Elippse 2010-02-20 12:33:12
The 3-blade ELIPPSE prop on the Lancair 235 doesn’t use a symmetrical
airfoil; it’s a highly-cambered NACA 63 series laminar flow airfoil,
with 13% thickness. It would probably be best defined as a 63 3 513.
Thin and symmetrical prop airfoils have very low L/D ratios, making
them unsuitable for high-efficiency props. The 3-blade ELIPPSE prop
designed for the “Phantom” biplane racer at Reno 2004 allowed it to
smoke the field. The plane went 20 mph faster (241 mph vs. 221mph) on
245 less rpm. See the write-up in the Fall 2004 “Sporstman Pilot”,
Corky scott 2010-02-22 00:32:28
I had originally posted some information regarding the ELIPPSE prop
here and confess to remaining extremely interested still. The concept
of the prop planform and airfoil design demonstrates some very astute
thinking to me, although I’ll be the first to admit I do not know as
much about props as I’d like. That’s why I’m glad Paul has joined the
It turns out that despite his being skilled enough with computers to
work with them to design the prop, he has not until his first post a
few days ago, posted to a newsgroup before. It’s a new world for him.
Please let’s not drive him away. The world of homebuilding in general
and props in particular can use fresh approaches to old problems.
Thanks, Corky Scott