Hi,

 

I'm building a Quad from sketch.

My goals are-

it needs to be stable,

it needs to carry a heavy DSLR

therefore i will go BIG. say around 80-100CM.

 

I'd like to get guidelines for choosing the motors.

rather higher or lower KV/(rpm/v) ?

small propellers with big pitch ? or large propellers with small pitch ?

 

any other tips for choosing motors and propellers ?

 

how about ducted fans ?

if i were to use 4 ducted fans instead propellers - is there a reason that all QUADs use propellers and not ducted fans ?

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dont you try to scare me... :P

actually, the Jdrome motors might be enough for me, if a normal unloaded quad uses about 50-75%, i'll need a bit more...

 

I'm really afraid of ordering FOUR motors that will be found as not powerful enough or too slow for lifting the load

that's FOUR motors to do nothing with, and FOUR new motors to order.

 

i plan on using strong parts a bit over the need because i know my build quality (weight-wise) will be a bit clumsy. I dont have access to the most light-weight materials and techniques... plus the heavy camera i'll attach to it.

do you think that the 24$ jDrome motors are enough for me ?

what STRONGER motor will you recommend for the 12" props from jDrome ?

Jani,

I see you are one of the the more experienced guys on here, so I'd like to pick your brain on a quad topic.  I am working with a few manufacturers of gearboxes to help me get a power train that can handle a max 9000 RPM for a gas engine quad.  My biggest unknown is my props/blades sizes.  I want to have a variable pitch system and use something like a T-Rex 500 or 700 three blade flybarless rotorheads and some 350mm or 430mm blades.  My big ignorance is finding out where to do the math or find a calculator that can take the engine horse power at different RPM and efficency of the gearboxes and settle on a rotor diameter that will lift around 30lbs giving stable hover and maneuver/flight abilities.   There are a few 80 - 120cc motors that are only about 7 or 8 lbs and put out about 5-8 HPs, but I need to find out what the lift/thrust abilities of four 700mm disks would be.

The begging to get the APM software to deal with collective and cyclic pitch for maneuvering a quad with those controls will start as soon as I can get this thing in the air a meter and hovering..

if you want to use it for arial filming it will be ussles due to vibraton....why would you want to do that??? it will end up like this http://www.youtube.com/watch?v=rcubbloN4HU

One of the main benefits of a quad is its mechanical simplicity.  If you're talking about using variable pitch linkages on each of the four rotor systems, you've just gone and made an aircraft which is a lot more complex than a conventional helicopter.

At that point, I'd be asking why?  You could accomplish what you want with a conventional gas powered helicopter design.

Hy!

 

I started to build my first Arducopter. Now, I am wondering which of the props. (10 or 12) you recommend to get the best results for short flying and long hovering. 

 

Thanks in advance!

 

Jani,

Are these numbers per motor or do they reflect power and thrust for all 4 motors together?

Those values were per single motor.

Thanks for the clarification Jani.  When looking at the thrust numbers, i'm a little confused.  I'm used to seeing thrust measured in units of force, not mass.  Are the grams suppose to read grams * m/s^2 rather than just grams?

It's grams measured using a spring balance against Earth surface gravity.

Thus 200g thrust will balance 200g against Earth surface gravity.

Everyone knows that grams aren't really a unit of force, but it's a simple way of measuring thrust that avoids most of the maths - we're not going to be flying on other planets so it doesn't matter.

in this case i would not looke for  cheapest.

buying here is a way to support diydrones, they started the project.... ( correct me if i am wrong) 

so even that ebay or other sources could you get it cheaper. is a nice way to support them  doing open source.

my two cents.

jDronesis best for providing those as we work with most of manufacturers and create new motors with them. Also original AC2830-358 and AC2836-358 motors are created but jDrones.

Original motors are now black to differentiate from clones. Also they have our logos on those motors.

In two weeks there will be one high efficiency motor coming and also big disk motors are coming. So keep looking postings in here

guys, i still dont understand what is the relation between motor KV , propeller size and thrust,

could you give some simple mathematic to convert motor KV and propeller size into thrust (its better if thrust in Newton)

thanks in advance

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