I can't say for sure that the original Sportster wasn't 'influenced' by Lou Andrews designs, but the appearance and construction are certainly very similar. AAMCO released the Minimaster which was a .25 sized design and looks similar to the Sportster. The original (prototype) Minimaster was actually a 40-45 sized airplane - sort of a modernized (at the time) Trainermaster: bolt-on wing; no rounded wingtips, a bit sleeker fuselage. If memory serves, both the Sportster series and Andrews '-master' designs had semi-semetrical airfoils. Great airplanes. Back in the '70s my dad and I built 3 Aeromasters, 2 Trainermasters, 1 Sportmaster; 1 Sportster .25; 2 Sportster 40s. They all flew great and most had long flying lives.
-Will B