Setting 0 degrees pitch at mid stick

[pg89]

I've spent all morning trying to get my head setup perfect, but I can't get 0 degrees of pitch at mid stick all the way around

Im using an Ikon fbl on a protos 500

I can set +12 & -12 degrees of pitch no problem, my servos are centered, at 90 degrees to the rods, all rods are equal as per the manual and swash is perfectly leveled...

I can get 0 degrees when my blades are in line with the heli, but if I turn the blades perpendicular my pitch is +3 degrees out on one side and -3 degrees out on the other. My cyclic throws are also a bit uneven.

The heli seems to fly ok, just a bit of tail drift which I was trying to eliminate. Am I right in assuming the digital pitch gauge should read 0 degrees in all positions at mid stick when turning the blades round by hand?

[mba83]

Use the screwdriver through main grip hole method (do a search)

[numbermonkey]

Originally Posted by pg89

Am I right in assuming the digital pitch gauge should read 0 degrees in all positions at mid stick when turning the blades round by hand?

Yes but ONLY if your main shaft is perfectly vertical. For most helis sitting on their skids, this is not the case.

There are a couple of approaches. The first is to build a levelling stand. Basically a block of wood on three adjustable legs that you can level. Search HF for more info. There's also the Soko Heli Tool which uses clever math and sensors to account for any tilt of the main shaft. Or you can use paper under the skids as shims and use a bubble level on the head.
Me? I assume that if my swash is perfectly level, and I get zero pitch with the blades in line with the Heli,then any variance at the sides is due to the rake of the shaft. And I check with a screwdriver through the main grip bolt holes. If you have zero pitch all the way around then it will always be parallel to the main shaft. The trick is to find a driver that fits snugly.

[Felix the cat]

Originally Posted by pg89

I

I can get 0 degrees when my blades are in line with the heli, but if I turn the blades perpendicular my pitch is +3 degrees out on one side and -3 degrees out on the other. My cyclic throws are also a bit uneven.

The heli seems to fly ok, just a bit of tail drift which I was trying to eliminate. Am I right in assuming the digital pitch gauge should read 0 degrees in all positions at mid stick when turning the blades round by hand?

That's a lot IMHO

Seems to be non-leveled roll axis from the start. I use two bubble levels / vials (pitch & roll) on the setups. My bench is as flat and leveled as possible, so far so good.

Also, if it's a digital pitch gauge, they are so precise.......... or finicky ? that can be PITA. Are you zeroing the pitch gauge in the intended axis ? After I've verified both bench and frame I use the motor or boom to zero out my gauge.

[newbheliusr]

I use the SOKO heli tool. Not cheap, but here is no better way of accomplishing more tasks with one tool than the soko. Plus, unlike most digital pitch gauges, this one doesn't mind being rotated around the head.

You can:
Level your swash
Set pitch
check CG.

All with one really cool tool.

Check it out.

http://www.soko-heli-tools.com/en/fe.../features.html

Says it works with small helicopters, but it's rather heavy for a 250 or smaller. I use it on all my helicopters.

[Solmanbandit]

I only check the blades for pitch with them facing forward only. Unless you can get the shaft vertical perfectly on all axis, then you could do that, but you would get the same result. Don't micro-manage the task would be my suggestion. If you set up your pitch gauge for being level for the blades being forward, the rest will fall into place. In the end, my tracking is spot on every time.

[jgiannakas]

If you want to check for 0 degrees fold the blades so that they are parallel to each other and check if they line up. If they do you have 0 degrees pitch.

Of course you'll need to do that after levelling your swash.

[ArchmageAU]

Originally Posted by jgiannakas

If you want to check for 0 degrees fold the blades so that they are parallel to each other and check if they line up. If they do you have 0 degrees pitch.

Of course you'll need to do that after leveling your swash.

Remember, if blade tips level up, this does not mean the swash is level. Just means 0 pitch. (also make sure no sloppiness in the grips)

As mentioned, swash leveling is a different exercise.



Just for fun, at 0 pitch with bladed foled to be level with each other, pull full elevator on the TX. BOTH blade tips should move but stay level. Now turn the head around without adjusting the blade angle to the head. BOTH blade tips remain level for the entire circuit of the head even though the swash is FAR from level.