From: highflyer <highflyer@alt.net>
Newsgroups: rec.aviation.homebuilt
Subject: Re: canards; high elevation performance?
Date: Mon, 28 Sep 1998 14:38:47 -0500

Scott McQ wrote:
>
> When the Beech Starship was a new airplane I remember reading about
> propellor problems in one of the magazines.  It seems that the
> propellor was flexing as it went in and out of the wing's wake and
> that could cause the metal to become brittle (crystallize?) and
> possibly snap off.  The author of the article was claiming that metal
> props were not suitable for any pusher.  Wood and compsite props
> apparently do not have a similar problem with flexing.
>
<snip>

There are significant problems to consider with a pusher propellor
that is mounted closely behind aircraft structure.  Problems include
air inflow into the prop disk, effect of lowering the pressure in
front of the prop disk, as well as wake traversal problems causing
varying loads in the prop blades.

Empirical experiment has shown that you do NOT want a prop blade
to cut the wake all at one time.  Especially if it is close to the
surface generating the wake.  It can break the prop in a few hours
of operation, whether it is metal or wood.

It is best to mount the prop centerline out of line with any surfaces
ahead of it in such a way that the prop cuts through the wake a bit
at a time.  It should slice through rather than whack through.  Most
of my information on pusher designs and relationship to the structure
ahead of the prop comes from Percy Spencer, who did a lot of work with
pusher designs of all different types.

From: erikavg@ix.netcom.com(Erik Shilling)
Newsgroups: rec.aviation.homebuilt
Subject: RE: considering canard style aircraft
Date: 26 May 1997 21:16:32 GMT

>  I'll give my 2 cents, but be advised I'm no engineer.
>  The first problem, an "advancing engine," sounds rather bogus.
>Whether the engine lands in my lap or hits me in the back will
>probably only matter to the guy who goes to rebuild the thing. I
>don't think that it has happened in a an Ez.

Speaking from experience:
I crashlanded a fighter on the side of a mountain and into a forest
of trees. The CW-21 had an R-1820 engine that weighted about 1,500
pounds.  When I finaly came to rest. The propeller was wrapped
around the engine.  The engine had had hit a tree dead on, whose
diameter was about 8 inches. The tree was torn off at its base. the
left wing was torn off at the fuselage. The airplane spun around to
the left. Then going sideways the fuselage, about 2 feet behind the
cockpit, hit a smaller tree about 2 inches in dia and tore it down.
I then spun to the right and finally came to a stop. I was
unscathed.  Just before I hit I remember glancing at the airspeed
as I hit. It was exactly on 100 mph.

What do you think would have happened to me if I had been flying a
pusher.

Erik Shilling