Del Magsam’s Sonex debuted in CONTACT! Magazine in issue #73, page 21, under the heading “Engine Controversy?” Story and Photos by John P Moyle, Associate Editor Del didn’t set out to be a rebel, or a pioneer, but when the desire to build and fly his own aircraft struck, it seems his natural curiosity led him towards those ultimate labels. Del Magsam lives in New Richmond, a small town in western Wisconsin, not far from Minneapolis-St. Paul. About five years ago he began to realize his life long dream of building his own aircraft, and he chose the Pietenpol Air Camper as his project. That choice naturally led him to the Corvair auto engine conversion, so popular with the Piet crowd. Del found another experimenter in Washington State with a Corvair engine already disassembled and cleaned up, but not yet
built. The west coast fellow sold his box of engine parts to Del, who was happy to be spared the effort of locating a satisfactory core motor. Using the William Wynne Conversion Manual as his guide, he built a standard 2700 c.c. aircraft conversion, with the intention of mounting it to his Pietenpol when he finished it. Another opportunity presented itself to Del, when one of the first five Sonex air-frames (to be completed) was offered for sale by the man who had nearly completed it. With only the firewall forward and canopy left to finish, it appeared to be a golden opportunity. Mr. Magsam felt pretty confident that his Corvair conversion could be made to fit, and would closely approximate the weight of the six cylinder Jabiru 3300 engine, which Sonex, Ltd. promotes as one of its factory approved power sources.
WEIGHT REDUCTION
Del was able to get the Corvair engine to fit in the stock Sonex cowl. Even though the Corvair is larger in length, number of cylinders, and has more cubic inches (cc’s if you prefer), it is narrower than the VW, and can be made to fit better in some instances. The cowl cheeks in the photo above could be trimmed down or removed completely if the builder wished to take the time. One such Corvair/Sonex builder in FL started with a clean piece of paper, and designed a cowl to fit the Corvair engine, with the front starter, and with a spinner large enough to cover the Warp Drive prop hub.
To get the Corvair into light weight trim, Del had to try many tactics in the effort to bring the Chevy engine down to the 200 pound (installed) limit imposed by the designers, Pete Buck (August Raspet Award winner) and Homebuilt Hall of Fame member John Monnett. Neither of these gentleman wish to see Sonex builders installing engines other than the Aero Vee 2180, the Jabiru 2200, or the Jabiru 3300, since these are the engines which have been installed and flown by the factory and the only ones that they can support with experience. They also are aware that their target market is the diverse group of persons known as “Experimenters”, and that the likelihood that someone would take it upon themselves to try another engine installation was nearly certain. This is a difficult area for the designers, because while they maintain a hope that they’ve offered enough power plant choices to satisfy the customer base, and thereby be able to provide support for every installation, this isn’t the case. The Corvair is believed by them to be too heavy for the Sonex, and it is, unless extraordinary steps are taken to lighten it. Del milled off the standard cast aluminum intake runners and replaced them with thin wall aluminum tubing, which is fed from the rear. The stock “log” is fed from the
CONTACT! ISSUE 75 PAGE 16