I recently returned to building a 2m patternship, after a few years off.

I use to have an Aresti III, and I use to run the following servos.

Futaba S9102 on the wings
Futaba S9202 on the Rudder
Futaba S9101 on the elevators (2)

I have now started looking at the digital servos, and it seems such a mine field out there.

What are the main pros and cons of going Digital?
There seems to be Digital, and Digital coreless? Which is better?

As I am on a rather tight budget, I was looking at using something in the Hitec range, as i have had good experiences with Hitec.
HS-5625MG for rudder and ailerons.
HS-5245MG for Elevators?

How much MORE battery capacity do I need, if any, using Digital versus my older coreless setup?

I use to happily use a 1100Ma 6v battery, that would easily last a whole weekend of competition.

Thanks in advance, Bruce T

Well I'm a JR person, so better for Futaba users to answer re: servos, but would say that although Hitec have improved a lot, and are fine for 3D(With the best selection of sturdy arms out there), they're not quite there yet for serious pattern use.
Re:Rx
battery capacity it seems to depend mostly on engine type---electric needs the least per flight, 4/strokes the most, and 2/strokes in between.
I managed on a 600mAH nickel metal hydride with a 2stroke, BUT recharged with a sophisticated field charger after every flight---on a windy day a prelim FAI schedule would use around 200mAH.
Nowadays I use an 1100 mAH nimi with a claimed 20C burst discharge capacity,and can manage 4 comp flights without problem, and no discernible (to me, at least) drop-off in servo performance.

Thanks f3a05

can you give me some JR possibilites, not at the extreme high end?

I am running a 4Stroke (YS 140 L).

Thanks

Rudder --DS 8401(not the 8411 with metal gears)----it has a very narrow deadband though--so slop -free linkage/closed loop is essential --or it will "hunt" the centre.
Elevator DS 8231 (one only) 2x DS3421, or, cheaper, 2xDS811.
Aileron---you could use the futaba 9102 still, esp. if you have them already---just don't expect a long pot/track life with the YS---some people claim that mounting the servo on its side inside the wing helps in this respect.
The best JR, IMO, is the DS9411sa, but it's not cheap, but the 9401 does well--or even the8401 again.

Rudder, now there's a problem
I have built this plane with the rudder servo down the tail, for a push rod onto the rudder.
Are you saying this will cause some hunting problems?

If I go with the JR's, is 1100 ma battery still ok?

What about progaming the JR's like the Hitecs can be with thier programmer.
Can this be done on JR, so like I can reverse one elevator servo?


Thanks.....

No--just as long as there's no slop in the linkage.

Should be.

Not sure re Hitec programer whether or not it works with other-make servos.
The higher -end JR Txs have specific programs for dual elevator(And everything else dual),as no doubt do Futaba.
Or the JR or Futaba Matchbox is another electronic solution.
Or of course if there's enough room, with a lot of care in the installation, (and some luck with a matching servo pair),if the servos are in the fus sides, you can simply have the two servo arms facing opposite ways(one up, one down)on the same channel with a Y lead.

The Hitec programmer will test all brands of servos but it will only program the Hitecs.


Bob

Well just for the info, I decided on using 4 HS-6975HB Hitec's in my new Exceleron 90.

Seems like an excelent servo for $76.50ea. I mean I have four of them being deliverd for a total of $305.76, not bad in my book for highspeed digital coreless units.

What do you mean regarding the pot/track life with the YS?

Is this just on the 9102, or coreless in general.

I just found 2 brand new 9102's in my drawer, that I must have bought nearly 10 years ago (had no kids and money then). I also found a 9202!!!
But still need something for the elevators. So was thinking of the JR DS811 or the Hitec HS-5245MG.

Thanks again everybody for answering these questions.
Bruce

When I used to use 9102s as ail. servos, the track used to burn out at the neutral point pretty quickly--some people had this more quickly than others,but mine always were short-lived, even though it was a 2-stroke installation with the wing seat vibration damped by a 1 1/2 mm silicone cushion.
This problem has been non-existent in my current model, a (composite) Abbra with 2-piece wing, and 8401s mounted on their side within the wing.
The geometry is a pain though---the longer servo arm, to clear the surface, requires a much longer ail. horn to get the servo travel anywhere near the optimum.

Thanks f3a05
so, when the track burns out on the S9102's, what are the symptons on the servo?

I have had some in my 'plane for about 5 years. Now I haven't flown it that often, probably only about 80-90 flights in that time.

It would be a shame to not use the 2 new ones I found in my drawer, on my new 'plane.



I have another question.

Analog coreless, versus Digital NON coreless. Which will centre the best?
(I am still trying to get some new servo's for my elevators, without killing my already extended bank overdraft).

It will start to jump about (jitter) when you return to neutral.

I'll leave that to someone else---I think you get what you pay for though----better centering, less gear slop, stronger case design,etc.etc.
With regard to digi v analogue, I'd just say that the holding power of the digi,and its ability to go quickly to full power whatever the amount of stick movement, will be felt fairly obviously by most flyers--even if it's only by the way of them feeling "faster" than analogues, whatever the printed specs say.

How great this forum is.
I have learnt something new, again.

One of my S9102's has been making the aileron bounce up and down, on the ground.
I thought it was because the ailerons were too heavy (they are VERY heavy on myAresti III, great lumps of wood).

I assumed that in the air, it would stay neutral, as I didn't really see/feel as if it was hunting.


A lesson learned.

Have just seen a special on JR8231, which will fit my budget.
Thanks for help.