Hi! I got the arducopter kit with the ultimate aim of using it for aerial imaging.
Been flying the arducopter for a while indoor. Had two crashes with one resulting in propeller cut in half and the other twisting the aluminum arms. Had to replace the aluminum frame with similar material I got from a local aluminum windows and door frame maker shop. As for the propeller replaced all with the sturdier 10x4.7 APC props and the rig flies ok.
I am only getting 4minutes tops for a 2200 20C battery.
Today, I took the next logical step of finding out if the camera I've identified for the aerial imaging can be lifted by the arducopter. Two d-340R cameras with batteries plus the arducopter resulted in a total flying weight of 2kg (might be a little heavier by a couple of grams).
The result, I have to throttle up to nearly 75% for the quad to lift from the ground and hover for a couple of seconds very close to the ground. At his point though, the battery monitor start turning red so have to stop the test. The ultimate envisioned set up is to remove the battery from the cameras and source out the battery requirement of 6.5v from the lipo. That should shave off some weights from the current 2 kg.
QUESTION: You think the 20C does not have enough juice to make the arducopter hover? Correct me if I'm wrong but with a higher C rating on the battery, the throttle stick can be lowered to accomplish the same motor performance, right? I mean with a 20C and 75% throttle, the quad lifts from the ground. Now if I have a 25 or 30C battery, I will definitely not need to put the throttle to 75% to accomplish lift off right?
Thanks.
Replies
Hi Roger
A boffin in England is a clever engineer or scientist or maybe a bit of a Geek too! I am just a pilot so don't really know much about the science!
I hope you are right about the resolution, that would be good news!
Here's a photo from a camera converted as you describe. The only light getting through to the CCD is over 720nm.
How about larger props? I use 12x3.8 APC props with Turnigy 2217 850kv motors and my Quad flies okay. It is 2.0 kg without any camera. I use a 4000mah 20C battery - the max discharge rate therefore is 80A. Each of the motors rarely even get close to 20A (they peak at 17A), so power is simply not a problem, even at full throttle. I can hover at about 50% throttle, however.
Because of the extra weight, I don't get as long as flight times and she's not as nimble as others. However, she is built like a tank and scrapes off minor crashes without a shrug.
John
yes, the battery alarm in form of a buzzer was sold out.
this afternoon i am buying one too :)
Can you replace the camera batteries with lipoly or a UBEC/voltage regulator? That might save some weight.
As far as the 20C, my understanding is that is the max rated discharge rate. Does that mean a 20C battery won't serve more than 20C's worth of amps?
I thought it meant if you draw more than 20C's worth of amps, the battery starts getting hot and you risk frying the battery and ESC
If that's the case, unless the battery is getting hot, I don't think you'll see any benefit from a 25C or 30C.
-The obvious solution is to reduce weight but it doesn't sound like it's an option.
-If the motor & prop were not matched appropriately that would be a source of inefficiency, but I suspect you've already done that as well.
I've read that electric motors run most efficiently at 50% of their max torque, so if your props or motors are too small for the payload and are running too fast as a consequence, that might exacerbate battery consumption.
Is there anything about the camera which can have it's weight cut down? Carbon Fiber is lighter than aluminum for instance.
If you increase the pitch or diameter of your props, that might address the throttle, but then you're looking at potentially upgrading ESCs or motors, & needing to use 25C or 30C batteries, ect. Bigger props, more amps and all that.
If propellers are just rotating wings/airfoils, perhaps you can polish their surfaces and do something about tip turbulence to increase efficiency?
Edit:
What about doubling the motor count to an 8-rotor? You'll need 2X the battery, but you'll solve your throttle problem which will likely improve efficiency. This is attractive because none of your existing parts would be wasted, and you can remove the extra rotors when the camera isn't attached or even make a second quadcopter.