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Old Dec 23, 2014, 07:15 AM
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Endurance FPV Quad

Hello all,

I'm starting this thread both to be a build log and to ask for some advice.
I have two goals in my contruction :
-Efficient quadcopter with 30 min fpv time
-Good, vibration free video

For the first goal I'm really divided between using EOD's construction or doing one of my own with square carbon-fibre booms. That way, I don't need circular mounts, motor mounts, etc, because everything can be directly attached to the booms. what's certain is that circular shape is far more resistant than square shape in this case.
For the power system, I'm thinking about using the rctimer 5010-14 360kv 5mm shaft motors. I wonder if the sunnyskyes and the multistars equivalent are better, that's where I need your help. I've heard the sunnyskyes have ceramic bearings, that's a pro but I'm supposing due to the 5mm shaft the rctimers have a pretty strong and big bearing. If i use the rctimer's, I'll use 15*5,5 inch propellers, with 4s, as they are more efficient than the 17 inch propellers ( I know, as a rule of thumb 17 inch would be better, but I've seen on youtube a guy who tests it and it turns out that the 15 inch is the most efficient). Also, I would need some advice with the esc. Most of the low amp escs can't deal with more than 4 cells, and i would like if they could handle it ( If the video gets to wobbly, I'll use 12 inch propellers and 6s). Bigger props are far more efficient, but they catch wind easier.

For the second goal, I'll use a custom made 3D printed gimbal, with the rubber dampeners from de dji zenmuse, and the storm32 controller. I believe the setup will be far lighter than the DJI Zenmuse H3-3D. My 3D design was based on francischie, but with a few mods I believe will improve the performance. One of them is to mount the gimbal, with the rubber dampeners on a tarot gimbal mount. That way, I'll get two dampening stages. I will also mount the battery on the tarot gimbal mount, since a lot in reducing vibrations as to do with the weight used to reduce them.

Summing up, my main goal is to reduce the weight as low as possible, boost the efficiency, and build a still very good platform for fpv.

In a few days I'll post my 3D design , and some math on the batteries I'll use.
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Old Dec 23, 2014, 03:08 PM
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my next build will be a long duration quad. So far with my tricopters, the have "Watts Up" meter has been indispensable. i reccommend it as you can refine the eCalc estimates to being way more useful, and then verify the battery capacity used, along with your charger putting power back in. In this way youll be able to get long flight times with good safety. (im paranoid when it comes to getting up to 120 feet, then having a battery or ESC quit )

in my humble opinion round CF tube is the hardest to used, since you need a circular clamp, but thats just me i guess.
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Old Dec 23, 2014, 03:41 PM
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Thanks for the tip, I've never thought of it , but I think I'll definitely buy one That way I can also compare prop efficiencies with different batteries, etc.. I've seen a cheap one on hobbyking, I think I'll be buying that one.
Yes, tube clamps make the build a little more difficult, but I'm having a hard time finding square carbon fibre tubes... I only know one from rcexplorer, and they are only 10 mm section...
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Old Dec 23, 2014, 05:18 PM
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my thrust stand.
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Old Dec 23, 2014, 06:33 PM
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Sweet! Maybe I'll do a similar one to get some data out of the rctimers, since the information on them is scarce, but firstly I'm gonna finish my 3D designs and order some electronics.
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Old Dec 23, 2014, 06:58 PM
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I believe if one uses too high kv motor or too high S-value battery 17 inch can perform worse than 15 inch, not because of lower propeller efficiency, but lower motor efficiency.
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Old Dec 27, 2014, 07:33 PM
http://www.fpvportugal.com
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Im planning to do something similar, i will share my calculations: http://www.ecalc.ch/xcoptercalc.php?...tch=5&blades=2
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Old Dec 27, 2014, 07:37 PM
http://www.fpvportugal.com
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With 8000mah 4s 42min flight time.
AUW 1523g.
Motors T-Motor MN3110-26 470Kv, props T-Motor 15x5, 20A hobbywing X-rotor 20A.

With Gimbal and gopro arround 1800/1900g and 30min flight time.
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Old Dec 27, 2014, 08:32 PM
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going 15" and up really makes a difference, im trying for a 26 inch or so. But im trying to avoid the super expensive pancakes like the U8's
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Old Dec 28, 2014, 07:48 PM
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Thanks for sharing your calculations Ghost Master. I will try to achieve 30 min with just 5000 mAh as I think that with these particular motors, efficiency really boosts up when they run less weight. But to do that I'll need to save weight everywhere. Right now my calculations are showing 1460 grams with all fpv gear and 5000mAh 4s. Soon I'll know if it matches with the real weight. I'm currently waiting for a local dealer to tell me if it cuts carbon fibre in the CNC machine, so that I can order all the parts. I don't know much about CNC cutters in Portugal, so, I guess I'll have to wait.
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Old Dec 28, 2014, 07:50 PM
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Yes, the bigger the more efficient the props, but I'm guessing that if they are too big it'll be very difficult to reduce the vibrations...
Tomorrow I'll hopefully post the almost finished design .
I'm really trying to decide between these 2 props:
http://rctimer.com/product-922.html
http://rctimer.com/product-706.html
Any thoughts ?
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Last edited by Eduardo Santos; Dec 28, 2014 at 07:56 PM.
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Old Dec 28, 2014, 08:52 PM
http://www.fpvportugal.com
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Quote:
Originally Posted by Eduardo Santos View Post
Yes, the bigger the more efficient the props, but I'm guessing that if they are too big it'll be very difficult to reduce the vibrations...
Tomorrow I'll hopefully post the almost finished design .
I'm really trying to decide between these 2 props:
http://rctimer.com/product-922.html
http://rctimer.com/product-706.html
Any thoughts ?
My advice is come to http://fpvportugal.com/forum/ because there are people that do CNC cut and 3D printing.
That could be handy. I have almost the same goal as you and you can follow my build there.
Regards.
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Old Dec 29, 2014, 07:33 AM
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Ok, thanks, I'll go there
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Old Dec 29, 2014, 09:58 AM
http://www.fpvportugal.com
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Quote:
Originally Posted by Eduardo Santos View Post
Ok, thanks, I'll go there
You are welcome there Eduardo.
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Old Jan 02, 2015, 03:16 PM
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Finally I got the 3D designs of the multirotor to cut in the CNC done. I'm still lacking the gimbal designs, I had no time to do them. Now, it's just wating for the materials to arrive.

I know the design seems a bit strange because the tubes from the gimbal mount are almost the same section of the booms, etc. Here are some reasons why it should work well :
1) The booms are only a 10mm by 10mm square section, but their fibres are 2-way oriented perpendicular to each other. This makes the square tube extremely strong in every direction (the most important one being torsion) and lightweight. Also, the tricopter from rcexplorer uses these booms and they show no bending (in this quadcopter the arms will be far less mechanically stressed, as each needs to carry less weight and is smaller, if you do the math you'll get it, if you don't, ask me and I'll post).
2) The center plate is small, but it's 2mm carbon fibre, so, it will handle it and it'll be very lightweight. I also don't need a large plate because the gimbal and the batteries will be held in the gimbal mount. this leads me to the next point;
3)The booms on the gimbal mount are massive. As said earlier they will need to handle the most heavy part of the quadcopter ( batteries, gimbal and camera) so, they will carry a lot of inercial momentum and consequently they need to be strong. They are also very big in lenght, because the camera needs to be held very far not to catch the propellers.
4) As for the general dimensions, I know nothing about aerodynamics and propeller interference, but I copied the measurements from the microdrone MD-200( it uses the same length propellers), and those guys should know a lot about it.

Please correct me if you think that anything is wrong.

Ghostmaster, I haven't posted yet in fpvportugal but I will when I recieve all the bits and pieces, as I believe it makes more sense.
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