Design Improvements for the Zenith 601 HDS: Fairing of Nose Gear

Fairing of Nose Gear

Any round tube exposed to the slipstream produces an amazing amount of drag. Thus, fairing the relatively long nose gear tube seems a good idea. Also, if the nose gear tube has no fairing, then it becomes covered with dust and grit, and the substantial up-and-down movement of the nose gear during taxiing, takeoff, and landing grinds down the Delrin bearing.

The fairing consists of two fitted pieces. Each is held together at the rear lip by a vertical wire inserted into a piano hinge. A spring loaded tube pushes the upper fairing against the nose gear bearing. The lower piece is held in place by a small tube welded into the nose gear. That tube is used by a lightweight tow bar that inserts a long AN3 bolt into the tube. The shiny surface is stainless steel tape on top of the aluminum of the lower fairing part. The same tape is used inside the upper fairing part, so there is no wear. Once a year the fairing is removed, and the nose gear tube is cleaned and lightly coated with grease. This has essentially stopped the wear of the Delrin bearing of the nose gear.

Optimal fairing would require that the width of the fairing is three times the diameter of the nose gear tube. This is not possible here since the turning of the nose gear and the channel bracket holding the lower nose gear bearing limit the width.

An alternate tow bar attachment is a follows. One drills a 3/16 hole into the nose gear tube, inserts an AN3 bolt with two spacers on the two sides, and keeps the bolt in place with a nylon stop nut. Sealant is used to prevent moisture from entering the gear tube. The tow bar is clamped to the spacers.

Here are details of the fairing. First a picture of the two nested tubes and the spring. The tubes are made from thin-wall PVC tubing. To get proper nesting, the outer tube was cut and widened in hot water. Each tube has a stop at the end. The spring is inserted into the tubes and thus pushes them apart. We could not get a soft spring of correct size and made it from two springs.

The next picture shows the lower part of the fairing. The sharp bottom lip is covered by spliced nylon tubing so that it does not damage the nose wheel fairing. The lower piece is held in place by the tow bar tube of the nose gear. The wire holds the back part of the piece together via a piano hinge.

Finally, the upper piece. It has two tabs that overlap when the fairing is held together with the wire. The spring-loaded telescopic tube pushes against those tabs to keep the upper piece snug against the bearing of the nose gear. The fairing was designed after we had added the tube for the tow bar. When planned at the same time, the tow bar attachment should be low enough on the nose gear tube so that the two cutouts shown in the picture are not needed.