10/31/2012. Remarks by Walter van Tilborg: "The Shoestring Formula One (Goodyear) racer was designed by Rodney Kreimendahl and the first example was built by a group called Mercury Air which included Carl and Vincent Ast. It first flew on August 8, 1948 and won the 1951 Continental Trophy and remained active as a racer for many years. Like all contemporary racers, it was fitted with an 85 hp Continental C85 engine.

Plans for amateur construction were later marketed by Condor Aero for an improved version as K-10 Shoestring. Several additional aircraft were built with engines such as the 100 hp Continental O-200-A, or the 90-95 hp Continental C90, and often with modifications developed by the builders. Production is estimated 8 to 10, and several Shoestring racers (often modified) remained active well into the 2000s.

At last one example (pictured here) was built in France by André Guignard and was first flown on March 7, 1987. It was raced by Willy Rawlinson in 1987, 1993 and 1996. By then it was owned by Xavier Beck, who changed the original fuselage skin for glass fiber, decreasing weight by 66.14 lb (30 kg), while the tail was also modified. A more efficient cowling replaced the original, and the ailerons control was modified. It was flown again in the St. Flour Grand Prix de France on August 24, 2003, flown by Thomas Passemard who placed the plane third. On February 10, 2005, the aircraft was registered to Claude James."