I was going to Pattern contests as early as 1970 and just about every plane at the time had retracts. To me the no retracts rule is kind of silly. Retracts were no more complicated or difficult to install or use than they are today. At the time the most trouble free Retracts were the Kraft Retracts they had there own servo motors built into the retract Mechanism and operated off the 5th or 6th channel. The Retract Switch on the transmitter did not become real popular until about 1972 as I recall

Pipes would be another issue at that time 1970 pipes were not used, mufflers were required however also at the time the most popular engines were the Webra Blackhead and the Enya 60, OS had a 60 too but the only person that I knew who used one was Don Lowe in his Phoenix 5 and oh he had retracts in that airplane too. :-)

As far as the idea that Retracts made the airplane go faster that was not the reason pattern fliers used them. The main reason for cleaner airflows and it looked Cool, with the emphasis on cool. If you wanted a fast airplane keep the weight down. One of the problems I remember from that era was one of our club members had built a fiberglass Banshee with a Webra 61 and Rom Air retracts this combo tipped the scales at almost 9.5 lbs and did not fly any faster than a plain ole vanilla Kaos without retracts in fact the plain ole vanilla Kaos that I remember that used to show up at our club field ( it really was Red ) was one of the faster airplanes at the club field. Its secret to speed was it weighed less around 5.5 lbs

I'm building my 1972 era Dirty Birdie as a tail dragger and with Retracts and a pumped OS 91 4 stroke.

My last comment I must mention one of the coolest pattern planes from that era this would have been August of 1973 one of our club members had built a Mach 1 with RETRACTS and it had I believe a HP 61 with NO PIPE! :-) but it did have a muffler

DLB