All of the "cubs" were flat-bottomed wings. The original E-2 were built by Taylor (he left and formed Taylorcraft); the first of the Pipers were J-3; military type were L-4; postwar cubs were designated with PA for Piper Aircraft: PA-11 enclosed cowl, PA 18 (also known as "Super Cub"), the PA-20 Pacer, the PA-22 Tri-Pacer ... etc. The PA-23 was the first twin "Apache". The evolution of the Piper Aircraft company is an interesting story. Many books have been written.