Wally D. Timm was born in Lakefield, Minnesota, in 1893. He worked closely with his brother Otto in designing aircraft. Wally started out in 1910 as a mechanic for Al Wilson in exchange for flying lessons. He worked for the Signal Corps Aviation School as an instructor in 1917- 1918. In 1921 he flew an airplane from Venice, CA, to Lone Pine, CA, and then to Bishop, CA, in a record time of four hours and five minutes. He also worked for Hollywood during this time with partner Frank Clark. He barnstormed from 1921 to 1928, and eventually, in 1934, he formed the Timm Airplane Company with his brother Otto. They designed the Timm T-S140.

After World War II, he partnered with Norm Larson to sell Beechcraft planes at Glendale Airport. One of these planes, a Beechcraft Bonanza, called the Waikiki Beach, was piloted by Bill Odom on a record setting flight and is now on display in the Smithsonian National Air and Space Museum. Wally remained active in aviation into the 1950s. He passed away in El Cajon, CA on April 29, 1978, at the age of 81.