I am designing a drone with a take-off weight of ~12kg+, and looking for a frame that can withstand it. I have analyzed many frames and selected a few such as Tarot T960 and Tarot T18. However I am not sure if I understand the properties of the frames correctly.
On this website, they give a configuration for 12kg AUW using Tarot T960. That seems OK, but it also states that “…using 5008-340kv motors and 6S LiPo we have 2kg of thrust per arm. The drone AUW with LiPo is about 4.5~5kg, that means you will have 3-4kg of payload.” It seemed contradictory to me, which one of these is true? It says design compressive load of T960 is 15kg on internet.
I want to use a hexacopter frame if possible, do you have any suggestions for such a MTOW? I just don’t want to buy a frame and break it during the flight. This is my first time designing a drone.
The frame breaking will not necessarily be your biggest problem, there are plenty of burned out motors and escs and plenty of unstable oscillations of copters that lead to crash and everything gets harder if you are operating near the mtow. Do some more reading.
Also the contradiction above with the weights is because they are saying it might weigh 4-5 or whatever invluding battery and then in the charts it says 5.3 without batt for the 50x series motors and 5.9 without batts for the u7. Then the more batt you install the less payload you get. The best hint is up the top where is says it will carry a mini slr and fly around for long duration. And that would probably be a fair statement
The frame breaking will not necessarily be your biggest problem, there are plenty of burned out motors and escs and plenty of unstable oscillations of copters that lead to crash and everything gets harder if you are operating near the mtow.
I am going to have a x2.5 weight margin for safety purposes and ease of the control while going with 100% of the thrust. According to my calculations, the 6 motors will be able to hover the aircraft at 50% thrust. I might increase the propeller size to achieve a little bit more thrust if necessary. Would this be a good safety margin to protect motors and ESCs from burning? I will definetly do more reading on the topic.
I am planning to go with T960 or Tarot X6 for a hexacopter. I will switch to a octocopter if this is not feasible.
I theoretically have some configurations. I am going to have a x2.5 weight marging at 100% of the thrust and the drone should be hovering with 50% of the thrust. I am planning to use:
T Motor U7 V2.0 420KV
17x5.8’’ propeller or 18x6.1’’ propeller
22000 mAh 6S Lipo Battery
According to my calculations this should give me 19N (1940g) and 22N (2250g) thrust for each motor depending on the propeller size.
I will also consider your suggestions. I have contacted with Tarot and they told me X6 should be enough for 10kg+ aircrafts. Is there anything else I should be worrying about?
That propulsion system with an 1861 propeller will dip just below a 2:1 T:W ratio (for a 12kg aircraft) near the end of your battery life. I would recommend trying to stay above 2:1 T:W at all times.
Use the newer Tarot X6 or X8 frames, the T960 is fairly old-school now.
The X8 has profiled arm tubes and mounts and wont suffer from twisted motor mounts.
I not sure I would use their power distribution board, less connectors between the battery and motors is better. In fact I’d almost take out the lower centre plate, which is fibreglass circuit board, and get an identical carbon fibre plate cut and drilled of similar or slightly greater thickness.
I would try to use ESCs that will mount inboard and use DSHOT. Long motor wires are not an issue provided you use the correct wire gauge.
This is preferable to the T-Motor Flame and Alpha ESCs that almost force you to have short motor wires, long power and signal wires, and use only PWM. That’s almost a perfect storm right there
It seems there is never the perfect frame that just works without any modification unless you design it yourself. So some changes are to be expected.
That propulsion system with an 1861 propeller will dip just below a 2:1 T:W ratio (for a 12kg aircraft) near the end of your battery life. I would recommend trying to stay above 2:1 T:W at all times.
Thanks, I will consider it.
Also - do you mind explaining why you would like to stick to a hexacopter configuration.
I am actually designing 2 alternatives, one is for a hexacopter and the other is for an octocopter. The weight is not a big problem using an octocopter but I couldn’t be sure if I can handle it using a hexacopter. The octocopter version will be using T18 or X8 probably.
Thanks, I am considering X6 now instead of T960. However the information regarding the weight of X6 is not clear. It says full weight is 2.7kg and net weight is 2.0kg. Does that mean the cargo pacgake is 2.7kg but the frame itself is 2.0kg?
Mounting won’t be easy, and it will definetly require a lot of work. I will take your advice about the cable lengths.
The X6 has plenty of real estate (area) for mounting everything. With those old frame kits like the 650 ironman or even the bigger 960, you end up with everything really jammed in and messy and brackets hanging off the sides for radios and antennas.
The X6 has plastic motor mounts. This will probably be OK for light loads. There’s 25mm aluminium motor mounts available, DO NOT choose any “with damper”. There are also plenty of non-tarot motor mounts that would fit, just depends where you can order from.
You can also think about famoushobby frames . They are quite stiff low vibration especially octagonal arms. And you can configure them in different ways.
The motor I am planning to use is T-Motor U7 420KV. According to the datasheet its diameter is 60 mm. Do I need a 60 mm motor mount or a 30 mm motor mount? I couldn’t find any 60 mm motor mount and this got me thinking if people design their own motor mounts for using this motor.
I advise you to spend huge amounts of time in ecalc before ordering parts, especially motors and props, which are easy to get wrong. On the T-Motor web listing for those motors it lists recommended props, but work out what’s correct for your copter, which might be different.
As much as I like those U7’s I cant make them work in ecalc with 12kg total weight and an X6. Or even with the X8 actually.
So there is quite a bit of selection work to do yet…
Right now I am using the Tarot X6 platform with those motors: T-Motor U7-420KV. I am using 18x5.5 propellers and everything works fine. I don’t know the maximum payload that it can carry though, because I have not tested it. With a 13000mAh battery, I have an approximate flight time of 17 minutes with no payload.
