Bro, you forgot about torque.
Pitch alone not enough.
Bro, you forgot about torque.
Pitch alone not enough.
Torque? U forgotten about V-22 Osprey and Chinook and SeaKnights.
They are twin rotor with variable pitch.
EDIT: Correct me if I'm wrong here...To compensate your yaw due to torque (quadrotor), u change motor speed right? In variable pitch, u change the pitch. Less pitch, less drag and thus, less torque it created. Two rotor spin opposite each other and thus cancel each other. Good thing of using this config is that, you don't worry about not able to find matching blades (CCW and CW). U just flip the blade over.
Yah, normally two props cancel each other out. But on a quad, if you want to yaw, one of the props have to slow down/speed up. Can't do that with only 1 motor and 1 esc?
If you are into coding and development of the firmware, then knowing which quadrant should speed up or slowdown to create the YAW effect....
A normal hobbist need not go so deep into the theory, let the firmware n microcontroller take care of the sequence, and it can speed up/down any pair to yaw without sacificing altitude\hover height...try yawing a heli 360 deg without compensating throttle input, it will sink in one direction and raise in the other direction...
You can even try using different pitch prop of different brand, it is still stable in hover n flight as demostrated by the prototype. As an experiment, the prototype now uses a pair of 2 bladed props(APC) and the other pair a 3 bladed props (GWS).
Come try it yourself with the prototype, nothing beats testing one yourself. You will be amazed !
What you get in the production RTF version will be as follows:
1) The single controller board supports all 3 modes of TRI, QUAD and HEX copter. User just need to choose and add/subtract arms accordingly.
2) The same frame allows user to change mode mentioned above easily, meaning if changing from Quad to Tri, simply remove one arms and arrange in 120 deg config, from Quad to Hex, just buy 2 more arms and arrange in 60 deg config. So owners can have the option to choose, buying a commerically available unit doesn't give you these choices. (Tri needs a tilting servo mechanism for Yaw in one of the arm)
3) No soldering is involved in the event of the need to change arms in the field for what ever incident that happened, its all quick connect replacement method of repairing on site, and gives you more time to enjoy flying it, if for example, a heli ever crashed, its heading back to home time, to repair n setup using pitch guage again...
If test flights n development are successful, then we may go for a small batch qty run (subject to response) with above 3 features mentioned targeting below SGD500 each RTF set.
So anyone interested may contact the guy holding the prototype now and get a feel of it, absolutely no obligations to buy at these stage.
Cheers and have great fun ahead.
The main attraction of tricopters are its simplicity – no links, swash plate, fly-bars and such to be content with. The availability of cheap gyros, ESC and out runners made it possible for me to build my tricopter for less than S$150. I like my toys cheap and dirty.
Your idea of using pitch instead of motor speed to control flight has it merits. I believe it will be similar in discussion between fixed pitch and CP helis. Indeed, my tricopter flew like a HB FP. One has to anticipate motor speed drops during fast turns and banks or it will make contact with Terra Firma before you realize it.
Having said that, there have been not many successful attempts in building a tricopter based on one motor, with variable pitch control around std heli tails. The main considerations, as you are aware, are power losses and need of studier frame to handle 3 belts. Throw in ‘vector thrust’ – a fancy way of calling tilt rotor, you will have a mechanical dinosaur – a dead end (in no way referring to Trex nor Raptor). Someone smart remarked that they don’t want to build another heli.
However, I would love to see one of our great rotor wing guru trying to prove them wrong !
500 S$ is still too rich for my blood.
I have one question though, can or will your controller handle twin rotors (tilting) ?
I do have interest in creating multicopter also. I was thinking of developing variable pitch instead because, I like said above, variable pitch changing is faster than motor speed changing.
But to develop mulitcopter using variable pitch, I think develop 4 rotor or quadcopter should be easier than tricopter due to do not required to change the angle of the rotor for stabilization (unlike tricopter whereby it change the angle of the rear rotor as part of the stabilization). Instead, you only need to change the pitch angle of all rotor disc. This do not required swash plate IF you are using the whole tail assembly of the heli.
Using variable pitch in tricopter is possible (i suspect) by tilting the rear rotor either by turning the whole rotor assembly (like V-22 Osprey) or tilting the rotor disc using swash plate (like Chinook).
Again, since I never try multirotor head before, so the mentioned above is just a theory. I already have an idea on how to drive 4 rotors using single motor and to turn the 2 rotor in opposite direction to the other 2 rotor by using parts from Mini-Titan's parts. I see whether I can do some shopping in local hobby shop this Saturday and see whether is it possible to really create it or not. Let u all know the progress....if "Variable Pitch Quad Rotor" project even get started in the 1st place
you may have missed the yew for Quad is by rotor torque so you still have to deal with variance of motor speed. Not sure it is worth all the setup.
If the objective is to have constant RPM then you may need foure servos, four motor with variable picth etc.. Complex and potential costly. And crash part also not cheap
fun for sure but still wont beat the objective of lower cost I think.
Just my 2 cents...
We are trying to give more features and bring down the costs of owning the Quad, or rather multicopter. The nearest commerically available kits is of course the German designed MK. They sell so call "kit set" has a very different meaning to what we comprehend in our mind set, their basic kit consist of every components you need but not soldered at all, can you imagine paying Euro 800 for a starter kit, and having to solder electronic component for all the blank SMD pcbs for 4 ESCs and the main controller board ? Only those hobbyists with slightly electronic inclined will buy n make them, while mosts of us hobbists are more mechanically incline....Not only the pricing puts you off, but the actually building and skill needed is quite steep for most of us.
The other side of the picture being using 4 gyros and transmitter mixing is of course more costs effective, but you can only do that for Tricopter, not in Quad or Hex configurations. And the amount of wirings all over is so unsighty !
Will you trust this tricopter flying (Gyro gain lower than 35% for stability), loaded with expensive camera or FPV stuff? Probably good only for fun fly. I too went thru this route, and its not very much cheaper considering 4 motors, 4 escs,some ply and countless trips to hobbyshop and hardware shop...will sets you back for around $200.... but now i has evolved further using microcontroller based system. Yes i agree its quite fun building your own from plywwod n spruce etc...the satisfaction you get when it does fly far outweight any $$ values.
Thats why i stressed that this is just a hobby, why pay a high commerial price tag for it ? I didn't says i want to sell it for $500, i said it will be lower than $500, but it all depends on the orders n responses that we get...i do have some order in hands from some old heli friend whom has tried it. It just more costs effective for us to produce in batch of small qty, once its sold n gone we may not produce anymore. These multicopter ideas was given to me by my old RC friend, and i loved these machines the moment i see one fly in youtube, so i came back to this hobby after 15 years of lull period...I build this for my own consumption n usage, thats why i m able to sell the rests at these affordable prices.
I like the way you think.
Your one controller board can do tri/quad/hex.
Don't need any mixing in the TX.
All these are competitive advantages to the MK design.
You really need to develop this further. I believe lots of people on RCgroups will find your product irresistable.
Further improvements you may want to think of:
1. Altitude hold and autopilot interfacing for handsfree operation.
2. Improve on the payload capacity. ESC handle more amps.
3. Provide DIY drawings or sell the frames.
It is like those variable pitch coaxial helicopter....like those "Kamov Ka-50" helicopter:
"...Yaw control is achieved by increasing the blade pitch on one rotor while decreasing the pitch on the other. The result is a differential in torque, resulting in a yawing motion..."
All 4 rotor are spinning in the same RPM and it is controlled by governor.
Cool info. Looks like my 2cents on the Yaw control is not applicable here...
No more 2cents.... downgraded to zero cent!
I better concentrate to the Quad journey....
Please let us know how you make out with your one motor quad.
How do you intent to implement the mixing scheme - onboard microcontroller,
or tx mixer a la tricopter style ?. I hope you could do it with the former.
Thanks Sirod and Sirod. I will sure need your help when I start this project.
beanlee999... sorry that it sounds like I hijacking your thread.
As for controlling wise, the controlling is actually eCCPM 90 movement but with phase offset by 90Degree.
But the controlling on the rudder is going to be tedious in the programming mix (TX). It also make it difficult to use gyro (Tail) for stabilization.
To solve this, I either use a series of V-Tail mixer or I see whether I can come out program/software and using PIC (microcontroller) to mix the eCCPM90 with rudder control or not.
I might use the PIC method instead.
EDIT: It should be eCCPM90 with 45Degree offset. Not 90Degree offset.
Last edited by Super-Hornet; 30-07-2010 at 08:02 AM.
Its a pity I'm not rich...otherwise I'll join you guys in all this R&D...
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