Hello all, I am stuggling to find an efficient motor/prop to use with a quadcopter I am going to build. I have seen on many forums people say that they can achieve over 1kg of thrust per 100W of power. I have taken all motors I could find on HobbyKing that have test data and have arranged it all in an excel document that calculates its thrust per 100W. The highest I could find is .675kg/100W. If anyone could help me that would be great. I am new to this, studying aerospace engineering at the moment so this is turning into a big personal project for me. I will include a screenshot of the top of my list in terms of thrust per 100w. If you have any other advice for me that would also be greatly appreciated. Thank you!!
You need to be a member of diydrones to add comments!
Replies
Hi Ben,
I don't think there is any big secret. I manage to get close to this efficiency with my quad (9.6g/w). For the best efficiency you need the lightest prop loading. This means big props with low pitch. However, if you go too big you will have problems with control as very small changes in prop speed produce large thrust changes in proportion to the load. Hovering at 40% throttle seems to be the recommended minimum.
Hello, its been a while since I started but I am happy to say that I flew it for the first time! Here is the video. Thanks for all of your help in the beginning!
Bravo! Nicely done.
=)
Sounds like it may be a little to late but take a look at this thread for high capacity long endurance: http://www.rcgroups.com/forums/showthread.php?t=2025307
okay I just layed everything out to see everything connected and it seems that I am missing the wires connecting the 8 channel reciever and the amp module.. Im not sure how i missed that. but now I am looking for them and cant seem to find them anywhere.. do you know what wires I need?
thanks
Any standard female-to-female servo leads will do nicely. Pololu probably has the more extensive selection from ribbon to twisted. Just decide what length you need and what style suits you.
A great shortcut would be to simply use eCalc for multirotors (the free version has limitations but a one month subscription is about a dollar). You can plugin your frame type (i.e. number of rotors), prop size, ESC size, battery size, and then select motors from a drop-down list. eCalc will then plot out compatibility and efficiency for that combo. It will also warn of mismatches. Ideally you want to hover at 50% throttle or a little less.
In your case, a good start would be to enter values something along ther lines of a 40C, 4S battery rated at 5000ma, paired with a 40A ESC, a SunnySky X3508S KV580 or Turnigy Multistar 3508-640Kv motor, and an APC 14x5 e-prop.
Thanks for the help! I have tried to use ecalc before but after a few hours couldnt get anywhere with it. I decided to buy the subscription, and I put in what you said and modified it a little bit to get almost 12 minutes of mixed flight. Is there anyway I can get this up any further? Also, something I need to keep in mind is that in the future I may want to add a camera gimbal/camera to the setup. I am not sure if this is reasonable to count on as it is a heavy payload.
Here is the list of components I have chosen so far:
controller: APM 2.6
http://store.3drobotics.com/products/apm-2-6-kit-1
battery:zippy 8000mah
http://www.hobbyking.com/hobbyking/store/__16226__ZIPPY_Flightmax_8...
Motors(8) sunnysky 380kv
http://www.himodel.com/electric/SUNNYSKY_X3508S_380KV_Outrunner_Bru...
ESC(8) Turnigy 10 Amp
http://www.hobbyking.com/hobbyking/store/__4204__TURNIGY_Plush_10am...
Blades(8) 14x4.7
http://www.hobbyking.com/hobbyking/store/__39776__14x4_7_SF_Carbon_...
FPV: I have already boughten my fpv equipment, have a lawmate 1.2ghz 1000mA transmitter and reciever along with a sony camera from hobbyking
the frame I am planning on building from square carbon fiber tubing from hobbyking
I am planning on making it in the x8 configuration, so I am not sure how that works with the apm 2.6, If you know anything please let me know
If you have any advice for me that would also be great, thank you!!!
Capture2.PNG
Capture3.PNG
Well I just wanted to let you know that I have almost everything in hand now! All I am wait on is a battery charger, ESCs, transmitter, and the power distribution board to arrive in the mail. I have taken a weight measurement of every piece and my total is coming to 2260, but I will count on 2300 for miscellaneous wires and such. With all of my information entered into ecalc, I will be able to achieve 31.8 minutes of hover, 12.9 minutes mixed, and 9.5 minutes regular. I am so excited to piece all of it together! I would like to thank you again for helping me get started in this hobby. I will send you pics/video when I have it all up and running!
Hi Ben. You've got some great kit there. There are a lot of factors that affect flight time and 12 minutes for mixed flight on a multirotor is actually pretty awesome! That's assuming you're tossing in some acro so, if you were limiting yourself so smooth camera runs you'd probably be hitting closer to 20 minute mark.
As far an X-8 configuration I not so sure that's your best bet. I've seen performance tests that show back-to-back counter-rotating motors on a multi are about 30% to 40% less efficient in a hover than a traditional layout. A small octocopter frame with 8 arms might get you better performance (and longer flight times) and would have the advantage of being more stable. Just a thought.
You'll also want to get larger ESCs. Those motors should each have at least a 20A ESC -- when they're pushed hard they can draw upwards of 20A.
As for the CF props, they're awesome but until you get your multi dialed-in 100% and have a few hours on it I wouldn't risk them. Get yourself a few pairs of e-props from APC. Try some larger props while you're at it. Those motors will should be very happy with 18x5.5 -- might get you a few extra minutes of hover time too.
I'd also recommend picking up a couple of cheap carbon fiber arrows from a sporting goods store, cutting them in half, and use tie-wraps to secure them under each arm -- sticking out past the tips of the props. That way you'll protect the props and the motors from damage when the copter tips over while your're practicing.
Looking forward to seeing your build.
Cheers!
-
1
-
2
of 2 Next