Matt Kirsch

My Feedback: (21)

Hey guys,

Any problems with using JR8101 servos in pairs for the ailerons on a 1/3 scale aerobatic plane? They meet the torque requirements set forth by the manufacturer with a good margin of error.

The reason I'd like to use them is because I got them for a killer price, and the wires have been extended by a professional to almost perfect lengths for the wing.

I plan on using JR Matchboxes to keep them in sync of course.

Don M.

My Feedback: (5)

You realize of course that these are NOT metal gear servos. I have 4 and although they are very good servos I was using one on the rudder of a 27% 300 and bumped the rudder with my arm on the bench and stripped the servo. I replaced it with a MG 2721 servo. They maybe fine but I think I would want MG servos on a plane of that size.

yarom

My Feedback: (82)

I would not use them as they are not solid enough, even if the torque figures look OK.

Minimal servos for single or double on 1/3 scale would be 8411. You could get away with 8311 but I think it's plastic gears.

If using analog servos, 4721s or 4735s might work with some limitations.

Rcpilot

My Feedback: (78)

Don't wanna hijack here, but I'm wondering about servo torque too.

I have the 30% Carden Cap 232, almost ready to drop in the servos, and I'm wondering about the stab servos. Well, all of the servos. Do you think it would be okay to use 4721 servos on the elevators and ailerons for this plane? I have an 8411 for the rudder and DS821 for throttle and choke.

It is 88" span with 1440 squares and should finish out at 18.5 pounds RTF.

Thanks

yarom

My Feedback: (82)

There is no religion in this area - mostly common sense.

The manufacturers requirements can be satsified with less that we normally use but there are other questions:

- What kind of flying do you intend this plane for?

- Are you under powered or over powered?

- What is the AUW of the plane (span and surface data are not enough)?

- What type of control surfaces it has - oversized?


My personal rule of thumb is to allow for 50% to 100% more torque than the intructions specify. This is because I tend to pick aerobatic planes with larger than average control sufaces, I like to fly IMAC and 3D and I tend to install an engine that is somewhat above the power required.

For a 27% to 30% aerobatic plane with a Da-50 I would personally install the following:

The minimal JR servo for each aileron would be 8411 or equivalent (sometimes two per)
The minimal JR servo for each elevator would be 8411 or equivalent
The minimal JR servo for rudder would be 8611a or equivalent
The minimal JR servo for throttle would be a 821, 8231, 811 or equivalent
I tend not to use a servo for choke to save weight

I use digital servos with metal gear only, mainly because of their holding power and precision. We are beyond the analog age and it's time to move on. I also use a DX7 radio and not really going back to FM/PCM 72Mhz ever again.

I use redundant LiPoly power going through a SmartFly SuperReg, typically 2 x 1500Mah.
I use 6v NiMh for ignition, typically 1100Mah, going through a SmartFly optical switch.

So that's the way I do it. You can pickup a variety of setups and opinions in the different build threads. One thing that I find common, is that quite everybody I learned from on RCU went digital and is using dual batteries.

Have fun...



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Tired Old Man

My Feedback: (1)

The 4721 and 8411 are both great servos. The 4721 is a coreless design that thinks it's a digital. Great performance and accuracy. Their only pitfall is that they are both nylon geared. If you're a 3D flyer then you might not want to use them in favor of a metal geared servo. As for bumping a surface with a live servo, you can take out the gears in any type. Been there, done that. It's a lot cheaper to replace nylon gears if you have a habit of doing that kind of stuff. Unfortunately, some servos have a gear set that costs almost as much as the entire servo. Futaba comes to mind here...

Rcpilot

My Feedback: (78)

The Carden Cap is strictly an IMAC plane. Thats why I was hoping someone would say it was okay to use the 4721 on elevators and ailerons. I won't be using a lot of surface deflection and I won't be doing too many violent snaps in the Basic and Sportsman classes. It's going to be overpowered--a lot. But, I know how to use the left stick. I'm not the type to fly my planes very fast anyway. I'm more after a constant speed throughout the whole sequence. I usually only use full throttle on uplines--and even then it's not usually for long.

Thanks for the help.