These wheels are better in several ways:
Lighter than even the 4″ solid tailwheel
Smoother and quieter – completely eliminates the Sonex tailwheel rattle
Reduced stress – Flexing of the tire reduces shock loads on the tail-wheel castor and pivot fitting.
Better grip – The tire conforms with the runway surface to provide better grip, especially on sealed surfaces.
Tony Richardson (Sonex 813, Jab 2200) recently fitted the lightweight Nylon/aluminium wheel. Read his comments on the Sonex Australia site.
This consists of an accurately machined 4130 steel pivot fitting with sintered-bronze bushings, a light 4130 steel castor to fit the larger-than-standard wheel and a lightweight nylon/aluminium wheel. Total mass is only 675 grams (1.5 pounds). Can also be supplied with the all aluminium wheel (middle photo)- total mass is 750 grams (1.65 pounds).
This is the type I use on my own Sonex. It is fitted with quality 6000RS sealed ball bearings and a bearing spacer, enabling full tightening of the axle nut. The wheel is machined from PA6 nylon with a removable 6061 Aluminium rim half. Standard tire fitted is 6″ x 1.25″ 4 ply. Mass of wheel and tire is less than 340 grams (0.75 pounds).
The same design as above but machined from 6061 aluminium. It’s heavier duty, but mass of wheel and tire is still only 440 grams (less than 1 pound), lighter than the stock Sonex 4″ tail-wheel. Note that the tire supplied is a grey “CST” brand as shown on the nylon wheel above.
The castor is fabricated from 4130 steel. Mass is only 150 grams (0.33 pounds), but the design of the castor is much stronger than the Sonex steel castor.
Tail-wheel pivot fitting
The fitting shown is currently undergoing evaluation on my Sonex. The standard brackets have been known to fail due to fatigue cracking where the tube joins the rear (large) plate. Failure probably isn’t dangerous but could be very inconvenient. This design uses a tapered tube which is thicker at the join and is allowed to flex slightly in the bolted joint. Finite element modelling indicates a halving of stress at the joint when compared with the standard mount. Mass is increased by 100 grams (0.22 pounds). Note that this part can be supplied either drilled to Sonex dimensions or un-drilled. If you are replacing a broken mount, the old part can be used as a template to match-drill the new part to your aircraft.
Gallery of the parts in use
The bracket fitted to my own Sonex
The Nylon 6″ tailwheel fitted to my Sonex
View of the right side – removable al disk retained by 4 screws for easy tire replacement.