MKIV Elevator Trim

[Gfry 11]

I cant for the life of me find what the elevator trim travel should be set to.  Can anyone shed any light?  if it makes a difference it has a Ray Allen 6 electric trim system.

[akflyer 1427]

As much as you can get is what I have found out.  Mine takes a lot of nose "up" trim when solo, but I can run the trim more neutral when loaded aft pretty heavy.  The more trim range you have the happier you will be.

[BryceKat 125]

Yes, you have to play around with it. Your cg will also affect the effectiveness of the tab travel. The more rearward cg the more effective the tab. 

[Gfry 11]

Thanks.  Maximum nose up trim possible is 17 degrees due to the hinge not allowing further travel. As for down trim it will go as far as the servo goes which is about 30 degrees.  So I guess that's what I have and that's the end of it.

[jackak 20]

Gfry,

Is your trim tab hinge on the top of the elevator or the bottom? If its on the top it could limit the nose up travel.

Jackak

[Gfry 11]

Hinged on the bottom.

[jackak 20]

Is the hinge pin up between the trim tab and the elevator, or down towards the bottom of the elevator?  When you have the indicator pointer in the middle of the indicator, is the trim tab aligned with the elevator? The construction manual I have shows the hinge pin up between the elevator trailing edge and the leading edge of the trim tab. Is there a mechanical reason that the hinge limits the travel in one direction to one half the travel in the other?

I'm sorry if these seem like dumb questions, but I can't picture how the hinge limits the travel rather the the stroke of the trim motor.

Jackak

[EDMO 1078]

Is the hinge pin up between the trim tab and the elevator, or down towards the bottom of the elevator?  When you have the indicator pointer in the middle of the indicator, is the trim tab aligned with the elevator? The construction manual I have shows the hinge pin up between the elevator trailing edge and the leading edge of the trim tab. Is there a mechanical reason that the hinge limits the travel in one direction to one half the travel in the other?

I'm sorry if these seem like dumb questions, but I can't picture how the hinge limits the travel rather the the stroke of the trim motor.

Jackak

Photos might help - Most trim tabs I have seen have more nose up (tab down) than in the other direction.  EDMO

[Gfry 11]

My bad...... the 17 degrees up I refer to is Tab up, and the 30 degrees is tab down.

[jackak 20]

Ok.. Shouldn't be a problem then , unless you're carrying some serious aft CG, then within reason a bit of flap should help hold or lower the nose.

Jackak

[akflyer 1427]

Tab down is actually nose up so you should be fine.  On mine I don't need much nose down but lots of nose up so I have mine set so that the tab is down about 1/4" when the trim indicator shows neutral giving me more nose up trim.  If I need the nose down more I can pull on a touch of flap.  Took me a few trys to get the mechanical adjustment right on the tab so I could get the needed nose up trim.  Sealing the gap on the elevator make a big difference as well.

 

[Gfry 11]

What gap are you referring to?

[akflyer 1427]

between the elevator and stabilizer.  Clear tape does good things.

[EDMO 1078]

between the elevator and stabilizer.  Clear tape does good things.

So does VGs under the stabilizer, according to Joey and others.  EDMO