For plane engineering aware person, all ok. - Commercial planes begin at about 50-60 seats, less are non-viable. Normal commercial size - 100 seats. For air-

For plane engineering aware person, all ok. - Commercial planes begin at about 50-60 seats, less are non-viable. Normal commercial size - 100 seats. For air-dynamics, 3 times capacity enlarge (from 6 to 18) typically possible, but more changes too much. And 3 times capacity in avia measured non linear, but with famous square-cube rule, which mean, change size will increase mass as square, but capacity as cube, so to got 3x capacity, need 1.443 increase of size (1.442^3=3.0046853).