Rotor Disk trouble

[Dinky]

Hi,
It my first time on here so please be gentle.
I have an Ark X-400 built from a kit, its only taken 3 years, but that's another story. I have upgraded the tail assembly and converted it to CCPM as well. My previous helis have all been pre assembled fixed pitch so I am in unknown territory. I believe all the mechanics are set up correct and the transmitter (DX6 2.4 GHz) is set up OK, but as I have a problem, I have gone wrong somewhere.

My problem is as follows.
When I spin up the rotors all seems well. The collective seems to be OK, but any control input on the cyclic seems to be about 45 degrees out.
The X-400 rotors turn clockwise (as seen from above), so the if you put forward in, the swash plate goes forward, the flybar/paddles go forward, but the rotor disk is pointing as if the input is left and forward. I can correct the disk by inputting forward and right. I have had a rummage on the web but I'm not really sure on a suitable search phrase.

Any suggestions are gratefully received.

Thanks.

[robgt]

The first thing that springs to mind is a phase issue.
Have you got the washout base located in the washout guide pins.
The pins stick down from the head block - the washout base slides up and down the main shaft carrying the lower mixing arms.

Cheers,
Rob

[machasm]

What you should get is looking at the heli from the tail.
If you input left aeliron then the swash should tilt left and right aeliron should tilt the swash right.
Looking at the way the blades tilt can seem counter intuitive as they can appear to be 90 deg out.
Have you actually flown it or are these just your observation whilst on the deck?

[Dinky]

Wow, that was quick! Thanks guys.

I haven't taken off yet, all observations are on the deck with it bolted
down, with the rotors turning at assorted speeds.

The swash plate does follow the the stick movement in all directions.

The wash out guide pin (there is only 1) is located correctly. I have noticed that the washout guide is offset at a slight angle compared to the rotor head, but that is by design. I will get some photos and post them when I get home, yep I am having a break at work at the moment, honest .

Thanks for the help so far.

[unwind-protect]

To the front and left? Not the right?

I found on all my cheaper plastic helis that a forward input would lead to the disk going to the right somewhat, especially on the ground. In the air it was usually much less pronounced, but on my Belt CP I still had to change the timing with some programmable mixes.

I believe not having the paddles aligned properly can cause similar issues.

[Dinky]

Im sure it is the left, but I will check again. I will also double check the paddles as well - thanks.

[moyesboy]

heres how it should be:


Its possible to put the washout base on upside down maybe or the washout links to swash on backwards, or somethinhg else in the wrong place to get the phasing a long way out.
The phasing on the x400 head is pretty accurate, but its a long while since I flew it and I probably wouldn't have noticed small errors.

a few notes, I'm assuming you have the plastic head, maybe you have metal bits already:
any sort of bump will snap the plastic head block. Get the metal one after the first crash, and the SHORT ali seesaw which fits the plastic flybar cage.
BUT before you spend much on ARK parts consider a full Trex head which is cheaper to service in the long run and fits straight on, onto the same mainshaft. Or yuo culd get something cheaper from sonix (3DX400/HDX400).
The x400 head is very stable which is good to start with, but in the end it is a bit slow on the cyclic for 3D flying.

The CCPM kit comes with a metal CNC swashplate which has the front two servo link balls on extenders. This lets you set up the swash as 140 degrees, rather than 120 degrees. Remove the ball extenders and fit the balls direct to the swash and you have the normal 120 degree ccpm. This fooled me for a while - I flew the 140 as 120 and then you get changes in collective with elevator.

One of the main problems is after you break the little tabs off the brittle undercart there is nothing to bolt trex undercart legs to. I made some little ali brackets to do it. Many trex parts fit such as canopy, main shaft - if you look at the forum in www.trextuning.com under the ARK400 section you might find a fairly comprehensive list I posted there a long time ago.

Have fun. I changed all the bits out of my X400 until there was nothing left in the end. Fatmantom got all the remaining bits a while back.

[Dinky]

Moyesboy,
Thanks for the pictures. I have attached some quick snaps of the head, unsure if they are good enough though. I will re-examine the build booklet to make sure I haven't been silly. You are spot on about the swash plate ball extenders. I haven't been overly impressed with the upgrade instructions, but I treat it all as part of the fun. I have been drooling over the t-Rex parts and will, funds permitting, upgrade later. I'm not overly impressed with the tail pitch slider upgrade. There is a lot of slack on the blade grip bearings, which when static results in poor control. I will pursue that when it is finally in the air.

Thanks again and to all who have taken the time to help. I will let you know how I get on later.

[robgt]

That head setup looks ok to me.

Cheers,
Rob

[Dinky]

Rob,
Thanks for having a look, I will still double check the build instructions.

Fred

[moyesboy]

It looks right to me.
If when you move the aileron only the front two servos move and the back one doesn't, then it should be right - and you should give it a hover and see if it behaves!

[Made2Fade]

looks correct to me too bud.
Cheers
Lee

[Dinky]

Hi Guys,
I think I've got to the bottom of my problem.
I took the head off and discovered the vertical pin from the head to the washout assembly (?) was bent, not the faintest idea how it happened. I have straightened it but will get a new one.

I would like to thank every one who gave their time and knowledge to help me. I will let you know how I get on at my indoor meeting tonight!

[callum]

Good Luck and have fun with it at the meeting!

[Dinky]

Cheers Callum.