Servos
 

What are the advantage of digital servos? Are they really that much better?

RE: Servos
 

Digitals use all of their energy to find a position; they are either on or off, hence 'digital'. This includes trying to find the center position - they use all of their energy to hunt for the neutral/center position. Analog servos use less energy but are absolutely fine for sport flying. To me, flying a plane with digital servos feels more 'crisp', responsive, and precise. I have 3 planes, and am pretty much only using analogs for throttle - because I already have them.

RE: Servos
 

unless your doing serious 3d/precision aerobatics, or are flying big planes that require big control throw's. dont waste your money
what plane are you thinking about putting digital servoe's in?

RE: Servos
 

They do very well in enhancing the wallet of those that sell them. They make those folks that like to have the "best/newest of everything" feel very good about themselves. ;)

I have 8 of them but none yet into an airplane. Digital servos idle at about the same current draw that analog uses for work. Having played with servos and current draw and watching what happens to a battery when several servos are loaded at the same time, I rather use my old analog servos. That was a main problem when NiMH first came on the scene. Even with analog servos, using several servos and loads at the same time, NiMH dropped too far below the needed voltage to force the current out there. Even for a brief period, such could cause bewilderment and "Wot tha' ELL?" in a pilot's mind, resulting in pilot disorientation and a crash.
In a very popular RC magazine that just recently left the playing field, a very excellent column writer discussed this topic at length. I guess that must of POed some of the suppliers and that superior column writer was very soon replaced with a much less informed writer. [:-]

Not about digital servos as they were not here at this time, but just servos in general: Some 20 years ago I was an agent for the World Engines Expert Radio, which, as a radio, was outstanding, but workmanship, materials etc. left a lot to be desired. I sold one to a coworker. I saw him a couple weeks later and he was complaining about the servos being slow. His club members, being unfamiliar with the radio, condemned it to death. We talked of other possible problems and I became aware that he had not sealed the aileron-wing areas, on his .60 size Dirty Birdy, IIRC. I told him how, and a couple weeks later we were working together again. He told me that after a couple flights those clubmembers were asking what kind of new servos did he buy and where could they get some. :D Troops, it is not always the equipment, but I suppose that is the best excuse. ;)

Like in everything else it is basically what YOU want to do.

RE: Servos
 

I'm with you Hoss! I think there's a lot of hokum going on in this activity!

RE: Servos
 

They center better, provide full torque almost instantly and use full torque to hold a surface in its commanded position. An analog servo needs to deflect a bit to provide full torque so holding power (picture holding a rudder in knife edeg in an aerobatic plane) is much improved.

The downside is they draw more current and cost more.

If you're flying a trainer you may never notice the improvement. If you're flying a high performance plane or helicopter, it will be like a different animal with good digital servos.


http://www.futabarc.com/servos/digitalservos.pdf

edited to correct link

RE: Servos
 

If you add it all up (all the above posts), for the average flyer, those that fly trainers, sport planes, most averge level warbirds, and some low to mid level aerobatic aircraft, the standard ball-bearing medium torque servo.. in other words, your standard $29.99 servo (and that may be a high estimate meaning that you most likely can find a good deal on good servos for less cost) will most likely be just fine.

Spending a hundred bucks per servo for a standard sport aircraft is a total waste of both money and servo capabilities.

As Baracuda said.. if you have a high end aerobatic aircraft, expensive 3D, helicopter, or any other that really needs the precision of a digital servo, those that use them realize that they need the extra battery so they are aware of what the digital servo can do and what it needs to operate properly.

A few years back, I spent about $70.00 per servo for high torque coreless servos with steel gears. These were not digital. They were fast and powerful, and did the job very well. But, later, I found out that I didn't need that expensive servo. I put them on the ailerons, one one each side.. was a waste. I removed them and put on good ball bearing medium torque servos, and that plane flew just as well as with the expensive servos. Those coreless servos are still in the box waiting for an appropriate aircraft. Oh, these particular servos were larger than the other I had.. they were the same length and width, but were a bit deeper, so they can be a problem in the wing with the real thin profile.

Servo selection comes down to what we need for the job we want them to do. 3D, pattern, helicopters, large scale, gas powered planes, may all need digitals for the energy they provide. Our average flyer will not need that expense and can get along very nicely with a good standard ball bearing servo.



CGr.

RE: Servos
 

Here's what I use (in general):

Nitro Helicopters - High Torque Digital Servos
3D Planes - High Torque Analog Servos
Sport Planes - Standard Analog Servos (or High Torque Analogs for larger planes)

RE: Servos
 

I just want to say that I just maidened a new plane with Hitec's latest and greatest 7000 series digital servos, and I am completely blown away. I thought my JR DS821 was nice, and now they feel like mush! With the new high performance digital servos, I feel completely locked in to my plane, and that the plane feels incredibly crisp and responsive. Not only does it move immediately as I give it input, the surfaces stop immediately, too. It is an absolutely wonderful experience. I thought I had a good feel of my (Venus) plane before, but it is absolutely nothing compared to the equal sized (Yak) plane that I'm flying with the upgraded digital servos.

I agree that there is no point to put digital servos on a trainer or one of your other first few planes, but as soon as you get something somewhat sporty, I say go for it. The DS821 was a nice improvement over a standard servo in my Venus 40 and I don't regret buying them; they are appropriate for that plane. However I will not be buying any more standard servos or entry-level digitals like the DS821, and will very shortly be replacing all the DS821 servos in my Venus II with something like the Hitec 6000 or 7000 series.

Just my $.02. If you are not totally strapped for cash and are flying a fairly sporty plane, give some nice digitals a shot. You will like them;)

RE: Servos
 

i really notice them on the ailerons most, i can do "ratchet rolls" on 3d rate with the 5985s, i previously had 985mg and they werent as crisp at all ....no kidding While using digital servos arent a must, especially if you are a sport pilot, but if are a demading pilot and can feel the difference then go for it