Alternative to S9254 with GY401

[Wazzer]

Hey Guys

I am currently using a cheapo Maxwell 831 servo n the tail of my Hurry and i m not all that impressed.

At the moment i cant justify the price of a new S9254 so i was wondering of there are any cheaper alternative true High speed Rudder servo's?

Any help would be most appreciated

Ben

[Tom Viper]

Not really, you should get the Futaba S9254 servo, you will not regrett that in the long run.
Another good tail servo, even if it might not be any cheaper is the Hitec HS6965HB. This servo is stronger, and very fast running 6V.

[Happy|Harry]

you can get a new 9254 for $62.50 here >>>

http://www.aero-fever.net/product_info.php?products_id=735&osCsid=54525d68d7447b2b871f0a2669528ca4


or maybe the $69 9257 may suffice for the hurricane? from here >>>

http://flying-hobby.com/catalog/product_info.php?cPath=17_80&products_id=1738

phil :)

[HighNear90]

Not really, you should get the Futaba S9254 servo, you will not regrett that in the long run.
Another good tail servo, even if it might not be any cheaper is the Hitec HS6965HB. This servo is stronger, and very fast running 6V.

I've got the Hitec 6965HB on my tail, but I've got a GY240 and it doesn't have a digital mode. BUT, it holds really well. Although I'm not a 3D pilot, I had a 3D pilot fly it and he thought it was solid.

I paid $85 from Tower Hobbies, but if you can get a 9254 for $62, I'd buy it and not look back.

--Leo

[istandalone]

the 9254 is a damn good servo. plenty fast and torquey enough for the hurry's tail.

[Wazzer]

you can get a new 9254 for $62.50 here >>>

http://www.aero-fever.net/product_info.php?products_id=735&osCsid=54525d68d7447b2b871f0a2669528ca4


or maybe the $69 9257 may suffice for the hurricane? from here >>>

http://flying-hobby.com/catalog/product_info.php?cPath=17_80&products_id=1738

phil :)

Hi guys thanks for all the responses

Happy Harry i found that shop with the 9254 a few days ago but I am living in Borneo, East Malaysia and the postage system is just NOT reliable plus i will get stung on import as it will have a US postal mark.

Funny how i cant find one in Asia for that price its by far the best i have seen, shows how much some shops are making on them!

I will see if i can find a secondhand one locally, there is a pretty big RC heli community in Singapore so will try there its almost local to me!!

One of the problems i am finding with the cheapo Maxwell servo is the tail stopping is not crisp. When i flick the tail from side to side it "bounces" before it stops, it is more pronounced in one direction, flicking nose left the heli stops with a bounce but flicking nose right there is a much bigger bounce.

Will this be eliminated with the 9254?

Thanks for the feed back guys

Ben

[Wazzer]

I must admit though

I do like the sound of the Hitec running on 6v as it saves adding a step down regulator.

Is the Hitec HS6965HB compatible with the Frames rate of the GY401 in Digital mode?

Cheers

Ben

[Wazzer]

If i have to buy a new servo

how about the new BLS251 Brushless from Futaba?

Is it compatible with a 401 as various places say its only suitabe for the 601 and 611?

Thanks for any feed back

Ben

[mjdee14]

One of the problems i am finding with the cheapo Maxwell servo is the tail stopping is not crisp. When i flick the tail from side to side it "bounces" before it stops, it is more pronounced in one direction, flicking nose left the heli stops with a bounce but flicking nose right there is a much bigger bounce.

Will this be eliminated with the 9254?

Thanks for the feed back guys

Ben

Ben...you might try a larger arm or moving it out a hole or two. The 821 shows .10 sec @6v if your using the bec and no stepdown...I would think .10 sec is fast enough to give good control. using a longer arm will move the tail blades faster...or you might try going in a hole...

You also might try playing with the delay...try one way of the other...it will bounce if trying to react too fast or too slow.

I just don't see your servo not being able to control the tail properly at your level of flying. The 9254 is the primo servo for hard core 3D guys...it's nice but overkill at our level of flying....

http://www.futaba-rc.com/team/team-tip-002.html

Look item #6 on this website....about the 401

[Wazzer]

Hi mjdee

Yep i know the current servo should do fine for my level of flying totaly agree, but when did that stop us wanting to upgrade!!!

I have tried playing with the delay a little but only reducing it, it is currently set at 0

so you think a greater delay might work?

cant remeber what my gain is set to but i have no wag

I already have quite a long servo arm with it set at its limit so you think i should try shorter?

Adding a 9254 will just eliminate another slight distraction.

thanks for the link its very interesting

Cheers

Ben

[mjdee14]

If you had a chance to read #6 I think what they are trying to do is actually slow down the gyro from over compensating. The bounce is not a wag...it goes to the point you commanded...and then tries to correct too fast,by adding the delay, it gives it a chance to settle into position.

try increasing the delay a little at a time, it might just fix your problem.

Mike

[Wazzer]

Ok will try tonight after work

Thanks for the suggestion

If I can get this servo to perfom better I can delay the purchase of the 9254, cant realy justify it at the moment anyway!
Unless I find a great deal that is!

Many thanks for your help I will report back tomorrow.

Ben

[mjdee14]

http://www.raptortechnique.com/gyroconfusion.htm

look at the bottom of this page also....they explain why...

also go to the home page....LOTS of good info on helis

Mike

her is another "great explanation from another forum...

28.1.3. GY401 Delay trimmer:
The Delay adjustment is on the gyro itself, and allows you to configure the gyro for the response of the tail rotor system. This is only used in heading hold mode.
The delay setting of 0 is used for very fast servos such as the S9253/S9254. The delay setting of 100 is used for very slow tail servos and for tail motor ESCs. A tail motor ESC (http://www.rcuniverse.com/buynow/keywordclick.cfm?bid_id=5300) requires at least half a second to go from half throttle to full throttle, which is about twice as slow as the slowest tail servos ( 0.25 sec/60 degrees)
For a heli with a tail servo, if the delay setting is too low, then the gyro will assume the servo is faster than it really is. So the gyro will send commands to the servo to move very quickly, and the servo will try to move to the new position but it will be too slow, and it will lag behind the gyro commands.
For a heli with a tail motor ESC, if the delay setting is too low, the gyro will assume the tail motor can change RPM very fast. So the gyro will try to change the speed of the tail motor very quickly but the tail motor RPM will lag behind the gyro commands.
This delay setting seems to affect the end of a turn (yaw). At the end of a turn, the gyro needs to increase the tail thrust to slow down the tail then decrease it to maintain a steady tail position.
For example, imagine you are performing turning the heli (yaw) and you suddenly stop. If the delay setting is too low in this situation, the tail will wag a few times before settling down because the gyro will overshoot the end of the turn and need to correct the heading a few times.
If you increase the delay, this may allow you to increase the gain, although you may not need this as a beginner.
I hope these links and copied text help the people that want to know how things work and not the experts that think they know but have to ask questions on public forums because they really don’t.
Ace

[Wazzer]

Man your a star many thanks for all the great info

I also dont trim it in rate mode so i gues the gyro is working over time when in HH

Willadjust the tail linkages to achieve steady hover in rate then fly in HH as this will help the system work much less.

Many thanks again

Ben

[Happy|Harry]

ben just for your info no the BLS251 wont work with the GY401 as it has a 760µSec control pulse which only the GY601/611 and the spartan DS760 can utilise :)

i have a spartan/bls251 setup on the CF hurricane i'm currently building :D

also Aero-fever is in kowloon hongkong ;)

phil

[Wazzer]

OK guys

I have re-set the tail control linkage so that when hovering in rate mode it sits nice with no drift at all, and did the 3 flips from rate to HH ending in HH. (Followed the directions as described in Team Futaba Link above)

I have tried increasing the delay a little at a time but it doesnt seem to have had much effect, i went all the way up to 50 and it was horrible and then ended up at about 10 but, Its the same as before. When turning quickly nose left it stops OK but when turning quickly nose right I still get a big bounce.

Strange thing is that in rate mode when i try the same quick tail flicks to about 45 degrees it stops very nicely in either direction, I thought HH would be much better?

Any more feed back guys?

Phil
I didnt realise Aero fever was in HK!!!!
hhmm.... thats got me thinking!

Cheers All

[mjdee14]

could your linkage be sticking when going to one side and not the other? Did you adjust the travel on the gyro so it dosen't bind?

Have you dropped gain to minimum to hold good?

I'm about out of ideas....but it sounds like your getting close if it's improved in one direction....

Obviosly when you turn in the direction of the bounce the gyro is either unable to react fast enough and overshoots (go out a hole/ or increase gain ) or it's too sensative and stops then corrects for the tiniest movement...( go in a hole/or reduce gain)

The natural tendency is for the heli to go nose left from the torque so all the tail is doing is letting it go...to turn right the tail has to overcome the torque and bite the air....

if all linkages are smooth...I would play a little with the gain....

What radio are you using and what gain setting do you have right now?

I know it's different on each heli but just curious what your using...

Good luck..

Mike

[mx400]

I had what you are describing once. I never did figure it out but it was not on a 401. I just swapped out servos and it stopped. You may want to check your servo gears and make sure they are fine and that the servo is operating smooth in both directions. I got a trex 600 tail on mine and its awesome.

[Wazzer]

Mike

Linkage is all smooth have carefully set the gyro travel limit so no binding

I already have quite a long servo arm don't really want to go longer or shorter as the linkage lines up very nicely.

I am using a DX7 and if i remember correctly the gain setting (using travel adjust on Gear channel) is about 55 i think that equates to about 39% gain at the gyro but i could be mistaken.

During normal hover and quick climbs the tail holds nice and still its just this annoying bounce when doing nose right, tail flicks.

The frustrating thing is that it doesn't bounce when in rate mode and i don't understand why.

I thought it might be head speed (all standard gearing on stock 850KV motor with 13 pinion)
but its fine in rate mode? Strange Huh?

I guess i will try lengthening and shortening the servo arm as thats all i haven't tried yet.

MX400
I now for a fact that the stock tail should work just fine at my head speeds so i want to get it right before i go spending on the Trex tail, will probably buy a 9254 before the trex tail anyway, thanks for the info i didnt realise the trex tail would fit.

Just out of interest how long are the trex 600 tail blades in comparison to the Stock Hurricane?

Are you using trex blades as well?

Maybe longer blades would help?

Many thanks for the feed back guys

Ben

[mjdee14]

[quote=Wazzer;532279]Mike


I am using a DX7 and if i remember correctly the gain setting (using travel adjust on Gear channel) is about 55 i think that equates to about 39% gain at the gyro but i could be mistaken.quote]

Ben

I'm using the Dx7 also but have my gyro assigned to my flight mode switch and am using 68%..but that just a little over the 50% mark putting it in heading mode..

You really have me on this one...if you increase the gain does it start to wag ?

If not go until it does and back off..

I was even going to sugest your servo isn't centering properly from one side but I would think it would do it in rate mode also....except rate mode dosen't correct for heading it just stops and goes wherever you stop the tail.

If you ever figure it out please let us know.....do you have another servo you can try? Are you using the smae on the cyclic...if so swap one out...

[Wazzer]

Hey Mike

Wow what time is it over there? Must be nearly midnight right?

I am pretty sure i have the gain set as high as i can as if i increase it a few percent i get a wag and if i drop it starts to slow wag.

I cant swap out servos as i have different ones on cyclics maxwell 821 tail is an 831.

I may ask a friend if he has spare servo for me to try as its now driving me mad wont get chance to test the longer / shorter servo horn for a day or so as taking wife out for dinner tonight as ive been neglecting her a bit too much since i've been flying the hurricane!!

As soon as i have it cured i will let you know!

Thanks for all the feed back most appreciated

Ben

[mjdee14]

Ben..

I'm in the Central time zone of the USA...it's 10:33 pm and I spend WAY too much time on this forum...but I can't fly, so at least I can feel connected to the heli world.

i also use the time to charge my lipos...Got to fly my ECO8 and the 550 Sunday afternoon and went through10 lipos....I have 2 sets of 2200 18c for the ECO, can get about 10 min or more flight time running 3s2p packs...and 3 pairs for the 550,
2 sets of 2500 polys and 1 set of 3300 polys. Since switching to the Z20 it looks like I can get 8 minutes maybe more on the 2500's and haven't pushed the 3300 too far yet, but the Z20 14t has really stretched out the flight time.

try a different servo maybe it will work...then you'll know it's the servo...if that doesn't fix it it has to be a setting or the gyro itself...but I don't think so.

Sign off and go take your wife out to dinner...

Good night !

Mike

[Wazzer]

Cheers buddy will let you know how i get on

Would love a Z20 but funds wont allow it at the moment

thanks for all the help

Ben

[Zoobie]

Had a simialar problem with an unbranded maxwell servo, a 9254 solved the problem. I just think that the servo was way to slow.

[Jungle Bob]

Hey Ben, was this problem there before you hit the ground recently? Oops, did I just tell the World that you crashed it ha ha ha. Saturday?, beach, flying? Tanjung Aru? Shorts and t'shirts? (oops, did I just tell the World we don't have a winter here...me and my big mouth eh?)