Probably a 49, but can't find a pic. This is a 48 DX model. The first letter needs to be cleaned off to see it for sure. Looks like an "F" as noted above by RustyGold.
The paint looks great!
Have you tried a wheel to see if it's 24"? The seat tube should measure 16" for a 24" frame. 18" for a 26" frame.
There is no 49 catalog I can find, but in 1950, the 24" boys DX frame like yours is a J30 or a J36. The catalog shows only girls frames in the illustrations of those two so I can't tell if one was a straight bar or not. The 1948 catalog shows it a BO or BOE model as a 24" DX frame.
A 26" DX frame is a D13 model. The Hornet was a straight bar frame, yours is a DX style, the second top bar has a curve in it.
I don't have a wheel yet. I measured about 15 3/4" up the seat post from the top of the bottom bracket. compared chain stay and seat stays to a 20" and a 26" frame and those measurements are in the middle, so I'm pretty sure it's 24" Thanks for the info Wildcat