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First Tri - Help with motor & prop selection

#1
Im looking at building my first tricopter very soon and I will start ordering the parts on pay day monday.
I'm looking to build it as light and cheap as possible. But, it needs to carry a GoPro and a 3s 2200 pack, oh and also run on the 12A ESC's that I got cheap.
Here are the motors that I'm looking at.
MOTOR 1
MOTOR 2
MOTOR 3
MOTOR 4
MOTOR 5
MOTOR 6
I know the motor current ratings are close to the ESC current ratings, but I'm hoping the motors wont be anywhere near full throttle because of the higher kv ratings.
I'm also struggling with prop selection. The Blue Wonder motors recomend about an 8x3.5 and the little red CF motors about a 7x4 prop. Would I be ok with something around a 6x5, 6x6 or 7x4 prop?

Cheers for any help.
 

colorex

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#3
The blue wonder has around 400 grams of thrust, which means the whole copter will have 1200 grams of thrust max - And in order to make the copter fly well, you'll need to have more than 2:1 thrust to weight ratio. That means under 600 grams. The 2200 weighs 200 grams, the GoPro weighs 170, and the motors and ESC's and stuff should get around 150 - 200 grams. Just under 600 grams.

I'd use this one: http://www.giantshark.co.uk/blue-wonder-1300kv-micro-brushless-outrunner-motor-p-402398.html

But if you want a good tip, make an X-quad instead. No crazy tiny yaw mechanism which always breaks, and 400 grams extra power for about the same weight. 1600 thrust grams is much better than 1200. You'll have a much more stable multicopter, with plenty of spare power to carry whatever you want.
 
#4
Thanks for that. Thats actually the motor that I was tempted to get.
I like quads, but for some reason I prefer tricopters. I dont mind building the mechanical yaw because I have a couple of ideas oh how to make it stronger. I also like the idea of folding the arms in so all the props are together for transport.
 

colorex

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#5
Thanks for that. Thats actually the motor that I was tempted to get.
I like quads, but for some reason I prefer tricopters. I dont mind building the mechanical yaw because I have a couple of ideas oh how to make it stronger. I also like the idea of folding the arms in so all the props are together for transport.
The latest FT episode showed an H-quad which can be easily modified to make it foldable. I was also a tricopter lover, but for some reason I just like quads better. Probably because they're much sturdier and stable.
 
#6
It can be foldable, but it then has to be stuffed into a rucksack. With a tricopter, the props can all stick out the top. But with a quad, It would have 2 sticking out and will be sitting on 2 in the bag.
 

colorex

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#7
It can be foldable, but it then has to be stuffed into a rucksack. With a tricopter, the props can all stick out the top. But with a quad, It would have 2 sticking out and will be sitting on 2 in the bag.
Not an H-quad. The H-quad folds inwards, so the props go towards the middle of the quad.

Not trying to preach which is better, just trying to give you another perspective.
 
#8
Its ok, preach all you want :D More info is good info. If I dont use it for this build, then I'll use it for the next.

I never thought of folding the H arms in. I did like the H review and can see it being used for a lot of things. Maybe that will be my next build.
 

colorex

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#9
Its ok, preach all you want :D More info is good info. If I dont use it for this build, then I'll use it for the next.

I never thought of folding the H arms in. I did like the H review and can see it being used for a lot of things. Maybe that will be my next build.
I think if I start working and earning money again, I'll build one too. It's so versatile! I must admit, I do like the spaceship-y look too :)
 
#10
The dt750s are super powerful but don't look that great. The NTM 28-30 750kv would be my second choice. Both will run 11x47 props so you should get plenty of lift.

I agree I love the way the tri's fly but the h-quad sure ticks all the boxes when it comes to aerial photography and FPV.

The yaw mechanism on the tri is always a worry, I like the rcexplorer v2.5 method. Mine rotates the entire back arm but I don't know if I would recommend it ? Then of course with a tri there is zero redundancy if you should lose a prop...
 

colorex

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#11
The yaw mechanism on the tri is always a worry, I like the rcexplorer v2.5 method. Mine rotates the entire back arm but I don't know if I would recommend it ? Then of course with a tri there is zero redundancy if you should lose a prop...
I was using RCExplorers direct drive mechanism, but one crash, and the $18 servo stripped. Now I use a bigger servo, and a control rod with break-away parts just hot glued in place. In a crash where the prop hits the ground and puts strain on the servo, the linkage just pops off. Let's just hope it doesn't pop off in flight...

As for redundancy, I doubt there is redundancy with a quad. You could program it, but it would still not work as well as a hexa or octo.

BTW, I like the look of the DT750s - if I had a way to mount them without using the tall motor mount they would look cool. Each to his own preferences.
 
#13
Thanks for the help guys.
I decided to go with David's design and use the DT750's
I don't intend to crash it, but it happens to the best of us. I have flown my wing a few times now. Flies great but i still haveen't actually landed it.
As for the servo tilt, I'm still kind ofworking that one out. I have seen many different designs out there. Its just a case of trial and error. I dont mind breaking a few servos because they are fairly cheap.
I do have an idea that I would like to run past you though for the yaw mech.
Using David's design from his V1 tricopter
tricopter15.jpg
but replacing the single solid link on 1 side with 2 springs, 1 on each side of the servo horn. This way, it would act like a pull-pull system but with a bit of give in it. If you know what I mean?

Oh, here are some buddy codes from my HK order
Save yourself a bit of money and help me out at the same time :p
CLICKY
 
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colorex

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#14
Have you seen my yaw mechanism? It has break-away parts so it doesn't damage the servo in a crash. It uses a linkage that is hot-glued on for this purpose.

It's a bit blurry but you can see what I mean.

 
#17
Thats a good idea. Theres only 1 problem for me though. When (not if) I do crash and it does give way, I would have to go home, get the glue gun out and re-melt the glue to fix it.
While I have a day off tomorow, I think I'll make up a test rig of some sort and try the spring idea.

Oh, Off topic.
How did you get the pic to appear in your sig?
 

colorex

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#18
Thats a good idea. Theres only 1 problem for me though. When (not if) I do crash and it does give way, I would have to go home, get the glue gun out and re-melt the glue to fix it.
While I have a day off tomorow, I think I'll make up a test rig of some sort and try the spring idea.

Oh, Off topic.
How did you get the pic to appear in your sig?
It was recently enabled. Go to profile settings, signature, and upload an image. Maximum sizes and dimensions apply.
 
#19
Either I'm doing something wrong or I dont have something switched on. I can't find anywhere to upload an image.
This is the image I want to use


and here is a screen shot of what I have


Untitled.jpg
Any ideas?
 

colorex

Rotor Riot!
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#20
It seems you don't have permissions - I don't know why I do, maybe it's the number of posts I have. If you check the Signature permissions box, you don't have permission to add images. Sorry, can't help you more than that...