Let's talk about the size of my tailfeathers

[Bluebird19kf]

So I have noticed a few people have extended their elevator and rudders. I am at a point where I could do this before I cover them. I have a few questions before I do though. My plane is a KF3

1. I'm under the impression this mod would improve low speed control authority. Are there any other benefits/downsides. Does this put any more stress on the air frame that I should be concerned with?

2. How much should I extend them? My first thoughts were to measure a new model and make mine similar.

3. Material? 4130 Normalized?

I would love to see some pictures and here others general thoughts on this.
Thanks

[David47]

I can help with (3). Yep, tube will be 4130 Normalised. Run some light oil or primer on the inside in the finished weldment. This stuff sets up surface corrosion fairly easily.

[HighWing]

Branden,
An Idea. I helped a friend add some authority to his - still in phase - I Avid Mk 4 by extending his elevator. He brought full size drawings obviously copied from an elevator that was laid over the paper. It was fairly straightforward and easy to do. I particularly liked the means of attaching the trim tab - so much easier than the cut out tab on the Kitfox. I have done several of the Kitfox style trim tabs as well - but without extending the elevator.

4130 from Aircraft Spruce.

[HighWing]

One more thought. I have never felt I have lacked elevator or rudder authority - First Model IV (900 hours) or present one - but my modifications are a carry over from the gap seals patterned after the Speedster mod on the rudder of the early Model IVs, but a bit more challenging on the elevator due to the reduced spacing resulting from the type of hinge used - concentric welded tubing vs. the Rod Ends.

[oldfox]

Yep add 10" up and 6" back. Made back change in low speed handling at roll in I would do it before you cover them