please suggest setup for 20m flight time @ 4kg

[Irwin]

would like suggestions for building a larger hexacopter, needing to lift about 4-4.5kg auw but need to use 4S as I have plenty of those batteries, most definitely would like 20-25min flight durations....would like to hear recommendations on frame (thinking 800mm size?) motors and props....please thanks.....(i dont think ecalc is accurate, for my previous copters it was always a bit off)

 

[econfly]

T-motor U3 motors with 12-13 inch props would work at 4S and lift 4-4.5kg. Motors would pull about 5 amps to hover, so figure 30 or 40 amps total in light flying. You need about 9,000 to 12,000 mAh of 4S power to get 20 minutes flight time at that burn rate. Just as a rough guess, total battery weight would be around 1.0-1.2 kg. That leaves 3kg or so for everything else. Personally, I would go 6s and U5 motors with 14" props, but understand you want to use the 4s batteries you have.

Not sure about the best frame. Your build is right between a hexacrafter 650 and 800. They have great specs on their website with build configurations (motors, props, etc.). I would check them out just for good ideas even if you choose a different frame make.

 

[eskil23]

Why not go for 8S and use your 4S batteries in series?

 

[Irwin]

T-motor U3 motors with 12-13 inch props would work at 4S and lift 4-4.5kg. Motors would pull about 5 amps to hover, so figure 30 or 40 amps total in light flying. You need about 9,000 to 12,000 mAh of 4S power to get 20 minutes flight time at that burn rate. Just as a rough guess, total battery weight would be around 1.0-1.2 kg. That leaves 3kg or so for everything else. Personally, I would go 6s and U5 motors with 14" props, but understand you want to use the 4s batteries you have.

Not sure about the best frame. Your build is right between a hexacrafter 650 and 800. They have great specs on their website with build configurations (motors, props, etc.). I would check them out just for good ideas even if you choose a different frame make.

thanks a lot....yea I have a number of 8,000 and 10,000 4S packs I definitely want to reuse, I have a Tarot 680 now with 13'' props (max size prop on that copter is 13'' w/o extending arms and all that), AUW is about 3.8kg and only getting like 15min with the 10,000 pack, I could double up the packs in parallel and get me to 23min, but its way too heavy with those dual packs in parallel, struggles....
I am looking at the kongcopter 800 with 15'' props but it looks thats a no go for 4s batts? maybe my best option is to dump some weight from the current 680....i just dont know what to get rid off!!!

 

[Irwin]

Why not go for 8S and use your 4S batteries in series?

thats an idea...but i thought pixhawk and APM can only handle 6S (25v max) ?

 

[Old Man]

With the standard power module this is true but after market power modules and a BEC let you do a lot more.


Sent from my iPhone using Tapatalk

 

[econfly]

thanks a lot....yea I have a number of 8,000 and 10,000 4S packs I definitely want to reuse, I have a Tarot 680 now with 13'' props (max size prop on that copter is 13'' w/o extending arms and all that), AUW is about 3.8kg and only getting like 15min with the 10,000 pack, I could double up the packs in parallel and get me to 23min, but its way too heavy with those dual packs in parallel, struggles....
I am looking at the kongcopter 800 with 15'' props but it looks thats a no go for 4s batts? maybe my best option is to dump some weight from the current 680....i just dont know what to get rid off!!!

What motors/props are you using on your Tarot 680? That build could tell us a lot about what you can expect from any 4S hexa. One motor that could be an answer would be the KDE 4215XF-465. It is rated for 4S and would provide the lift you need with 15" props. The good thing about going that route (as opposed to a U3) is you would be using a much more powerful motor at the low end of its range and could always get a bunch more lift by moving to 6s later. The U3 is going to be maxed out at 4S with 13" props. You could also try a T-Motor U5, which is rated down to 3s, but T-Motor only provides thrust specs at 6s.

 

[Pumpkinguy]

Wouldn't a quad be better suited for longer flight times? I have 6 of the 4215-465 motors kicking around and was thinking about building a 650 sized quad for mapping. Haven't worked out weights yet but I'm thinking it would be about 4kg.
Those motors wouldn't flinch at 1kg each.

 

[eskil23]

Wouldn't a quad be better suited for longer flight times?

Yes, it would. A quad of the same size have space for larger and more efficient props. What you win with more arms is stability and (to a degree) redundancy, not power or efficiency.