i prefer that the end point is at 100%, and then use the servo arm and horn to maximize the throw. I have read that servo resolution is optimal when it is set at 100% of travel, more or less diminishes the resolution.

(granted, you need to use servos that are up for the task (high torque))

i will give you an example:
i have a 91" yak, and i set up the rudder servo for 150%, it had max throws, i was happy. however, even though i made high rate expo to 65%, when i would go to knife edge, it was twitchy, meaning, it would not do it smoothly, not the servo movement, i am referring to the flying characteristics.

so, i got a bigger servo arm, and was able to move the linkage further out, and then i lowered my travel to 100%, and now, it when it moves to knife edge it looks real smooth and nice.

hard for me to explain it, hope i have not confused anyone.


read this article:


http://www.rcgroups.com/forums/showthread.php?t=1590199

Originally Posted by Ohio AV8TOR

Which is basically 90° to the servo case.

Yep
+1

i was trying to simplify it for him.

Originally Posted by orthobird

i prefer that the end point is at 100%, and then use the servo arm and horn to maximize the throw. I have read that servo resolution is optimal when it is set at 100% of travel, more or less diminishes the resolution.

(granted, you need to use servos that are up for the task (high torque))

i will give you an example:
i have a 91" yak, and i set up the rudder servo for 150%, it had max throws, i was happy. however, even though i made high rate expo to 65%, when i would go to knife edge, it was twitchy, meaning, it would not do it smoothly, not the servo movement, i am referring to the flying characteristics.

so, i got a bigger servo arm, and was able to move the linkage further out, and then i lowered my travel to 100%, and now, it when it moves to knife edge it looks real smooth and nice.

hard for me to explain it, hope i have not confused anyone.


read this article:


http://www.rcgroups.com/forums/showthread.php?t=1590199

Orthobird, this is not correct. It is imperative to always make sure you have maximum mechanical advantage with your set-up. You want to get the most throw possible using the shortest arm you can to achieve this. Typically endpoint adjustments in the range of 125-140 are best but there is noting wrong with using 150 if you are not overdriving the mechanical limits of the servo. You want the servo to move through its full range to give you the best resolution. If you use a long arm and achieve maximum deflection with the servo only moving 30 degrees then you have minimized resolution. Not trying to step on anyone's toes but I feel this needed to be clarified as I want everyone to get the best out of their planes and proper setup is essential. Hope this helps.

Originally Posted by EXTREME FLIGHT

Orthobird, this is not correct. It is imperative to always make sure you have maximum mechanical advantage with your set-up. You want to get the most throw possible using the shortest arm you can to achieve this. Typically endpoint adjustments in the range of 125-140 are best but there is noting wrong with using 150 if you are not overdriving the mechanical limits of the servo. You want the servo to move through its full range to give you the best resolution. If you use a long arm and achieve maximum deflection with the servo only moving 30 degrees then you have minimized resolution. Not trying to step on anyone's toes but I feel this needed to be clarified as I want everyone to get the best out of their planes and proper setup is essential. Hope this helps.

I learned that from horizon hobbies website to set the end points high and adjust the throws via dual rates. And yes don't set it to 150% if the surface has reached max throw before the tx stick is at the end of it's travel.

Originally Posted by EXTREME FLIGHT

Orthobird, this is not correct. It is imperative to always make sure you have maximum mechanical advantage with your set-up. You want to get the most throw possible using the shortest arm you can to achieve this. Typically endpoint adjustments in the range of 125-140 are best but there is noting wrong with using 150 if you are not overdriving the mechanical limits of the servo. You want the servo to move through its full range to give you the best resolution. If you use a long arm and achieve maximum deflection with the servo only moving 30 degrees then you have minimized resolution. Not trying to step on anyone's toes but I feel this needed to be clarified as I want everyone to get the best out of their planes and proper setup is essential. Hope this helps.

no toes were stepped on!! we are all here to learn and share info. point well taken. i was not saying to go under 100 anyways. that would not be good, as this would for sure decrease the resolution of the servo. i personally do not set it up for 130 or 150, yes, definitely true, if you use the servo arm hole farther away from the servo output shaft, this will place more stress on your servo and decrease the torque. that is why i mentioned you have to use servos that are up to the task. on my Extreme flight Yak, 91" airplane, there is one servo per surface, but i am using JR MP 82 T servos, that run on 2 s lipos, and those servos are rated for over 530 ou/in of torque. i have never experienced blow back with these servos and with my linkage set up. again, set up of linkage is critical, and i did follow the manual, but for some reason, i have great throw, and my travel is at 100, not 130 or 150. the argument is, does setting the travel over 100% do anything to your resolution?? this is the question. if going from 100 to 125 does not increase the resolution, then why do it? the servo resolution is the imaginary number of "clicks" or "ticks" the servo motor will move as you move the transmitter stick. if you decrease the throw by setting it at 80%, lets say, that means that now, there is less fine movements, since the stick travel is now spread out more. however, i believe, if you go beyond 100%, this may be a different case that will be determined by your specific radio system.

one thing for sure, i will not be changing the way i set up my airplane, as i will stick to the 100% travel in the original set up. This works for me, and as i mentioned earlier, i did want to max out the rudder travel so i increased the end travel to beyond 130%, but i noticed that when i went to do a knife edge, the actual flight characteristics revealed a non smooth , kind of quick, snappy movement of the airplane in the air, even with 65% expo, but once i moved the travel to 100% and i used a outer more hole, this now became a very smooth appearing transition during flight when i do my 4 point rolls or knife edge. i would personally start at 100, use your servo arm and linkage to get the throw, use good servos up to the task at hand, and then, if you still need more throw, then creep the travel adjustment up. Do not set the travel adjustment down. I am certain if you peruse my Tx, you will see some of the throws are 115%, 120% or even 125% as i try to max out the throw for 3d rates. just my 2 cents.

Originally Posted by EXTREME FLIGHT

Orthobird, this is not correct. It is imperative to always make sure you have maximum mechanical advantage with your set-up. You want to get the most throw possible using the shortest arm you can to achieve this. Typically endpoint adjustments in the range of 125-140 are best but there is noting wrong with using 150 if you are not overdriving the mechanical limits of the servo. You want the servo to move through its full range to give you the best resolution. If you use a long arm and achieve maximum deflection with the servo only moving 30 degrees then you have minimized resolution. Not trying to step on anyone's toes but I feel this needed to be clarified as I want everyone to get the best out of their planes and proper setup is essential. Hope this helps.

Considering to what Chris said the original question remains unanswered then.

I'll keep the EPA's to 135% to allow room if we need to add (Hitec A9 max at 140%)

This is ASSUMING ALL SUB-TRIMS ARE ZERO. LET'S ASSUME SUB-TRIMS DON'T EXIST.

There are following two options.

1. If we are imperative that we want the arm to be 90° we can achieve that as in Picture 1. But we get more travel in one direction and less travel in the other direction which was my original problem. Am i doing something wrong here OR DO I NEED TO USE THE PROGRAMMER TO CHANGE ANYTHING?????

2. But what Chris said above, "You want the servo to move through its full range to give you the best resolution". In this case which i think might be the correct option, the servo arm can't be 90°. Rather we are looking for that position for the arm to go on in which TRAVEL IS MORE OR LESS EQUAL IN BOTH DIRECTIONS. Picture 2

Even more confused

this will be my last post here. i finally found the post that mentions the reason to aim for 100 % and not higher. bear in mind, i am not saying to go lower either.

http://www.rcgroups.com/forums/showthread.php?t=1089904

this was the question asked by someone:

I read somewhere that, when setting up a plane on a computer radio that you should set servo travel adjustment to the maximums to acheive the best resoultion of stick movement to servo travel. Is that a good practice? Will it damage the servos?

I have tried this and even with setting the control arms up for the smallest amount of travel, I need to set my rates to less than 50%. I gues I don't understand why the rate setting doesn't affect the resolution.

Any help?



this was answer:

by two different people:



answer 1.
CustomPC
Registered User
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Australia, NSW, Cherrybrook
Joined May 2004
1,502 Posts
Yes, it's a good idea to use 100% of the servos travel to increase the resolution.

Setting it at the maximum, 125% or 140% depending on your radio, is not always a good idea as you could overdrive the servo if you use any mixes.

Try setting your radio to 100% and adjust your mechanical linkages to reduce the control surface throw.

Move the link on the servo arm closer to the servo by a hole or two, and move the link on the control surface further away if you can.

This also has the benefit of increasing the mechanical advantage (leverage) of the servo's power.
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answer #2
Daedalus66
59 years of RC flying
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Canada, ON, Ottawa
Joined Feb 2006
15,877 Posts
One reason to avoid going much past 100% throw is that you get into a region where the angle of the servo arm makes the resulting control throw increasingly non-linear -- a kind of reverse expo. Indeed, you can think of a moderate amount of expo as simply correcting for this effect.

On the other hand, using a lot less than 100% is like throwing away resolution. Always adjust your linkages so maximum desired throw corresponds to somewhere in the general range of 100%.

Also, use the farthest out holes possible on both the servo arm and the control horn (consistent with following rule 1!). If you use close in holes at both ends, any kind of mechanical slop in the linkage or hinges is magnified as a proportion of control throw.



best regards to all!!
not trying to be argumentative. just wanting to back up my statement.

Originally Posted by orthobird

this will be my last post here. i finally found the post that mentions the reason to aim for 100 % and not higher. bear in mind, i am not saying to go lower either.

http://www.rcgroups.com/forums/showthread.php?t=1089904

this was the question asked by someone:

I read somewhere that, when setting up a plane on a computer radio that you should set servo travel adjustment to the maximums to acheive the best resoultion of stick movement to servo travel. Is that a good practice? Will it damage the servos?

I have tried this and even with setting the control arms up for the smallest amount of travel, I need to set my rates to less than 50%. I gues I don't understand why the rate setting doesn't affect the resolution.

Any help?



this was answer:

by two different people:



answer 1.
CustomPC
Registered User
CustomPC's Avatar
Australia, NSW, Cherrybrook
Joined May 2004
1,502 Posts
Yes, it's a good idea to use 100% of the servos travel to increase the resolution.

Setting it at the maximum, 125% or 140% depending on your radio, is not always a good idea as you could overdrive the servo if you use any mixes.

Try setting your radio to 100% and adjust your mechanical linkages to reduce the control surface throw.

Move the link on the servo arm closer to the servo by a hole or two, and move the link on the control surface further away if you can.

This also has the benefit of increasing the mechanical advantage (leverage) of the servo's power.
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answer #2
Daedalus66
59 years of RC flying
Daedalus66's Avatar
Canada, ON, Ottawa
Joined Feb 2006
15,877 Posts
One reason to avoid going much past 100% throw is that you get into a region where the angle of the servo arm makes the resulting control throw increasingly non-linear -- a kind of reverse expo. Indeed, you can think of a moderate amount of expo as simply correcting for this effect.

On the other hand, using a lot less than 100% is like throwing away resolution. Always adjust your linkages so maximum desired throw corresponds to somewhere in the general range of 100%.

Also, use the farthest out holes possible on both the servo arm and the control horn (consistent with following rule 1!). If you use close in holes at both ends, any kind of mechanical slop in the linkage or hinges is magnified as a proportion of control throw.



best regards to all!!
not trying to be argumentative. just wanting to back up my statement.

Don't believe everything you read on the internet!
If you ask any of the top competition pilots in the world they will verify my setup advice. Been doing this for 3 decades and have had the opportunity to work with many of the top pilots and pick their brains about setup, what works, and what wins competitions. These pilots look for every advantage in setup, servo resolution and mechanical advantage. If you find what works for you by all means use it, I am just relaying what I have learned from doing this and being around it for a long time.

Originally Posted by bluefear

Considering to what Chris said the original question remains unanswered then.

I'll keep the EPA's to 135% to allow room if we need to add (Hitec A9 max at 140%)

This is ASSUMING ALL SUB-TRIMS ARE ZERO. LET'S ASSUME SUB-TRIMS DON'T EXIST.

There are following two options.

1. If we are imperative that we want the arm to be 90° we can achieve that as in Picture 1. But we get more travel in one direction and less travel in the other direction which was my original problem. Am i doing something wrong here OR DO I NEED TO USE THE PROGRAMMER TO CHANGE ANYTHING?????

2. But what Chris said above, "You want the servo to move through its full range to give you the best resolution". In this case which i think might be the correct option, the servo arm can't be 90°. Rather we are looking for that position for the arm to go on in which TRAVEL IS MORE OR LESS EQUAL IN BOTH DIRECTIONS. Picture 2

Even more confused

Glad to help you out here. First your setup will depend on what type of flying you want to do. Typically most guys are looking for maximum throw for aggressive 3D flying. I'll address that here.
Place the servo arm at 90s degrees (perpendicular) to the servo case. You will always be able to get more movement up than down due to the physical limitation of the G10 control horns hitting the bottom of the stab. I usually setup the elevator to allow as much up travel as possible as this allows for great elevators, positive tumbles and such. I then get as much down travel as possible until the horns are touching the bottom of the stab. I then use my triple (or dual rates as the case may be) to adjust the travel of the elevator with individual settings for precision flying, 3D, and aggressive tumbles.

Hey Chris, it is all good!! I am not arguing with you!!

No argument here, it's all good!

Originally Posted by EXTREME FLIGHT

Glad to help you out here. First your setup will depend on what type of flying you want to do. Typically most guys are looking for maximum throw for aggressive 3D flying. I'll address that here.
Place the servo arm at 90s degrees (perpendicular) to the servo case. You will always be able to get more movement up than down due to the physical limitation of the G10 control horns hitting the bottom of the stab. I usually setup the elevator to allow as much up travel as possible as this allows for great elevators, positive tumbles and such. I then get as much down travel as possible until the horns are touching the bottom of the stab. I then use my triple (or dual rates as the case may be) to adjust the travel of the elevator with individual settings for precision flying, 3D, and aggressive tumbles.

Thanks Chris you clarified the G10 horns have more up rather than down travel.

So Chris what could be the reason that I'm getting only 38° down elevator on max. 140% EPA. Or is 38° the right figure???.....I was just wondering maybe 45° either direction.

I think might need to use the programmer to get perpendicular bang on.......And one other thing.....Can end-points be further increased using the Hitec programmer?..Or would that lose resolution?

Hi there,

I have flown the model with the OS-GT 33 with pretty good results. But now I have sold it. With that plane I had some of my best flying moments.

Extreme Flight Extra II (7 min 46 sec)

Extreme Flight Extra 300 Fun (8 min 22 sec)

Now I seriously think of getting a new one (gas version) and place a DA-60 that I have spare. After seeing the balistic performance of Jase Dussias EF Edge 88'' with the DA-70 I look for something similar in power. Chris and rest any opinions?

Please advise.

Originally Posted by bluefear

Thanks Chris you clarified the G10 horns have more up rather than down travel.

So Chris what could be the reason that I'm getting only 38° down elevator on max. 140% EPA. Or is 38° the right figure???.....I was just wondering maybe 45° either direction.

I think might need to use the programmer to get perpendicular bang on.......And one other thing.....Can end-points be further increased using the Hitec programmer?..Or would that lose resolution?

You can use the Hitec programmer to increase the end points of the servo. You should be able to get a minimum of 45 degrees travel in each direction.

Been so busy with the big boys I felt like I've been neglecting smaller gassers! Here's one from yesterday with the 78" EF Extra. I've been running the VVRC 40cc twin with the Falcon 20x9 CF and wanted to try a 21x8. While the higher RPM on the 20x8 and 20x9 are great, I live more in the low and slow world so bigger props suit me best.

Went with the Xoar beechwood since we're still waiting on Falcon to produce the 21x8 CF but was more than pleased with the results!! Only dropped about 400rpm going to the larger prop, still great pullout but tons of airflow over the surfaces. Feels a lot more locked in and more like a larger plane than even before!!

VVRC 40cc twin and Xoar 21x8 (1 min 35 sec)