I believe Wooten & Berryman used the Voodoo and Big Iron in the Nats in 1961 or 1962. The Goldberg single Voodoo hit the market around that time. The Double Voodoo was a quick response to the Top Flite double Combat Cat at $4.95.
The Big Iron was a bigger and better plane than the Voodoo, but also more work to build. I assembled a Veco Big Iron kit and was not happy with the quality. The ribs were out of whack. Future copies with the ribs stack-sanded came out well.