EAA Sport Aviation - October 2009

Welding and Sheet Metal

Designed by the late Ed Marquart of EAA Chapter 1 at Flabob Airport in Riverside, California, the plans-built Marquart Charger consists of wings constructed with built-up wood ribs with wood spars, a steel tube fuselage, aluminum formers, and screen-door channel stringers. About 500 sets of plans have been sold for the MA- 5 Charger, with an estimated 100 completed.

Mark was comfortable working with wood, but he had other skills to learn. He attended welding workshops at AirVenture and also learned firsthand from Mike Finney, who coached him and welded some of the more difficult parts of the airframe. Mark’s next challenge was learning how to work with sheet metal, the prospect of which he found rather intimidating.

“Again, a fellow EAA chapter member, Jerry Groshong, helped me learn the ins and outs of working with aluminum,” said Mark, “such as how I needed to deburr it, to Cleco, what my rivets needed to look like, how to back rivet, and things like that,” said Mark. “I used carpet tubes and pieces of carpet on the garage floor, rolling it back and forth to get the curve of the aluminum just right, and learned how to bend the aluminum in a sheet metal brake. All the aspects of the aluminum work have been the most gratifying part of the project.”

Dope and Fabric

The Charger is covered with Ceconite and finished with Randolph nitrate and butyrate dope. Close inspection reveals neatly applied pinked-edge tapes and a lustrous finish, which was achieved by painstaking sanding after each coating was applied. “I went through 300 sheets of sandpaper in various grades, just on the wings alone,” chuckled Mark. “I wore a respirator and used compressed air for painting, and worked in a two-car garage with an old furnace fan as an exhaust fan. I put plastic over my tools in the garage to protect them from overspray.”