Dan, you got me investigating again! I googled" Carl Goldberg " and the AMA biography of him came up. Hers what I found so far, Opened hobby shop in 1935 and designed the Valkyrie
After several yrs went to work for Comet as chief designer & designed comet Clipper and Zipper Stayed there 6yrs
1947 worked under the name of Top Flite produced Zing, Cumulus, Trainer, Rascal, & a dozen Jig time kits
1955 went into business for himself." Carl Goldberg Models" designed $1.00 kits & Later came Blazer, Ranger, &
Swordsman. Biography states that Carl Goldberg Models were on there way when he produced the Shoestring.
The earliest advertisement I have so far is the 1961 Febuary-March issue of Flying Models. I'll keep searching to
try and find an earlier date. I have a friend that has an original kit and possibly there may be a date on them. Any
one with a more concrete date please let me know. Gene