Yes, my newly acquired Bel Air Imperial is a Singer 15 clone. Once I knew this piece of information, the google searches brought up an endless amount of information on the clones.
I found quite a bit of information at Sew-Classic Blog. It is very informative, plus you can download a Singer 15 clone manual there.
It seems they were all made in the same factories in Japan, but the name printed on them was up to what American store or company ordered them. As you can see in the following pictures.
|Sears Commander Machine|
|My Bel Air Imperial|
|The Real Singer 15 Machine|