The original 1897-1898 version was to have 22 lift-fans, however it was never built and only small model tests were done, as well as separate full-scale propeller tests.
The next design was still a monoplane, but had two large lifters instead of 22 smaller ones. It was built in 1906 (or '07?), but failed the test in 1908 because of only one underpowered 10hp Stanley steam engine, instead of the two 50hp engines.
Davidson returned to Britain and attempted another design based on the previous ones. This time it was a tandem biplane with two large lifters, similar to that on the 1906 model. A wooden frame was built with the lifters and one engine was installed, but the project was abandoned because of lack of sufficient funds.
The next design was still a monoplane, but had two large lifters instead of 22 smaller ones. It was built in 1906 (or '07?), but failed the test in 1908 because of only one underpowered 10hp Stanley steam engine, instead of the two 50hp engines.
Davidson returned to Britain and attempted another design based on the previous ones. This time it was a tandem biplane with two large lifters, similar to that on the 1906 model. A wooden frame was built with the lifters and one engine was installed, but the project was abandoned because of lack of sufficient funds.