and a minimal load is applied. This is due to the high resolution circuit adjusting for slight position variances in the gear teeth. This usually only occurs with minimal loads, for example, when the plane is on the ground in a static position. Once airborne the servo experiences flying loads and the issue resolves itself and should not impact on the flying experience.
HS-20110524 HS-7940/7945/7950TH Jumping/Glitching
In some cases, when using the 7940/45/50's in applications that require a very long extension, they may randomly jump (glitch) when powered by 2S LiPo/Li-Ion batteries. Although this may occur with many systems, it is most commonly found when using JR/Spektrum type RX's, especially the Power Safe versions. We have discovered that due to the resistance in long extension wires, the signal voltage drops, thus causing the issue. We recommend that only high-quality, twisted, 22-guage, high strand count, gold connector extensions be used. In the event that this does not resolve the problem, there are a few options. The use of a signal line booster like that made by Spektrum, and soon to be available by Hitec, resolves the issue in almost all cases. Another option is to solder a .22 tantalum capacitor between +/- on the extension. These solutions are typically only needed when using Li-Po/Li-Ion batteries to lower the voltage below 7 volts and is not needed when using 5-cell NiCd/NiMH or LiFe batteries.

We are aware that these are high voltage servos designed to operate at the maximum voltage allowed for maximum performance. However, to accommodate some radio systems, steps may be required to assure the above issue will not occur. Hitec apologizes for any inconvenience this may cause and is working on a series of new Ultra Heavy Duty extensions (with and without boosters) that will resolve this issue.
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Old Apr 02, 2012, 10:29 PM
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Sorry I kind of got off topic.


So, I originally did a main gear alignment with Loctite, I need to do it again. Starting to crab walk. Nose wheel fine off smooth runways.
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Old Apr 02, 2012, 10:49 PM
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Had a hotter than normal touch down from unsuspected breeze and i caught the dreaded main strut n wheel turning. Really a pain in the !
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Old Apr 03, 2012, 12:55 AM
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United States, CA, Lake Forest
Joined Nov 2010
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Quote:
Originally Posted by Maxthrottle View Post
Turns out we are all right and it can depend on the source of the issue.
More common though has been load.

A quick scan of the Freds source, Flighing Giants, Hitec and others come back with;
Efficiency and Noise
Due to noise and control circuitry requirements, servos are less efficient than DC motors uncontrolled. To begin with, the control circuitry typically drains 5-8mA just on idle. Secondly, noise can more than triple current draw during a holding position (not moving), and almost double current during rotation.
Noise is often a major source of servo inefficiency and therefore should be avoided. Ever notice your servo jitter or vibrate? This is because your servo is rapidly jumping between two different angles due to interference. What causes this interference? Well the signal wire is no different than a long antennae, capable of accepting unwanted foreign signals and sending them straight to your servo as a command. A common interference source is usually from other nearby servos and/or servo wiring. How to prevent this problem? Keep your signal wire short, meaning do not add say 3+ feet of extension cables to your servo. If you have many servo wires going through one area, and it isn't feasible to keep them apart, then twist them together. Supposedly this reduces cross interference and I've heard it works, although I cannot really tell for sure myself. You can also buy something called a servo booster extension which buffers and amplifies the signal.

Digital servos use a high frequency amplifier that updates the servo motor position 300 times a second or at 300Hz. By updating the motor position more often, the digital servo can deliver full torque from the beginning of movement and increases the holding power of the servo. The quick refresh also allows the digital servo to have a tighter deadband.

Hitec
Q. My digital servos jitter when they are at the end of their throw.
A. One cause of this phenomenon is having a Futaba or JR transmitter with the end points set beyond 120%. Try reducing the EPA below 120% and see if this cures the issue, otherwise call or e-mail our service department.
Q. What do I do if my Servo jitters while idling at center or through its travel?
A. This may be a dirty potentiometer. Open the case and remove the gears. Spray a zero-residue tuner cleaner into and around the "pot" and work it in. Once the cleaner has dried, re-install the gears and close up the case.



HS-20100520 HS-79XX Series Servo Minimal Load Jitter
#HS-20100520 HS-79XX Series Servo Minimal Load Jitter
Applies to HS-7965/7985/7955/7954/7940/7950 servos
Customers have noticed that these high resolution servos have a tendency to jitter when using 7.4 volt power packs and a minimal load is applied. This is due to the high resolution circuit adjusting for slight position variances in the gear teeth. This usually only occurs with minimal loads, for example, when the plane is on the ground in a static position. Once airborne the servo experiences flying loads and the issue resolves itself and should not impact on the flying experience.
HS-20110524 HS-7940/7945/7950TH Jumping/Glitching
In some cases, when using the 7940/45/50's in applications that require a very long extension, they may randomly jump (glitch) when powered by 2S LiPo/Li-Ion batteries. Although this may occur with many systems, it is most commonly found when using JR/Spektrum type RX's, especially the Power Safe versions. We have discovered that due to the resistance in long extension wires, the signal voltage drops, thus causing the issue. We recommend that only high-quality, twisted, 22-guage, high strand count, gold connector extensions be used. In the event that this does not resolve the problem, there are a few options. The use of a signal line booster like that made by Spektrum, and soon to be available by Hitec, resolves the issue in almost all cases. Another option is to solder a .22 tantalum capacitor between +/- on the extension. These solutions are typically only needed when using Li-Po/Li-Ion batteries to lower the voltage below 7 volts and is not needed when using 5-cell NiCd/NiMH or LiFe batteries.

We are aware that these are high voltage servos designed to operate at the maximum voltage allowed for maximum performance. However, to accommodate some radio systems, steps may be required to assure the above issue will not occur. Hitec apologizes for any inconvenience this may cause and is working on a series of new Ultra Heavy Duty extensions (with and without boosters) that will resolve this issue.
Interesting..
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Old Apr 03, 2012, 03:48 AM
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USA, CA, San Francisco
Joined Dec 2009
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Quote:
Originally Posted by v8truckin View Post
speaking of your fixed wing, did you ever receive a new 1 from your vendor (not gonna mention name)?
They did better than that. To make up for the trouble and aggravation they actually sent me a whole brand new SU-35, no questions asked. I was happy with that final resolution and they gained my confidence again. I have since bought from them again and had the usual fast shipping and great product.

I thought about keeping it as a spare or selling it on RCG but in the end I decided to sell the brand new jet to vhuang168 at a good discount since he helped put my original one in the air by giving me a few of his crashed parts, without which I would have been grounded for a month.
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