Minimum/recommended servo torque/speed?
 

I'm working on a pattern-style Widebody 60/90 and am starting to wonder if I'm overdoing it on the servos. What's a good rule of thumb for pattern and aerobatics? I'm sure more speed and torque doesn't hurt, but at what's the inflection point of diminishing returns? In past aerobatic planes, I've generally followed the high side of the design recommendations, but this is my first truly pattern-style aerobatic ship.

For background, the plane will probably be around 7lbs, YS FZ91 for power and per design have one servo per aileron, one servo driving both elevator halves and one servo for the rudder. I am currently planning the following, believing in the "more is better" axiom:

Ailerons: JR 9411 digital each (82 in-oz, 0.15s)
Elevator: JR 8417 digital (82 in-oz, 0.10s)
Rudder: Futaba 9402 analog (89 in-oz, 0.09s)

These are all 4.8V ratings, but I will be using a 6V pack (can't seem to find any 6V ratings documented for JR servos).

I also have some JR 8231 digitals (88 in-oz, 0.22s) at my disposal, but was thinking they might be "too slow". However, how fast does an aileron servo really have to be since they are usually very effective?

OK, I'm sure there will be a temptation to say "if you have to ask, you don't need them". :D However, I'm more interested in the why's of relative speed and torque on each control surface. Rudders need lots of torque for knife edge, etc., but what's important for elevators and ailerons?

Minimum/recommended servo torque/speed?
 

IMO,
Those are overkill for a 60/90 size plane. I fly my 1/4 Giles for 3D with lesser servos. Futaba 9202s actually. The digitals are good for a pattern type plane and servo speed is essential for a good feel. You will have to watch your batteries when you run digitals at 6V. They really suck the batteries dry in a hurry. You might consider ganging two together for rudder to get both speed and lots of torque but you must get them matched and working together without any binding. If you already have the ones you listed I wouldn't hesitate to use them.
I've looked at these Widebody's and I talked to Planes Plus this morning and I'm going to wait till they get the 140 size out and use my OS 160 on it. It should be a great flyer.
Let us know how yo ulike your Widebody once you get it in the air. A review for this site would be cool too.
Later,,,basmntdweller

Minimum/recommended servo torque/speed?
 

Thanks for the feedback...I was wondering if they were overkill, although they are already lying around and need to put them somewhere. :D

I have both 1100 and 1400mAh packs I can use...with 3 digital servos, will the 1100 be enough juice for 4 flights or so (my usual outing at the field)? I hate to stuff in the extra weight of the 1400mAh pack if I don't really need it...

Minimum/recommended servo torque/speed?
 

As long as you are flying it pattern style versus 3D it should be fine. The rapid extreme throw moves pull on a pack alot harder than smooth gradual control inputs.
again this is my opinion based on my experiences.
Later,,,basmntdweller

Minimum/recommended servo torque/speed?
 

Does any of you guys know who sell the servo support that holds the output gear for high torque?.

Thanks

Minimum/recommended servo torque/speed?
 

Miniature Aircraft, the maker of the X-cell line of helis has a kit for their Fury line that supports the output shaft. I think it sells for about $35. Their helis are ready to accept it but the hardware could be adapted to almost any application.
later,,,basmntdweller

Good Choices
 

I recommend the servos your chose...I'm currently running the 9411's on my wings the 8417 on the elevator...( I like a quick elevator servo in the snaps) and the 8411SA on the rudder...

The 8411SA is becoming a standard servo for us pattern guys.....its lasts a long time before servicing and have tremendous power and speed. I know many that are using this servo all around.

IMHO and I know everybody has one......the faster and stronger the better. The 9411's are great aileron servos. Yes your doing a 90 size plane but I challenge anyone to put a stronger servo on the wings and then pull a corner. The stronger servos will hold the ailerons better and if the wings are level and the plane is properly trimmed it will loop straighter. Also take the Pepsi challenge with the analog servos in the snaps compared to the digitals....You will never fly another pattern plane on analog servos again. I promise you it is like night and day.

Yes a lesser servo will move the control surface. The 9202 Futaba is in the 60oz range and analog. They are good servos, precise and work well....but they don't hold a candle to the digitals. They compare pretty close to a JR 4131 (except the 4131 has more power) and I use those for throttle now.

I like a good servo on the throttle but don't have a use for the 4131's on flying surfaces any longer. The digitals just out perform them all the way.

Another good combo is the 8231's all around and perhaps a 8411SA on the rudder....These are excellent servos a little slower...but have a good life span and don't suck the juice as bad.

My experience is about 15%-20% more with 6V....on the JR servos many of the Futaba servos don't like 6V and recommend only 4.8V.


I'm running my stuff on 4.8V and like it....The 6V is good but I don't think its needed...If you are using analogs then by all means 6V all the way.


Good Luck

Troy Newman
Team JR

Minimum/recommended servo torque/speed?
 

Thanks Troy for the feedback...extremely helpful. My current thinking is putting 8231 servos on the ailerons and doing the rest as I originally planned (8417 elevator and 9402 rudder). If I'm unhappy with the aileron speed (the torque is equivalent), I'll put in 9411 servos.

Out of curiosity, why the 8411SA for rudder vs. the original 8411? I presume it's because the plastic gear train will have less backlash and wear better, but I've normally used metal gears on my rudder servo (I fly off a grass field). I might give the 8411SA a try on a future plane and see how well it takes the grass field abuse.

I've never really worried about the throttle servo...I usually use what I have laying around, typically a standard BB servo. What advantage does a high end servo have for throttle (or is it primarily that you have some of these lying around)?

I hadn't heard that some many Futabas don't like 6V. I've run a number of them (and Hitecs) on 6V without any trouble. The 9402 packaging actually specs it out at 6V, so I would certainly hope that it is 6V capable...

Thanks again!

Minimum/recommended servo torque/speed?
 

If you setup the servos to fully utilize their output - you can save a lot of money and battery power.
My new pattern setup has ailerons measuring 4" x24 " each and tey are controlled by JR811 servos - a cheap digital.
I have used almost all the JR servos -and fly em in big IMAC models as well . --this new 811 is a bargain!
Extremely accurate and yet are rated at 53 in oz on 4.8 v.
Setup your servos to rotate as much as possible on full rate .
If you are into 3D stuff - then double the servo strength -
By 3D I mean lots of very high full deflection stuff.
For elevators- the small digitals (JR3421) are great .
For rudder - the 8411 w/wo plastic gears is still the best.
The plastic gears are cheap to replace and unless you love to bang the tail on the ground- the best choice.
I run 6V -no reg on this setup.
Engine is ZDZ40 so there is lots of prop blast on the surfaces when needed.

New 811 servo
 

I haven't run the new 811 yet but plan to.....My guess is it would be great....The real reason I say go digital is because of the holding power...You really only need like 50-60oz for an aileron or a single elevator...but the holding power of a standard analog servo is not good enough for my tastes...The 811 may just be the ticket.....Dick still has some good ideas for an old guy <VBG>

I like the nylon gears because of the number of flights I put on a plane. Gears are mechanical parts and will wear...The nylon gears seem to last about 2-3 longer before they need replacement....Now the Metal gears are really good on the big planes when doing the 3D flip and flop around stuff. The reason they are more robust and take the impact loads of full deflection one way then immediately going the other way. The Nylon gears work better with lighter loads over a longer period of time.

I think stuff even up to 33% can get away with nylon gears....but at 33% it depends on how your flying them.


The 3421s are a good choice for the elevators if you want to run separate servos...I know Chris Lakin did this last year in his Gator Giles. I also know Quique is running these in his F3A models on the elevators.

I still like a single elevator servo...but its getting temping since the little digitals are so precise.

As far as 6V goes on the Futaba stuff...Some servos don't care but I know at one time several of their servos the digitals included had a warning of 4.8V only....Not that this is bad just something to be aware of....There was for sure one of the high torque servos like a 9204 or a 9304 or something that said on the package 4.8V only...I'm sorry I'm not as versed on the Futaba product as some other people. I do know that the JR servos all like 6V.


Troy Newman