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Old Mar 04, 2012, 01:41 PM
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Help!
Powerplant requirements for Quadrotor

Hey I am planning to Design and Develop a Quadrotor. So I need some formulas and calculations that might help me to choose the optimum powerplant requirements for the vehicle. For example lets say the Quadrotor is confined within a 1kilogram weight inclusive of all the components (frame, motors, payload,etc..). So how do i theoretically find out the optimum RPM required and the optimum Propeller dimensions and also an optimum battery to support the flight.

THANKS IN ADVANCE
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Old Mar 04, 2012, 07:04 PM
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Canada, ON, Kincardine
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This site does exactly what you need.

http://ecalc.ch/xcoptercalc_e.htm?ecalc
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Old Mar 06, 2012, 02:16 AM
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Thank you very much it was a great help. But it would be more helpful if you can elaborate the steps or formulas based on which the calculator actually works.
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Old Mar 06, 2012, 07:26 AM
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Mark Wood's Avatar
United States, CA, Bear Valley Springs
Joined Feb 2000
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http://www.rcgroups.com/multi-rotor-helis-659/

mw
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Old Mar 09, 2012, 01:01 AM
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I have selected these for my quadrotor can you take a look and let me if they are good? This small help from you gurus can help me a lot.


MOTOR:

http://www.hobbyking.com/hobbyking/s...dProduct=21480

BATTERY:

http://www.hobbyking.com/hobbyking/s...dProduct=11956

ESC:

http://www.hobbyking.com/hobbyking/s...ontroller.html

PROP:

http://www.hobbyking.com/hobbyking/s...5pcs_bag_.html

THANKS IN ADVANCE
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Old Mar 12, 2012, 12:08 PM
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UK, Buckinghamshire, High Wycombe
Joined Feb 2007
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Quote:
Originally Posted by Vishnuasalways View Post
I have selected these for my quadrotor can you take a look and let me if they are good? This small help from you gurus can help me a lot.


MOTOR:

http://www.hobbyking.com/hobbyking/s...dProduct=21480

BATTERY:

http://www.hobbyking.com/hobbyking/s...dProduct=11956

ESC:

http://www.hobbyking.com/hobbyking/s...ontroller.html

PROP:

http://www.hobbyking.com/hobbyking/s...5pcs_bag_.html

THANKS IN ADVANCE
motor 84grams x4 = 336grams
lipo = 457grams
esc x4 = 112grams
905 grams

no wire to connect everything
no servo leads
no flight controller
no frame

if your really good? might be able to make a frame for 200grams

so the very lightest you can possibly make your quad? 1.1kg

see the problems yet?

those props will snap like twigs

those props and motors together will be hard pushed to give enough thrust to fly

if you can make a 200gram frame it might just fold like a pretzil when you try to lift off at 1.1kg your build with everything will probably be more like 1.3kg

it will not fly!
read this and start again!

link fixed '
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Last edited by n3m1s1s; Mar 12, 2012 at 01:44 PM.
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Old Mar 12, 2012, 02:23 PM
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Why wont it fly ?? the overall weight is only 1.3 kg (max).. the 6x5 propellers with WOT on a 1800Kv motor provides a thrust of 732g of thrust so for quad it is 732 x 4 = 2928g... so why wont this fly??

"those props will snap like twigs"

I am sorry I don't understand why will it break?? please care to explain??

Thanks in advance
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Old Mar 12, 2012, 04:41 PM
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Bruce Abbott's Avatar
Hastings, New Zealand
Joined Jan 2001
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Quote:
Originally Posted by Vishnuasalways View Post
"those props will snap like twigs"

I am sorry I don't understand why will it break??
Those plastic slowfly props will not take the 16000+rpm required to get 732g thrust. They will flutter, and the blades probably will snap off.

Besides, a prop with high pitch to diameter ratio is very inefficient at producing static thrust. You would get much better performance with a lower Kv motor (eg. Turnigy Park450-890) and larger diameter lower pitch prop (eg. APC 10x4.7).
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Old Mar 13, 2012, 11:26 AM
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Cumbria in the U.K
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Hi,
Go for a lower KV motor. Something around the 900 to 1,000 KV range.

Props of around 10inches * 4.5 inches will work well with this range of motor on a quad.
Most use slow fly style props or GWS 3 bladed props, although these take a lot of balancing.

The 5,000 mAh battery will be heavy. 2200 mAh would probably be sufficient - unless you need long flight times.

The ESC you chose may not work well - some ESC's don't work well with multirotors, I think this may be one of those that give problems. Try the Hobby King SS ESC's. These are cheap, many people use them and they are known to work well.

Lower KV motors give better response for multirotor craft. I use E-Power 2215/25 motors and SS 25 - 30 Amp ESC's on my quads. These weigh around 1 kg or so without camera and lipo.

You will get more advice here http://www.rcgroups.com/multi-rotor-helis-659/

I use the multiwii controllers, which I build myself, and you will see there is a VERY large thread on these. The first page (of many) is here
http://www.rcgroups.com/forums/showthread.php?t=1261382
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Old Mar 13, 2012, 01:00 PM
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Thank you for your replies.. But i still have a problem.... I have designed and fabricated by quadrotor frame using carbon rods the overall dimension is 500mm x 500mm ( app 19" x 19") so can a quadrotor of this size support the propeller dia of 10 x 4.7?? wont the vorticity of the propellers affect each other?? If not can i make a 7 x 4 prop and a 1200 kv motor??

THANKS IN ADVANCE
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Old Mar 13, 2012, 01:20 PM
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United States, AK, Fairbanks
Joined Aug 2009
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You'll also need two reverse-rotation props to cancel torque effects.
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Old Mar 14, 2012, 01:41 PM
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Cumbria in the U.K
Joined Jan 2008
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Quote:
Originally Posted by Vishnuasalways View Post
Thank you for your replies.. But i still have a problem.... I have designed and fabricated by quadrotor frame using carbon rods the overall dimension is 500mm x 500mm ( app 19" x 19") so can a quadrotor of this size support the propeller dia of 10 x 4.7?? wont the vorticity of the propellers affect each other?? If not can i make a 7 x 4 prop and a 1200 kv motor??

THANKS IN ADVANCE
No problem.
A lot of quads are built with 15 inch arms and use 10 * 4.5 props.
It's advised to allow the diameter of a propeller between propellers.... 10 inch props would have a distance of 10 inches between the prop blades when the tips were facing towards each other. That's just a rough guide.

Quads are built with less clearance than this and seem to fly well. Longer arms of 15 inches and above tend to be best for a quad that is going to be used for photography.

Arms of 15 inches length give good stability without having flex problems. Try the 19 inch arms and see how it flies. If necessary you could always cut them shorter after you have tested it.

The links I posted have lots of information, more than you will get here.
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