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Old Jan 20, 2013, 01:29 PM
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Basic Questions about stability

I'm about to start experimenting with aerial photography and have been researching parts/control boards for a scratchbuilt multi.

My main concerns right now are regarding stability. The following questions come to mind as I begin my research:

1) What format will offer the greatest stability (keeping in mind this will be used for photography)? I see 3, 4, 6, and 8 rotor configurations out there. Is one inhenrently more stable than the other? My intent is to mount redundant motors on each arm for safety, even if efficiency suffers, so it seems there must be a "sweet spot" from a cost/safety standpoint.

2) What is considered the most stable controller board currently? I see people using the NAZA, the Arducopter, Hoverfly, KKPlus, etc. Do any stand out as the most stable? I can envision needing to be able to hold hover and position and also utilize waypoints.

Thanks for any insights you can give me. I'm willing to do my own research but I just thought it might be good to get advice from you more experienced guys.
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Old Jan 20, 2013, 01:55 PM
we dont NEED roads!
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answer to #1 is 8 motors

answer to #2 is NAZA
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Old Jan 20, 2013, 03:15 PM
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And the NAZA is best...why?

Is there a consensus on this forum about that?

Is there a sgnificant difference in stability between 4 and 6 rotors?
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Old Jan 20, 2013, 03:19 PM
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I am sure if you spent 20minutes scanning through the first few pages of this forum you would find hundreds of different opinions.

In my eyes its a waste of money. But for the newb out there, its the easiest way to get into the air. Especially if you expect your quad to sit still and photograph something, or if you want return to home with only a few clicks of the mouse button & a flick of the switch.
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Old Jan 20, 2013, 03:20 PM
we dont NEED roads!
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Originally Posted by steambc View Post
Is there a sgnificant difference in stability between 4 and 6 rotors?
Yes.
Just watch a few youtube videos.

Watch the Octocopters and see just how stable those are.
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Old Jan 20, 2013, 03:24 PM
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Originally Posted by subaru4wd View Post
I am sure if you spent 20minutes scanning through the first few pages of this forum you would find hundreds of different opinions.

In my eyes its a waste of money. But for the newb out there, its the easiest way to get into the air. Especially if you expect your quad to sit still and photograph something, or if you want return to home with only a few clicks of the mouse button & a flick of the switch.
I'm not sure what you mean by saying that the NAZA is a waste of money when you said up above that it is the most stable board according to how I couched my question. Maybe I'm missing something...would you mind elaborating? I'm looking for stability both in flight and hovering above all else, and money is no object.

Thanks, I'll take a look at the Tube videos regarding 8 vs. 4.
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Old Jan 21, 2013, 03:07 AM
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I hate "money is no object" posts...
Is this still a hobby forum? or we should migrate elsewhere free of "pro" usage posts...
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Old Jan 21, 2013, 09:18 AM
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Why some buy Porsche an others VW Golf ?
They're not pros, it's only for the pleasure to drive a better car.
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Old Jan 22, 2013, 12:26 PM
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I hate "money is no object" posts...
Is this still a hobby forum? or we should migrate elsewhere free of "pro" usage posts...
Well, renatoa, you certainly have a significant amount of spare brain power and time to devote to being upset about "money is no object" posts.

I have an excellent idea. How about deciding not to participate in posts that upset you?

If it makes you feel any better, I'm a hobbyist who is turning his eye toward a possible way to increase his income and have fun at the same time with the skillset he was born with and has developed. I have no company, no financial backing. I'm simply willing to spend the necessary funds to experiment and see what is to be seen. It's a challenge for me.

Is that ok with you?
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Old Jan 22, 2013, 12:29 PM
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Originally Posted by steambc View Post
Well, renatoa, you certainly have a significant amount of spare brain power and time to devote to being upset about "money is no object" posts.

I have an excellent idea. How about deciding not to participate in posts that upset you?

If it makes you feel any better, I'm a hobbyist who is turning his eye toward a possible way to increase his income and have fun at the same time with the skillset he was born with and has developed. I have no company, no financial backing. I'm simply willing to spend the necessary funds to experiment and see what is to be seen. It's a challenge for me.

Is that ok with you?
That would be a whole lot easier if more people would read the information already available... instead of asking stupid questions like those above.

Common sense would tell you 8 motors is more stable than 4
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Old Jan 22, 2013, 12:29 PM
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Originally Posted by Mortimer View Post
Why some buy Porsche an others VW Golf ?
They're not pros, it's only for the pleasure to drive a better car.
Also, remember that this is a "scratchbuilt" forum. It's about people wanting to challenge themselves and their craft. There are plenty of commercially available devices out there. My challenge is to take myself to a new level by creating my own multirotor and to see if I can leverage it into some spare income (photography).

Most people would find that admirable, but it seems our renatoa is very sensitive about that.
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Old Jan 22, 2013, 12:32 PM
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I also suggest you read up on the laws about profiting from aerial photography.

Your business plan is about to shatter. Unless you know some friends in the FAA
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Old Jan 22, 2013, 12:46 PM
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Originally Posted by subaru4wd View Post
That would be a whole lot easier if more people would read the information already available... instead of asking stupid questions like those above.

Common sense would tell you 8 motors is more stable than 4
I can't imagine you speaking like that to anybody's face. Nobody could possibly be that disrespectful in real life. It's easy to launch little direspectful missles from behind your keyboard, but do you really conduct yourself this way with people face-to-face?

Your sticking your nose into someone else's conversation with silly name-calling speaks volumes of who you really are.

I imagine that you're a kid, (else you wouldn't conduct yoruself this way) so I'm going to help you with something...

Most educational resources, whether a university, a high school, or a hobby forum encourage basic questions and discourage calling other peoples' questions "stupid". This is supposed to be a place of learning. The question goes far deeper than you were able to grasp. "Are there unkowns (to a new person) about 8 vs. 4"? "Is there a diminishing return as more rotors are added?" "Do 8 rotors provide enough additional stability to justify the time and expense?" You get the idea.

If I were you I would be very slow to pounce on new forum members who come in with sincere questions desiring to learn from the experience and knowledge of others.

Yes, it is "common sense" in theory that 8 rotors would be more stable than 4. However, that is "common sense" in a theoretical sense. I have always found it wise to consult with those who have gone before me to avoid costly mistakes and to avoid re-inventing the wheel.

But apparently this is "stupid" to you. I disagree as in my 55 years on planet earth I have helped many, many younger men with engineering concerns, music, vintage machinery restoration, and several other pursuits. Not once did I feel the need to lash out at anyone and declare their question to be "stupid". I've had the honor of helping them, and that has been a true blessing in my life.
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Old Jan 22, 2013, 12:50 PM
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Originally Posted by subaru4wd View Post
I also suggest you read up on the laws about profiting from aerial photography.

Your business plan is about to shatter. Unless you know some friends in the FAA
LOL, thanks for your concern. I actually do have several friends in the FAA, so you can relax, I'm gonna be ok...
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Old Jan 22, 2013, 12:51 PM
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LOL- this can be a prickly and unforgiving forum to post newb questions in some times.

But the OP asked politely, so here's the scoop on 4, 6 and 8 motors:

With 8 motors, you have redundancy. If you lose a motor, the device will continue to fly, which is helpful if you have thousands of dollars worth of camera equipment airborne and hope to get it down intact.

It is said that 6 motors can do the same thing, but less reliably. If you lose a motor on a quad, a crash will inevitably follow, unless the quad happens to already be on the ground at the time. Same goes for a tri (3 motors).

I don't think stability comes into it as much as redundancy and reliability. I've seen great video from quads as well as hexes and octos. Intuition would suggest that octos are most stable, but in fact, they can all be stable if properly set up and tuned. Many people find this to be their downfall however.

Subaru4wd is alluding to the fact that making money doing AP with multis looks easy, but in reality is quite difficult. Do some research and you'll find out why.

Good luck with your endeavor.

Rick
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