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Old Feb 24, 2013, 03:17 PM
Registered User
Arkhangelsk, Russia
Joined Apr 2009
40 Posts
Quote:
Originally Posted by nadine View Post
You could post,pid settings for the craft!?
What servos you use it!?
regards
servos: http://www.hobbyking.com/hobbyking/s..._13g_0_10.html
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Old Feb 25, 2013, 02:52 AM
1400 watt RW Zephyr
matwelli's Avatar
Taranaki New Zealand
Joined Sep 2003
1,336 Posts
Quote:
Originally Posted by native18 View Post
CG location is below the axis of rotation of rotors.
55cm length of the model
Weight 620g
screws 9x4x3
flight controller MultiWii Lite v1.0 (Bi)
motors - D2822/14 1450KV
battery 2S 3000
thanks for that, can you tell be how far below the motor pivot point the CG is ?
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Old Feb 25, 2013, 12:32 PM
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Arkhangelsk, Russia
Joined Apr 2009
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Originally Posted by matwelli View Post
thanks for that, can you tell be how far below the motor pivot point the CG is ?
The photo shows that motors are deployed down. Screws further. Ideally, the CG must be below the screws. My model is at CG screws.
Sorry, my English is not their native language.
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Old Feb 25, 2013, 02:40 PM
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Ran D. St. Clair's Avatar
United States, CA, Sunnyvale
Joined Dec 2006
996 Posts
It doesn't matter if the screws (propellers) are up or down. Either way, the thrust line is through the pivot point. What matters is the location of the pivot point relative to the C.G. I think you have effectively answered that question.

Thanks.
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Old Feb 25, 2013, 07:00 PM
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v22chap's Avatar
United States, IN, Granger
Joined Jan 2003
3,129 Posts
I love native 18 's reverse engineering on the motor pivot points ... using a blade grip the wrong way around is a really neat idea ....
It took me quite awhile studing the picture to pick up on that ,,, enlarging also helped !!!

This would work great on tricopters also ,,, it will be filed away for future use
Thanks for sharing
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Old Feb 25, 2013, 11:37 PM
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Ran D. St. Clair's Avatar
United States, CA, Sunnyvale
Joined Dec 2006
996 Posts
It certainly is a great looking thing. 10 out of 10 points for style!
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Old Feb 26, 2013, 05:04 AM
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VTOLicious's Avatar
Austria
Joined Oct 2007
281 Posts
Quote:
Originally Posted by Ran D. St. Clair View Post
It doesn't matter if the screws (propellers) are up or down. Either way, the thrust line is through the pivot point. What matters is the location of the pivot point relative to the C.G. I think you have effectively answered that question.

Thanks.
True, thrust line is always through pivot and adequate pivot-CG-distance is crucial.
But it does matter if the motors are pointing up or down if the nacelles are not balanced itself - consider the weight shift! Dependent in which direction they are mounted the (longitudinal) CG will move with or against the desired pitch movement.

Rgds Michael
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Old Feb 26, 2013, 09:34 AM
Will fly for food
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United States, CA, Carlsbad
Joined May 2011
532 Posts
Quote:
Originally Posted by VTOLicious View Post
True, thrust line is always through pivot and adequate pivot-CG-distance is crucial.
But it does matter if the motors are pointing up or down if the nacelles are not balanced itself - consider the weight shift! Dependent in which direction they are mounted the (longitudinal) CG will move with or against the desired pitch movement.

Rgds Michael
This is true. I noticed with my bicopter if I let it hang by the arms, and disturbed it with the motors powered down, it would oscillate almost indefinitely. When I reverses the gain to be backwards, I could get it to almost immediately dampen out a disturbance.
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Old Feb 26, 2013, 12:32 PM
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Ran D. St. Clair's Avatar
United States, CA, Sunnyvale
Joined Dec 2006
996 Posts
Quote:
Originally Posted by VTOLicious View Post
True, thrust line is always through pivot and adequate pivot-CG-distance is crucial.
But it does matter if the motors are pointing up or down if the nacelles are not balanced itself - consider the weight shift! Dependent in which direction they are mounted the (longitudinal) CG will move with or against the desired pitch movement.

Rgds Michael
Good point - R.D.
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Old Feb 27, 2013, 06:37 PM
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United States, CA, Los Angeles
Joined Aug 2009
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Actually, there are a number of factors that goes into determining where the CG is on a Bicopter. 1. If it is an OAT or FAAT, 2, How high the props sets above the Spar and 3, the angle of rotation are the most important ones.
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Old Feb 28, 2013, 01:19 AM
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Arkhangelsk, Russia
Joined Apr 2009
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Originally Posted by rimshotcopter View Post
2, How high the props sets above the Spar and
This is high enough? This model flies much better Gress Aero.
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Old Feb 28, 2013, 01:37 AM
vtol fan
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Joined Jul 2009
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Quote:
Originally Posted by native18 View Post
This is high enough? This model flies much better Gress Aero.
Native18,where is located the mwc board and the battery!?I never seen one foto of this...
Cheers
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Old Feb 28, 2013, 01:40 AM
vtol fan
nadine's Avatar
Joined Jul 2009
627 Posts
Quote:
Originally Posted by rimshotcopter View Post
Actually, there are a number of factors that goes into determining where the CG is on a Bicopter. 1. If it is an OAT or FAAT, 2, How high the props sets above the Spar and 3, the angle of rotation are the most important ones.
What is mean,OAT and FAAT !?...sorry my ignorance
At point 3,can you make one drawing?!
Regards
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Old Feb 28, 2013, 08:07 AM
vtol fan
nadine's Avatar
Joined Jul 2009
627 Posts
Hi native18.
How far down is your cg from propps!?
I attached on foto also...What dim.have there!?
PS.hope matwelli,d'ont kill us,for highjacking his thread
Regards...
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Old Feb 28, 2013, 08:50 AM
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Arkhangelsk, Russia
Joined Apr 2009
40 Posts
Quote:
Originally Posted by nadine View Post
How far down is your cg from propps!?
CG just below the screws. Bending aluminum tube made ​​in order to raise the screws above the cab soldiers.
Photo provisions battery and controller I will later.
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