hi.....i m currently added with this site & it seen to be very useful.
well i ashish from kanpur, u.p. & i wanted to make a rc quarotor but don't know anything about it so will you please guide me telling the basics like what motor should we use & what would be it's rpm & torque??

There are many quad-rotor threads here, but many are incomplete. I guess many of them are college projects, so people are not keen about posting details here after completion.

Motor, prop and ESC selection have also been discussed widely, and you should remember that it all starts with the AUW of your model.  So unless you post in much more detail about your model, people will find it difficult to respond (it is not that they don't want to!).

well sir as i said i don't know much but since i googled a lot & find a lot of things like motor & all the other things but since we don't know what is gyroscope do in quadrotor?

I am sure you can find enough and more information about what a gyro does in general on this forum and Google. 

But to answer the question why it is needed in a quad is that even the best of the best pilots would find it difficult to correct the inherent instability of quad-rotors with their stick control movements alone.

Anwar, With more and more people today planning to build quadrotors, I thinks its a good idea to make a sticky thread that has a complete quad setup if any available in any thread on this forums, as to what are the parts required to build one, Total cost etc.

The cost on the other hand to build one is high, 4 Outrunners, 4 ESCs, 4 props and 2 to 3 Gyros means, costs shooting up more than 7000 Rs(For the smallest setup), NOT including transmitter, receiver, frame, battery, Lipo chargers, spares due to accidents when testing etc. Which will end up with almost 12 to 13K or even more when fully built.

This info when made sticky should give a basic Idea for college students, who are usually tight on budget, and are planning to build quads as college projects etc. as to what to expect from a quad.

Vinay -

The basic information is here :  http://www.rcindia.org/self-designed-diy-and-college-projects/quad-rotor/

I have made this sticky, and I hope people search and find it.

Thanks to Sai, this is one of the most informational posts here, so I am adding it to the Gems list too.

Hi. I'm currently building a quadcopter. I have done a little research on quadcopters and it turns out they are very unstable so you need a computer + an Inertial measurement Unit to balance it. An Inertial Mesurement Unit uses3 accelerometers and 3 gyroscopes to calculate the tilt of the quadcopter with respect to the x, y and z axises. Cost is a little high (I have spent around 8k as of now). Its not that difficult to make one and I encourage you to make one.

Welcome to RC India, Gaurav !

Would love to see some pictures/videos of your quadrotor work so far

I know you need gyros, but does one really need accelerometers ?  I have got all the parts to built one per the above link/design, just need to sit on it as time permits.

Accelerometer is required if you need full stabilization. Theoretically, gyros initialize when the aircraft is level and you use the gyro in HH mode it should work. But gyros are said to suffer from drift. May be one of these days I should take off the heli and see if the tail can hold its position without any inputs for minutes. Accelerometers can give the g force vector at any time. This is used to correct the gyro drift.

Accelerometer output will be affected by the movements of the quadrotor, so its output will be the resultant vector of g force and the acceleration due to movement. Gyros is not affected by movement( they respond only to rotation), so gyro output can be used to cancel the errors due to movement in accelerometer output.

That is a poor explanation of the theory in a nutshell. Gaurav should be able to give a better explanation and details of his craft.

Thanks for your welcome! Actually gyros calculate the rate of change of the angle wrt to x,y,z axes, to calculate the angle you do need to use accelerometers. Rotorzone correctly pointed out that accelerometer will be affected by the movement of the copter, which is corrected out by the gyros, so in essence we are using both the gyros and accelerometers combined. Actually my quadcopter aint much, its just 2 aluminum crossbars with 4 motors now, without batteries, without anything else. Please give me your contact number/email id so we can discuss more freely, I have a lot to learn from you.

I would also like to ask you guys where I can buy 4000mah 25C Batteries with charger in India. I'm right now in Hyderabad and will be going to Delhi. Are there any shops you know of?

Hoping to hear from you soon (via PM).

Quote from: RotorZone on May 02, 2010, 09:03:05 PM
Accelerometer is required if you need full stabilization.

That is if you are after UAV style projects, right ?  Basic stability seems to be achievable with just gyros alone (with help from the thumbs of the pilot, very similar to hovering a heli); judging from material (especially videos) posted online.

In other words, what would constitute "full" stabilization ?  That it does not drift from one place at all ?  Is that possible even with accelerometers ?

I didn't mean position hold when I said full stabilization. If you level the quad rotor and take your hands off the controls, it will eventually tilt because of the gyro drift. Here is where the accelerometer comes in. It can be used to detect the direction of gravity vector and correct the error from gyro.

well my company is developing the whole controller board (includes stabilization system, etc) for quads after which you wont be needing to buy seperate esc's for each motor and you wont be spending time digging up the internet for all the info, It will be available in market shortly..
it is strictly targeted for students and DIYers , The code will be open source so that all can develop if they want.
but sorry "nothing for now", seems like ppl and me have to wait.

Harsh - Any update on your controller board ?

Here is a good video on gyro versus accelerometers.

Anwar Gi, I remember reading that you will start building a quad rotor. Did you start one 

You mean this ? http://www.rcindia.org/self-designed-diy-and-college-projects/quadrotor-build-thread/

Ya, But what happend to that project  ?

I am confused   If you read that thread, that is the actual status/progress (slow!).  I posted an update a day or two ago.  I am working on it slowly, as time permits.

Actually it's me who got confused   There were so many links and threas in that post I got carried away 
Sorry about that... 

I average about one quad every 5 days in my spare time. As fast as I build them I have a queue waiting to buy it. I use the KK2 board $27.99 from HobbyKing. Out of stock at the moment. It has stability hold but it always makes me laugh when people keep raving about this hold and that hold. Unless you are a commercial photographer with thousands of dollars to spend and just want to FLY then why spend all that money trying to get something that flies to sit still.

I launched my $1,000.00 quadcopter last Saturday. It had FPV and NAZA controller with GPS. It was the best flight of any aircraft including fixed wing I'd ever had. No hint of instability. On full hold it would simply just sit and do nothing. It stayed at the right height and in the same spot without flinching but the fun came when my friend joined in and he chased me all over a 4 km square of land. We had a ball. Both of us on Goggles and flying through goal posts and between trees. The only killer was returning to change batteries. To top it all off I flicked the RTH (return to home ) switch and switched my transmitter off. The quad was 2 km away. It dipped it's head towards me and swiftly flew to right above us. It slowly lowered itself and gently landed roughly 5 or 6 feet from where it originally took off from.

The technology is here for planned waypoints. You set where you want it to go and what you want it to do and basically turn your transmitter off and have a beer. The quad will do exactly what it's told to perfection and fly home, land, disarm and switch off. It's expensive at the moment. My Naza was $550.00 but given time it will drop.

Now is the time to get used to multicopters. The parts are cheap and a complete kit from China is worth $139.00 complete with everything you need except battery and radio equipment. I've built one and with the KK2 board it flies better than a fixed wing and a lot easier to handle. I still fly fixed wing but quads have my attention at the moment. By the way, all those gadgets mentioned earlier are built into the KK2 and you don't need a computer for anything. It has it's own LCD readout to set it up.

Forget Y=X=Z+A and all that trigonometry and science. It's not needed. No slide rules or calculators. There are numerous tutorials on YouTube on how to set the KK2 up. So if you can put parts together with nuts and bolts, use velcro and know a clockwise prop from an anticlockwise prop that's about it. It simply isn't rocket science. So far I've built over 20 quads and all but six have flown, only because I haven't had the time to test them all. Don't think about it, do it.

Good show Stu, heard your "Quad Hat" story...Nice Story

Propfella...I like your post .....this should be the approach of a hobby flyer.....too much mind over matters takes the fun out of it....

It is recommended to start with a quadcopter kit or a pre-built model if you are new to building RC quadcopters, as it can be a complex process and require knowledge of electronics, soldering, and programming. There are also many online resources and tutorials available to help you get started. You can check the quadcopter kit at https://robu.in/?s=+quadcopter+kit&product_cat=0&post_type=product.

It's good that you want to make your own drone but if u little bit interested in purchasing homemade drone than u can buy it from me.
I designed it by yourself on my homemade frame.
Used:-
930kv ready to sky brushless motor with 9inch propeller
30amp esc(ready to sky)
APM 2.8 flight controller
GPS module
Flysky fs i6 transmitter
Fly very stable and RTL works very accurate

U just need battery and it's ready to fly

Reason for selling - need of money for my next project

U can watch it's making and flying video here

on YouTube channel