Tail wheel cable/spring angle

[rosslr]

I would appreciate your thoughts on the difference between the 'angle of pull' of the cable/spring arrangement between the rudder horns and the tail wheel horns. In the pics below you will se that on my friend Craig's KF4, the angle is of pull is much greater than that on my KF7. I am trying to improve the ground handling at the moment for him before he returns from the US. You may recall that I delivered this plane back home for him after he bought it but I was concerned about the ground handling. I am having the wheel alignment done next week as the scrubbing on the tyres suggest it may be well out of alignment. But having the 2 aircraft in the hanger together it was clear that the angles of pull are very different - I suspect the more direct or flatter the angle of pull when operating the rudders, the more efficient the ground steering will be? The model 7 uses 'bent' horns on both the rudder and the tail wheel which flattens this angle considerably. Have any of you guys with the KF4 modified your setup to that of the KF7? and if so, did it improve ground steering noticeably?

Appreciate your thoughts. ross

This is Craig's Model 4 setup - note the approx. 30 or 40 degree angle of pull.
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The 2 pics below are of Model 7 - note the different angle of pull achieved by the 'bent' horns.
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[Av8r3400]

I used these (http://www.aircraftspruce.com/catalog/hapages/eyeboltsan44.php) to offset the chains to make the pull more straight.

I used the drilled versions with castle nuts so they can turn on the horns without loosening nylock nuts. Down on the rudder horn and up on the tailwheel.

[jrevens]

Ross,

I did it like Av8r3400 did, and used S.S. eye bolts. 2 advantages - yes, you'll get better mechanical advantage and less force wasted trying to pull the rudder horns down & the wheel horns up (the force vector that is actually trying to turn the wheel will diminish as the angle increases). Secondly, you'll have less wear & tear on the holes in the rudder and wheel horns. I like to tighten the eye bolts instead of leaving them loose enough to turn in the holes, so that they are aligned straight with the axis of the springs when the rudder and tailwheel are straight/neutral. That way I get no wear on those other holes - only on the replaceable eye bolts. I don't know if you'll perceive better handling or not, but the force exerted through the cables and springs to turn the tailwheel should be less & the springs will stretch a little less before the wheel begins to move.

[rosslr]

Thanks Larry and John,
This sounds like a fairly simple mod that have few downsides and can only add to the effectiveness of the steering.

Appreciated as always.

ross

[TY2068]

What problem are you having with ground handling exactly ? When I got my IV I immediately realized I couldn't turn the damn thing around in a 20 acre field with a 20mph quartering tailwind. What the heck is going on here ? Not having a clue as usual I found some info on tailwheel adjustment, rudder deflection, chains-springs and all things of the sort (Yeah I read it on the internet). I made some simple checks-adjustments to the springs-chains and wow what a difference. No problem now, bit of power, smash a little pedal-brake and walla ! More than likely I have it all adjusted "wrong" according to some guy somewhere but hey I like it ! No unhitching, groundloops or any of that just yet. Maybe next flight, We'll see ;)

[jiott]

This is a link to the tailwheel spring adjustment procedure I and many others use. I personally set the spring tension just a touch tighter than this video recommends. It gives good ground handling, eliminates most shimmy on landing, and still allows tailwheel unlocking but not too easily. This adjustment procedure assumes you already have the proper negative caster angle on the swivel vertical axis.

https://www.youtube.com/watch?v=QtokU8mIDQk

[efwd]

Thanks for that Jim.
Eddie