C-ARF 3.3M Yak CG

[JagerBomb]

http://www.flyinggiants.com/forums/f...-ailerons.html

[pfact]

Actually our plane has a manufacture date from 2005, it must have been sitting in the warehouse for a long time (I guess the Schulman scheme isn't very popular). I approached the build based on reports from others expecting it to be tail heavy. I initially had the batteries up against the motor dome and the servo tray more forward. Now, I only the smoke tank and Powerbox are front of the wing spars.

Given the relatively light weight and odd balance my guess is C-ARF went light on the resin on this one. I think they are all different - across the web people report a wide range of final weights. I don't think C-ARF uses pre-preg glass so I'm guessing they might have been short on resin the day they made mine.

I spent a lot of time on aileron throw. What stopped the downward movement of the ailerons was the control horn hitting the aft edge of the L wing, once I notched the skin and cleaned up the back edge of the wing I picked up a few more degrees of down aileron. The end result is that lower lip of the aileron tucks into the wing much better so that the left control horns sit flat on the bottom of the wing. The right sided horn is 5mm further back so it is unable to touch the wing surface. We had the same issue on the our Bobcat, C-ARF 2.6M Yak and 3.0M 260. Upward movement at this point is limited by the servos and 2" SWB servo arm. If I changed to the C-ARF servo arms I could get some more up but not down.

Joe Nall is doubtful for us.

Phil

[pepatrick]

Mark...I agree..it does not add up. One..42 lbs even with lite resin..I think that most people that report what their plane weighs is usually full of it anyway. There are just certain limits that you go cant beyond without structurally messing up the plane. 47 degrees on alierons...I want to see pics of the the throw meter. I dont care how much the arms are cut....and I am pretty sure that only the recently built 3.3s were made without the carbon web. Whas up??..I dont pretend to know everything..but I know the CA Yaks pretty well.

Phil, Im not trying to stir up trouble...but the numbers just dont make any sense for this plane. In any case..your build looks very clean and regardless of the weight..it will fly great.

[pfact]

Gentlemen,

Here are 2 photos of our right aileron flexed up and down. On the photo with aileron down you can see the lip of the wing bending, can't go much further without tearing something. On the up side the control and limit of travel of the servo limit the aileron, not the hinge. Perhaps I should lower it and tilted it forward over the hinge line or should I search for an even longer servo arm and add a 3rd 8711.

Mark - thanks for the link. Looking at your work is humbling. How are you going to achieve the throws needed to move the control arm the distances required to travel through 100 degrees of up and down? What servos, servo arms, and control horn are you going to use?

Phil

[JagerBomb]

From what I see it is 41 degrees of down and 49 degrees of up You will need to reduce your up to 37 degrees to get the differential correct. Still 41 degress is impressive and I'm sure if you measure the amperage to the servos to acheive this number you will find it unacceptable.

On my center hinge project you will notice I built 3 conventional servo boxes. The arm only need to be 1.5 inches to acheive the 50 degress of throw.

Mark

[mike chandley]

	Quote: Originally Posted by pfact
	Gentlemen, Here are 2 photos of our right aileron flexed up and down. On the photo with aileron down you can see the lip of the wing bending, can't go much further without tearing something. On the up side the control and limit of travel of the servo limit the aileron, not the hinge. Perhaps I should lower it and tilted it forward over the hinge line or should I search for an even longer servo arm and add a 3rd 8711. Mark - thanks for the link. Looking at your work is humbling. How are you going to achieve the throws needed to move the control arm the distances required to travel through 100 degrees of up and down? What servos, servo arms, and control horn are you going to use? Phil

Where do you get that throw meter I like it.

[mike chandley]

I have flown my yak for two years for imac flying. I have a 210 and pipes had all 8611s in it mine after adding weight to the nose it used to weigh 52 lbs without fuel.
No smoke system in it. I put it on a diet and got rid of 8611s and replaced with less 8711s(one each elev. 2 for rudder mounted in stock location) reduced the throws on the elevators and only used two on the rudder. I ended up leaving the 6 8611s in the wings as I fly with full throw, and did some testing with it at 47 lbs, let me say at 52 lbs it would fly the unlimited sequence pretty well. When I put it on a diet I replaced the alum. pipes (wich kept breaking) with stainless. The stainless where 1 1/2 in. shorter and it lost a ton of power. I have since added the 1 1/2 "back but have not flown it.
I added over 2 lbs of nose weight to mine with the wing in the rear posistion and it tracked a whole lote better, thats what made me put it on a diet.
I will get to test it soon. I still have a extra pound of batteries in it (2 8000 mill packs)
This one is well worn probably 600-700 flights on her.
Mark, I would love to do you mods to it and if I keep her I will, as the ailerons are about wore out on it I have added the inside hinges already.
Thanks for that trick I saw it on your web site a week or two ago.

[pfact]

Mike,

The incidence meter is available at: www.aeroperfect.com. Its a bit expensive ($239) but everything else pales by comparison. it's especially useful for setting midpoints and throws of ganged servos in the C-ARF servo mounts.

2lbs of nose weight? With our wings in the back position we need 2lbs of tail weight! Perhaps we have an extra heavy 210?

Regards,

Phil

[mike chandley]

	Quote: Originally Posted by pfact
	Mike, The incidence meter is available at: www.aeroperfect.com. Its a bit expensive ($239) but everything else pales by comparison. it's especially useful for setting midpoints and throws of ganged servos in the C-ARF servo mounts. 2lbs of nose weight? With our wings in the back position we need 2lbs of tail weight! Perhaps we have an extra heavy 210? Regards, Phil

Thanks,
I will order one.

[alec taylor]

how heavy are these things with no gear , no moter. bare airframe weight? alex

[mike chandley]

	Quote: Originally Posted by alec taylor
	how heavy are these things with no gear , no moter. bare airframe weight? alex

I don't remember the fuse but the wings rtf with 3 servos are all over 6lbs each.
The spar weighs almost 2 lbs in each wing

[rcalbuquerque]

Mine is right at 50lb dry with
ZDZ 210/BMP Canisters
2 8711's each wing
1 8711 each elevator
2 8711's mounted in tail for rudder
50oz tank
C/F spinner and prop
2 2300 A123 with JR 12 receiver
1 2300 A123 for ignition
I cannot see any way to make it lighter
YAK has great vertical and flies very light at 6000ft