A question if allowed. What are the aerodynamic drag penalties or advantages in
this contrast.
Low wing monoplane on twin floats vs low wing monoplane on single main float
with small wign tip stabilizers (IE Grumman duck).
In the former example the main float attachment scheme may be central pylon(s),
peripheral struts, and/or a fuselage width faired in structure.
My thought exercise is prompted by the fact that, it would be easier to
implement amphibious tricycle gear on single float, and single float would be
able to handle higher sea conditions.
C. Smith



D. F. Hoerner, in his book "Fluid Dynamic Drag" [possibly
chapter 8] shows data for drag between two identical struts
when flown at varying distances apart.  When the two struts were
about 4 of their own diameters apart, total drag for the two
was about the same as it would be for a single such strut
multiplied by two.  When the struts were moved closer together,
however, total drag increased over 'single strut times two.'
This is called interference drag, and exists between any two
aerodynamic bodies relatively close together.  I would guess
from this, that if your single main float had a substantial
cross-sectional area, that it would have to be farther from
your fuselage than would smaller dual floats, in order to
minimize this kind of interference drag with the fuselage.
Gene Kahn


Good job Gene

Paul Lamar

Thanks for the reference. I think I've heard of this phenomena before. It's the
reason for the dimples in the fuselages of execu-jets by the engine pods. Any
other good title suggestions on the topic? Hoerners book runs around $150 and
up. Maybe I should build some models and little tunnel, see for my self. 8-D
C. Smith