A Million Questions

[teecee]

I have completed my first build and all is well but I just feel like there are so many gaps in my knowledge and I don't want to discover any of them the really hard way (crash).

This is what I built:
-CarbonCore H6 950mm
-DJI A2 Flight Controller
-Maytech Opto ESC 60amp - No BEC, Simon K Firmware
-HYPERION G3 VX 5400mAh 6S 22.2v 35C LiPoly Pack
-Rc Tiger Navigator Series MN4014 Brushless 400kv Motor
-GemFan DJI S800 Style Propeller 15x5.5
-DJI Retracts
-Futaba T14SG TX (Built in A2 RX)

I bought from RC Drones and they spec'ed out the package based on what I told them I hope to do with this rig. I plan to fly my Canon 5D MKIII on DJI Z15-5D Gimbal which I have but have not put on yet.

I did a half dozen flights with no weight and she flies awesome! Very quiet, stable and responsive. Did a few RTH tests and all good there too. As for battery with no weight I get 5 minutes to yellow flashing light (in -5C) and usually fly for around 7 min. As a test I went all the way to red flashing light (hovering just off the ground) and got 14 minutes before red flashes and self land kicked in.

Now I have begun piling lead weight on to simulate the weight of the 5D, gimbal and all that gear. With 5lbs extra I get 4 minutes to yellow light and with 6 lbs I get 2.5-3 minutes. 6lbs makes my gross take off weight 17.7lbs. I can hear that everything is working harder too for sure but she flies fine . After each flight I touch all major components to check heat. ESC's and motors a tiny bit warm and no heat anywhere else but it is bloody cold out so...

As this is my first build I have a lot of questions:
-Just how reliable are these things? I am still terrified that it will fall out of the sky at any moment. My experience before this was with my Phantom, H3-2D gimbal and GoPro so this is a huge step up on all levels.
-Does this sound like the right hardware for the job I hope to do (fly 6llbs of 5D & Gimbal).
-Can someone walk me through the calculations for lift capacity? I find it very confusing.
-How can I get more flight time?
-How much testing should I do before going for full $$$ payload?
-What other kinds of testing should I do?
-Can someone supply me with a good, generic preflight checklist that I can build onto?
-How perfectly balanced should the multirotor be for take off? With the batteries on the back and gimbal on front it is a lot of monkeying around to change from flying with gimbal to no payload?

Any and all advice greatly appreciated. Thanks in advance.

TC

 

[teecee]

Oh, and one more question on the voltage protection. Is it wise to lower the voltage for first level protection (yellow light) or should I always leave that at factory defaults?

 

[cbuk]

I'm no expert but I would recommend using eCalc or some other similar app. You don't mention prop size and pitch. That's going to be the crucial variable that will determine what you can lift safely. By safely, I don't mean just get it into the air, but to have enough spare throttle to fly the craft responsively. If you put all your variables into eCalc (including expect AUW) then the app will tell you the amount of throttle you need to hover. If this is getting anywhere near 80% then you're risking it.

Is the H6 a flat 6 configuration and if so what are the biggest props you can fit on it? I suspect you may be slightly underpowered when lifting the 5D but like I say, eCal would give you an idea.

Hope that helps a bit.

 

[teecee]

Is the H6 a flat 6 configuration and if so what are the biggest props you can fit on it? I suspect you may be slightly underpowered when lifting the 5D but like I say, eCal would give you an idea.

Hope that helps a bit.

It is flat. I could probably fit 16" props on there. I have been fiddling around with eCal but it doesn't like my data. What am I doing wrong there? Here is a screenshot...
View attachment 15699

 

[cbuk]

The screenshot is too small to read, even when I open it. Cant see what it is complaining about...is the current?

When I put your set up into eCalc with 8 kg AUW, 6 x tiger MN4014 and 15 x 5.5 props it comes back with a hover efficiency of 67%. So you should be ok but I'm no expert.

 

[teecee]

Sorry, I don't know why it shrunk down like that. Here it is as a JPEG. Perhaps this will work better.
This is what it said...

• Running below the Current of optimal Efficiency is inefficient. Use a smaller motor
• Your Setup is unrealistic and way out of Limits!

My problem with ecalc is, being a newbie, I don't know all of what it is asking me. I couldn't find my exact battery specs for example. And in "model weight" is that my gross weight with camera, gimbal and everything else?

View attachment 15700

 

[cbuk]

You're in propCalc and not xcopterCalc..... That's why your calculations make no sense. Use xcopterCalc and you'll be able to input the number of motors. You should get realistic results then.

e2a: As for the weight. Enter say 8000 g with the default "include drive" from the drop down list next to it. This will then show up in the results (bottom left) which also summarise the additional weight you could carry without going over the 80% hover limit. Hope that makes sense.

 

[teecee]

Wow, that (obviously) makes a huge difference. It now says I am at 78% throttle at hover. Should I be comfortable with that number?
My next big concern is flight time. How do I increase that number WITH this payload? More battery...?
View attachment 15701

 

[cbuk]

I'm a little out of my comfort zone here giving advice because I dont want to be giving you the wrong advice. If it were me, 78% is a little too close to the 80% limit for comfort. You would have very little thrust in reserve should you get into any problems. Descending might also be a bit hair raising.

Another lipo would increase your flight time but also your AUW so I suspect you would still be facing the same hover throttle problem. Hopefully someone else will chip in.

 

[Motopreserve]

If all your components are listed in the drop-menus - select " without drive" and it will calculate in the weight of each individual component on its own. The only weight you put in the field is the frame/FC weight.


If the battery is new - you can probably choose "full" next to battery type.


After you plug in all the info - the bottom will tell you the payload capacity - which would be where you see if it will lift your camera/gimbal rig.

You our definitely want to be at around 50% throttle @ hover. Below is what I got when I entered the data into eCalc. Not sure if I got everything correct - but notice that the battery is entered as "6S" and "2P." The 2 P is an additional battery of thesame type. They don't list 5400, so you can put in 5000 (you may get better results than shown here with your extra 400mah). Also, enter in the 35C as the lower number in the options - that's what your battery is capable of.

This is how I was taught to use ecalc anyway...

View attachment 15739

 

[teecee]

OK, now I am confused again. What exactly is considered "drive" in ecalc? I don't have my frame/FC weight as the whole rig is assembled. I do know total weight. If I say "incl. drive" does that assume that I have accounted for all components myself? It doesn't seem to as it is putting 1864g in the "add payload" on the bottom right.

OK, I just ran it again with my actual weight (no camera and gimbal)of 5300g and set "incl. drive". It lists 4564g as "add payload" on the bottom right with 60.8% efficiency at hover listed. Does this mean I can add 4564g and be at 60.8% efficiency?

Here is a screen shot.View attachment 15740

 

[Motopreserve]

Sorry, didn't mean to make it more confusing. Yes, the "including drive" means you plug in your all up weight. If you use the other option (without drive) you plug in the weight of the frame (I looked up your frame - shows 780 grams). Your results show a hell of a lot of payload capacity. Roughly how heavy will the gimbal and camera be?

The big issue with your eCalc results is that A) it is over the 50% throttle mark for hover, and B) it gives you under 5 minutes flight time. Spirited flight is closer to 2 minutes! That doesn't leave much room for fun and whatnot.

Also, change your battery to show 5000mah, 35C/50C. Start messing with the prop sizes. And add a battery if your payload will not be completely be used by the Camera rig. See if these hep the flight times on the lower left of the ecalc window. Put the prop type in there too (Slow Fly, etc - although this doesn't change the flight times much)

 

[teecee]

Sorry, didn't mean to make it more confusing. Yes, the "including drive" means you plug in your all up weight. If you use the other option (without drive) you plug in the weight of the frame (I looked up your frame - shows 780 grams). Your results show a hell of a lot of payload capacity. Roughly how heavy will the gimbal and camera be?

The big issue with your eCalc results is that A) it is over the 50% throttle mark for hover, and B) it gives you under 5 minutes flight time. Spirited flight is closer to 2 minutes! That doesn't leave much room for fun and whatnot.

Also, change your battery to show 5000mah, 35C/50C. Start messing with the prop sizes. And add a battery if your payload will not be completely be used by the Camera rig. See if these hep the flight times on the lower left of the ecalc window. Put the prop type in there too (Slow Fly, etc - although this doesn't change the flight times much)

My camera and gimbal will be just over 6lbs.

 

[Motopreserve]

So you should have plenty of payload left over for another battery. That means in eCalc you plug 2 into the "P" section of the battery area.

 

[teecee]

Oh... There is another flaw with my original calc. I actually have 2 on there already...

 

[teecee]

Now that I have added the second battery (that I actually do have) these calculations seem far too rosy. How accurate are they? According to this I can fly 6741G of additional weight. That just seems crazy...
View attachment 15746

 

[Motopreserve]

You still need to change the battery to 35C.

The payload you're seeing is correct (according to eCalc), but check out the flight time. Also, do you know what type of props you have (slow fly? Etc). Might as well plug the info in as accurate as possible.

I think you might want to mess around in eCalc to see if changes will up the flight time. Currently you can lift a compact car, using only 38% throttle! but can only do it for roughly 3 minutes.

 

[tombrown1]

Nice choice of build components. You want to use at least two of those batteries. I would probably use two 8000mah lipos. Nanotechs are decent and cheap.

Don't use DJI low voltage protection. Turn it all off. The best way to not run out of batteries:
- time your lipos - run them for a few minutes, then when you charge them find out out many mah you put back in - do the math to find out a flight time that takes you to an 80% depleted lipo. Always use a timer when you fly.
- cheap lipo alarms
- telemetry

To get hover throttle - just go into manual mode and see what throttle you need to give to make altitude constant. ecalc is not perfect.

Good luck,

TB

 

[jbrumberg]

Teecee- eCalc appears to be fairly accurate (not perfect) in its predictions based on my newbee experience. ECalc is very popular so it must be relatively accurate with a lot of builder/owner/operators who really know what they are doing. There is no perfect mix of components. It's all a mix of tradeoffs between all up weight which is relatively constant or changeable to a given degree, and hover and mixed flight times which are relatively undefined and variable, but controllable with variables dependent upon ESC's, motors, props, and batteries. I play around with this. More lift capacity- maybe more hover time, less flying performance generally. More flying performance- maybe more hover time, less lift capacity generally. There is only so much one can do within established physical parameters and gravity. If it's too good it's suspect.....

 

[tombrown1]

If you're going to do AP or AV, then flying performance is unimportant. Everything will be slow and steady. You should be able to get 10-15 minutes out of your rig. Throw somewhere between 10 and 20000 mah on it and it should fly great.