Elevator servo speed

[POF]

I'm looking for a elevator servo for my new Supra. I already have a Supra where I use DS368 for both elevator and rudder. This seems to be good but I was wondering if a faster elevator servo would be better?

I remember that I heard that a fast elevator servo is important to make a good zoom/catapult but is it overkill even to think about using twice the money for a servo that is twice as fast?

Any comments?

Thanks in advance.
Peter

[Ollie]

Lets us assume the plane's velocity of 100 feet per seconds in a zoom. The DS368BB Digital Micro MG Servo has a Speed: .21 sec/60°. Let us assume 1/2 of speed or 0.1 second. So, the plane moves about 10 feet in 1/10 of a second. Is that good enough?

[davidjensen]

You got to ask yourself "how fast are your fingers?" How often do you slam the stick from full down to full up and need that response in less than .21 seconds? If you were flying a heli I would agree faster is better but with a 3M TD ship its not.

[Jurgen]

.....but with a 3M TD ship its not.Hmm, for the flying part you are very right, for the dip-zoom-job it does matter, at least for some tophotshot pilots around and also for my own experience.
Jurgen.

[cody303]

You should take a look at the Airtronics 94761Z it is faster, smaller, and stronger than the DS368.

http://www.airtronics.net/ATX_servos.htm

Cody

[POF]

Thanks for all your replys.

Lets us assume the plane's velocity of 100 feet per seconds in a zoom. The DS368BB Digital Micro MG Servo has a Speed: .21 sec/60°. Let us assume 1/2 of speed or 0.1 second. So, the plane moves about 10 feet in 1/10 of a second. Is that good enough?
I know that the DS368 is good enough. I already use it for the elevator job in my Supra#1. But do I gain anything if the servo is faster? And what is "good enough"?


You got to ask yourself "how fast are your fingers?" How often do you slam the stick from full down to full up and need that response in less than .21 seconds? If you were flying a heli I would agree faster is better but with a 3M TD ship its not.
I have used fast servos for flaps and ailerons only because of the landing. To be able to get them up close to the ground. In this case my fingers are fast.


Hmm, for the flying part you are very right, for the dip-zoom-job it does matter, at least for some tophotshot pilots around and also for my own experience.
Jurgen.
Topshot? Thats not me :o

You should take a look at the Airtronics 94761Z it is faster, smaller, and stronger than the DS368.

http://www.airtronics.net/ATX_servos.htm

Cody
Does that mean that you recommend the fast elevator servo? Or is it just a recommendation of a good servo?

[Robglover]

I've got 6 of the Airtronics 94761Zs in my Supra. Faster, more torque, and smaller than the DS368's. Either servo will work, but if you want a faster servo there it is. It also fits better in the wing tip sections.
happy trails

[Jurgen]

Topshot? Thats not me :o Yo brother, me too ;)
Just because of that you dont want to make the dip-zoom harder to control by using a good-enuf servo. I had Futaba3150 first, almost exactly the same speed like the DS368 under load. Then i took a faster servo, man this realy releaved some difficulty in mastering the dip-zoom phase.
We, the non hotshots, need to pamper ourselves where possible, who else is going to do that for us? :D
Jurgen.

PS: i see lotta US guys going for the JR DS3421 and the Airtronics already mentioned, i cant get both where i live, now i move to Graupner DS3728. Do not use nylons, i ripped some.

[cody303]

Does that mean that you recommend the fast elevator servo? Or is it just a recommendation of a good servo?

Both... It is always better to use a servo that is faster if you are not giving up any torque, but there is no reason to pay double for it considering what you have works. The Airtronics 94761Z is stronger, faster, and cost less than the DS368 so there is no reason not to use it.

Cody

[POF]

Then i took a faster servo, man this realy releaved some difficulty in mastering the dip-zoom phase.

Can you explain some more, please?


now i move to Graupner DS3728.
But DS3728 is 0,16 sec/40° and DS368 is 0,11 sec/40° :confused:

[POF]

Both... It is always better to use a servo that is faster if you are not giving up any torque, but there is no reason to pay double for it considering what you have works. The Airtronics 94761Z is stronger, faster, and cost less than the DS368 so there is no reason not to use it.

Cody
Thanks. I think I will try to find the servo in Europe.

[onemetre]

I my investigating I've also found many to use the JR3421 on the elevator. I think another item might be missing. It's not just the speed but also the strength. A digital servo will stall but use all it's power to get there as quickly as possible. The solution I think that's occurring is to use a faster but also stronger servo to have the authority in the control surface.

Rob

[Jurgen]

Can you explain some more, please?Jo Grini stated once in a post that his zooms became much better since he used faster/powerfull servo's, he went to Volz. I had some trouble making my dips just as short and effective as possible following an upzoom at an desired angle (using futaba3150-short arm). So i followed Jojoens advice and got me a fast servo. My local store has good futaba connection so i got the fastest one, 9650. I thought nylon would be OK, it's not! But before the teeths broke i realy could control the dip much better (how much) and also better pointing angle of the nose upward after line-release at top speed in the bucket. With the 3150 it happened more than once the plane flew on the back towards myself after line release (over-pull), this never happened with the fast servo.
But DS3728 is 0,16 sec/40° and DS368 is 0,11 sec/40° :confused:See picts below, under same load the 3728 is slightly faster than 368, but thats not the big deal here. Deflection under load is also the same. The 3728 is more robust (bigger/more torque + ball bearing versus no ball bearing for 368) making it able to carry a longer servo arm and this makes higher arm-end speed possible just what we want.
Manufacturer data:
368: 3.1 kg.cm takes 0.11s to 40°
3728: 3.6 kg.cm takes 0.12s to 40°

I admit not installing the 3728 yet, its ordered and i'm impatient :)

POF, if you find the airtronics 94761 (Sanwa) in europe please feedback. I did find sanwa but not the type we want. Same for JR3421, i dont see its equivalent in Graupner.

Jurgen.
PS: all numbers i got are from (manufacturer data included): http://www.teaser.fr/~osegouin/aeromode/servos.phtml

[oakman7004]

The response of the glider is always important. especially in the zoom phase...

So therefore I use FAST and strong servos for elevator control. We have over the years gone to faster and faster servos here in Sweden (and used them in WC conditions)...now the setup looks like this!

For a allmoving stab my first choice is allways Graupner/JR DS8418
Power ca. 46 Ncm (4,6 kg/cm)
Hold power ca. 88 Ncm
Speed ca. 0,054 s/40°
Weight ca. 59 g
Size(L x B x H) ca. 39 x 19 x 40 mm


or if space is cruicial I use Futaba s9550.
Volts Torque Speed
4.8V 66.6 oz-in. 0.14 sec/60°
6.0V 83.3 oz-in. 0.11 sec/60°

Dimensions Weight
1.6 x 0.8 x 1.0 in. 1.6 oz.

For a V tail I use Graupner/JR 3781. (do not use for DS)
Power ca. 18 Ncm (1,8 kg/cm)
Hold power ca. 47 Ncm
Speed ca. 0,04 s/40°
Weight ca. 28 g
SIze (L x B x H) ca. 33 x 15 x 27 mm

With a setup using these servos both launching and speed turns in F3B have been more accurate, i.e. better.

I will have the 8418 in my SUPRA which I will maiden later this year....I don't see why I shouldn't use the same setup in my SUPRA as in my F3B ships...

/Jonas Ekman

[POF]

The solution I think that's occurring is to use a faster but also stronger servo to have the authority in the control surface.

Rob
All the servos mentioned are all pretty strong

With the 3150 it happened more than once the plane flew on the back towards myself after line release (over-pull), this never happened with the fast servo.

Did that too - not sure if I can blaim the servo for that :o


POF, if you find the airtronics 94761 (Sanwa) in europe please feedback. I did find sanwa but not the type we want. Same for JR3421, i dont see its equivalent in Graupner.

I have just ordered two Airtronics at Tower hobbies. I was not able to find it in EU.


For a allmoving stab my first choice is allways Graupner/JR DS8418
/Jonas Ekman
Seem like a good servo for the job. I have just checked the size and it should be possible put it in there. I have a servo that size in my Europhia II.

Thanks to all for comprehensive answers :)

[Richard S]

Hi Jonas,

Thanks for the information. My only worry is that the JR DS8418 seems quite a heavy servo at 59 grams. Particularly while the current new breed of F3J models seem to be aiming for drastic reductions in all-up-weight.

The Volz high speed servo "Speed-Maxx-XP" is only 19grams, and has 32N power.

In your view would this be a good choice for an all-moving tail, or would something with a bit more power be a better choice.

I'm getting 2 new f3j models over the winter period, an ExperiencePro and a Pike Perfect. I want to make sure I am putting in the best possible gear inside them (Mutiplex IPD synth RX, 5 cells etc)

Also when doing the "down-up-down" for a zoom launch, what levels of control input do you think you are putting on the sticks?

I've always been worried about over-stressing my current model (kevlar Graphite2) by overdoing the control movements on this part of the launch. Possibly I am being too conservative?

[Jurgen]

I have just ordered two Airtronics at Tower hobbies. I was not able to find it in EU.I wish you succes with recieving those. I heared they are pretty suspicious for importing electronics into europe. RoSh compliance (environmental friendly contents approval) and CE-labelling can trow dirt in the process. That was the reason why my local store cannot order those servo's, they don't carry the CE label and no big importer /distributor has done the effort to become the CE label for that line. Let us know if all worked out.
Jurgen.

[davidjensen]

Rich FYI
The Experience Pro will fit 368's in the wing tips and 3421's for flaps. These servo's just barely (but do) fit.

[POF]

I wish you succes with recieving those. I heared they are pretty suspicious for importing electronics into europe. RoSh compliance (environmental friendly contents approval) and CE-labelling can trow dirt in the process. That was the reason why my local store cannot order those servo's, they don't carry the CE label and no big importer /distributor has done the effort to become the CE label for that line. Let us know if all worked out.
Jurgen.
Really? I was thinking about ordering a ZLog @ Kennedys but that would be a problem too? The CH dealer would have the same problem?

[psoff3x]

Hi Richard

On an all-moving cross-tail I've used the JR DS3421 (US spec and sourced from the US) but more recently settled on the UK version which is the JR DS3401 - 15mm thick, 30g, 4.3kgcm-1, 0.19sec/60°. It's not as fast as Jonas' suggestions but faster than, say, the JR DS362 (UK spec) that I used to use. For me, the servo's speed improvement has made a big improvement to the zoom. At 30g I just put a little less lead in the nose.

Beware though that the UK spec of these JR servos qualifies them for 4-cell operation only, unlike the Graupner or US specs.

See here for details
http://www.jrpropo.co.jp/radio/products/pdf/servo_spec.pdf

Pete

[Jurgen]

I readed that the Zlog was not exported to europe as long as the RoSH compliance certificate was not proceeded. I dont know if it is okey by now. This was producer talking, maybe there are other sources dealing the Zlog out of stock.
Jurgen.

[Bernd Brunner]

Zlog??

i´ve ordered one in june. Six weeks later it was in my postbox. No problem. Additional I had to pay the german VAT, nothing else.

Bernd

[oakman7004]

Hi Jonas,

Thanks for the information. My only worry is that the JR DS8418 seems quite a heavy servo at 59 grams. Particularly while the current new breed of F3J models seem to be aiming for drastic reductions in all-up-weight.

The Volz high speed servo "Speed-Maxx-XP" is only 19grams, and has 32N power.

In your view would this be a good choice for an all-moving tail, or would something with a bit more power be a better choice.

I'm getting 2 new f3j models over the winter period, an ExperiencePro and a Pike Perfect. I want to make sure I am putting in the best possible gear inside them (Mutiplex IPD synth RX, 5 cells etc)

Also when doing the "down-up-down" for a zoom launch, what levels of control input do you think you are putting on the sticks?

I've always been worried about over-stressing my current model (kevlar Graphite2) by overdoing the control movements on this part of the launch. Possibly I am being too conservative?

Richard,
Personally I think that less than 40N is a little bit to low. This is the reason I've never used 368 (4 or 5 batterycell) as elevator servo on a allmoving setup (eventhough it works for most people). The risk is ofcoarse getting somewhat sluggish control. And considering the speeds the gliders have in both F3J/B starts one don't have the "time" waiting for the controls to move (this is somewhat difficult explaining but once it's experienced, it make sense).

Yes, its heavy. But usually the extra 20-30g of the servo will in reality be 5-15 g since the weight is on the "correct" side of CG. It is worth the extra weight...

The stick movement is rapid and done quick. Don't overdo it. Think that you want to have the stab in movement as short time as possible. The line tension is gone quickly. On a winch use small radius on down and up when looking at glider. In F3J be quicker....

Regarding the volt specs I use 4,8 volt on my JR servos while my clubmate Pasi Vaisanen has used 6 volts for years, this without problem. Getting to the extreme some friends have tried 8-10 V for launchphase...the servos will beeing punished/pushed like this have shorter lifetime, but they do work a season or so, but performace is nice...

When will your gliders be in UK?

// Jonas

[Richard S]

I've been quoted about 6 weeks for an xperience pro as I want custom layup/colours. I turned one down last week which was exactly the layup I wanted, but with blue and white wing (I really struggle with visibility with white models at distance.)

The Pike is a different matter. I'm on the waiting list direct with Samba, but their quoted delivery time to me is April. If I can source one before then (possibly if a dealer has someone back out a purchase) I will take it.

I have a Graphite2 (kevlar wing) and a 2nd hand erazer extreem(for windy weather) to get me through the winter months. We have a series of 6 monthly winter competitions. (The first one was just over a week ago). I would like to get the new models in the air within the series.

[Jurgen]

Zlog??

i´ve ordered one in june. Six weeks later it was in my postbox. No problem. Additional I had to pay the german VAT, nothing else.

BerndIn august 06 Hexpertsystems had this published:
"NOTICE: until further notice, we can not ship to EU or EEA countries due to the RoHS initiative becoming effective July 1st, 2006. The manufacturer who builds our products failed to prepare for this. We are currently working to get a new manufacturer."
Good news, that statement is off the site now.
Bernd, nice to hear things work out for us, i'm interested in Zlog too.
Jurgen.

[Jurgen]

Richard,
Personally I think that less than 40N is a little bit to low...That makes me considering of putting the graupner DS 3728 on flaps (next plane) and aim abit higher for elevator.
Jurgen.

[oakman7004]

That makes me considering of putting the graupner DS 3728 on flaps (next plane) and aim abit higher for elevator.
Jurgen.

3728 is an excellent choice for flaps (as for the 368 if space is an issue) and with a good elevator servo you'll end up among the starts... in a launch. ;)

/J

[POF]

I wish you succes with recieving those. I heared they are pretty suspicious for importing electronics into europe. RoSh compliance (environmental friendly contents approval) and CE-labelling can trow dirt in the process. That was the reason why my local store cannot order those servo's, they don't carry the CE label and no big importer /distributor has done the effort to become the CE label for that line. Let us know if all worked out.
Jurgen.
I got my 94761Z servos today from Tower Hobbies. There was no problem getting them into EU while they DO have a CE label.

First impression is good. Less play in the gear than usual and tested in my servo tester they seems to be faster than DS368. Nice.:)

[Jurgen]

Thats a nice thing to hear !!! Seems RC store managers do not have al the wisdom, i'll take their words from now on with more care. Maybe he was just protecting his market. Thanks for the very valuable input.
Jurgen.

[torcgolf]

im using 761z's in my supra and they are fine. the only thing i dont like about them is their centering.

[Jurgen]

Some comparison pictured downstares.
The airtronics twice as fast as 368.
Play-deflections indeed bigger.
One could conclude using shorter arms on the aitronics for "neutral" protection without jeopardising speed on the control surface.

[POF]

Some comparison pictured downstares.
The airtronics twice as fast as 368.
Deflections indeed bigger.
One could conclude using shorter arms on the aitronics for "neutral" protection without jeopardising speed on the control surface.
What is the last one "fléche sous 5,0 v, en degrés"? Never had French in school :o

[Jurgen]

Read that as a kind of error against finding the 100% perfect arm position. The bigger the load, the more the arm deviate from ideal position.
Vitesse = speed. Consommation= current. Couple= torque. Euro= what makes women looking strange when we spend it on another model.

[Jurgen]

When you see the last curves, about the precision (fleche), the 3150 looks king of the pack. BUT the graph is very likely measured on new servos. I readed some writing of people saying that 3150 suffer some wearing-out on the gear faster than other servo's when used for load-jobs like flaps. At that moment mine were already installed on the flaps. Now i can testify i have some play indeed on my 3150-flaps combo but i cannot compare that to other servos due lack of experience.

I start to think of this as a good and (for me important) economical setup:
ailerons + rudder : 3150 (40euro)
flaps : graupner DS 3728 (is sturdyer and ball beared towards 368) (85 euro)
(full flying) elevator : volz micro max XP (105 euro) or bigger digi if there is place for it.

Jurgen.

[POF]

I start to think of this as a good and (for me important) economical setup:
ailerons + rudder : 3150 (40euro)
flaps : graupner DS 3728 (is sturdyer and ball beared towards 368) (85 euro)
(full flying) elevator : volz micro max XP (105 euro) or bigger digi if there is place for it.

Jurgen.
That makes sence.


If was rich i put volz anywhere, every plane, my car, the toilet water flush handle, for rubbing my back etc etc
Jurgen.
That makes sence too :D

According to the measurements it seems like the 94761Z is a bit high on error and maybe it’s not so perfect for an full-flying elevator? Or is an elevator only under heavy load during the start?

[Jurgen]

I broke a nylon gear in launching while dip-zooming, so that must be the hard load.
Remember those graphs are likely new servo's and do not include wearing resistance, the results after 1 or 2 seasons might be different. Some hard core 94761 users might assist you here.
Jurgen.