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Old Jan 23, 2015, 09:18 AM
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StarHopper44's Avatar
United States, NC, Richlands
Joined Jun 2011
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AS3X & Digital Servos

Hi guys,
I just picked up a couple of Spektrum AR635 Rx's w/AS3X, intending to use one in a nice 80" plane I just bought. I wanted to try the AS3X function in this bird (electric, warbird trainer to be used for scale flying) because its landings tend to be a bit touchy, and our club field lies in the heart of the Land of the Eternal Crosswinds - thinking the stabilization system would be a help against the cross-gusting.

In the support documentation for the AR635, I discovered Spektrum's statement that the Rx should only be used with Digital servos because of their superior positioning accuracy & speed. This came as a bit of a shock, as the plane is equipped with a mixture of digitals and analogs, good quality units at that, and the way the plane's constructed, most would be very difficult to replace. Not to mention, the expense!

I of course haven't read all the 'AR-' manuals, but did check what seems to be the next upstep as recommended by Horizon Support, the AR636. And was surprised in not seeing any mention of Digitals Only in its manual. It's also an AS3X unit, so why the (apparent) difference?

The plane's control linkages et al are good & tight, with quality 'med-heavy duty' servos....and I'm wondering if I can get away with it as-is, or are Digitals really that critical to successful operation? I realize I could just fly it with AS3X turned Off, but that seems like a waste of resources.

Looking for some expert advice, & no guesswork please! What say ye?
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Old Jan 23, 2015, 09:41 AM
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Joined May 2011
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I've got a multiplex acromaster with AR635 and analog hitec servos. No problems. Lots of flights. One aileron servo died after >100 flights though.

Another thing you should keep in mind: you've got only one flight mode on 635. Second flight mode is highly limited in settings and virtually useless. If its ok for you to fly with stab always on - that's fine. If you want different flight modes - you'd better get AR636 with much more options to play with.
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Old Jan 23, 2015, 11:35 AM
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United States, UT, Salt Lake City
Joined Oct 2007
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Quote:
Originally Posted by StarHopper44 View Post
Hi guys,
I just picked up a couple of Spektrum AR635 Rx's w/AS3X, intending to use one in a nice 80" plane I just bought. I wanted to try the AS3X function in this bird (electric, warbird trainer to be used for scale flying) because its landings tend to be a bit touchy, and our club field lies in the heart of the Land of the Eternal Crosswinds - thinking the stabilization system would be a help against the cross-gusting.

In the support documentation for the AR635, I discovered Spektrum's statement that the Rx should only be used with Digital servos because of their superior positioning accuracy & speed. This came as a bit of a shock, as the plane is equipped with a mixture of digitals and analogs, good quality units at that, and the way the plane's constructed, most would be very difficult to replace. Not to mention, the expense!

I of course haven't read all the 'AR-' manuals, but did check what seems to be the next upstep as recommended by Horizon Support, the AR636. And was surprised in not seeing any mention of Digitals Only in its manual. It's also an AS3X unit, so why the (apparent) difference?

The plane's control linkages et al are good & tight, with quality 'med-heavy duty' servos....and I'm wondering if I can get away with it as-is, or are Digitals really that critical to successful operation? I realize I could just fly it with AS3X turned Off, but that seems like a waste of resources.

Looking for some expert advice, & no guesswork please! What say ye?
In a "perfect world" the AS3Xand each servo it controls, would respond as one ---
In the real world -a compromise is acceptable-- based on type of flying being done.
Bear in mind - the servo will be constantly provided with" change position" data and this will vary with wind- your flying needs etc..
Use servos which are up to the task at hand .
there are a number of very good lower priced NON digital servos which are fast enough and accurate enough.
some digitals are prone to dithering or oscillating etc..so simply being digital is not the answer .
it's a compromise.
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Old Jan 24, 2015, 12:32 AM
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Joined May 2013
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A friend of mine has been flying a Visionaire now for nearly two years and hundreds of flights with the analogue Hitech HS-85MG servos and has never had an issue. I have HS-5085 in my VA, but can't tell the difference between the two in the air.

I can't guarantee it will work for you of course as every application is different. I'd guess you are not going to use the 3D mode so you application should be a little easier on the servos. Still given your setup isn't a 42" foam job replacing some servos will give you piece of mind.

The other thing you could look as is to change one of the modes gains to zero so that you can effectively turn the AS3X off with the flick of a switch if things go wrong.

At some point I am going to try a 636 RX on my 58" Slick with HS-225 analogues.
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