Walkera 4 blade problem

[thomasfuller]

Hi,

My Walkera 4 is having a few problems. When I push forward on the left stick, the blades tilt forward and slightly to the left. When I pull back, the blades tilt back and slightly the left. Pushing the right stick tilts the blades right and slightly forward, and left tilts them left and back slightly.

I just had the main rotors off and reset the flybar paddles to what looked horizontal/parallel to the rotor holder (don't have a pitch guage), then fired up the chopper and got it spinning without a great deal of vibration. Then I attached the main rotor blades and got them spinning without alot of vibration aswell. I got the swashplate as level as I could get it, but the blades still don't tilt the way they should (to my limited knowledge anyway haha).

Anyone have any idea what is going on and how I can fix it? I have a feeling it has something to do with the flybar paddles maybe. Thankyou in advance

Tom.

[Aztek1701]

Hi Tom,

Isnt the Walkera 4 a fixed pitch heli?

If so, you dont need a pitch guage because the pitch is already set. But your problem sounds like there may be some mixing the servos going on IE push forward and the elevator servo moves mostly but there is some unwanted movement from the aileron servo as well. If this is the case then Im guessing the mixing is being put in electronically either because you have a setting in the wrong place on your transmitter or the TX might be faulty (quite unlikely but possible). If the servo doesnt move then Id look at the swash. Either a control is binding on something or maybe the swash is twisted round a bit (Quite likely). And instead of the linkage pushing vertcally its pushing at an angle.

Either way, what you need to do is to power the heli but not spin it up and observe very carefully what happens to the swash / servos when you put in a stick movement.

Hope this helps... Azzy

[thomasfuller]

Thanks for your reply Aztek.

Yes it is fixed pitch, my bad. I thought I may have needed a pitch guage for the flybar paddles.

But your problem sounds like there may be some mixing the servos going on IE push forward and the elevator servo moves mostly but there is some unwanted movement from the aileron servo as well. If this is the case then Im guessing the mixing is being put in electronically either because you have a setting in the wrong place on your transmitter or the TX might be faulty (quite unlikely but possible).

While moving either servo, there was some limited (2mm) movement at the swashplate end of the other servo rods from side to side, but it didn't look to be moving up and down a great deal.

And instead of the linkage pushing vertcally its pushing at an angle.

The servo rod (linkage?) on the aileron servo seems to be at a bit of an angle, picture:
http://img405.imageshack.us/img405/1...onservosp5.jpg


Also, when full stick is applied on the elevator or aileron, the flybar tilts like so:
http://img249.imageshack.us/img249/2253/bladesek2.jpg
I understand that the aileron/elevator servo adjusts the flybar paddle pitch at different stages on the main rotor rotation to alter their pitch, so I'm thinking this is normal, but it struck me as odd so I thought I'd mention it just incase.

Sorry for the quality of the photos, our main camera is out of action at the moment.

Thanks in advance,
Tom.

[Aztek1701]

Hi Tom,

From what I can see, this heli has the same swash assembly as most helis of this ilk the swash doesnt move much, also the the paddles pitch will change depending on where they are in the rotor arc at the time so yes your right, it is normal.

Ive seen a problem like this on my Bell47 Twister which has a very similar setup to you. On mine the problem was that the bottom of the swash isnt physically attached to the top of the swash, it just sits on it. The result was that in a hard landing one time, it seperated slightly and the bottom of the swash dropped because it is only properly supported on 2 sides.

The solution was to put my fingers under the swash and lift it gently towards the blades, pulling it back into alignment with the top part. After that my problem went away.

It might be worth giving this a try and seeing if that makes a difference.

Take care.... Azzy

[thomasfuller]

Azzy,

I tried lifting the swash plate, didn't seem to do anything. I inspected the whole setup for while, but I couldn't see anything that seemed out of place.

The whole time I've had it rubber-banded to a cardboard box lid so I could work on it without fear of interference sending it ape and cutting my head off (it almost happened once). After fixing the vibration and everything, I noticed the blades seemed to tilt incorrectly. That's when I posted this thread.

Eventually I just thought "oh well, maybe the blades just tilt that way all the time" and took it into the loungeroom. Had a few scoots around the floor, then a hop, and then I got my first hover! It was pretty damn fun.
Called in the family to watch, but as you'd expect, I ran into a wall and bent a blade. Unimpressed, they left. Got some pretty stable hovers going, I'm pleased for my 3rd flight.

Many thanks for your friendly advice, Azzy.

[Aztek1701]

Hey Tom,

No worries . Congrats on the hover, its quite a buzz innint

Good luck with your future flights

Take care... Azzy