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Old Jan 23, 2013, 12:22 AM
The wheels touch down FIRST??
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Insomnia... LoL

BJ
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Old Jan 23, 2013, 05:18 PM
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Doing my ordering ...
Can anyone recommend a servo from the Hobby King US warehouse? Thanks.
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Old Jan 23, 2013, 06:14 PM
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Ncr, I myself have no idea abboout any of the H/K servo's, except the really really cheap ones, the ones I used in my clouds fly. They were fine, but I would have a prob with trusting them in a siren! But I hope some one can recomend some digitals that work, I need to replace the hitec's that I stole out of my mini titan for the siren! But from what I found out, any of thier range of digitals in the 10 to 15 dollar range that fall in to a spec range of MG hitec should be ok...so I have been told
Maybe someone could be a bit more specific.
Neal
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Old Jan 23, 2013, 06:44 PM
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If there is one aspect of this hobby that I don't fully understand, it is servos. I will look around on HKs site and see what I can find.
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Old Jan 23, 2013, 07:11 PM
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Servo's, I have a half decent understanding of, the problem is more along the lines of reliability, a decent servo that has good centering and good resolution that costs 10 bucks is absolutely no worse than a 40 dollar servo, not forgetting torque rating,( that I nearly forgot to mention! ) I t is the build quality,or more the consistancy of the build quality. That is about the only reason I tend to stick to the bigger name brand,,, there a known quantity, usually, I have no prob with a servo from H/K or other cheaper brands, IF some one can say that they have bought a few of them, and they consistantly do ok, I'll buy. I have found reading the feedback on H/K is a good way, if you remember to take some of it with a grain of salt, some people will bitch about anything!
I did get some good teedback in relervant section on this and other forums.
Neal
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Old Jan 23, 2013, 09:21 PM
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I picked up some (cheap) digital servos for a project, I'll let you know what I think about them. I usually use hitecs, but my buddy at the field is having a lot of fun with them, so we'll see.
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Old Jan 23, 2013, 09:26 PM
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What is the major difference between digital and analog, when it comes to servos?
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Old Jan 23, 2013, 10:31 PM
The wheels touch down FIRST??
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There's a few spiels around that may help explain the diff, Neal.

Here's one: http://www.rchelicopterfun.com/rc-servos.html

BJ
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Old Jan 24, 2013, 07:00 AM
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BJ,
Thanks for the link... I feel like I just gained a couple years worth of knowledge in 10 minutes.
Demon, which servos did you just pick up?
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Old Jan 24, 2013, 09:57 AM
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Does the operating voltage make a difference foir servos. I see some that require 7 volts. Will these work?
How much torque do the servos in this plane require at a minimum?
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Old Jan 24, 2013, 05:18 PM
The wheels touch down FIRST??
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Well... if you go back to Power = Volts x Amps, and you're feeding 6 to 7 volts through your higher-spec servos instead of 4.2V, you should be producing more power for the same amp draw - or, conversely, drawing less amps for the same power.

In the more-power scenario, you'd expect that a servo would be producing more holding torque... no?

I know some of the Slope guys are switching to the higher Volt rated servo's - must find out exactly why. But I'm guessing it would have to do with more holding torque.. (??).

I'd be careful hanging 'high voltage' servo's off a 'normal' ESC/BEC system (the ones we usually run in our foamies, balsa's etc.) Electricity is one of those things that behaves strangely at times - the more you ask of a system, the more it will try to provide. In a gasser system, you motor performance just flattens out and eventually drops off if you ask too much of it (e.g. too big a prop etc.)

In an electrical system, it'll just keep on trying to provide until something gives - usually the weakest link. e.g. if the motor is under-spec'ed, it'll burn out. Likewise with the ESC and/or LiPo e.g.. run a 20A ESC in a 40A system and it will try to provide the 40A until it fails. Same with the LiPo - try and draw 40C out of a 20C system, and the LiPo will let you know pretty quickly that it's not happy at that draw rate and bloat (maybe even explode) on you.

So... if you're thinking of ever upgrading to 6V and beyond servo's, it would be wise to ensure that your BEC/servo battery system is up to the task - in both rated Volts and Amps.

Oh... and of course, make sure that you're not going to end up unknowingly feed your Rx too many Volts

BJ
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Old Jan 24, 2013, 06:30 PM
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That's about what i thought. Thanks BJ.
How about my other question... About how much torque should I be looking for in a plane like the Siren?
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Old Jan 24, 2013, 06:32 PM
Dir. of Innovation at Alert 5
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Quote:
Originally Posted by NCRealEstateGuy View Post
BJ,
Thanks for the link... I feel like I just gained a couple years worth of knowledge in 10 minutes.
Demon, which servos did you just pick up?
I picked these up (see link), I wanted to see how good a $3 Digital servo could be? (or not)

Servos 101:
The Digital has more torque and better centering on something that already had great torque and centering...

http://www.hobbyking.com/hobbyking/s...dProduct=25453
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Old Jan 24, 2013, 06:40 PM
Dir. of Innovation at Alert 5
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United States, FL, Fort Lauderdale
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Quote:
Originally Posted by NCRealEstateGuy View Post
That's about what i thought. Thanks BJ.
How about my other question... About how much torque should I be looking for in a plane like the Siren?
The HS65 specs are more than adequate.
Most any 9<12g servo could suffice...
I say could and not should... These planes are way quick and god forbid the unthinkable (servo failure from a real low grade servo). While I myself have purchased my fair share of HK finest "budget" servos, I generally put them in my foamies or slow fly stuff... I'm sure they would work fine in a Siren, no doubt in my mind... but, I buy the Hitecs for her, guess I'm superstitious!
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Old Jan 24, 2013, 07:19 PM
The wheels touch down FIRST??
BJ64's Avatar
Australia, VIC, Melbourne
Joined Jun 2009
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Yah - likewise. Anything around the 1.5kg mark should do the trick.

It's not like the Siren is a big 3D plane or a super-quick Slope DS'er, so there shouldn't be all that much load on the control surfaces.

RC Planet suggest servos in the 16oz range: http://www.rcplanet.com/GP_ElectriFl...p/gpma1065.htm

Most of the HK servos in the HXT900 or 9g metal gear range are quite up to the job. Reliability is... well... 'reliability'. I'm pretty sure a lot of that stuff comes out of the same factory - just with different brand names on the stickers. And I've seen big name hundred-dollar+ servos fail too.

With the Chinese stuff, I've found it either works, or it doesn't i.e. if it's still working after you've bunged on the links and horns and connected it all up and done your surface checks, it should still work ok in flight.

The only thing with HK HXT900's and other plastic-gear servos is that you need to be careful not to knock a control surface during transport - they hold well when working from their end, but a quick movement coming from the other end - e.g. knocking a control surface - can easily strip a plastic tooth on the servo.

You can usually tell if this has happened during your pre-flight (you are doing pre-flight checks, yah?). If the control surface stutters anywhere along it's movement to max in a direction, DON'T fly the plane. Ask me how I know...

BJ
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