Size: 36mm wingspan
The Skeleton Tank also known as the Spider Tank was an experimental prototype tank built in 1918 by the Pioneer Tractor Company, Winona, Minnesota for $15,000 ($ 249,900 in 2019). The Prototype was ready for trials by October 1918. Designed with several innovative features, some of which were controversial at the time, the Skeleton Tank project did not proceed beyond the single prototype tank.
(More on Wiki HERE)