Mixing or linkages?

[rjflyer]

On my Intrepid Gas, going into forward flight there is a strong tendency to veer left. The swash appears level top to bottom on the bench.It hovers nice. Are there any linkages to correct this or do I need to correct it with mixing in the radio?

I am understanding this heli more and more, and it is purring like a kitten :wink: Just need to correct this and have never done any mixing.

[zflarez]

How are your trims in hover. Maybe while in hover it is well trimmed but once forward flight starts the blades become more efficient cousing the trims to have a much stronger effect. And the reason so much trim is needed is because the model is not balanced properly. That is just my best guess.

[ShawnK]

This may sound strange, but are the pins from your washout base going into the slots on the head?

How 'bout this: Take a picture from the side of your helicopter so that I can see everything from the swashplate up (get in close, please), and then a shot kinda from the top down.

It's a physical impossibility (because of the design) for the head on that machine to be more than a couple degrees off optimal in terms of phasing. If you're having a heavy veer to one direction, then you either have something built incorrectly (like the washout pins not being in the head block correctly), or you have some kind of radio program mixing going on that you're not aware of.

It's a little difficult to tell in this picture, but your head should look pretty much like this:

http://www.helifreak.com/album_mod/upload/1fed7d83836098bf815cde6003f8cb4e.jpg

[MarkWebber]

Yeah. Something strange going on there. Mine has always tracked right where I point it. Chris saw Rick's heli at Ashland. I can't imagine he'd miss the pins coming out of the head. When I initially built mine, I did have too much down on the washout causing the pins to come out of the head. It would just lock the collective with negative pitch. I can't imagine you could be hovering with that condition existing. I would check out the radio for errant mixes.

[rjflyer]

Buddykitchen, I uploaded some pics in my gallery I just took. If you need more or a different angle let me know.
Mark, I went over the radio and saw nothing in the mixing department.
zflarez, all trims a zeroed.

[PaulH]

I can't think of anything that would affect it like that, but here are a few things to check:

- O-rings in the head block are not worn and are lubricated
- All of the bearings in your blade grips are in good shape.
- Flybar bearings are in good shape.
- No binding as swashplate moves up and down.
- Aileron servo wheel is not flexing.
- Aileron servo is mechanically centered.

I'm grasping at straws here, but you never know...

I had a problem where everything worked, but the heli would not lift off, even at full throttle. It turned out that the thrust bearings in the blade grips were bad. Every time the head got up to speed, the grips would seize. I never would have thought to check the bearings...

[Brady Longmore]

If the guide pins were completely out of the slots in the head I don't think he'd even be able to get off the ground. It forces the blades into negative pitch and doesn't allow them to angle into positive. It's happened to me before. At first I thought there was something wrong with the engine, until I discovered the pins were out of their slots. That was my own experience at least.

[MarkWebber]

When you do a function check on the ground(engine off) do you note any aileron movement if you only input elevator when the collective is about hover?

[rjflyer]

Mark, I see what you are thinking, just checked and the inputs are pure.
Paul, some good ideas I will check out the head tomorrow
Thanks all

[Malorie]

Try either reversing your washout bellcranks or add a mix (13% elevator to aileron & 7% aileron to elevator, if I recall correctly.). :)

The interaction you're seeing is pretty normal for the way your washout arms are setup. Reversing them will get you closer to neutral (about 1/2 as much mix in the opposite direction). Note: The amount of interaction is partly due to the nature of the older head that is on your bird. The newer heads have the slots slightly changed (sort of by accident) and it has helped to zero out the shwashplate timing with the washout bellcranks reversed from the way your's are. :)

Hope that helps you out some,
Malorie

[MarkWebber]

Malorie's answer makes more sence. I noticed the 'BMT' insignia on the head but hadn't heard that there were any differences from the older heads.

[Malorie]

There are a few minor differences including 1/8" more space between the seesaw and the head axle, provisions for mounting a head button, and a slightly beefier pinch bolt area on the bottom edge of the head. The phasing change was unintentional but turned out to be a good thing. :)

[rjflyer]

Malorie, Just to clarify and I understand it correctly, flip the washout arms so that the raised portion at the center will be on the inside toward the main shaft?

[ShawnK]

I believe she's referring to this:

http://www.helifreak.com/album_mod/upload/22b06058d6ba30e58f5221c4a0ec71d6.jpg

[rjflyer]

thanks Buddykitchen, that makes it as clear as a bell :noteworthy

[PaulH]

Okay, so here are two dumb questions:

1. Which version is the correct version
2. If you need to flip it over, how do you get the pins out and press them back in?

[rjflyer]

Paul, that was what I first thought until I looked at the instructions and found out that there are four holes in the washout (I think that is what it is called) opposite each other for the set screw. So they can be put on either way. I just changed mine and will try a test flight later.
I think with the older version head they need to be reversed or the left to right set-up. Newer heads Rt to Lft set-up

[ShawnK]

Paul,

You don't pull the pins out. You just unscrew the washout arms and mount them in the opposite side holes. As Rick pointed out, there are 4 holes tapped for the washout arms, so all you gotta do is screw 'em into a different hole.

[Malorie]

I have found that the Left to Right setup makes the washout timing closer for FF and aerobatics with any of the heads. With an older head you will need about 3% aileron to elevator mix and 7% elevator to aileron mix to get the machine to flip and roll straight. With a newer head, you will have no aileron to elevator mix and 3% elevator to aileron.

With the Right to Left setup and an older head, you will need around 7% aileron to elevator and 13% elevator to aileron in the opposite direction. I don't know what the mix would be with a newer head and a Right to Left setup as I have never set up one of my machines that way, but I would imagine it needs more (say 10% aileron to elevator and 16% elevator to aileron) as the timing has changed in the wrong direction for that setup.

For clarification, the newer head I am referring to is the head that has the two tapped holes in the top for the headbutton mount. The only thing that you would change for this setup is the drag links and the place the bellcranks mount on the washout base. There is a left and a right draglink. If you look at them closely, the link end of it is not symetrical, meaning that it is meant to snap onto a ball in one direction only. The more recent kits came with two sets of draglinks for this reason.

Malorie

[MarkWebber]

The more recent kits came with two sets of draglinks for this reason.

I wondered why my kit came with the extra set.