Proper Tailwheel Steering Springs?

How to keep the Cessna 170 flying and airworthy.

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GAHorn
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Re: Proper Tailwheel Steering Springs?

Post by GAHorn »

Joe Moilanen wrote:
GAHorn wrote:The “steerable” tailwheels’ steerability depends on several factors, not to exclude:
1- Weight & Bal ...the amount of weight on the tailwheel can vary quite a bit, not only from plane to plane but from flight to flight.
2- Tailwheel MainSpring-Angle: The caster affects the ability of the tailwheel to rotate or steer because a “positive” caster (king-pin/bolt head FWD) will require the tailwheel to actually LIFT the weight upon the tail landing gear. The “free-space” of reduced-effort is a narrow band, ...It is so much easier to remain within the narrow-angle, the wheel constantly “searches” for that band....and that allows “shimmy”. Negative caster (king-pin/bolt head AFT) will allow better rudder-only steering because it does not require the tailwheel to lift the weight of the airplane to deflect from side-to-side. This forces the wheel to remain within the detents ...so the steering mechanism remains engaged. This keep the turntable/friction-discs clutched...and reduces the tendency to “shimmy”. This might seem counter-intuitive ....nonetheless, incorrect caster is what primarily causes “shimmy”.

The on-line video (produced by one of the tailwheel mfr reps) of how to adjust the tailwheel steering by raising the tailwheel off the ground in the hangar.... is simply wrong, sad to say. They should know better, but it’s an example of how misunderstood this subject is.
Wouldn't "positive" castor mean (king-pin/bolt head AFT) instead of FWD? The bolt would angle forward at it's bottom end if the castor was positive?

Joe
4518C
THAT WAS A TEST.... (yeah...THATs the ticket!)..... That was only a TEST. If an ACTUAL example had existed then I would have posted a picture..... and caught my error. Doh! :oops:

YES!.. POSITIVE CASTER is when a line is drawn thru the pivot and the bottom of the line is FORWARD of the contact (footprint) of the wheel. I mistakenly used the King-bolt NUT when describing the geometry. THANK YOU JOE! For catching my mistake. I will edit my earlier post to draw proper attention to the issue. Here’s a “pic” of Positive/Neutral/Negative CASTER:
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'53 B-model N146YS SN:25713
50th Anniversary of Flight Model. Winner-Best Original 170B, 100th Anniversary of Flight Convention.
An originality nut (mostly) for the right reasons. ;)
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GAHorn
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Re: Proper Tailwheel Steering Springs?

Post by GAHorn »

Here is a pic sent to me this week from one of our Members who experienced a firm “Bump” on take-off.

The Member was making a short hop to another field to use their wash-ramp...and when he got to the ramp and de-planed...what he found was a tail-wheel steering cable had been ripped loose and was trailing behind the aircraft.
Tailwheel Steering Cable Pulled Out (Maule Compression Spring)
Tailwheel Steering Cable Pulled Out (Maule Compression Spring)
His A&P (at the A&Ps own initiative) did him a “favor” and had previously removed tension-springs and installed Maule-style compression springs to “improve” the customers’ tailwheel handling.

The aircraft is now having its’ vertical and horizontal stabilizers removed in order to access the area for repair.

It is yet to be discovered if any additional damage has occurred to the rear bulkhead, etc., until the area is accessed for inspection and repair.
'53 B-model N146YS SN:25713
50th Anniversary of Flight Model. Winner-Best Original 170B, 100th Anniversary of Flight Convention.
An originality nut (mostly) for the right reasons. ;)
Tailwind Farm
Posts: 16
Joined: Fri Nov 20, 2020 8:59 pm

Re: Proper Tailwheel Steering Springs?

Post by Tailwind Farm »

DaveF wrote:Don't waste your energy trying to make the steering work. Just put the pieces and parts together as they're supposed to be, and then get good at using the brakes for steering. I've tried new leaf springs, tight chains, loose chains, three pressure plate springs and five, different kinds of grease, different tire pressures and different tires. Nothing made even the slightest difference in steering performance.
It becomes an obsession!
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