Here are the details of the Fly-By-Wire bell crank used in my 2012 W/C's model.

The basic structure is our standard take apart spar assembly and bell crank modified to accommodate a magnet holder and stationary hall effect sensor.

The Pic's:

All the component parts.
Note the object of the assembly is to rotate a set of magnets about a central axel inside which is a stationary hall effect sensor.

Bearing caps installed on main spar.

Bell crank with magnet holder assembled to main shaft.

Fully assembled bell crank

Assembly with hall effect sensor. (sensor is just the tip of the wire)

Sensor installed.

Bell crank installed in wing center section.

Wing flap servo mount (note the leadout!)

Yes Virginia, there really was a fly-by-wire model at the W/C's

_____________________________________________________

The electronics measure the angular deviation of the sensor from the rotational midpoint of the magnetic field and convert that to a standard servo signal to move the control surface.


Kim.

Fascinating Kim.  How about some particulars on the servo installations.

Kim it is interesting but what is the reason for this system?

Crazy!!
So, I believe it would be possible to program the throw, like Igor's system, but one could experimente with diferente combinations just by pushing buttons, like you are setting your eletric motor, you will set the controls...
Is it legal?

Please, post more info... Did i guess right??

Marcus

Mark,

I added a picture of the wing flap servo mount. I never took a picture of the elevator servo. (I was in a bit of a hurry!!)

Robert,

This is the "Fly-By-Wire" system that was so pointedly talked about a couple of years ago. The bell crank is not connected to any pushrods, it simply moves without load generating a signal that is translated into a servo movement and an associated control surface movement. There is no "Netzeband Wall" with this system. The feeling on the handle is not so different than a standard control system. The granularity of the system is very fine and the servos are as fast as you can move so there is no lag. All control surfaces have endpoint control, expo, mixing etc.

Kim.

"The more complicated you make the plumbing, the easier it is to stop up the drain".

Montgomery Scott.

Quote from: MarcusCordeiro on August 22, 2013, 06:27:05 PM
Crazy!!
So, I believe it would be possible to program the throw, like Igor's system, but one could experimente with diferente combinations just by pushing buttons, like you are setting your electric motor, you will set the controls...
Is it legal?

Please, post more info... Did i guess right??

Marcus

Hi Marcus,

Yes it is completely programmable. Yes it is legal. It passed technical inspection at the 2012 World Champs in Bulgaria.
We have a programming card and can change any parameter as easily as you could with an R/C transmitter. We are not doing anything that could not be done by changing mechanical connections or linking surfaces to a mechanical  mixer. There is quite a lot written about this in other posts on this forum.

Kim.

Very awesome Kim!  Thanks for showing the details. Im sure the feel is much different with no feedback from the flight loads on the control surfaces?

Jason

There's some Scale guys doing this with pots & servos.
As long as the bellcrank is mechanically linked to the leadouts and controls the elevator via the handle, it's legal.

What does this system weight compared to a standard pushrod / mechanical system ?

Am I correct that if you totally lose the battery power you lose control and have just a plane on a string with no more control than a teather model ??

Quote from: Douglas Ames on August 22, 2013, 09:03:25 PM
There's some Scale guys doing this with pots & servos.
As long as the bellcrank is mechanically linked to the leadouts and controls the elevator via the handle, it's legal.

For FAI, apparently, you don't even need that.

For that matter, I just looked at the AMA rule book, and the rule (rule 2 in CL General) appears to allow other connections than mechanical.  It may be interpreted that way, but it does not call out any difference in the control of the elevator and, say, the pilot waving:

Movement of control surfaces, and any other of the model's operational features, may be accomplished by mechanical means, by electrical impulses transmitted through the line(s), or by any other control system that does not interfere with the control of any other model or present a safety hazard to competitors or spectators.

If there's some further rule that says that you do, indeed, need mechanical control from wires to elevator, then I missed it -- but I'd love it if it were there.

So if you want, you can be the first pilot in the US to get lynched at a control line meet while protesting "but it's legal!"

Quote from: Motorman on August 22, 2013, 09:23:48 PM
I guess this pretty much trumps a carbon fiber push rod.


MM

Except for weight.

Quote from: Robert  Storick on August 23, 2013, 07:33:57 AM
Except for weight.

Except that the whole model including battery, servos and electronics only weighed 64 ounces.

I know, a real lead sled.   

Kim.

Which servos are you using?  I assume you have one per flap and one for the elevator?

Kim,

Have you thought about working to incorporate a heading lock gyro?  I use the AR7200 Beastx in my Heli and in the heavy winds it will hold the yaw and pitch axis during hover. The body maybe hanging way off to the left or right but it will just sit there.  Of course I have to stay on it as the winds are always pushing it around.  I have to keep it in one spot.  Only once an input in given will it let up and move to that new input and hold there.  It's quite an insane little piece of equipment. It's lightening fast as well.  I am thinking you could use small trim tabs on either end of the wing and it could constantly keep the plane from rolling.  Then you could have a very small moveable portion of the rudder than would constantly be working to keep the yaw angle at a set rate.  I am certain it could be done seeing what it can do on the heli.  I just wouldn't have a clue where to start with programming it.....

Your bell crank input would go into the BeastX receiver and it mixes the output to the flap and elevator servos.  While the gyro works on the axis at all times.  Is it legal?  Who knows? But it sure would be cool!

On another note there are some pretty beefy brushless metal geared servos out there you could use on your flaps and elevators and the weight gain wouldnt hurt too bad and the stripped gear would not happen again.  I mean I was less than 2 points out this year with my 68 oz plane.

Actually the flap servos would go through the beastx and it would mix the output to control the roll. Just have to run one of them reversed so they go the same direction when BC input is given. But they would also always be acting opposite to control roll!!  I have a friend who is pretty good with it I Amy have to make a call and talk some....  Oh it would be so cool!!

Quote from: Doug Moon on August 23, 2013, 02:02:12 PM
Kim,

Have you thought about working to incorporate a heading lock gyro?  I use the AR7200 Beastx in my Heli and in the heavy winds it will hold the yaw and pitch axis during hover. The body maybe hanging way off to the left or right but it will just sit there.  Of course I have to stay on it as the winds are always pushing it around.  I have to keep it in one spot.  Only once an input in given will it let up and move to that new input and hold there.  It's quite an insane little piece of equipment. It's lightening fast as well.  I am thinking you could use small trim tabs on either end of the wing and it could constantly keep the plane from rolling.  Then you could have a very small moveable portion of the rudder than would constantly be working to keep the yaw angle at a set rate.  I am certain it could be done seeing what it can do on the heli.  I just wouldn't have a clue where to start with programming it.....

Your bell crank input would go into the BeastX receiver and it mixes the output to the flap and elevator servos.  While the gyro works on the axis at all times.  Is it legal?  Who knows? But it sure would be cool!

On another note there are some pretty beefy brushless metal geared servos out there you could use on your flaps and elevators and the weight gain wouldnt hurt too bad and the stripped gear would not happen again.  I mean I was less than 2 points out this year with my 68 oz plane.

Doug,

Congratulations on a great performance at the Nats.

Both Pat and I fly Helis and we have talked about this. There is still so much to learn and so little time or money to do it. I believe it would be legal as you set it and can not change it during flight. I am definitely going to try to incorporate the rudder at some point.  We used composite gears to save weight. (Dumb!!) Metal gears on the next model and a larger servo for the elevator just in case.

Kim.

Have been looking forward to hearing more about this - CONGRATS Kim & Pat on a great accomplishment.

"Movement of control surfaces, and any other of the model's operational features, may be accomplished by mechanical means, by electrical impulses transmitted through the line(s), or by any other control system that does not interfere with the control of any other model or present a safety hazard to competitors or spectators."

That language does not really rule out very much at all.  It doesn't even specify any sort of actual physical line being connected to the aircraft.  I'd be willing to bet though that the first time anyone showed up at a contest with a completely RC controlled plane, even if attached to a tether, the rules committee would convene in a right panic to plug the "loopholes".

Mark, the CL-General rules can be found at http://www.modelaircraft.org/files/2013-2014CLGeneral-1.pdf. Pertinent to your comment is this:

---

2. General. A Control Line model is flown on one or more' steel or GSUMP, commonly referred to as
Spectra or Dyneema, lines' steel wire line(s) or metal line(s) of equivalent strength, attached to the model in
a manner providing aerodynamic control of the model's elevation through manipulation of the control
surfaces during flight. "Lines" are that portion of the control system between a connection at the aircraft
and a connection at the control handle consisting of steel wires or metal of equivalent strength. Note that
....

---

The rules then go on to say

---

... Manipulation of control surfaces, and
any other of the model's operational features, may be accomplished by mechanical means, by electrical
impulses transmitted through the line(s), or by any other control system that does not interfere with the
control of any other model or present a safety hazard to competitors or spectators. The use of radio control
to accomplish any control functions on Control Line models is specifically prohibited except as follows.
The use of 2.4 GHz (utilizing spread spectrum, 47 CFR Part 15) radio control to accomplish functions other
than providing aerodynamic control of the model's elevation on Control Line models is allowed, but only
to the extent and in the manner specifically allowed by the rules of the individual event. All control
functions must be under the direct control of the pilot and only the pilot.

---

(Colors and bolding mine for emphasis.)

I don't see where there is any real question about what can and cannot be done.

Kim
I agree with Dennis, I have been waiting for more of your research into this innovative control system.
Question, when looking at the servo are you looking at the speed or the torque, I agree that a metal gear servo far surpasses the nylon for durability.
These from HK are super fast.05 sec - 60deg, but may be a little light in the torque only 1.4kg.
http://www.hobbyking.com/hobbyking/store/__23467__TGY_212DMH_Metal_gear_Coreless_Digital_Servo_w_Heat_Sink_1_4kg_05sec_16g.html
But they are also light 16g.
Where as this one is much stronger at 3.9kg, but also slower at .13sec - 60deg. Again also 16g.
http://www.hobbyking.com/hobbyking/store/__23459__TGY_210DMH_Metal_gear_Coreless_Digital_Servo_w_Heat_Sink_3_9kg_13sec_16g.html
Any how Kim I am happy that you are continuing your research. And looking forward to updates.
Mike

From what I am reading it would seem the flybywire would be legal in AMA as well.  He is manipulating the control system with the standard lines connected to a mechanical device, Bell Crank, then it sends the signal for deflection to various places within the model.  There is no RC input here.  The input for deflection of the surfaces is still mechanical.

I think this is a very bad idea.  Stunt will become an autopilot contest. 

I see it is here again. Kim will probably write again that I am stopping world from spinning, but my meaning about it is, that it is not good idea. One thing is playing with such stuff, it is ok, I also did many tests also with gyros etc some years ago, may be someone will remember my pictures with servos attached on fuselage, but pushing that stuff to contests is in my eyes not good idea. Yes replacing pushrods with wire does not violate anything, but it opens doors to several unwanted things. In rules working group we analyzed it some year(s) ago, Doug got it immediatelly, it is very easy to connect stabilizing gyros. It is question of minutes and noone can ever check it, because electronic is blat box for outside spectator. Then we can incorporate altitude stabilization from quadcopters. It is also existing and available solution. We can continue this way until we come to battle of programmers or bank accounts. If you do not believe it is doable, you can see several quadcopters flying paralel the same aerobatic pattern on youtube. There are several such videos.

I cannot say that I am not comfortable in such contest, I will certainly enjoy it, but I do not thing it should be done in event dedicated to competition of human abilities. So my meaning is, that "primary function" as defined in FAI F2B rules should stay mechanical.

And I also affraid of safety risks of such solution. But we are here in electric section, so I will not open it.