During their time in Massachusetts for the Eskimo Pie detour, Clayton Brukner made an important financial contact in the Simpson family, which built steam engines. The Simpsons agreed to finance WACO, and as part of the bargain, a family son was to be trained as an aircraft mechanic. The training didn't work out, and Simpson soon left, but Brukner used the funding to buy out Buck Weaver's share in WACO. In 1923 the company was reincorporated in Massachusetts as the Advance Aircraft Company -- production stayed in Troy, and the planes were still known as WACOs.

The first Troy factory was located on South Union Street, with some production and storage located in several other buildings around the downtown. During this time several new employees were added, including Clayton Brukner's brother Clem, but money was still tight. The WACO 7 was the company's next design. Again, it was a three-person aircraft using a Curtis OX-5 engine. This plane was the most successful yet - 16 were sold. 
 

After briefly using grass areas on the south side of Troy to fly out completed aircraft, WACO started using a pasture space across the Great Miami River from the impressive Miami County Court house. This area was called Boak Field. Today this area is occupied by the Troy High School Memorial Football Stadium, the Troy City Pool and an enlarged river levy.

The completed fuselages were towed or hauled over from the factory to a barn, where the wings and tail sections were attached, and the planes were flown off of the grass pasture. This barn was located were the Hobart Arena now stands. Since then, the barn has been moved across the street to a city park and is used to stage community theater.

The first cabin WACO was built in 1924, the WACO 8. It could carry six passengers inside and had an open cockpit for a crew of two located behind the cabin. The plane was not successful in drumming up sales, and was the only one built. Some time later it was sold, and was eventually used to map the Ozark mountain range.