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Old Dec 20, 2013, 10:47 PM
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Is flying a Tricopter "backwards" more efficient?

Hello, all! This is my first time posting on these boards

My interest in tricopters has just been piqued the other day, and while I don't currently have one, I've been trying to stuff my brain with knowledge about them ever since.

At any rate, one thing I've been wondering is if flying a tricopter with the yaw motor out front might be more efficient in forward flight than the more common configuration of steering from the rear. The logic is that when it's out back, it needs to produce more thrust (vs hover) to tilt the craft forwards, whereas when it's leading, it need to produce less thrust (vs hover) to tilt it forwards. While the difference might be negligible on common crafts, I'm wondering if it would be more noticeable on larger ones.

Anyone have any thoughts about this?

Cheers,
Mark
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Old Dec 20, 2013, 11:25 PM
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Welcome to RCGroups.

Not sure about efficiency but many tricopter pilots seem to prefer the "tail authority" a tricopter gives you.

Check out David Windestål's website, he knows his way around a tricopter
http://rcexplorer.se
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Old Dec 20, 2013, 11:26 PM
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No, that's not how it works. Your thinking too hard.
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Old Dec 20, 2013, 11:54 PM
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Originally Posted by mkmkmk13 View Post
Welcome to RCGroups.

Not sure about efficiency but many tricopter pilots seem to prefer the "tail authority" a tricopter gives you.

Check out David Windestål's website, he knows his way around a tricopter
http://rcexplorer.se
Thanks. David's site was on of the first I came across when I started looking into them. I'll go ahead and ask him as well.

Quote:
Originally Posted by CG Photo
No, that's not how it works. Your thinking too hard.
Could you elaborate on this a little? If the yaw rotor was in front, would the rear rotors need to pick up the slack during forward flight?

I wouldn't say I'm thinking too hard about it, but I'm legitimately curious.
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Old Dec 21, 2013, 12:11 AM
1sq
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You'll be the first and post your observation.
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Old Dec 21, 2013, 12:33 AM
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Sweet tri.

Mine is a bit different: two motors are 80 degrees apart in stead of 120, the yaw motor is pivoted just below the prop instead of on the bottom of the motor giving better balance.
The yaw prop is 1 inch longer and 1 inch greater pitch. Oh, and the pointy end goes first.
Flies beautifully.

Lyle.
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Old Dec 21, 2013, 11:16 PM
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Originally Posted by 1sq View Post
You'll be the first and post your observation.
I just might have to be

Quote:
Originally Posted by Lyle
Mine is a bit different: two motors are 80 degrees apart in stead of 120, the yaw motor is pivoted just below the prop instead of on the bottom of the motor giving better balance.
The yaw prop is 1 inch longer and 1 inch greater pitch. Oh, and the pointy end goes first.
Flies beautifully.

Lyle.
Hey Lyle. I tried doing a forum search to find your tri, but I didn't come across anything
If you've posted it before, could you link me to it?

What was your logic behind using a larger prop on the yaw motor? I didn't note the user's name, but the other day on this forum I saw a tri with a smaller tail rotor than the other two, which I presume had the CG closer to them.

With my first build (T frame and motors 120 degrees apart), I'm planning on having the yaw prop pivot along the horizontal plane of the prop disk (also level with the other two).

Cheers,
Mark
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Old Dec 22, 2013, 11:11 PM
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I had a feeling something was wrong, so after researching a bit more on how multi-rotors fly, I've found the flaws in my reasoning. I thought thrust inequalities between rotors were responsible for translational movements, when in fact they only change the pitch/roll of the craft. That throws the whole premise of efficiency gains depending on what rotors are in front completely out the window.

Nothing more to see here.

-Mark
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Old Dec 24, 2013, 10:00 AM
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The Truth in my opinion is, you can get anything to fly with the right motor mixing. Just have to invest sometime figuring that out because, the standards mixing may not work to expectation.
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Old Jan 10, 2014, 03:40 PM
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No, you were right the first time. In a traditional Tri as the rear motor is turned (creating yaw) the tail drops. This makes for an ugly turn, so you have to increase thrust to the tail to compensate. It would be more ideal if the turning motor was in the front, so as you yaw the nose digs into the turn.
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Old Jan 10, 2014, 05:26 PM
Yep, Naza-controlled Tricopter
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Where are you gonna put the camera?
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Old Jan 13, 2014, 08:01 PM
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Quote:
Originally Posted by quaDR View Post
No, you were right the first time. In a traditional Tri as the rear motor is turned (creating yaw) the tail drops. This makes for an ugly turn, so you have to increase thrust to the tail to compensate. It would be more ideal if the turning motor was in the front, so as you yaw the nose digs into the turn.
My understanding is that even if the motor was in front, you would still have to increase thrust to it while turning to offset the thrust needed to turn (and more in one direction than another). Regardless, that's not what I thought in my initial posts; I though that in translational flight, some of the motors are constantly providing more thrust than others which isn't correct - differential thrust is used only to provide the initial change in pitch/roll.
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