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Old Nov 29, 2012, 10:52 AM
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New tail system from hobbyking
http://www.hobbyking.com/hobbyking/s...Mount_Set.html
What do you think about it?
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Old Nov 29, 2012, 11:47 AM
Lets make it remote control!!!
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its great plug in tail if you use carbon fiber tubes to make tri
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Old Nov 29, 2012, 12:44 PM
Arizona Rim Country
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OK - here's a little tweek that might be of interest

http://www.gizmag.com/hytaq-rolling-...m_medium=email
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Old Nov 30, 2012, 06:57 PM
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Auckland New Zealand
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Quote:
Originally Posted by Jorgemaria View Post
New tail system from hobbyking
http://www.hobbyking.com/hobbyking/s...Mount_Set.html
What do you think about it?
Well it sure looks nice
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Old Dec 06, 2012, 01:45 AM
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how do you all find the CG of a tricopter ? does it like quads that just need to draw a straight line between motors and find the center
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Old Dec 06, 2012, 07:19 AM
Lets make it remote control!!!
abletowinginc's Avatar
USA, FL, St Augustine
Joined Jun 2009
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Quote:
Originally Posted by WonderKing View Post
how do you all find the CG of a tricopter ? does it like quads that just need to draw a straight line between motors and find the center
i find that i make it tail hevy to add photo equip to front...... but depends on your needs..
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Old Dec 06, 2012, 11:54 AM
Fly, crash, rebuild.
United States, NY, Shelter Island
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Quote:
Originally Posted by WonderKing View Post
how do you all find the CG of a tricopter ? does it like quads that just need to draw a straight line between motors and find the center
I believe it is. Equally important is the placement of the flight controller as close to the frame cg. Adding gear should be functional for visibility and clear radio transmission for FPV etc... But then use none location critical equipment to balance the tri, such as the battery, equally front or back and side to side. A flight controller can compensate to a degree but efficiency will drop if your frame is unbalanced. A tail heavy tri will fly but the rear motor will have to work harder to level off. A good cg and balanced multi will hover hands off without trimming to compensate and fly longer on the same charge.
H
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Old Dec 06, 2012, 11:59 AM
Fly, crash, rebuild.
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Another observation, tris like the weight to be more on the front motors because you get a drop in lift efficiency with a tilting rotor in the rear. So I find my tris are balanced better and fly better with a slightly forward cg of dead center to the 3 motors. I can't confirm that scientifically. Just an observation. In my talon tricopter the controller is further forward of the center of the 3 motors and it works well when the cg is on the flight controller than over the dead center of the 3 motors.
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Old Dec 06, 2012, 04:48 PM
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I have found a cg in the center or slightly back causes pitch up..
A forward cg is definitely better in my case.
Can anyone confim ?
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Old Dec 06, 2012, 08:30 PM
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Quote:
Originally Posted by jbalat View Post
I have found a cg in the center or slightly back causes pitch up..
A forward cg is definitely better in my case.
Can anyone confim ?
You may be correct. I have always balanced in the center and definitely get pitch up. I'll try moving it forward and see what happens. Do you have a formula for how for forward to go?

Later;

D.W.
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Old Dec 07, 2012, 01:54 AM
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You may be correct. I have always balanced in the center and definitely get pitch up. I'll try moving it forward and see what happens. Do you have a formula for how for forward to go?

Later;

D.W.
Yep...Trial and error

I just replaced my 11x4.7's with 9x4.7's..
I can honestly say it flies much better both in fast flight and hover. I still have to try it in windier conditions and compare flight times, but there was more than enough lift at similar throttle position which makes me think that maybe the bigger props were not running at their most efficient load and speed.

Dont worry it wasnt my idea, I noticed David uses thes props on the rc explorer build. I assume they behave better in the wind and they are quicker to react to changes in engine speed since they dont carry as much inertia ?
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Old Dec 07, 2012, 05:20 AM
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so how do i can find the center then? do i need some Pythagoras calculation
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Old Dec 07, 2012, 12:18 PM
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Sweden, Uppsala County, Balsta
Joined Jun 2012
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@Wonderking
I'm guessing this is your first Tri build, so forgive me if I'm bloating.

Keep it simple.
Make your booms equal in length (Motor shaft to inner end. You have to account for the yaw mechanism on the tail boom) and space them 120 degrees apart. If you can, use 10mm square pinewood for booms

The geometric center is where the booms meet, if you imagine a line continuing from the inner boom end.
Try to keep your CoG close to this point, and design your LiPo-holder so you can shift the CoG later with the battery.

I just drew a line on the frame at this point, and check the pitch balance by holding my fingers there. For roll balance, I put one finger under the front center of the frame, and another finger under the tail boom.

Small variations in CoG are not critical to get a Tri airborne and resonably flyable.
Far more important are good ESC:s, Motors, flight controller, balanced props of right size for your build, and preferably no vibrations.

Safe landings,
/J
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Old Dec 07, 2012, 07:17 PM
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If you have a complex setup then i would create 3 points in space on a cad program.
Measure distances from motor to motor and feed these back into cad. Join the 3 points with a circle and then you can find the center of the circle !!
Use the radius from this circle to swing a string from each motor. Where they intersect is the cg..
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Old Dec 07, 2012, 09:53 PM
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Quote:
Originally Posted by jbalat View Post
I just replaced my 11x4.7's with 9x4.7's..
I can honestly say it flies much better both in fast flight and hover. I still have to try it in windier conditions and compare flight times, but there was more than enough lift at similar throttle position which makes me think that maybe the bigger props were not running at their most efficient load and speed
Yep much better in the wind. Just tried it in 25 knots, had to keep the nose down about 45deg to hover in the one spot and it would only glitch a little when gusts came through.

Anyone else using smaller props with dt750's ?
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