YAK 85, rotation speed for barrel (rolling)  
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All Forums >> RC Airplanes >> Giant Scale Aircraft - 3D & Aerobatic >> Quique's Aircraft Support >> YAK 85, rotation speed for barrel (rolling)
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YAK 85, rotation speed for barrel (rolling) - 5/3/2007 4:24:12 PM   
bart-rennes


 

Posts: 58
Joined: 5/17/2006
From: Gévezé, FRANCE
Status: offline 		I have my yak 85" with a ZDZ50NG and since the beginning i found that speed of rotation for rolling (barrel) is very very low: around 2.5 seconds to do a rotation !!
My ailerons settings are bigger than the manual, i change all servos (from TowerPro 995 to Blue dird) and result is the same.
Any idea ? is it normal ?

Thanks jean-claude

< Message edited by bart-rennes -- 5/3/2007 4:57:30 PM >
       Post #: 1

RE: YAK 85, rotation speed for barrel (rolling) - 5/3/2007 8:21:29 PM   
Aero104



Posts: 37
Joined: 10/18/2002
From: Antioch, TN, USA
Status: offline 		I am not sure which Blue Bird Digital servos you are using, but the biggest I was able to find online was about 140 oz/in of torque.

Based on some internet servo calculators (http://www.csd.net/~cgadd/eflight/calcs_servo.htm) you would need a MINIMUM of 300 oz/in for this size of aerobatic plane.

I think the instruction manual for the 86" yak states "JR8611a or equivalent." (8611a running on 6v, gives you 320oz/in). The same would most likely be true for the 85"yak.

You will be risking control surface flutter and crash with anything smaller.

Most people here in US are using JR8611a (320oz/in) or Hitec HS-5955TG (333oz/in.).

I hope this was helpful.

Aero104


(in reply to bart-rennes)
       Post #: 2

RE: YAK 85, rotation speed for barrel (rolling) - 5/3/2007 8:37:20 PM   
bart-rennes


 

Posts: 58
Joined: 5/17/2006
From: Gévezé, FRANCE
Status: offline 		Thank you Aero104 for your answer, my current servos are BLUE BIRD BMS 610 MG+HS give for 9.7kg (around 342oz) and before it was TowerPro MG995: given for 12kg (around 428oz), same result !!

jean-claude

(in reply to Aero104)
       Post #: 3

RE: YAK 85, rotation speed for barrel (rolling) - 5/3/2007 9:21:32 PM   
Icaro2004


 

Posts: 14
Joined: 2/11/2004
From: Bakersfield, CA, USA
Status: offline 		Jean-Claude
If you use a programmable radio, Have you checked servo speeed?

(in reply to bart-rennes)
       Post #: 4

RE: YAK 85, rotation speed for barrel (rolling) - 5/3/2007 9:28:59 PM   
Rezagh


 

Posts: 1810
Joined: 6/10/2004
From: Rancho Santa Margarita, CA, USA
Status: offline 		Jean-Claude,

That speed is extremely slow. I have to back down my throws because the plane rolls so fast to keep up at full deflection. Please check your servos and battery system.

Let me know about your findings.

Reza

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Quique's Aircraft Company

(in reply to Icaro2004)
       Post #: 5

RE: YAK 85, rotation speed for barrel (rolling) - 5/3/2007 10:24:12 PM   
Aero104



Posts: 37
Joined: 10/18/2002
From: Antioch, TN, USA
Status: offline
I think there is a conversion problem here...

I found this link for the blue bird 610 mg and it lists 9.7kg/cm or 132oz/in.

http://www.clodparts.com/products/servos/9.html

---> NOTE the torque data is measured differently for US and metric.


Force (kg or oz) x Arm (cm or in) = Moment (torque: kg/cm or oz/in)


Therefore a smaller distance OR weight will cause overall torque to be less. You can't just covert the 9.7kg to oz, you have to account for the distance difference (10cm approx 1/4 in)

So, long story short... servos are way too small.

Does that make sense?

I just learned something here myself... I think ??

Best of luck,

aero104

(in reply to Rezagh)
       Post #: 6

RE: YAK 85, rotation speed for barrel (rolling) - 5/3/2007 10:33:54 PM   
Aussie_Knife_Edge


 

Posts: 260
Joined: 8/21/2005
From: Sydney, AUSTRALIA
Status: offline 		My Hitec 5955TG's are rated at 24Kg and have 333 oz in of torque at 6V.

Your servos are less than half at 9.6Kg so your torque would be less than 150 oz in.

Try some decent servos and I think you'll be amazed at the difference.

Cheers
Jason.

(in reply to bart-rennes)
       Post #: 7

RE: YAK 85, rotation speed for barrel (rolling) - 5/4/2007 8:36:53 AM   
bart-rennes


 

Posts: 58
Joined: 5/17/2006
From: Gévezé, FRANCE
Status: offline 		Ok, thanks to all, i will try another servos and let you know the result.

jean-claude

(in reply to Aussie_Knife_Edge)
       Post #: 8

RE: YAK 85, rotation speed for barrel (rolling) - 5/4/2007 10:14:36 AM   
bart-rennes


 

Posts: 58
Joined: 5/17/2006
From: Gévezé, FRANCE
Status: offline 		I've just check availability in France for JR8611A servo, we can find only the JR DS8711. So which is the best: HS5955TG or JR DS8711 (JR price is lower) ?

Thanks
jean-claude

(in reply to bart-rennes)
       Post #: 9

RE: YAK 85, rotation speed for barrel (rolling) - 5/4/2007 3:18:31 PM   
Rezagh


 

Posts: 1810
Joined: 6/10/2004
From: Rancho Santa Margarita, CA, USA
Status: offline 		Jean-Claude,

The 8711a are stronger. I love mine.
I think you should go for it.

Reza

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Quique's Aircraft Company

(in reply to bart-rennes)
       Post #: 10

RE: YAK 85, rotation speed for barrel (rolling) - 5/9/2007 10:36:36 AM   
bart-rennes


 

Posts: 58
Joined: 5/17/2006
From: Gévezé, FRANCE
Status: offline 		So more information about my problem. I use an automatic battery switch from Robbe for security purpose (http://at.robbe-online.net/rims_at.storefront/464192e5003567b9271b3e0dc1460679/UserTemplate/1/?ISID=464192e5003567b9271b3e0dc1460679). I discovered that the switch give 3.5A continuous and 5A at peak, do you think it is enough for the yak 85 ?
For testing i remove the switch and tried to move the aileron with my hand: result very hard, i set the switch and result: more easy to move...

Thanks
jean-claude

(in reply to Rezagh)
       Post #: 11

RE: YAK 85, rotation speed for barrel (rolling) - 5/9/2007 3:27:51 PM   
Rezagh


 

Posts: 1810
Joined: 6/10/2004
From: Rancho Santa Margarita, CA, USA
Status: offline 		Jean-Claude,

I would at least use a switch with over 6 amp continuous rating. I guess your regulator/switch rating is LOW for this plane! I think you have to get a good power system + good servos and regulator or it will be just a matter of time before something giving up! The least is you will not be enjoying the plane because your set up is not right.

Thank you,
Reza

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Quique's Aircraft Company

(in reply to bart-rennes)
       Post #: 12

RE: YAK 85, rotation speed for barrel (rolling) - 5/9/2007 3:41:02 PM   
bart-rennes


 

Posts: 58
Joined: 5/17/2006
From: Gévezé, FRANCE
Status: offline 		Thanks reza, i will change all of this. The servos Hitec 5955TG has been ordered, which battery regulator/switch do you think i should use at good price ? (smart-fly standard regulator ?)

Jean-claude

(in reply to Rezagh)
       Post #: 13

RE: YAK 85, rotation speed for barrel (rolling) - 5/9/2007 3:47:31 PM   
Rezagh


 

Posts: 1810
Joined: 6/10/2004
From: Rancho Santa Margarita, CA, USA
Status: offline 		I'm not sure what kind of smart-fly regulator you need. I think you need to research that yourself from their website.

Quique and I have been using one Duralite heavy-duty failsafe switch with 6 volt regulator. Here's the part number #65060-HD and here's the link http://www.duraliteflightsystems.com/accessories4.html#Heavy it goes for $59.95 (switch and regulator). I have been using the same set up in my 102" Yak as well. Never had a single problem.

Good Luck,
Reza

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Quique's Aircraft Company

(in reply to bart-rennes)
       Post #: 14

RE: YAK 85, rotation speed for barrel (rolling) - 5/18/2007 3:28:04 PM   
bart-rennes


 

Posts: 58
Joined: 5/17/2006
From: Gévezé, FRANCE
Status: offline 		I've just tested the hitec 5955TG on ailerons and result is a better b