A search of Aerofiles (one of my favorites) came up with a handful of a/c builders:
Stauffer
O L Stauffer, Elkhart IN.
Stauffer Gyroplane (EAA)
Gyroplane 1939 = 1pOBAg. Revolving upper wing locked in place to convert the aircraft into a biplane. Any connection with Herrick?
Applegate-Weyant
Ray Applegate & (?) Weyant, Tecumseh MI, Elkhart IN.
Dart GC with Lycoming O-320 [N31696] (Dan Shumaker)
Dart GC 1946 (ATC 674) = 2pClwM; 100hp Continental A-100. Acquisition of rights to Culver G Dart with similar data. POP: about 10 before lack of sales halted production.
Hatfield
Milton Hatfield, Elkhart IN.
Little Bird aka Flying Wing 1986 = 1pClwM; 27hp or 50hp Rotax; span: 17'0" length: 10'0" load: 210# v: x/60/30; ff: 5/25/86. A series of Arup-like airplanes with low-aspect-ratio delta wings. POP: 3.
I've found the local EAA Chapters usually have a local av history nut who you could mine for info:
http://eaachapter132.org/http://www.elkhartindiana.org/egov/docs ... 894448.htmhttp://www.in.gov/history/files/aviationinindiana.pdfInfo is pretty sparse, good luck!