Bicopter A2212 1400Kv Motors Multiwii Fc

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About: I love making things. I have for as long as I can remember liked to make stuff. Now days I have two kids (Thomas and Emma) and most of the things I do are safe for them! I love electronics and Microchips, I ...

Experimental Bicopter. based on a multiwii fight control board and two motors/propeller's each able to swivel and controlled by servo's.

For this build I am using one of my favourite construction method.

1) I draw out the parts on a Raspberry PI using Qcad.

2) I print out the drawings at a scale of 1:1.

3) I stick the paper onto 3mm plywood using "prittstick". and double up as necessary (front and back, two sides)

4) Cut out the bits on my fret saw.

5) Stick all the bits together using Gorilla glue.

the last picture shows the model assembled but not glued, with this type of construction you should be able to make the model lock and hold itself together, and before I glue the model I always fit all the pieces together to make sure they are going to fit.

I just added a couple of screen shots from the raspberry PI qcad program (LibreCAD).

To add qcad open terminal and type

sudo apt-get install qcad

And if you are going to print then you will also need to install cups

open terminal and type

sudo apt-get install cups

Step 1: Putting the Bits Together.

So after cutting all the bits out and checking they fit I then in one go glued all the bits together using gorilla glue which I find very good. It only takes about 2 hours maximum to fully harden and foams up to fill small gaps.

With the main structure glued I then added pieces of 3 mm ply to the back sections where the servos will be mounted.

At the same time I glued threaded inserts into the ends of 12mm carbon tube. this design allows the tube to turn by twisting on bolts screwed into the threaded inserts in the end of the tube (the picture shows it better than I can explain it) you can also see in the picture the motor mounts pushed onto the end of the tube. at the outer end of the tube I have used a piece of fibre glass sheet to support the end.

The servos are also screwed into place. the servo used have metal gears which is a must otherwise as soon as you have a crash landing the gears will strip.

Step 2: Mounting the Hardwear.

Now its time to get all the bits into place.

To allow the motors to move they need a connecting arm, which is also made out of fibreglass and screwed to the motor mount using two of the motor screws. at the end of the arm is a pushrod fitting which holds the push rod into place using a grub screw.

The flight control board is mounted at the top, I choose this place as its near to the roll centre of the propellers. the holes to mount the board were drilled before the ply was glued into place.

With the motors and flight control board in place you can now put all the wires in and tidy up the spare cable by wrapping it around the frame.

The receiver is fitted into place using tie wraps and the connections made to the flight control board.

At this stage I decided to put Velcro strips down the side to fix the top section to the bottom where the battery is held.

Step 3: Completed Model.

So the last bits are the propellers and links from the servos to the motor mounts.

the propellers are 9" *4.7 and obviously counter rotating.

Its very important to get the neutral values correct so make sure you hold the model upright and securely and then connect the horns to the servos at as near to horizontal as you can. then adjust the link to make the motors mounts exactly horizontal and exactly the same as each other. You can see in one of the pictures that there is a connector in the connecting rod to allow for adjustment, this connector is just a terminal block as removed from a terminal strip. (we call it choc block in UK but I am not sure if that will translate!)

I put the model on the scales and it weighs in at 923g (including the battery but not the propellers)

Step 4: Flying the Model

This model is very hard to fly! it needed a lot of adjustments just to allow it to fly (PID's) And it will only fly in the calmest of conditions, as soon as the wind pushes against the model it runs out of servo travel and stops yaw control.

still it is fun and its quite an achievement getting something you made to fly!

Epilog Contest VII

Runner Up in the
Epilog Contest VII

3 People Made This Project!

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78 Discussions

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JIHHANA

10 months ago

hi plz can anyone help me for my project to realise a birotor tandem

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JIHHANA

Question 10 months ago on Introduction

HI I HAVE A PFE IN CONSTRUCTION OF BIROTOR TANDEM AND I WANT TO KNOW HOW CAN GET THE MATERIEL AND REALISE THE STRUCTURE ;I DIDN'T UNDERSTAND REALLY

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AryaVenugopalan

2 years ago

It has a lot of vibration, but if you think about it it has many practical applications especially because for one quadcopter, you get 2 of these

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mr_fidAryaVenugopalan

Reply 2 years ago

If i had progressed this i would have spent a lot of time sorting out the PID settings to correct the vibrations. i may have another go with this next year!

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AndreMendesmr_fid

Reply 2 years ago

Sounds good for me, I wanna see this with out vibration in fly, I like so much, mainly design.

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mr_fid

2 years ago

Hello One of the picture above has the numbers written on the back.

so if you are using a multiwii with 328p then...

on one side you have 11 = Servo and 9 = ESC

and on other side you have 3 = servo and 10 = ESC.

In the picture above the model is on the floor face down (so you can see the back) and the arrow on the flight board will be facing into the floor. The other channels just connect to your receiver .

Regards

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ulisses

2 years ago

can put wiring diagram on the board Crius?

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osterac

3 years ago

I love this! Some suggestions: the shape of the craft looks like it would catch a lot of wind. If it could be constructed more like a traditional multirotor in a horizontal configuration, only with the battery hanging down to stabilize it, perhaps it would catch less wind. I'm not familiar with the multiwii flight controller, my personal preference is the KK2. I have one in my tricopter and I do remember seeing a dual rotor setting in the menu.

7 replies
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osteracosterac

Reply 3 years ago

You also might want to experiment with how much tilt you put on the the rotors if you haven't already- you can always use more lift.

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osteracosterac

Reply 3 years ago

Come to think of it, why are they tilted? Seems like it would create turbulence.

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mr_fidosterac

Reply 3 years ago

Lots of comments! like this model it needs lots of trial and experiment's!

Why are they tilted???? well the original idea was for this model to be a backpack for an action man toy, so the shape was chosen to match the action mans shoulders! it turned out that the action man had eaten too many pies and was far to heavy to lift!!!

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derekiswisemr_fid

Reply 3 years ago

You might be able to vacuum mold a copy of the figure if you have access to a vacuum-form machine. Then you would have a very light copy of the figure that them could be carried by the bi-copter.

If you don't have a vacuum-form machine there are some very good designs online to make one using an adapter that fits onto a normal vacuums hose, and uses some relatively cheap ni-chrome wire to heat the plastic.

Best of luck, Thanks for the intructables.

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mr_fidderekiswise

Reply 3 years ago

Good idea. If I was to continue this model, I would have made the man out of balsa wood with carbon fibre arms and legs. only problem is the kids... if they see me attacking action man with a hacksaw they wont be impressed. I just finished a Tricopter for the action man and that works well, with a few improvements it should fly very nicely with a full weight action man. Check out my "Action Man Tricopter"

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osteracmr_fid

Reply 3 years ago

Haha, that's a fun idea. I can't imagine a bicopter carrying much cargo though- it's like a table with two legs and it's pretty impressive you got it flying in the first place. A tricopter will give you much more lift and stability but may look strange as a backpack.

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BeeblebroxTheHalfth

3 years ago

Awesome job! Could the wobbling be due to the servos not being strong enough or the tilt joints not being stiff enough? I had the same problem with a tricopter I built. In my case, I used a tiny 9g servo to control the tilt system and even though the control gains were set correctly, it used to wobble and go crazy cause the servo couldn't keep up. But I may be wrong cause your servos look beefy enough and the twitching is due to it being hard to control.

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Also the angled motors might work better if the were angled the other way, as in the thrust being directed outward rather than inward as the airflow would be cleaner and less turbulent. Same reason why a quadcopter descends unsteadily when descending straight down, as it's entering the 'dirty' air.

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molvikpm

3 years ago

If you set the D and I gains to zero do your oscillations eventually damp out at zero stick input, or does your model become unstable with increasing oscillation?

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mr_fidmolvikpm

Reply 3 years ago

Its hard to say, but I did spend a lot of time getting to this stage. And now its flying I can try a small adjustment each time and see if it improves, however its fun to fly it and ignore the oscillations!

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molvikpmmr_fid

Reply 3 years ago

I'm guessing (an educated one) that the answer to my question is that it would become unstable. If you haven't already, you can try implementing a moving average window to both moderate and slightly delay the system response to the error input. The window size will be a trade off between crisp input response and stability. You might also try to program in a small dead band around zero error to minimize hunting. You will get more drift with a dead band, but it should eliminate the hunting if you get it right. Dead banding will also help reduce the effects of mechanical hysteresis (slop) in your bearing/linkage system.