Manual Elevator Trim Knob Location

[TX7A]

I will be installing the manual elevator trim. I would like to do something different to eliminate the half loop that the cable makes up to the fuel selector cover where it mounts. I am considering routing the cable through the tunnel cover & making a bracket/cover to mount the handle to. The trim knob would be slightly aft of the fuel selector handle and would be operated "back-handed". I've simulated this by placing the knob in the proposed position & sitting in the seat just to see how it "feels". It doesn't seem awkward and I'm sure I could get use to it.

My question:
Has anyone done/seen this? If so...got a picture?
Does anyone see a problem with doing this sort of install? (interference, etc.)

I've searched the archives for this particular idea, but have yet to see anything about it.

FWIW, I've seen a trim knob mounted on the sidewall & don't like that much either. And no electric trim for me.

Thanks for any ideas on this.
Sam

 

[hevansrv7a]

Manual Trim Knob Alternate Location

Sam,
I'm trying to deal with a problem of locating that knob caused by adding the electric pump for FI. I would like to see a picture of what you are planning. I couldn't figure out where you were planning to put it. Remember the "off" position for the fuel selector is pointing straight aft - I think. What means "backhanded"? Thanks.
hevansrv7a

 

[TX7A]

Sam,
I'm trying to deal with a problem of locating that knob caused by adding the electric pump for FI. I would like to see a picture of what you are planning. I couldn't figure out where you were planning to put it. Remember the "off" position for the fuel selector is pointing straight aft - I think. What means "backhanded"? Thanks.
hevansrv7a

hevansrv7a,
I'll have to post the picture tomorrow.
The position of the knob assembly will be lying along the inclined portion of the F-739/F-740 forward seat floor, between the seats. Some sort of bracket/cover assembly would need to be made to attach the handle assembly to. I don't see that as a problem though.
"Backhanded" (to me) means that the palm of your hand will be facing aft as you turn the trim knob, rather than forward as in the standard setup. The knob would be about 3 or 4 inches aft of the fuel selector and doesn't look like it would interfere.

Sam

 

[hevansrv7a]

Backhanded

"The position of the knob assembly will be lying along the inclined portion of the F-739/F-740 forward seat floor, between the seats. Some sort of bracket/cover assembly would need to be made to attach the handle assembly to."

That's clever. It also gives me an idea I will pursue at the shop tomorrow. What about just going vertical in the center, just aft of the spar instead of going through the spar? I wonder if the angle is too tight? One drawback would be preventing the use of a center arm rest or console. My friend's Mooney has the trim between the seats, down low.

Thanks.

 

[arffguy]

My question:
Has anyone done/seen this? If so...got a picture?

I've searched the archives for this particular idea, but have yet to see anything about it.

Sam, I think you would probably be the first one to try this.

 

[sf3543]

If the manual cable is too long as a result of your new configuration, you could either create a loop in it back in the fuselage cone, if it is long enough, or just leave the extra cable in a half loop back there. You should have planty of room to do this, but just make sure you have it fastened down so it doesn't flop around. (A straight run is nice, but not necessary.)

 

[RivetDriver01]

RV-6 Manual Trim Install

Here's a photo of my "backhanded" installation.

The install was complicated even further by competing for space with the Aileron trim control. The aileron trim knob is 1.5 in diameter and is hollowed out for the threaded portion of the Elevator trim control to pass through. The excess cable is rolled behind the aft baggage bulkhead.

The positioning seems natural and I don't think the reverse turning will be a problem.

-Mel

 

[TX7A]

Manual Trim Knob Location

RivetDriver01,

That's it! That's the idea I had in mind.
I also wondered about the trim mechanisim and if it would interfere. I appreciate any more suggestions regarding this setup. I'm leaning towards this concept.
Thanks again for the pic rivetdriver01.
Sam

ps
Here's a link to a pic of my basic thought on the location.

 

[arffguy]

Oops. Spoke too soon. Guess you are not the first Sam. Good job Mel. I also like the new aileron trim knob. Gotta love this site.

 

[RivetDriver01]

Thanks for the positive comments!

It's really pretty straightforward to install. The only comment I have is to position it as far forward as you feel comfortable. This will allow you to keep the knob assembly centered with the tunnel and have enough space to bend the upper part of the cable to attach to the side of the floor rib. That cable doesn't like sharp bends!

The aileron trim knob took a lot of trail and error fitting, along with equal amounts of filing with a die grinder. It's not CNC quality, but that's what the cover plate is for...

I'll try to round up (or take) a couple more pictures of the components.

-Mel

 

[TX7A]

Manual Trim Pics

Mel,

Any additional pics would be great, especially of how the aileron trim fits in the scheme of things, and any other pictures of the "innards" of the system.
I appreciate you sharing this work-around. I can see how this may be an attractive solution to the "looped-around" trim knob for others.

Sam

 

[RivetDriver01]

A couple more pics...

Here are a couple shots of the knob and mounting bracket.
The knob is 1.5 inch diameter solid stock. There is a .5 in diameter hole bored in the base for attachment of the Aileron trim. The large hole angled through the side matches the angle of the Elevator trim controller. It is widened out substantially (with die grinder) to give approximately 40 degrees rotation off-center. The small holes are to provide a better grip (and make it lighter!).

The Aileron trim is removed in anticipation of the first mounting of the wings, but you can get a pretty good idea of how everything fits together from this shot.

-Mel

 

[williamgbell]

Pictures of Manual Elevator Trim location

Hello,

I'm brand new to using a forum and I'm getting ready to order an Empennage kit.

My question is: how do I view the pictures that are posted here?

I am a pilot and have flown several aircraft that have electric trim, but I prefer using manual elevator trim.

Thanks for the help.

Bill Bell

 

[JonJay]

Dont forget what you use it for!

The manual trim system is great, easy, and effective. The only thing I would be concerned with is the ergonomics of your proposed location. When work load is highest, your in the pattern. I oriented my flap switch next to my throttle (centered in panel). The standard location of the trim knob makes it very easy to adjust power, move to flaps, make trim adjustments, move to flaps, move to throttle, quickly and smoothly. The flaps, throttle, and trim are all in the same basic area and orientation. Your position is not that far off, but operating it backwards and flipping your hand over will take some getting used to.
If you fly more than one airplane, it will seem ackward as the convention is "clockwise-screw in-nose down, counter-screw out, nose up". ...or push for nose down, pull for nose up, same as your stick. Yours will operate in reverse. That would not be acceptable to me, but to each his own. It looks like a nice clean install but frankly, the loop is not that big of a deal. I put my ELT remote switch on the trim bracket too.

 

[TX7A]

Changed my mind

Way back almost two years ago when I made the original post, I was trying my best to keep the manual trim AND get that hokey trim cable loop out of my leg-room area. I'm just hung-up on keeping the leg area free & clear of 'stuff'. I liked the back-handed trim knob idea and I think it would work fine with some cutting, fitting & experimentation.

However, I have since moved over to the "dark side" and will be installing electric trim instead.

 

[Charles in SC]

It's all what you get used to.

I flew old pipers for years that had the trim in the ceiling above the gap between the seats, that seemed kind of strange at first but I got used to it. I am planning to mount my trim knob on the dash just because it seems to be kind of the expected place for it. If I was puting the engine controls somewhere else I would want to use the same hand to operate the trim so it would not require changing the stick hand. Just my .02 cents.