Designed by Terrence O'Neill, President OAC, Magnum is a bush-type, originally designed to suggestions offered in response to a questionnaire which was sent to all Charter (bush) pilots in Alaska in 1981.  Some 22% of all Alaskan Charter pilots replied.  Magnum was flown to Oshkosh back in 1944 with swing-wings.  It was modified in 1986 to swingtail-loading and an aero-converted Ford 351W, later supercharged to 380-hp.

Wing sweep is variable by modifying the length of the front auxiliary wing mount lug.  This allows a builder to compensate for different weight powerplant installation, by swing the wings forward or aft, to place the mean aerodynamic chord in the correct location over the CG, and no ballast is required.  Brake masters, battery, etc., for service are out in the open for easy maintenance access.  Tail can be made to swing open (Swingtail option) to load bulky cargo, such as four-by-eight plywood sheet flat-on-the-floor, or a snowmobile, or ATV.  Opening: 48.5" w. by 36" ht.   Roll control by Robertson-type spoilerons for STOL aircraft. Large flaps, spanning 12 ft. on each side, deflect downward 55 degrees. Horizontal stabilizer has unique two-position slots which prevent tail-stall to flight angles of attack of about 30 degrees, thereby  retaining un-stalling power of the tail.  Slots also work to supply more pitch control margin when the full flaps are deflected.  All fuel is carried in a single external under cabin instantly DROPPABLE gas tank, to greatly increase passenger safety in the event of a forced landing.  Angle of Attack Indicator plans are included, and strongly urged to be installed, for safety.

Large cargo loading via swing tail; cabin can carry 4x8 plywood flat on floor or a snow-mobile in cabin.

Plans built