Tail Wheel Assembly  
 

The original Q2 tail wheel assembly suffered at least four design deficiencies; The wheel itself was hard rubber which in addition to providing poor traction, acted like a phonograph needle transcribing the rough surface of the runway into an amazing amount of sound coming up into the cockpit from the tail cone.

Another problem was the angle of the tail wheel pivot. I have forgotten the proper technical term for the problem, but the result was that when a downward load was placed on the tail wheel, it wanted to flop to one side or the other rather than remain in trail with the aircraft.

Yet another problem with the original design was the lack of compliance in the cable system. It is ridged from the rudder peddles to the wheel on the ground where as most tail draggers have springs in the cables that connect the peddles to the tail wheel. The lack of compliance makes it much easier for the pilot to over steer the aircraft, and for the pilot to 'break loose' the tail wheel with too forceful an application of rudder peddle pressure.

Original Tailwheel Assembly

Finally, the tail wheel spring, which was a 5/8" round fiberglass rod was prone to breaking on a bounced landing. When the rod broke, the rudder cables would go limp and there would be no rudder control, making it difficult to conduct a go-a-round.
(space for a photo of the original spring when I find it)

Various corrections were tried, but the solution which seems to have been accepted by the majority of Q2/200 pilots is called the Jim-Bob Six Pack. Named for it's two developers, Jim Hamm and Bob Farnam, it consists of a set of six modifications. It has been installed on several Q's to the great satisfaction of the owners.

The first change is to replace the tail wheel with an Aviation Products tail wheel assembly which includes a 6" pneumatic tire and a pivot angle which corrects the instability of the original assembly. This tailwheel assembly has a mechanism which unlocks the wheel from the bellcrank when the wheel deflection exceeds a certain angle. Very nice for ground handling!

(note: this is not a photo of the unit which I used, but is similar)

American Products, Inc. tailwheel assembly

 

Secondly, the original circular tail wheel spring is replaced with a larger oval spring from the Dragonfly aircraft. The Dragonfly tail wheel spring was manufactured in two different cross sectional sizes. Bob Farnam's, purchased in the 1990's, is smaller than the one that I purchased in 2002. Like the Q2 spring, the Dragonfly spring is wrapped in layers of BID.

 

I cut a sheet of BID the length of the spring and wide enough to go around three + times. After rolling on the BID I rolled on a layer of peelply.

 

Then I chucked it up in a lathe and trimmed down the end to fit the American Product tailwheel, smeared the inside of the tail wheel socket with flox/epoxy and jammed the spring into the socket.

 

Before floxing the tailwheel spring to the tailcone, I loaded the airframe up to approximately gross weight. This allowed me to set the tailwheel so that the aircraft waterline would be at about 7-8 degrees (if I remember correctly) relative to the ground.

The American Products tailwheel assembly comes in several different pivot angles. You pick the one that best suits your application. Mine forms an 80 degree included angle relative to the tailspring.

 

See, honey! I told you it was strong!

 

That's five 40lb bags of wood pellets. About 20lbs greater that the weight of my Jabiru 3300 engine.

 

Additionally, the rudder and tail wheel cables are completely reconfigured with springs are added per the Jim-Bob Six Pack modifications.

Finally, independent hydraulic toe brakes with floating calipers are installed.

A complete write up describing the Six-Pack modifications appears in a 2005 Quickie Newsletter.