C/n given on the display plate in the museum as AO118 and by Air-Britain Archive Special No. 5 as 1181, but neither are valid Mi-1 c/ns. If c/n 1811 was correct then it would point to the factory at Rostov as the producer as the highest known built there ends 1810. OH-HRC was manufactured in January 1961 registered in in February 1961 so that fits nicely