On another thread it says Mike Gretz was designing the Banshee concurrently with the super chipmunk. So, that puts it in the 70s.
The The Super Chipmunk was credited to Mike Stott, and it is NOT classic legal. The SIG Van Loo Chipmunk, kit #CL-3 IS classic legal, and was originally designed by Jim Van Loo. SIG produced the kit on a limited basis at first, as Glenn did not think it would sell well, and it didn't even have a kit number for the first run because of that and was even in a shorter box that they wanted to use up. Sales went better than expected, so the kit was refined a bit, given the kit number CL-3. Top Flite had it's Nobler and the Flite Streak to compliment it as a "practice plane" at that time also. Mike Stott was working for SIG at the time and since sales of the Chipmunk were going so well, Mike was tasked by Glenn SIG to design a practice plane that would fly similarly to the Chipmunk. He designed the Banshee along the same moments and such as the Chipmunk so it would fly similarly, and that is why it has the longish nose that it does, as it was designed around the Fox .35 which was the most popular stunt engine at that time because of it's light weight, and Fox engines did not come with a muffler at that time, either.. The Super Chipmunk came along quite a bit later and is a different airplane that the VanLoo model. Mike Gretz had mentioned through the years that he was pretty sure that the model had been designed before the December, 1969 deadline but there was no record of it and no record that it had been put into production by then either. Mike Gretz has since passed away but has told this story here on the forum before and it can be searched up. Mike Stott is still with us I think but he has no record of it nor can recall for sure the specific time lines. With no definite documentation, not one has been flying it in Classic or Nostalgia competition. Keep in mind, that the Classic class has been around a long time now, pushing 30 years or so, and most of this has been hashed out several times before and a lot can probably be found out on the internet about it. The same thing about the Twister. Mike Gretz used to have a web page with the history of all the SIG C/L stunt designs but I do not think it exists any longer. There is a web site about the history of all SIG designs but I couldn't come up with a link right now. So , basically, to fly classic, the model must have existed, was designed, kitted or published by December 31, 1969. Tom Morris had put together two compilations of Classic legal designs and Old Tyme legal designs in book form and published by PAMPA, that you might be able to find copies of here and there to use as a source also.
Type at you later,
Dan McEntee