RCtimer low KV motors and 16’’ props.
This drone is made from aluminium because I can get it easily and cheaply and I have a laser cutter that I can cut at with a short waiting period. When this works I will look at converting to carbon.
It now uses a leg clamp method as suggested. Top and bottom plates with legs between the plates. The area of the leg that is clamped is about 50mm.
Top and bottom plates are 200mm x 150mm
I can also remove one bolt per leg to collapse the drone if I need to
Leg bolts go from under the drone through countersunk holes so that I can use the underside of the drone for things like a gimbal and a battery.
The motors attach to the legs directly to get them as flat as possible. There are no motor clamps that can break off, but only 2 bolt holes are used.
It has a Storm32 gimbal so that it can carry my GoPro 10
Total leg length is 330mm.
Legs are 25mm x 25mm x 1.6mm channels. I am hoping this will not have the same twisting issues that I have with the 10mm x 10mm x 1.6mm channels.
Pixhawk is on top and all electronics are in the body. Hopefully, the body will act like a Faraday cage and stop any electrical noise from leaking
ESCs are inside the legs. I will have to monitor this to see if they get too hot but I am hoping the air passing by the legs should extract the heat inside the legs using the venturi effect
VTX is at the back and in the middle because it is one of my heavier components. It doesn’t have bolt holes so I have to attach it with cable ties and double sided tape.
The receiver is under the VTX. It will be attached with double sided tape and the same cable ties that I use to attach the VTX. The VTX and receiver shouldn’t interfere with each other since the receiver has long legs/wires that will be cable tied to the back legs.
The telemetry transmitter is on the side and it can point down. I noticed with my current design I lose connection constantly. The transmitter is on the front in the current design.
The GPS holder base is inside the cage and protected. I have gone through many of them every time the drone flips over and crashes. I use balsa wood as the shaft. So if the shaft breaks then it will keep the holder safe.
In the past month you have created a new thread roughly every 4 days to ask another question regarding the exact same topic. Suggest you stick to one thread and heed the advice you’re given.
If you mean 2200mah battery then you’ll barely get off the ground before that battery runs out of capacity.
If you mean 22000mah then those motors wont lift that weight.
I don’t know yet what the weight will be with the aluminium design. It is a cheap and quick way to prototype vs getting carbon in because carbon has to come from China so every order takes a month.
The current crashes I think is because I am mixing motor speeds and the twisting of the thin arms. I can easily twist the arm if I turn the motors.
The calculator shows 15 minutes flight time. While I auto tune I can get 20 minutes. I don’t know if that is considered high usage. I would think so because the amps shoot up to the 13A range from an average 6A when I just fly slowly around.
The aluminium drone will be heavier for sure, but it isn’t meant to be the final product. Purely to get something up and running to test and learn at this point.
The calc has 240kV motors. I actually started with 530kV motors but it was too powerful. It lifted off at 10% throttle so I went down to the 260kV, but waiting on a shipment of 360kV so that I have a little more power. I destroyed most of the 530kV and 260kV motors because the motor mounts broke off with crashes and as the motors flew in different directions they ripped the wires out. I changed the design to just tape the wires to the frame now and not cable tie them to the frame so that they would disconnect safely after a crash. It worked well with the crash yesterday.
When I threw a few numbers into ecalc I assumed a heavier take-off weight, so that will be a key difference.
The motors abilities may come back into focus when you add payload though. Be aware that kv is not the only specification used to choose motors, and many people focus on that, but also the power.
Also it’s very easy to go for props that are too big, and we see a lot of that lately. Smaller props spinning fast give more stability and control than big props spinning slowly - but it can depend on your motors and ESCs and budget too.
I don’t know about others but I went with bigger props because they are supposed to be more efficient. I think I will look at smaller props for more stability because safety is more important than flying 20+ minutes at this point.
legs of your design are way too small (cross section wise)
use square or round tubes not U-shaped profiles (very easy to twist)!
check the material number and get square tubes made of EN AW 6060 (or round tubes EN AW 7075). Tubes/profiles available in DIY stores are usually made of soft/cheap aluminum.
I just ordered the standard Tarot retractable legs. They have 16mm tubes for the legs. I just created a placeholder design so that I could get the holes and spacing right. Tarot legs
The gimbal looks nice because I downloaded that from Grabcad. I also downloaded the motors. I can’t remember where I downloaded the Pixhawk from. Probably also Grabcad. Everything that is pretty is what I didn’t design
Yep I mean one with 4 sides (hollow)
I should have been clearer.
I saw a video where the one guy explained he uses rounded rectangle carbon tubed on his drone and he gave some calculations on why. So I will also try that and see how it goes.
I will try for 20mm because then I can fit the esc on the legs inside the body and keep the wires short from the esc to the PDB and pixhawk.
Monday I will go to the supplier and see if they will allow me to clamp the aluminium on a table and twist it. I want to make sure the 20mm does not twist. I will post a video shortly to show how badly the arms twist at the moment
