With the demise of the A.C. Gilbert company, the Erector brand is now owned by their long-time British competitor, Meccano. It is still sold under the Erector name in the USA. Meccano actually introduced a similar construction set two years before A.C. Gilbert claims to have invented it in 1903. There are a handful of Erector Sets from the 1920s to the 1950s on display in the Miniature Engineering Craftsmanship Museum.
This is Erector Set No. 10181 “Motorized Helicopter.” This erector set is not currently on display.