[chris mitchell]

I am using the electric trim system. My first inclination was to set the tab at neutral (ie in trail with the elevator) with the indicator light in the middle. This ought to give equal movement up and down. Is that the best thing to do? How much travel in each direction is needed? Also I think that there will be a restriction on the tab UP movement when the push-rod binds on the edge of the elevator, and this point will be well short of the max up of 40 degrees. The fix for this restriction could be a new control horn on the tab (not keen) or bending the push-rod (not keen on that either).

As ever grateful fr advice and experiences of others.

thanks

Chris

 

[pierre smith]

Hi Chris.....

....these tabs are very, very effective and use little movement, unless you have a fairly heavy (250 pounder) in the back, then you'll need quite bit of upward movement of the tab. Can you open the hole in the elevator a bit?

Level point is a good beginning.

Regards,

 

[Rick6a]

I am using the electric trim system. My first inclination was to set the tab at neutral (ie in trail with the elevator) with the indicator light in the middle. This ought to give equal movement up and down. Is that the best thing to do? How much travel in each direction is needed? Also I think that there will be a restriction on the tab UP movement when the push-rod binds on the edge of the elevator, and this point will be well short of the max up of 40 degrees. The fix for this restriction could be a new control horn on the tab (not keen) or bending the push-rod (not keen on that either).

As ever grateful fr advice and experiences of others.

thanks

Chris

Chris,

Your inclination to set the tab at neutral with the LED light in the middle is an excellent base line reference to start with. Later on, as flight testing dictates you can always readjust and you may end up making a minor adjustment to do just that. As to the second part of your query, I'd be disinclined to bend or replace that control horn unless and until flight testing reveals a problem. Flying my -6A, I have never needed anywhere near 40? of electric elevator tab travel in any flight regime. Again, I would wait and see what your unique flight testing dictates as to the best course of action, if any.

As an aside, installing an adjustable speed controller such as a MK-111 in the electric elevator trim system will insure adequate servo performance at both high and low end RV speeds. Many builders have neglected to do just that and then go on to report less than adequate servo performance....usually complaining about it being too twitchy. That potential twitchiness can be easily adddressed simply by using a speed controller.

 

[Andy Hill]

Since you have copied most of our build (apart from the HOTAS syndrome ) your trim requirements are likely similar...

At takeoff, we use neutral for Dual, and maybe 10-20 degrees tab down Solo. It goes Tab Up for higher speed flight, but I would be surprised if it went far, nor would Van's design an aircraft that required a significantly deflected tab at cruise.

Good tab down deflection is what you need in the -8 for solo / slow speed flight.

Just need to convince your inspector now

Andy