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Thunder Power RC ProModeler
wjvail

Key Veteran

Meridian, Mississippi

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I've been flying one of my helicopters with a 2S LiIon battery regulated at 5.5 volts to protect the older BLS251, BLS253 and BLS451 servos. I'd like to buy a newer Futaba BLS276 tail servo but it is rated at 6.6 to 7.4 volts. I've also been considering the MKS HBL880 rated at 6.0 to 8.4 volts.

Can I run a tail servo rated for 6 or 6.6 volts at 5.5 volts? There are a million threads asking if you can run a servo at higher than rated voltage. Can I run a servo below it's rated voltage?

http://www3.towerhobbies.com/cgi-bi...?&I=LXDLPG&P=ML

http://www.experiencerc.com/store/p...oducts_id=15250

Cheers,

Bill

Edited to correct servo number...

"Well, Nothing bad can happen now."

09-02-2016 01:08 AM
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don s

Key Veteran

Chesapeake, VA

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Will have less than rated torque and speed, but will still work.

E820, Raptor G4N, X50F/E, E620, Forza 450, and some planks.

09-02-2016 02:34 AM
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wjvail

Key Veteran

Meridian, Mississippi

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Thanks Don. I assume you have done this?

I had guessed speed and torque would be reduced. I'm more worried about the performance of the IC in the servo. A receiver functions as a receiver until it reaches some minimal voltage and then shuts off or resets itself. An under voltage servo will still function as a servo right? There is no issue with the internal amp, voltage reg, ESC, etc not functioning properly below the specified voltage?

Futaba in particular list a lot of specification beyond speed and torque. Can I assume these remain unchanged?

Bill

----------------------

BLS265
Pulse Width: 760us
6.6V 7.4V
Speed: 0.055 sec/60° 0.05 sec/60°
Torque: 61.12 oz/in (4.4 kg/cm) 69.45 oz/in (5.0 kg/cm)
Dimensions: 1.57 x 0.79 x 1.45" (40 x 20 x 36.8mm)
Weight 2.12oz (60g)
Power Supply: 6.0-7.4V
SBus Programmable Defaults
Dead Band Degree: 0.08
Damper Factor: 72
Stretcher Gain: 4
Boost: 10
Neutral Offset Degree: 0
Travel Adjust Percentage: 100%
Reverse (Normal/Reverse): Nor
Stop Mode (Free/Hold): Hold
Buzzer (On/Off): Off
Smoother (On/Off): On
Boost (On/Off): Off
Soft Start: 3.0

"Well, Nothing bad can happen now."

09-02-2016 01:19 PM
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ICUR1-2

Key Veteran

Ottawa, Ontario

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That is a good question

Personally I would bump up the voltage to 6V and bench test the snot out of it to be sure

spending time, paying attention

09-02-2016 04:46 PM
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Four Stroker

Elite Veteran

Atlanta

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Why don't you find out how low the voltage can go and the servo still work. For example BLS451's will work down to about 3.2 volts. So 5.5 would be plenty of head room. I always test receivers and servos for low voltage limits just so I will know. Futaba RX about 2.7. JR DMSS RX about 3.5. Test your FBL as well.

I would ASSUME that any digital servo has a 3 volt processor. BUT you remember the Benny Hill joke.

09-02-2016 05:05 PM
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Dr.Ben

rrMaster

Richmond, VA, USA

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Bill,

I know for a personal fact that a BLS276 works great at 6v (as do the 272SV's) if that gives you any idea of what to expect.

Ben Minor

Team Synergy Team Futaba Team Kontronik USA
Progressive RC

09-04-2016 01:36 PM
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helifanatix

Veteran

Fountain Valley, CA

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Simple Answer: YES

- Scott

09-04-2016 09:44 PM
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wjvail

Key Veteran

Meridian, Mississippi

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Hey Guys... Sorry it took a day or two to get back to this thread. I've been really keeping busy. There is a lot of good advice here and I'm about to pull the trigger on a new tail servo for my old Tempest.

I'm torn between the MKS880 and Futaba BLS276SV. The numbers look really good on the MKS servo and I've been impressed with the HV93 and DS95s I'm already flying - but I'm reminded of the advice that Futaba gyros really like Futaba servo.

I'd like to spend some time playing with the Futaba programmable functions and find out what that is all about. But again, the numbers on the MKS880 look good and I know I like their product.

They're both about $200.

Any thoughts? Any other servos I should be looking at?

Bill

"Well, Nothing bad can happen now."

09-07-2016 11:00 PM
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ICUR1-2

Key Veteran

Ottawa, Ontario

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I'd like to spend some time playing with the Futaba programmable functions and find out what that is all about
I think you answered your question

spending time, paying attention

09-07-2016 11:56 PM
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Dr.Ben

rrMaster

Richmond, VA, USA

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Complaints about BLS276SV performance and reliability are about as common as lock outs with FASST and Tennessee beach front property.

Ben Minor

Team Synergy Team Futaba Team Kontronik USA
Progressive RC

09-09-2016 06:16 AM
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wjvail

Key Veteran

Meridian, Mississippi

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Complaints about BLS276SV performance and reliability are about as common as lock outs with FASST and Tennessee beach front property.
Funny!

I have to do some traveling this week - I just ordered a 276 so it would be here when I got back.

Bill

"Well, Nothing bad can happen now."

09-09-2016 12:24 PM
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wjvail

Key Veteran

Meridian, Mississippi

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Hey All,

I just got back from some work travel. As my Grandpa used to say, "If I could give up eatin', I'd give up workin'".

Anyway... I received my Futaba BLS276SV. It's a good looking servo and I look forward to installing it some time today. As others suggested, I will spend time time testing it at voltage below the recommended 6 to 7.4 volts.

I got to thinking... Many of Futaba's servos are rated at 6.6 to 7.4 volts. These number stuck in my head for the last week. They are odd numbers to quote and something about them is familiar. Of course they are the NOMINAL voltages for LiFe and LiPo batteries. My guess is that Futaba is simply suggesting these servos can be used with unregulated higher voltage LiFe and LiPo batteries. If this is the case, the WORKING voltage for a LiFe 2S battery is somewhere around 5 to 7.2 volts. The WORKING voltage for a 2S LiPo is between 6.0 to 8.4 volts. These number would suggest a working range of between 5 and 8.4 volts for a Futaba HV servo.

I also took the time to look at the programming functions of the 276SV. This will require some reading! I mentioned earlier about wishing to learning something about Futaba programmable servos. At this moment all I can say is that there is a lot that can be done and I know little more than I did a year ago. The first step is always just gaining access to these functions and I've done that. Now on to what the different options represent. Anyone know what "Stretcher Gain", "Smoother Setting", or "Damper Factor" are?

Of course there is the option to simply install and fly the servo as shipped. I'm certain Futaba shipped this servo to function perfectly with the default settings - but then I wouldn't have learned anything...

Cheers,

Bill

"Well, Nothing bad can happen now."

09-17-2016 04:08 PM
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don s

Key Veteran

Chesapeake, VA

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Don't overthink it, and what's in the second photo?

E820, Raptor G4N, X50F/E, E620, Forza 450, and some planks.

09-17-2016 05:09 PM
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wjvail

Key Veteran

Meridian, Mississippi

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Don't overthink it...
Well. I'm not sure it's a question of overthinking. It's a question of learning what there is to be learned. Of course I could ignore it all but I've never really bought into the ARF mentality. On the other hand, lacking further instructions for S.Bus servo programming, I will have to simply install this servo using the defaults. That, of course, completely defeats the purpose of having a programmable servo in the first place. The full description of this servo is "Futaba BLS276SV S.Bus2 HV High-Speed Programmable Servo". Notice programmable servo is prominently included in the naming.

Or were you suggesting I was overthinking the voltage requirements?
...and what's in the second photo?
The second photo is a picture of the servo setup screen on my 18MZ for programming this servo.

"Well, Nothing bad can happen now."

09-17-2016 05:37 PM
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don s

Key Veteran

Chesapeake, VA

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Don't mind my nonsense, I shoot for plug and play with things like servos. I was hoping that was an 18SZ pic, but it's pretty anyways.

E820, Raptor G4N, X50F/E, E620, Forza 450, and some planks.

09-17-2016 09:00 PM
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wjvail

Key Veteran

Meridian, Mississippi

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...I shoot for plug and play with things like servos.
In times past, I have heard myself say "I will never buy a servo that can only be used on a helicopter tail rotor". Looking at it from the perspective of someone who began in this hobby before transmitters were programmable and things like servo reversing and end point adjust were just a dream, a servo that had a single use was too much to ask.

Much more recently I struggled to see an immediate need for a Serial Bus as applied to model aircraft.

Needless to say, times have changed. It remains to be seen if programmable servos are the coolest thing since Spread Spectrum or just a passing fad but I'd like to experiment some and find out.

I've been looking for something to read on the different settings that can be set with Futaba's servos. At the moment, this is the best information I've found: http://downloads.hobbico.com/softwa...ink_WEB_ENG.pdf

Bill

"Well, Nothing bad can happen now."

09-20-2016 04:43 PM
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don s

Key Veteran

Chesapeake, VA

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The first two servos I ever tried to program, I smoked. The next four came out OK. (Hitec fwiw)

E820, Raptor G4N, X50F/E, E620, Forza 450, and some planks.

09-20-2016 07:13 PM
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Andy from Sandy

Key Veteran

Bedfordshire, UK

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Where are your other servos being used? Is the 276 to replace the 251?

I know from several years of use the 451s will quite happily work on 6.6 volts supplied from a LiFe pack.

If the other servo is for a throttle servo for instance then what might consider is replacing it with a Futaba S3072 which is a HV servo and plenty good enough will also quite happily run on 6.6 volts.

Simplify the setup and remove regulator and old battery for LiFe.

10-03-2016 10:01 PM
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