RC India

Have been working on this project in the background for a month now. After lots of reading, researching, tweaks and trims, I have reached this stage(video below). Now I need all the veterans to help me here to further stabilise the whole system. The roll and yaw are fine, the pitch is very difficult to control especially at high throttle inputs it becomes very unstable and has a tendency to fall backwards(dont know why, because the battery and inverted motor positions are ought to keep it in stable equilibrium) but for some reason it isn't working to the optimum capacity, though it is far far better then what it was when I first started!

Video :
http://www.youtube.com/watch?v=bsjSCw1714o&feature=youtu.be

WOW! Can't wait to see her - I hope she will be ready by mid March?

Trying hard. Running out of ideas though!

Saw the video. She seems good. Is there any way that I can help?

hey which control board r u using???

Its seems to be a KK board and the code seems to be something similar to the Flycam twincopter. You may have a look at it for details and help...

http://www.kkmulticopter.kr/index.html?modea=flycamfc (http://www.kkmulticopter.kr/index.html?modea=flycamfc)
The code is located around middle of the page.

The board is a normal HK quad board reflashed with the KK Twincopter firmware.

@VC bhaiya: I can't figure out why it wants to fall backwards at high throttles, that is why you see me flying it very close to the ground. As soon as I take it up the pitch becomes very unstable and its reactions get exaggerated to small control inputs most of the time it wants to fall backwards. I tried changing the trims, gains, adjusting the C.G but this is the best I have come  up till now.

I request all the veterans to help me with this.

Another thing is that it is very responsive to throttle inputs too, if I reduce the throttle by a tiny bit, it falls to the ground!

Looks OK for the most part. Throttle sensitivity can be partially handled with a proper throttle curve.  Selection of props and KV of motors will also affect throttle sensitivity.

Be sure to turn on some expo (like -40 on Futaba or +40 on other radios) on the aileron and elevator channels, especially if you are not an experienced heli flier.  Note that being a plane flyer does not help much with flying these types of crafts which are mostly controlled like how helis are controlled.

Of course gains and PID tuning would have an impact.

Will a dihedral help ??? I mean instead of using a straight boom what if booth arms are kept at slight angle like in dihedral wings  :-\

Thanks Anwar Sir. Yes I'll incorporate the suggestions in the next test flight specially the throttle curve. I do have expos on the roll and pitch. What is PID tuning BTW?
My only concern is that when it is low to the ground it flies pretty well, but once I take it up high above the ground, it has a tendency to fall backwards, i mean it starts to oscillate and any pitch corrections make it even worse, lastly it goes into this suicide fall backwards even though the battery(which I have purposely placed at the bottom) is supposed to bring it back to the neutral position but it doesn't.

@sunlikestar : Yes I was also thinking about that, will incorporate it in the next build, presently i'm trying to gather as much data from this one.

nice..and so inspiring efforts..Rohit.. :hatsoff:

Thank you Rupesh bhaiya. BTW your efforts are the real inspiration for everyone out here!

Very inspiring efforts!!

Can you please list the parts used in this project?

Thank you,
Atul

Rohit,
The VTOL motor mounts are adjustable to forward, backward direction. But the lateral swing starts this unbalance. Proportional, Integral Derivative (PID) control may be introduced in board. But I think, dihedral (For motor mount in addition to battery at bottom) may help or make more unstable as per code adjustment.

Just test by keeping battery little top by moving CG Up to match the program parameter.
Later Just adjust program parameter. As, I am not even see the code even for once, I may be wrong, but first take out CG position and then adjust CG & take another Data.

More on phone next day.

Thank you Kalyan Da. Actually, I have chalked out a number of changes to the design that I will incorporate in the next model, currently I'm busy searching for materials/components that are required for the next design.

Oh BTW , I need to talk about the PID control.

@ Atul : I am really sorry, I forgot to reply. Actually I haven't used anything out of the box for this model. Basically a wooden dowel(rectangular cross-section) over which everything is attached. I mounted the motors to a foam piece through which I have run a carbon fibre rod that is free to rotate and is connected to a servo on either side. The motors are the normal CF2812(1534 kv, 140 watts), 25 amps HK esc's, an HK Quad board reflashed with the KK twincopter software and a 2.2ah 3s battery. 

Cool, thank you for details Rohit!

Hope to see full function VTOL soon. keep us posted :)

Thank you,
Atul

Hey Rohit!

Hope you are doing good.

Any progress on this project? 

Thank you,
Atul

Hi, Atul. Yes I am working on this project, it took me some time to get all those required stuffs but I have them now and I have started working on it again. Will update as soon as I find time.

Hi Rohit, we all look forward to seeing your VTOL fly/hover :) Keep-up the good work !

Thank You Ritesh bhaiya, well I am looking forward to it too!