2nd Time
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2nd Time
I posted this here 3 days ago 'cause I wanted an answer and the powers that be deemed it necessary to move it with the result that a lotta people looked at it but no one answered. Maybe they will leave it alone this time and y'all will get a chance to answer.
Not wanting to start a debate on who makes the best servo here but I have gotten into a small (so far) debate on the proper size servo for a 1/4 scale aerobat and it got me to wondering. What criteria do you use when determining which servo to use for a given plane? I mean I will use standard ball bearing servos for a .40 size trainer, I'll use sport digitals i.e. JR 811's or Hitec 5475's for a .60 size cub or Funtana or similar, but when it comes to the bigger planes I try to make the servos output power match the weight of the plane. I would never use say a JR 8611 on a Sig Extra 300XS but I would use a JR 8231 or a Hitec 5645.
What do you guys use and how do you come to your decision?
Not wanting to start a debate on who makes the best servo here but I have gotten into a small (so far) debate on the proper size servo for a 1/4 scale aerobat and it got me to wondering. What criteria do you use when determining which servo to use for a given plane? I mean I will use standard ball bearing servos for a .40 size trainer, I'll use sport digitals i.e. JR 811's or Hitec 5475's for a .60 size cub or Funtana or similar, but when it comes to the bigger planes I try to make the servos output power match the weight of the plane. I would never use say a JR 8611 on a Sig Extra 300XS but I would use a JR 8231 or a Hitec 5645.
What do you guys use and how do you come to your decision?
#3
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RE: 2nd Time
I take the quality/price of a plane/engine and go from there--examples
1-PW Extra with Taurus 2.6-- Multiplex Royal digitials all around
2-Lazer 3D funfly-- JR 811 and Hitec 5475
3-Giant Weeks Solution Hitec 5945s all around
4-Giant 90 Miles Reed Extra 260--5945s all around
5-Miles Reed 80" Extra 260--8102s all around
6-Miles Reed Challenger with Taurus 3.2-- 5945s on tail surfaces and 8102s on ailirons
1-PW Extra with Taurus 2.6-- Multiplex Royal digitials all around
2-Lazer 3D funfly-- JR 811 and Hitec 5475
3-Giant Weeks Solution Hitec 5945s all around
4-Giant 90 Miles Reed Extra 260--5945s all around
5-Miles Reed 80" Extra 260--8102s all around
6-Miles Reed Challenger with Taurus 3.2-- 5945s on tail surfaces and 8102s on ailirons
#4
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RE: 2nd Time
I rarely step above standard servos. I won't hesitate to use a single standard servo for both ailerons on a 60 size aerobatic plane (Not 3-D)
The way I see it, that's how it was done in the past, and I never had any problems, why should I change it?
Last year I reviewed a 120 size GeeBee "Y" powered by a Saito 150. The instructions called for standard servos, so that's what I used. The plane flew great (Of course there were no Radical maneuvers done, buy I did all of the basic manuevers - loops, rolls, spins, etc.)
My "go to" plane is a GP Super Skybolt that I really put through it's paces. It is powered by a YS 91AC, and equipped with standard servos (Although last year I upgraded them to Standard BB Servos, just because I had some kicking around)
Now, if I were going to fly a larger 3-D plane, or 120 size areobatic plane, then I would step up to a stronger, faster servo, but for most 60 size and below, I think standards are just fine.
The way I see it, that's how it was done in the past, and I never had any problems, why should I change it?
Last year I reviewed a 120 size GeeBee "Y" powered by a Saito 150. The instructions called for standard servos, so that's what I used. The plane flew great (Of course there were no Radical maneuvers done, buy I did all of the basic manuevers - loops, rolls, spins, etc.)
My "go to" plane is a GP Super Skybolt that I really put through it's paces. It is powered by a YS 91AC, and equipped with standard servos (Although last year I upgraded them to Standard BB Servos, just because I had some kicking around)
Now, if I were going to fly a larger 3-D plane, or 120 size areobatic plane, then I would step up to a stronger, faster servo, but for most 60 size and below, I think standards are just fine.
#5
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RE: 2nd Time
cstevec,
I'm the culprit that moved your first post about servos to the RC Radios, Receivers, Servos forum. We try to keep topics for discussion in the appropriate forums. That makes it easier for everyone to find information. The Clubhouse is for RC related posts that do not fit in other forums. Since there is a forum specifically for servos I thought that was the best place for a question about servos.
Eric
I'm the culprit that moved your first post about servos to the RC Radios, Receivers, Servos forum. We try to keep topics for discussion in the appropriate forums. That makes it easier for everyone to find information. The Clubhouse is for RC related posts that do not fit in other forums. Since there is a forum specifically for servos I thought that was the best place for a question about servos.
Eric
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RE: 2nd Time
Understand Deputy. I just got to wondering about this servo thing and I knew there were people who posted here who's opinions I respect and figured I would get some answers to an important (to me) question. When it got moved and had had not a single response after 3 days. I reposted. No Harm, No foul. Good responses though, maybe you might wanna let this one ride for a few days.
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RE: 2nd Time
You could always figure the surface area of the control surface being moved multiplied by the speed at which the plane is moving and factor in the mechanical advatage (or disadvantage) the the linkage is set at and find out how much torque is needed and than add a safety margin to come up with a range for the required servo. I'm sure there are some engineer types around here that could give us a formula.
The speed of the servo is probably more a function of the style of flying you are doing and how much travel is needed with the obvious that 3D should have faster servos than a trainer would need.
The easiest and least expensive upgrade to your plane and the one I see rarely being utilized is switching to a five cell battery pack. Why people don't upgrade from the 600mah 4.8 cell battery that comes with most radios to a 6 volt with around 1000mah is beyond me. They are inexpensive and give about 1/3 more torque and speed with the only downside being a little added wieght that most wouldn't notice anyway.
The speed of the servo is probably more a function of the style of flying you are doing and how much travel is needed with the obvious that 3D should have faster servos than a trainer would need.
The easiest and least expensive upgrade to your plane and the one I see rarely being utilized is switching to a five cell battery pack. Why people don't upgrade from the 600mah 4.8 cell battery that comes with most radios to a 6 volt with around 1000mah is beyond me. They are inexpensive and give about 1/3 more torque and speed with the only downside being a little added wieght that most wouldn't notice anyway.
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RE: 2nd Time
I have a servo calculator on my site you can look at.
http://www.geistware.com/rcmodeling/...calculator.xls
http://www.geistware.com/rcmodeling/...calculator.xls
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RE: 2nd Time
I'm with Minn; been flying for years, and all I've ever used (with the exception of one) are standard non-BB servos.
I've never had anything larger than .61, but we have done a bunch of wild flying, and the only two servos that gave me trouble were
Royal "heavy duty"- crapped out on it's first flight, and I landed my Astro Hog with NO ELEVATOR!
JR standard- I believe I just got a bad one, it was on it's 5-6 flight in an Alpha Trainer and it just quit. No as pretty a landing with no elevator this time!
My reasoning?
In the ultralights I fly, the stick forces are around 5 lbs. A standard servo with 42-48 oz. of torque puts out 4 lbs. of force. The models fly faster, the surfaces on the U/L's are bigger.
That's my story, and I'm stickin' to it!
NEVER STRIPPED, OR WORE OUT A SERVO!
Jetts
I've never had anything larger than .61, but we have done a bunch of wild flying, and the only two servos that gave me trouble were
Royal "heavy duty"- crapped out on it's first flight, and I landed my Astro Hog with NO ELEVATOR!
JR standard- I believe I just got a bad one, it was on it's 5-6 flight in an Alpha Trainer and it just quit. No as pretty a landing with no elevator this time!
My reasoning?
In the ultralights I fly, the stick forces are around 5 lbs. A standard servo with 42-48 oz. of torque puts out 4 lbs. of force. The models fly faster, the surfaces on the U/L's are bigger.
That's my story, and I'm stickin' to it!
NEVER STRIPPED, OR WORE OUT A SERVO!
Jetts
#11
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RE: 2nd Time
Quite simply, I'll use the best servo I can afford that is sufficient for the job. First of all, I'll say that I use Futaba servos. The quality is superb and the prices have taken a recent dive into reality!!! I use standard BB servos in a .40 sized trainer. All around, no problem. Everything else I will use the strongest and fastest that fit the application.
Example, in my Madness 2 I use very high speed digitals (Futaba S9550) with medium torque and a low weight. The torque is very sufficient and the speed and accuracy give huge amounts of performance over the old coreless 9202s that I liked to use a few years ago. Many people use standard servos or the 9202s all around in the same style of airplane and I have flown several combinations. I find 9202s quite slow but with good torque, allowing me to perform most maneuvers with reduced precision and snap compared to mine. The standards, adequate for many pilots, leave me fairly helpless to perform my flying style. So, I find that using an $80.00 servo in my little funflyer to be a great idea.
For F3A, I want high torque with lightening fast response and great accuracy. S9451s (I think that is correct) are fast with enough torque to hold a steady position in all flight regimes for F3A on rudder and elevator, with a lower profile, lighter weight, but high speed for ailerons. Futaba has quickly gone through several designs of digital servos for ailerons in F3A to find an appropriate combination of torque and speed. Speed here really helps get the snaps around quickly. I want real time reponse with my thumbs.
For giant scale, the same principal applies. Fast, but here high torque is even more important so if need be, I sacrifice a few hundredths of a second for more torque. Again, Futaba has come out with newer designs giving higher speed with even more torque in smaller, lighter packages.
As far as what servos are best...I have never had trouble with Futaba, many people live by JR, Hi-Tec I have seen but I have never flown them in a good comparison. I have flown airplanes with Hi-tec servos but the airplanes were nothing that I could use to make a comparison in regards to servo performance.
Last input I shall provide here is linkage. Servo accuracy means nothing without linkages to support it. Sloppy linkages, no accuracy. Pushing torque is irrelevant if the linkage flexes and extreme torque/metal geared servos will not stop flutter with flexible linkages. Speed loses its effect if the geometry allows binding and excess friction, not to mention uneccesary power drain. Clevis that fit tightly into the pin holes, push rods that are solid without fexing, and geometry that does not bind are a necessary compliment to great servos to realize their full advantage.
Regards,
Mark
Example, in my Madness 2 I use very high speed digitals (Futaba S9550) with medium torque and a low weight. The torque is very sufficient and the speed and accuracy give huge amounts of performance over the old coreless 9202s that I liked to use a few years ago. Many people use standard servos or the 9202s all around in the same style of airplane and I have flown several combinations. I find 9202s quite slow but with good torque, allowing me to perform most maneuvers with reduced precision and snap compared to mine. The standards, adequate for many pilots, leave me fairly helpless to perform my flying style. So, I find that using an $80.00 servo in my little funflyer to be a great idea.
For F3A, I want high torque with lightening fast response and great accuracy. S9451s (I think that is correct) are fast with enough torque to hold a steady position in all flight regimes for F3A on rudder and elevator, with a lower profile, lighter weight, but high speed for ailerons. Futaba has quickly gone through several designs of digital servos for ailerons in F3A to find an appropriate combination of torque and speed. Speed here really helps get the snaps around quickly. I want real time reponse with my thumbs.
For giant scale, the same principal applies. Fast, but here high torque is even more important so if need be, I sacrifice a few hundredths of a second for more torque. Again, Futaba has come out with newer designs giving higher speed with even more torque in smaller, lighter packages.
As far as what servos are best...I have never had trouble with Futaba, many people live by JR, Hi-Tec I have seen but I have never flown them in a good comparison. I have flown airplanes with Hi-tec servos but the airplanes were nothing that I could use to make a comparison in regards to servo performance.
Last input I shall provide here is linkage. Servo accuracy means nothing without linkages to support it. Sloppy linkages, no accuracy. Pushing torque is irrelevant if the linkage flexes and extreme torque/metal geared servos will not stop flutter with flexible linkages. Speed loses its effect if the geometry allows binding and excess friction, not to mention uneccesary power drain. Clevis that fit tightly into the pin holes, push rods that are solid without fexing, and geometry that does not bind are a necessary compliment to great servos to realize their full advantage.
Regards,
Mark