1929 Travel Air 4-D, Pilot: Bruce McElhoe. The Model 4-D is similar to the earlier Model B-4000, but the 4-D has a very reliable seven-cylinder J6 235 hp Wright engine as well as "outrigger" gear with pneumatic struts, providing gentle and forgiving landings for the pilot. The American Barnstormers 2012 Tour visits the Fargo Air Museum.