Tailwheel Swivel Adjustment

[skippydiesel]

My Sonex has  50 Hobb hrs  - from the start I have had great difficulty in getting the tailwheel to break away/swivel in a hard left turn. The right turn performs flawlessly.

 

The  4"  ingle fork, tailwheel assembly is by Aviation Products Inc  (API) https://apitailwheels.com/ (yes have written and waiting for response).  Similar slightly larger unit by  API, featured in Kitplanes https://www.kitplanes.com/tech-tip-tailwheel-tune-up/

 

Observations:

 

• The aircraft tracks straight on the ground ie tail wheel is correctly aligned with airframe.
• Mechanism - a cam operated spring loaded pin designed to unlock at about 33 degrees from centre/straight. Appears as new, in good condition.
• My steering, from rudder horn to control arm, is via a single rod (some adjustment available).
• Right rudder horn is on stop, just before swivel action (break away) available .
• Left rudder horn is on stop and mechanism will not swivel.
• Have relocated steering arm in towards pivot point by about 25mm - swivel works well both directions BUT occurs just before rudders horns engage stops.

 

My concern is that it is now possible to ground loop inadvertently  (ie before rudder hits stops, which is the warning to pilot that swivel steering may be activated) when almost full rudder defection is achieved. Is this a safety issue?

 

Bear in mind that some of these aircraft operate an uncontrolled/spring cantering tail wheel ie all taxy steering is purely on differential brakes.

[facthunter]

Don't think I'd be happy with a non steering tailwheel.  It's bad enough when the nosewheel is like that. As a bit of useless information the First Fokker F-27's were just Castering nosewheels with AIR Brakes Too.    Nev

[skippydiesel]

6 hours ago, facthunter said:

Don't think I'd be happy with a non steering tailwheel.  It's bad enough when the nosewheel is like that. As a bit of useless information the First Fokker F-27's were just Castering nosewheels with AIR Brakes Too.    Nev

So no comment/advice on potential for inadvertent ground loop?

[facthunter]

I'd have to actually see it before I'd like to comment beyond what I have Skip. Everything can be right and still a ground loop may happen. Many Tail wheelers were steered with the tailwheel and the stick held right back  especially with planes with small rudders. My Citabria POH advised against steering  with  brakes (on landing ground roll) which were Clevelands and very strong. The Tiger Moths I flew all had NO brakes. AS yet I've never groundlooped but come close a few times with students, where I've taken over and gone around. I have however been subject to one when I was in the Pax seat. I think that one was caused by landing with a brake on and did 360 degrees in less than 2 seconds. (I'm not exaggerating) and strained my neck. How the tyres stayed on the wheels is beyond me. It just continued taxiing as if nothing happened. IF you'd blinked, you would have missed it. Nev

[Thruster88]

I would need to see it or at least some good pics. I recall seeing a vid about a sonex, is the tail wheel operated by a single push rod? Differential action came to mind due to the angle of the rod. More left than right etc, good in an aileron system not so much in steering.  

[skippydiesel]

On 28/10/2023 at 7:31 PM, Thruster88 said:

I would need to see it or at least some good pics. I recall seeing a vid about a sonex, is the tail wheel operated by a single push rod? Differential action came to mind due to the angle of the rod. More left than right etc, good in an aileron system not so much in steering.  

Well if it is a differential effect, due to steering rod angle/alignment, its more right than left.

 

The left rudder horn appeared to be making contact with the stop a little earlier than the right - I filled it until it (effectively increasing the amount of travel) now  has the same degreed of contact - no apparent change to tail wheel brake away.

[facthunter]

The common way is 2 cables with  springs. I prefer them to be in compression as they eventually bottom out and become solid. You still have to correct how the breakaway mechanism works reliably.  Nev

[skippydiesel]

There being little comment/advice on the matter - I feel that I will have to live with the latest set up, that is the steering rod connecting to an inner hole (closer to centre pivot point), changing the "throw" of the left turn so that it can break away/swivel.

The L & R swivel action now occurs before rudder horn contacts the stops and is significantly easier to initiate.

My ground opps. will have to be carried out with a higher degree of caution and my line up will include a check for posative straight steering before commencing ground role. 

 

[facthunter]

That's a good thing to do anyhow.   The only real issue I've had was with tailwheel shimmy and that ruined the tire real fast.  Nev

[facthunter]

There is no breakaway with that. Simpler. Nev

[skippydiesel]

This is how my tail wheel steering is configured now, giving about equal breakaway/swivel left & right. You can see the "old" steer rod position just to the left.