On Nov 1, 12:09*am, Alan Baker wrote:
In article
,





*BobR wrote:
On Oct 31, 2:59*pm, Alan Baker wrote:
In article
,

*BobR wrote:
On Oct 31, 2:09*pm, Alan Baker wrote:
In article
,

*BobR wrote:
On Oct 30, 5:12*pm, "Gregory Hall" wrote:
"Vaughn Simon" wrote in message

....

"Gregory Hall" wrote in message
...

It looks too much like an irresponsible, hot rod, stunt plane to
me.

* Well, you sucked me in at first, so on a troll scale of
zero-to-10
you
rate at least a five. *How are things in France?

Vaughn

France? *I don't live in France. I built and used to fly a Rotec
Rally
2B
many years ago. It was a tail dragger with a high wing and the
motor
was
mounted atop the wind with a pusher prop.

When I got it trimmed out correctly at cruise speeds I could lean
forward in
the seat to nose it down and lean back in the seat to nose it up.
Even
as
well-balanced as it was at about half throttle, when the engine
quit it
would pitch up immediately and drastically because the high engine
placement
and pusher prop had enough leverage so that the proper trim at the
tail
counteracted the nose down force of the engine and prop. If you
didn't
immediately push the stick way forward when the engine quit it was
a
matter
of seconds before it would nose up fast and stall and then you
would
have no
control at all from the stick until it fell for a while and the
nose
dropped
(thank god for that) so you could gain speed provided you had
enough
altitude to get control of it again. But it didn't glide too well
being
a
single surface wing with wire bracing. Perhaps 2:1 glide ratio. But
it
was
easy to land with no power but you had to come in hot and steep and
at
the
last second pull back on the stick and flare it.

It looks to me like the Legacy would act pretty much the same if
the
engine
quit.

--
Gregory Hall

Oh for gawd sake, you are talking about two totally different designs
and the aerodynamics of the two are totally different. *The Lancair
is
NOT a pusher and the engine is mounted forward of the CG instead of
on
top of it. *When the engine quits it will not pitch upward. *The
plane
you flew had the engine well above the center of gravity with a
pusher
prop and as a result produced a force that pushed the nose of the
aircraft down. *The two planes would not act pretty much the same at
all. *The weight of the engine on the Legacy is forward of the CG and
as a result always pulling the nose of the plane down. *The counter
to
the nose down is the horizontal stabilizer and the elevator. *Look at
the angle of incedence on the Horizontal Stabilizer and you will find
a slight downward angle, not an upward angle as is common on the
wing. *This counteracts the force from the weight of the engine. *An
engine out condition will not have a significant effect on pitch
until
the airspeed changes and that will result in a nose down, not nose up
pull.

The one thing not quite right is that there is no important difference
between tractor vs. pusher configurations with respect to directional
stability.

Not sure what you are replying to but I never said anything about
directional stability. *The discussion was regarding pitch forces..

Which is essentially the same thing.

Pusher or puller doesn't affect pitch forces. What affects pitch forces
is the length of the moment arm between the centre of mass and the
thrust line.

Like some of the early rocket designers (e.g. Goddard), you are falling
into the fallacy that somehow pulling is more stable than pushing.. This
is not so.

--
Alan Baker
Vancouver, British Columbia
http://gallery.me.com/alangbaker/100008/DSCF0162/web.jpg- Hide quoted
text -

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--
Alan Baker
Vancouver, British Columbia
http://gallery.me.com/alangbaker/100008/DSCF0162/web.jpg- Hide quoted
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Again Alan, I never indicated any issue with pusher vs tractor. *The
layout of the two planes being discussed is totally different. *One
involved a tractor configuration with the thrust line being very near
the vertical center of gravity. *The second involved an plane with the
engine mounted on a pylon with a thrust line well above the vertical
center of gravity. *This configuration, rather it be a tractor or
pusher will induce nose down forces that must be countered by the
horizontal stabilizer with an upward force. *This is contrary to the
standard configuration which requires a downward force to counter the
weight of the engine. *The post I was replying to was trying to link
the characteristic of the pylon mounted configuration to the Legacy.

Sorry, man, but you made specific reference to the plane being a pusher
as if it was a relevant factor:

"The Lancair is NOT a pusher and the engine is mounted forward of the CG
instead of on top of it. *When the engine quits it will not pitch
upward. *The plane you flew had the engine well above the center of
gravity with a pusher prop and as a result produced a force that pushed
the nose of the aircraft down."

When you include extraneous details, you make the essence of the
situation harder to glean.

And you're doing it again. You're conflating thrust line induced pitch
changes with weight of engine. One is changing, one is constant.

The only part that you had to talk about was the fact that the thrust
line was significantly above the centre of mass. The weight of the
engine doesn't matter (in an aircraft that has it's centre of gravity
appropriately located), nor does pusher vs. puller.

--
Alan Baker
Vancouver, British Columbia
http://gallery.me.com/alangbaker/100008/DSCF0162/web.jpg- Hide quoted text -

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Well excuse the holy hell out of me for not phrasing things the way
you want it. My references were based on the specifics of the two
planes involved in the discussion and if you can't gleem that fact
from it, too ****ing bad.