RC India

Hello Guys

We at RCBharat are starting a very huge quadcopter project .

Project Specifications

200KV Motors  , each motor weighing almost 750Grms which can pull anything above 10Kgs at ease
100Amp ESC
16 x 4.5 Wooden Props
22.2V 5000Mah Lipos x4
Laser cut frame made out of thick nylon
Multi Wii Pro Control board ( Searching for a better board if any)

And this will also be carrying a Go Pro cam below it

This quad can carry a payload of almost 20-25Kgs and this is made for a defense organization based out of Hyderabad.


Pictures will be posted out soon as all the material landed today.

Sai Krishna
www.rcbharat.com

 

Hmmm... quad.

Something I wondered, but never investigated.  How well would multirotors handle failure of one motor (or ESC, same thing) ?  For quads, it is clear they would tumble out of the sky.  I expect hexas to do better, but don't know if they can gracefully handle the failure of one motor.  Seems like octas would be able to handle this reasonably.

Anyone who has done this research/reading/analysis ?

Yes Anwar Sir,
It is very true that a quad would tumble out if any motor, esc a failure happens and the same scenario can well handled by hexa or octas
This is basically a prototype considering the budget of the client's organization. If anything on this scale works out, I'm pretty sure that the organization will be ready to shed a few more bucks on the project.

Need some tips from the big guys as this is my very first exposure to such a scale.

Sai Krishna
www.rcbharat.com   

Check out the motor specs!!!

The ability of a multicopter to land safely despite losing one motor is usually called redundancy... I have read a few threads about that on rcgroups....
Even hexas don't have good redundancy... It requires a very experienced pilot to land a hexa with one motor down.. Quads should be out of question... octas are fully redundant..

@sai Krishna

So this is the quad we were talking about over phone... I am eager to see the pics and a flight video when it's made.. :thumbsup:

Yes the same one.
Will post pictures tomorrow.

Same excitement here also on the outcome.

I would have thought that the obvious solution would have been
to mount two motors on the same vertical axis eg. a tricopter
with six motors or a quad with 8 motors.

Of course this is just theorising

I have a noob question :P If octas have better redundancy, why not use two motors which can lift 5 kg instead of using a single motor of double capacity?

Very good one!!

The decision of quad was from the organization.
I'm very sure this would just survive as a prototype of something even bigger and reliable.

@saikat @lastRites
That design of two motors on the same arm would call for a custom firmware since this is not a conventional type. OR one could use a Y-plug between the ESCs of the same arm but this would be too experimental.

Most common high end FCs support y6 configuration I think. And I was talking about a conventional octa :P And a Y-plug wont be of any use cause no two escs are exactly identical and the fc must be able to control each directly to keep the whole thing stable..

Few Pictures of the electronics

1. Complete Electronics
(http://www.rcbharat.com/Pics/Combo.JPG)

2. Motors
(http://www.rcbharat.com/Pics/Motor%202.JPG)

3. ESC
(http://www.rcbharat.com/Pics/ESC.JPG)

4. Batteries
(http://www.rcbharat.com/Pics/Battery.JPG)

(http://www.rcbharat.com/Pics/Battery%202.JPG)

Comparison pics
1. Compared to a 930KV Motor (800grms thrust)
(http://www.rcbharat.com/Pics/Motor%201.JPG)

2. Compared to a 2200Mah 11.1V Lipo
(http://www.rcbharat.com/Pics/Battery%20Comp%201.JPG)

(http://www.rcbharat.com/Pics/Battery%20Comp%202.JPG)

That's why I said it would be too experimental. :P

Tried this already, but the motors suck up the lipo too fast, inspired from a video ( HK Bear Lift winning one!!)

Yes right that's the problem.

Is a single big motor more efficient than two smaller motors if the power on both setup are equal? I know this will depend on the quality and type of the motors but still is there any relation between the efficiency and size of brushless motors?

I personally assume that two motors are better than one provided the vibrations are well under control.

Big guys need to comment here!!

Sai Krishna

Hey Sai,  First of all all the very best in your Mega project.  That's something I would die for.
Now coming to redundancy which a couple of us have already pointed out, for such a Mega project, it would have been better to opt for motor/ESC redundancy.  May be the guys sponsoring the project have only heard of a Quad and not considered other factors such as esc/motor failure which I am almost plagued by these days.  So if the project is successful, would they be sponsoring for a redundant test?  They might just ok the quad and say that it works and no need for redundancy!!!!!
But in either case we are all keeping our eyes open and watching this forum for new developments from you.  Thanks  for trying out this one out.

sai
one i have realised in quad building and flying is, it is important to work out Cost Benefit analysis, that is to say efficiency vs powerdraw and quad vs tri vs hexa, that suits your application. more discussion in person, may be today ;)

Hey dreamfly

Thanks very much for your inputs, yes the the client organization were well informed about the redunrency, but they were keen to go for the quad   initially and I'm sure will also be interested in hexas or octas once this becomes a success.

-Sai Krishna

Gusty Sir,
Marriage season at it's peak here in Hyderabad, and this is keeping me damn busy, very very eager to meet you in person, will pull out this weekend for you.
Hope we have some good time over dinner

sai, just curious to know marriage, season & you are busy. Is rc got to do something with marriages or something else.

Nothing related to rc.
Many of my friends and relatives are getting married, so only busy attending their marriages

good work @rcbharat . i have a question about the payload you mentioned, as with 20-25kg of load how much altitude it can fly on with this setup and time duration? as i have saw couple of video from HK beer contest and most of videos the altitude as very low.

like in the below videos, they don't fly too high.
 
http://www.youtube.com/watch?v=pa5u4Se4MTY or http://www.youtube.com/watch?v=UVwt7oWC5fc

Hello Anand

A small change has been done to the configuration mentioned earlier.
The FC is now APM 2.5 with the sensors required for automation flights. So may be controlling and this may not be a problem.

Sai Krishna

@rcbharat - the AMP 2.5 will be for controlling, but what about my other query for payload and altitude ?

The payload will be increased gradually till the quad has a very stable lift off and flies at desired altitude. Rest is taken care by the FC . We will employee the loitter mode once the required altitude is reached.