Espritmodel.com Telemetry Radio
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Old Jan 20, 2011, 01:32 PM
Looptastic!
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Enschede, Netherlands
Joined Nov 2009
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Thanks for explaining the tail bounche cause. It makes sense to make the servo speed higher by going further out on the servo horn. I was thinking the gyro had an automatic tail thrust reversing algorithm that kicks in when you try to stop a piro. i thought such a feature set up to agressively would start to overcompensate and results in a wag.... but your explanation of thew lack of reaction speed makes a little more sense.

-Meng, can you tell us about how you programmed the gyro to react to the tail motions and transmitter inputs? Did you indeed program something like a piro stop algorithm?
Also what recommended setup you have for us as a starting point? This way we can understand a little better what is happening on our heli's.



Oh...
A governor on eheli looks great! we can get a cheap and simple ESC and still get a fancy governor mode
Only thing is it would need an sensor to measure the headspeed. A gov inside the esc doesn't need the extra wiring.
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Old Jan 20, 2011, 02:35 PM
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Bundesrepublik Deutschland, Rheinland-Pfalz, Kaiserslautern
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Quote:
Originally Posted by derelicte View Post
it seems you can get used align 3g units pretty cheap too, but not beastx.

I just watched that video. does the vbar receive the throttle channel? I can't figure out how the fbl could control the throttle.
There's a forum here, where such rc-stuff is traded. Maybe it's because there are more beast's sold over here, I guess.

The vbar uses a satellite receiver and has the throttle input anyway. It just didn't use it without the governor software. You just need an additional hall sensor (to get the rpms) and plug the ESC into the vbar. Timo described it in a local forum here. He even said, that the vbar controls the softstart, so I wonder if those cheap ESCs without a usable softstart would work with governor?

http://www.rc-heli.de/board/showthread.php?t=172414

(sorry, thread only in german available).

But I guess there are some threads on governor also in US forums. I.e.

http://rc.runryder.com/helicopter/t616210p1/
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Last edited by daybyter; Jan 20, 2011 at 02:41 PM.
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Old Jan 20, 2011, 03:15 PM
crashs come easy patience dont
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USA, MI, Shelby Township
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Quote:
Originally Posted by branflake12 View Post
What dictates this as a cyclic servo? its far faster than needed for cyclics, (.06 on 6v), I am not sure why it would induce wag.
I bought it as it was A)digital B)fast C) $5. If it wags too much (cant be worse than the esky servo on it already), it goes in the pile for a foamy build. If it burns, i see how good my autorotation skills are.

size,

these small micros just dont have the brute muscle really for the tail.
there is alot more force on a tail servo than a cyclic servo.

will the ds-919mg work? some what, but its not my idea of a trust worth tail servo.
iv`e sen alot of post about bounce back, then i see they are using these small servo`s. i tend to believe the small micro servo is the reason for the bounce back.
it can be fixed with alot of D/R and EXPO, but i dont run either.
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Old Jan 20, 2011, 03:24 PM
Looptastic!
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Enschede, Netherlands
Joined Nov 2009
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Just did a test flight with my other servo (emax) with the ball furthest out on the small round wheel (about 10mm). Tail slider does still have a little slop, even after the CA fix.

Result: had to lower the gain a lot and still: wag wag wag
tail is not holding direction anymore in flips and pitch pumps.

So... i need to put the ball further inward to pull down the mechanical gain down and get more resolution on the servo.

I have a video (night flight) but resolution is poor and no use to upload it.


More testing tomorrow.
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Old Jan 20, 2011, 03:30 PM
Looptastic!
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Enschede, Netherlands
Joined Nov 2009
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Quote:
Originally Posted by bad400 View Post
size,

these small micros just dont have the brute muscle really for the tail.
there is alot more force on a tail servo than a cyclic servo.

will the ds-919mg work? some what, but its not my idea of a trust worth tail servo.
iv`e sen alot of post about bounce back, then i see they are using these small servo`s. i tend to believe the small micro servo is the reason for the bounce back.
it can be fixed with alot of D/R and EXPO, but i dont run either.


I run 26g mini servo's and they are great compared to all the cheaper micro servo's i tried.
The forces on the tail servo are pretty high indeed, but i did the Chinese weight mod on my birds and this results in more than 50% reduction in the force needed to move the slider at target rpm.

Im running carbon tail blades on the tail now. i might try the less efficient stock blades. this also results in a lower mechanical gain and might help a little to be able to crank up the gyro gain.
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Old Jan 20, 2011, 05:42 PM
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A governor that controls pitch, and throttle would be nice, like in the Revlok30/40.
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Old Jan 20, 2011, 06:17 PM
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Australia, VIC, Melbourne
Joined Aug 2010
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Quote:
Originally Posted by branflake12 View Post
What dictates this as a cyclic servo? its far faster than needed for cyclics, (.06 on 6v), I am not sure why it would induce wag.
I bought it as it was A)digital B)fast C) $5. If it wags too much (cant be worse than the esky servo on it already), it goes in the pile for a foamy build. If it burns, i see how good my autorotation skills are.

Wow i missed a few post. I don't get any tail wags on my esky belt cp v2, all stock servos. The tail case is modded, lipo, and esc.

I bought 5 of these 919mg servos, 2 weeks and i'll get them in the mail.

I can't wait to try them,1520 is the definate setting, 250/333 is what i'll be playing.
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Old Jan 20, 2011, 06:43 PM
as much as I can
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NZ
Joined Jan 2010
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Quote:
Originally Posted by sp00fman View Post
Just did a test flight with my other servo (emax) with the ball furthest out on the small round wheel (about 10mm). Tail slider does still have a little slop, even after the CA fix.

Result: had to lower the gain a lot and still: wag wag wag
tail is not holding direction anymore in flips and pitch pumps.

So... i need to put the ball further inward to pull down the mechanical gain down and get more resolution on the servo.

I have a video (night flight) but resolution is poor and no use to upload it.


More testing tomorrow.
I don't think the servo arm position is the answer to the bounce. My 450 sport had the ball on the DS420 at 7.5mm, and I could set the gain to true 90% and it still didn't wag, but the bounce was still there.

The GP780 was the same, as far as gain went, but there was no piro stop bounce.

I've now flown with the servo arm out a hole and the gain is now at true 34%. The bounce is still the same, perhaps a bit worse. Haven't tried the foam change yet.

You would think a gyro could learn the piro stop gain required by seeing the result of the stop.

Depending on how the GA250 works, I wonder if reducing the limits in the setup, would help with the bounce.
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Old Jan 20, 2011, 06:50 PM
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Quote:
Originally Posted by sp00fman View Post
Just did a test flight with my other servo (emax) with the ball furthest out on the small round wheel (about 10mm). Tail slider does still have a little slop, even after the CA fix.

Result: had to lower the gain a lot and still: wag wag wag
tail is not holding direction anymore in flips and pitch pumps.

So... i need to put the ball further inward to pull down the mechanical gain down and get more resolution on the servo.

I have a video (night flight) but resolution is poor and no use to upload it.


More testing tomorrow.
What distance was the ball before the move to 10mm?

Have a read here:
http://www.spartan-rc.com/resources/...&search=bounce

Couple other things to try as by your description the tail is alot worse than before.

Try smaller ball position and or larger tail blades (one at a time)

As pitchup mentioned nose right stops are good. Do you see that too?

Obviously a left piro is in the direction the tail wants to go due to the clockwise rotation of the main blades. This means the tail has to be quite aggressive to stop.

The other direction (nose right) is against the direction the tail wants to go so it is alot easier for the tail to stop nicely as it can "ease" into this stop by simply reducing the pitch of the tail rather than an opposing pitch action that is required for the nose left stop.


I'd also test full rudder piro. Maybe this is like the Quark in that full rudder yields crazy fast piros. But mid rudder yields less than half that piro speed due to bulit in expo. Ie the rudder is not linear and is way to fast at the ends and comparibly too slow in the middle. Expo this out so the mid is still the same but the full is more "normal".

Either way though if you piro at a certain speed that speed will be dictated by your thumb position and changing expo, and rudder endpoints won't change the gyros stop request...but you never know how things correlate in these cheaper componants until you f with them alot.

Amp
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Old Jan 20, 2011, 07:15 PM
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USA, IA, Iowa City
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Quote:
Originally Posted by pitchp View Post
Wow i missed a few post. I don't get any tail wags on my esky belt cp v2, all stock servos. The tail case is modded, lipo, and esc.

I bought 5 of these 919mg servos, 2 weeks and i'll get them in the mail.

I can't wait to try them,1520 is the definate setting, 250/333 is what i'll be playing.
Thanks for the setting info. As far as it being "not the best" tail servo, thats fine, though i realize it might not show what the gyro can really do.

I was looking for a tail servo that would work on my 450 but also maybe down to a 250. The align DS420 isnt very big size wise, but it appears to do ok on the T250.
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Old Jan 20, 2011, 07:50 PM
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[QUOTE=branflake12;17166106]

I was looking for a tail servo that would work on my 450 QUOTE]

you can try this, GS D9257.

http://www.nitrodude.com.au/catalog/...oducts_id=7857

the price there maybe not right.i think you can find cheap in other shops. pay attention,the GS D9257 have two types, one is 1520us,another is 760us.

one of our team pilot think this servo is better than DS520.

meng
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Old Jan 20, 2011, 07:59 PM
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Originally Posted by ASSAN View Post
pay attention,the GS D9257 have two types, one is 1520us,another is 760us.

Which one is recommended?
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Old Jan 20, 2011, 08:11 PM
LEL
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And this servo. Does anyone know its specs, i can not find them. It would work well with GA-250?

http://www.servodatabase.com/servo/kds/n590
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Old Jan 20, 2011, 08:30 PM
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Originally Posted by Tag1260 View Post
Which one is recommended?
our guy use 1520us version.

but i think both good.
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Old Jan 20, 2011, 08:35 PM
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Thanks. That's the one I have ion a 450.

http://www.hobbycity.com/hobbycity/s...dProduct=13422
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