November 23, 2024, 04:53:00 PM

Author Topic: Servo Question  (Read 4189 times)

Offline Chris Wall

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Servo Question
« on: August 13, 2014, 02:35:04 PM »
Alright, I know the Futaba 255HV/256HV (272SV/274SV) servos have been discussed in many threads, but I have to ask - why does everyone like them so much?  I am about ready to purchase another set of servos to get rid of the RJXs in my fleet (tired of having to re-initialize 2 - 3 times every flight - and yes I am running a 2S lipo).  When I look at the specs of the Futaba's versus other name brands the torque values seem to be lower than comparably priced and lower priced servos (they are fast though).  I do have a few sets of the Torq/MKS servos, but I was looking to try something new...  I am running mostly vbar silverline as my FBL.  Is torque an overrated spec to look at?  Thoughts?
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Offline Chris Sexton

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Re: Servo Question
« Reply #1 on: August 13, 2014, 03:20:50 PM »
I have played with servo brands and models.  I am personally loving the BK servos, the combined value with stats are great

That being said, I have 4 sets of BLS255/256 servos in operation right now.  My favorite part is the efficiency and low maintenance.  The power consumption is just ridiculously low. They are super smooth and hold up very well in a crash.  I don't know if Futaba tests their servos differently or if all the other servo makes are flubbing their numbers, but for the stated torque on the Futaba BLS servos, they hold up just as strong on my speed machines as my higher torque models.

When you are flying 1500-2000 worth of machine you want servos that you trust.

Just my 2 cents.
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Offline Rodney Kirstine

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Re: Servo Question
« Reply #2 on: August 13, 2014, 03:27:43 PM »
You definitely can't go wrong with Futaba servos.  They work really well and they last a long time.  As Chris mentioned, they're very smooth and also efficient.

I have BK servos on two of my helis now and am very pleased with them.  They are really quiet and smooth and the cases and gear trains are very nice.  I also have RJX servos on both my N7s and have been really happy with them, too, though.  I guess I'm lucky because I have never had the init problems with the RJX servos that a lot of people seem to have.
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Offline Richard Rollins

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Re: Servo Question
« Reply #3 on: August 13, 2014, 07:48:06 PM »
I have all futaba 255/256 on my birds , but at IRCHA I wanted to try a different tail servo so I bought a BK brushless for n5c and so far love it. Very fast and efficient but not as efficient as futaba.
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Offline curmudgeon

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Re: Servo Question
« Reply #4 on: August 13, 2014, 10:05:29 PM »
I am about ready to purchase another set of servos to get rid of the RJXs in my fleet (tired of having to re-initialize 2 - 3 times every flight - and yes I am running a 2S lipo).

I don't know much about the RJX servos, but it seems to me that you may be looking for servos that perform very well, but that are also efficient enough to work within the current limitations of your system.

I power the electronics on 5 helicopters with the BEC Pro with 6S input and 7.5V output.  For cyclic servos, I use the Futaba BLS 255HV's and the MKS HBL 950HV's.  For rudder, I use the Futaba BLS 256HV's and the MKS HBL 980HV's.  I cannot get the system to brown-out at the bench with the VBar Pitch Pump Test (VBar Silverline Pro, Pitch Pump 100, Tail Torque Precompensation for Collective 100, and Tail I gain 0) with any combination of cyclic and rudder servos in any of the helicopters.  Interestingly, I can get the Align DS620/DS650 servos at 6V to brown-out the system with VBar Pitch Pump Test.  Also, unlike the annoying buzzing noise of the Align DS620/DS650 servos, these Futaba and MKS servos are Prius quiet.

Although both the Futaba and MKS servos perform excellently, I prefer the MKS whenever possible.  The MKS have a sexier metal case, have all metal gears, and are generally cheaper than Futaba.  The MKS also have less slop than the Futaba's when tested by hand.  However, the Futaba servos are shallower so they fit perfectly on the Synergy helis.  The MKS are deeper, so generally need to shim the left and right cyclic servos to avoid butt-to-butt contact.  Still, pilots claim no impact or detriment in head geometry from shimming the MKS servos.

Now that the Futaba 255/256HV servos are discontinued, and the 272-274SV have a substantially higher price tag, I don't know if the higher price tag is worth it for the average pilot.

I would be interested to learn if the BEC Pro with BK servos combination at 7.5V can survive the VBar Pitch Pump Test.

Offline curmudgeon

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Re: Servo Question
« Reply #5 on: August 13, 2014, 10:07:59 PM »
...I bought a BK brushless for n5c and so far love it. Very fast and efficient but not as efficient as futaba.
How can you tell that the BK's are not as efficient as the Futaba's?

Offline Mike Spano

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Re: Servo Question
« Reply #6 on: August 14, 2014, 09:50:30 AM »
i fly savox servos in most of my birds now. i still have a few sets of torque servos in service, and my N7 has the futabas that your talking about in them. i like them all. i have had a few torque tail servos fail lately, i am stepping away from them....

i personally am not drinking the futaba "cool aid" and going to say they are absolutely the best. my savox servos are supposed to have much more torque and still just as fast....they also look much better. to date i have not had one fail either (about 150 flights on them now). and these are installed in my gasser, aka vibration machine....

the futaba servos seem great, but the low torque ratings scare me a bit for a heavy 700 like an E7 or a gasser. the N7 is light though, so i don't worry about it....
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Offline James F

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Re: Servo Question
« Reply #7 on: August 14, 2014, 10:10:45 AM »
I have the same servos in my e5 that were in my gasser.  Still going after totalling my e5.  Savox btw.

They are a bit more power hungry but my wr super bec pro witb powerbus has no issues.  Even doing manouvers with high forces on the servos in the gasser they did not fail.  BTW doing any 3D with a G20 when people around say it can't do is so much fun.  I had alot of interest in my setup at last years helis east by those running the same heli.  It had some presence in the air.   Can't wait to get the funds together to rebuild my e5 now.  It won't happen before this years heli's east (this weekend) but that is ok.  There is always next year.  I do like flying heli's that are not the norm here.

Offline Richard Rollins

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Re: Servo Question
« Reply #8 on: August 14, 2014, 11:27:59 PM »
I'm just comparing the drain on my battery to same amount of time in air (futaba to BK ).  Not very scientific but tells me enough to keep a closer watch on my batteries.
Rick
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Offline Randy

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Re: Servo Question
« Reply #9 on: August 15, 2014, 06:15:11 AM »
You know I sign on to blog about my tail servo going out last night for me its hard to fly a heli while its spining out of control but some how i managed to save it...Anyway I have a djx servo on the tail of my N7 and so far they seem pretty good other than the tail going out. Im not sure what is actually wrong with it you can hold on to it and while lightly trying to move it, it will start working till you stop moving it. Has anyone had this to happen? I could understand if I had crashed in the past but this heli now just has 6 tanks threw it plus I dont fly hard so I know I haven't hurt it Heck Rob Cherry fly's them and i have never herd him say a negative thing about them  And now im going to put the futaba's bls256hv I think thats the rite numbers. I have the servo on my E5 and im now wishing I had spent the cash and done the same for my N7. Well this may be something off the wall that has happen and may never happen again, but the thing is i really dont want to go threw that again.

Thanks  Randy
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Offline Chris Wall

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Re: Servo Question
« Reply #10 on: August 15, 2014, 07:35:45 AM »
At my field we have had several of the RJX tail servos fail, one person had 3 alone.  And they always seem to go out at the worsted time!!!  Good save!

You know I sign on to blog about my tail servo going out last night for me its hard to fly a heli while its spining out of control but some how i managed to save it...Anyway I have a djx servo on the tail of my N7 and so far they seem pretty good other than the tail going out. Im not sure what is actually wrong with it you can hold on to it and while lightly trying to move it, it will start working till you stop moving it. Has anyone had this to happen? I could understand if I had crashed in the past but this heli now just has 6 tanks threw it plus I dont fly hard so I know I haven't hurt it Heck Rob Cherry fly's them and i have never herd him say a negative thing about them  And now im going to put the futaba's bls256hv I think thats the rite numbers. I have the servo on my E5 and im now wishing I had spent the cash and done the same for my N7. Well this may be something off the wall that has happen and may never happen again, but the thing is i really dont want to go threw that again.

Thanks  Randy
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Offline Randy

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Re: Servo Question
« Reply #11 on: August 15, 2014, 11:42:50 AM »
Lol im glad you knew I was talking about Rjx servos lol its hard to type on my cell at times the buttons are so close.  Anyway yeah just came unto a slight sive to start back up and I had just startled into a tail slid when it started to wag really hard and then it turned loose. i hit TH got it leveled back out and floated it back down thing is I haven't auto this thing yet only just 5 feet or so off the ground is about it anyway now that the tail has went its got me to think now is one of the cyclics going to fail on me?
Randy Woods

Offline Chris Wall

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Re: Servo Question
« Reply #12 on: August 15, 2014, 03:15:08 PM »
Anybody tried the BSL273SV, very expensive, but they have a lot more torque...
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Offline Barry Tilson

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Re: Servo Question
« Reply #13 on: August 17, 2014, 08:25:57 PM »
I have the high dollar SV servos on the new E7se I like them however I don't have enough skill to tell if they are better than the next. I don't know any better and have the time to fuss with it so I just by the Futaba's. They crash great and seems to work well for my internal BECs on the Kontronik's.
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