Okay, so I may not think the 1900 is so beautiful . . . .
How about this? The legendary, immortal Supermarine Spitfire has always struck me as one of the most beautiful shapes to ever fly. Years ago I went through a "purist" stage and thought the early Marks were the prettiest.
Now, however, I look at this Mark, the XVIII, and see such a refined airframe. It bears the most resemblance to the Mark XVI, but replaced the XVI's Merlin with the RR Griffin of nearly 2,400 HP driving a 5-bladed propeller. Teardrop canopy, large rudder, rounded wingtips, and a trim fuselage all contribute to a truly classic, haunting form.
The (real) LOOTM for April!
The Supermarine Spitfire Mark XVIII.