abufletcher

I'm new to 1/4 scale. Can I just use the same standard servos as I've always used on my smaller models (for example, the Futaba S3001)?

geezeraviation

My Feedback: (3)

I have always liked servos in the 75 to 80 ounce torque range for 1/4 scale and use one per surface. If it has a real big rudder around 100 oz there. If you run with 6v that bumps your standards up some but not enough to suit me. My 2p
Doc

abufletcher

Thanks. I should add that this "1/4 scale" model will be a 2-seater so it's in the 98"/12kg size class. That's almost 1/3 scale for a small fighter. But then I wouldn't be flying it like a fighter either.

geezeraviation

My Feedback: (3)

I didnt mention I was talking about scale flying and not an aerobat or a speed demon.
Doc

geezeraviation

My Feedback: (3)

My SE 5a weights 23 1/2 lb and fares well with servos as I mentioned and it's fairly agile as well.
Doc

Chevelle

My Feedback: (2)

As you know, there is quarter scale and then there is quarter scale. WWI scale is a whole different world than 3D stuff. I am a big fan of HiTec servos. I use pretty much use just three servos for all my planes. HS425BB (57in-oz @ 6v, $13), HS635HB(83in-oz @ 6v, $28), HS645MG(133in-oz @ 6v, $32). For my WWI stuff I general use the HS635HB on the flying surfaces.

The AVRO Triplane will be a different story for roll control though. It is a wing-warper and the outer edges of the upper and lower wing have to warp. It's hard to say how much torque I'll need there. It was surprised as how easy it was when I turned the wheel on the replica in England. It is a long way before I get to that point but I expect to use their HS755MG (200in-oz @ 6v, $39) for the wing warping.

abufletcher

So would the something like the Futaba S3010 be a good choice?

http://www.futaba-rc.com/servos/analog.html

Or the HiTec HS-485HB?

http://www.hitecrcd.com/products/ana.../hs-485hb.html

abufletcher

By the way, I don't understand the idea of using 6V. I thought all Rx batteries were 4.8V. Again, my ignorance of all things electric is boundless.

abufletcher

http://www3.towerhobbies.com/cgi-bin...&I=LXDTB3&P=ML

http://www3.towerhobbies.com/cgi-bin...&I=LXXCZ9&P=ML

http://www3.towerhobbies.com/cgi-bin...?&I=LXFRS6&P=7

I've used HiTec servos and have a good impression of them. But one disadvantage for me in Japan is getting replacement arms.

Chevelle

My Feedback: (2)

I think<strike> both</strike> all three of those servos would work just fine. Check with your receiver but most are designed to work over a wide range of voltage that includes 4.8v-6v. With the cost and weight difference between them so low these days, I just go with 6V for everything.

geezeraviation

My Feedback: (3)

Yeah the arms are another issue. I always use the Du Bro super strength ones or now and then aluminum but usually the Du Bro.
Doc

abufletcher

I don't have any problems with the plastic arms. It's just that HiTec acessories are impossible to find in Japan. So we're talking about using an Rx battery something like this?

http://www3.towerhobbies.com/cgi-bin...&I=LXNHS4&P=ML

I'd be using it with this Airtronics receiver:

http://www3.towerhobbies.com/cgi-bin...?&I=LXTZU8&P=V

Steve Percifield

My Feedback: (14)

The surfaces on WW1 planes are normally very large. There is a lot of force returned to the servos, especially on landings and bumps. Use only metal gear servos, what ever the brand. One on each elevator half. I like to err on the side of safety and use 100oz-in as a minimum. I always run 6 volt receiver batteries, and in 1/4 scale and up, I use 2, 6 volt batteries. Since most controls are pull/pull, I also attach the wires to a bellcrank, and then the servo via a short pushrod. This isolates the servo from the control pressures and allows me more adjustment and also makes servo changeout easier. I normally use Hitec 645Mg or 5645MG. They have proven rugged and reliable.

sp

Steve Percifield

My Feedback: (14)

abufletcher

A real plus for me at the moment is that very strong yen. The cost of the HS-645MG from Tower is less than the cost of a standard servo here in Japan.

abufletcher

Someone is just going to have to TELL me which battery size to buy because I'm never going get things like amp draw.

geezeraviation

My Feedback: (3)

The pack you linked to is fine. Most of my batteries are from 1800 to 2200ma at 6v for radio and 4.8 for ignition. I'm still using NiCd as they have served me well, I tried NiMh but didnt stay with them. Though Im leaning heavily towards putting a LiPo in my transmimtter.
Doc

GerKonig

Your Rx battery pack has 4 cells. Add one cell (5 cells) and you have 6V. As a result your servos now are quite more powerful:-) Same servo = more powerful = same price (win win situation)

Gerry

semeraro

I have Futaba 3303 servos in my 1/4 albatros. Reasonably priced and have never had a problem.

abufletcher

I didn't find a Futaba 3303 on Tower but found a Futaba S3305 that looks good.

http://www3.towerhobbies.com/cgi-bin...?&I=LXDWF8&P=7

abufletcher

By the way, when you guys talk about a "servo on each surface" I'm not sure what that means in terms of the elevator. Since I would ALWAYS be using a pull-pull cable system on both elevator and rudder, won't I just be using one servo to operate the bellcrank?

Steve Percifield

My Feedback: (14)

It's 1 servo per each half, or 2 servos for the total elevator. Handle it like it's 2 control surfaces. You will have pull/pull to each elevator (half), run from 2 independent servos. 1 for each side.

abufletcher

That sounds like a dangerous solution in the event that one servo fails...or that they may not be completely coordinated...let alone the "aesthetics of scale." It also sounds like it might be difficult to make sure each separate pull-pull loop is exactly the same as the other. Would it be possible to "gang" two servos onto a shared bellcrank? But I do see that the MR Strutter plans call for two (apparently separate) elevator servos with no indication of a bellcrank being used.

Joe Westrich

My Feedback: (95)

I run one servo per elevator half and always run the Hitec 645MG. To me, its a bargin and fits almost all applications. Like you said, its cheaper than a standard servo over in Japan.

I would drive home one point..... you should use metal gears. In most flying situations, you will have little stress. However, if for any reason you develop flutter in the very large control surface of a 1/4 or 1/3 scale WWI aircraft, it may save you an airplane.

My pick, HS645MG on all surfaces and two 2000mah Rx packs that you have listed from Tower (redundancy).

More than you asked for but...............

I would also check you servos on an annual basis and replace your batteries every 2 to 3 years.

In the last 10 years of flying giant scale, I have never lost an airplane to a battery or servo failure.

Steve Percifield

My Feedback: (14)

Actually, I have found it's more scale as most have control wires running to each half. It also provides redundancy, which is safer. And it's not hard, with todays radios, to coordinate both servos. As far as the bellcranks, that's my solution, most just run the cables directly to the servos. Either will work, I just prefer to isolate the servos from the strain. BTW, forgot to mention, but the servos, especially with direct connected cables, need to be ball bearing.

Here is a bad picture of my set up. This is actually the system used by SR Models in their Eindecker. I have used it on 4 models now and like it. But, use what ever you are comfortable with. The center servo (not hooked up yet) will operate the horizontal bell crank which runs to the rudder. The 2 outer servos hook up to the vertical bellcranks which run to each half of the elevator.