William Wynne

The Corvair Powered Zenair 601XL

January 31, 2004

Friends,
Here's this month's update. Grace is holding up the Vans 13” spinner in front of the cowling plug in progress, above. This plug is made of urethane foam. It was a light color and hard to get a good flash photo of. The cowl will have a 12” deep nosebowl made of glas or carbon in a female mold we are pulling off this plug. All the compound curvature in the cowl is in the nosebowl. Aft of the bowl, the cowl is made of aluminum, all in easy single curves. We are putting hinges and camlocks on it, so it will take 30 seconds and a screwdriver to see 90 percent of the motor. The inlets are formed around PVC 4” couplers, which are close to 5” round. This nosebowl has our front starter inside with 5/8” clearance. The design was a group effort. The fine points of styling were specified by Gus, and Kevin is doing the finishing and mold making. The fuselage of the Tri-motor project is on its gear behind Grace.

The above shot is a look inside the cockpit. The airframe is 90% done. The panel and the engine compartment are where most of the remaining work is. This is a very simple plane, a truly clever design. Our plane has the dual stick control option. The sticks are all done, just removed for working room.

Above is the second done wing. The fit of the factory parts was exceptionally good, and all the work fit in the category of preparation and assembly, with no real fabrication required. The jigging specified in the assembly manual is very minimal but does the trick nicely. Digital levels showed both wings to be within 1/10 of one degree of each other in twist. This was not done by luck or with extreme craftsmanship. This is just a well made kit with good building instructions.

The builders’ manual has simple clever techniques to get things right, like the match up above between the wing skin and the flush gas cap. A simple Plexiglas template which picked up the rivet pattern made this possible with no critical measuring.

The factory welded tank, above, is about 12.5 gallons. This is the left wing tank with the sender installed. The tank is a close fit, and it is held snugly in place by adhesive backed cork padding.

Above, Steve Upson vacuums out drill chips just before the wing is closed. Both wings were built on these steel horses, with just 4 small wooden blocks for jigging. The wing is lightly zinc chromated inside. The structure is 6061 alloy, which is comparatively immune to corrosion if modest care is taken. Grace’s 1946 Taylorcraft is in the background.

Corvair/Colt builder Dave “The Bear” Vargesko installs the wing tiedown, above. Many of you who have been to an East Coast Corvair College or Sun ’N Fun have met Dave or seen his engine in person.

The mount is on the plane for the last time, but the case in the photo above is just there to mock up the installation. Our firewall was originally built as a tri-gear, but the brackets have been trimmed to match the Zenair taildragger supplemental drawings. We are keeping in mind that most 601 builders are going with tri-gear, so all the parts we’re making are kept out of the area occupied by the nose gear. This will make it much easier for other 601/Corvair builders to follow in our path.

We are hard at work on the plane and are looking forward to wrapping it up in a few weeks. I owe a huge debt of thanks to my crew of friends: Gus, Dave, Steve and Kevin. And my always supportive better half, Grace Ellen.

Thank you.

William Wynne