"Byrd, Ray" wrote:

I agree. Any large-scale modification can have a myriad of effects...many
can be expected to have negative impact on the  performance goals.

I'm not familiar with the concept of vortices at the juncture of a canard
and its fuselage.  Tips...yes.  Please continue.

Perhaps vortices is not quite the right word.
It is usually defined as interference drag when a wing intersects a fuselage.
It could be defined as mere turbulence. The axis of the vortices is

perpendicular

the to fuselage as in curlicues :-)> High pressure on the bottom and low
pressure on top. A lot depends on the gap between "elevator" and fuselage
and "elevator" trim deflection. If the gap is large enough it will be a
true longitudinal axis vortex for sure. PL

I haven't done comparative drag numbers on Cozy/Velocity vs EZs.  Should be
revealing. Has anyone done that?

I too would like to see that well documented. Perhaps in a side by side
race. PL

Sometimes happy gremlins pop up. I remember the recorded surprise at
Lockheed when the F-80 was stretched to a dual trainer as the T-33...and
it's cruise-power speed was found to be noticeably faster than the 80.

Ray Byrd

Here is something from Hoerner. Not really pressure recovery fuselages
but good data never the less.
Note this is based on wetted area and not frontal area so a fatter body
of the same length would have much more wetted area.
The drag coeff might be lower but to calculate the drag one
must adjust for the increased wetted area. Now here is where I doubt,
in the case of the Cozy or Velocity, that a fatter body really
results in less drag over a Long EZ because the wetted area is
much greater while the length is about the same.

The Questair Venture  is a shorter airplane than its competition so
there may not be that much difference in wetted area and the lower
coeff. pays off.

Paul Lamar

Fatter isn't lower drag, just not necessarily higher.   The Cozy is not faster
than the LE, about the same, slower if loaded heavier.   Most ARE
loaded a lot heavier, so they use bigger engines.  At the same weight, the
Cozy is within a few mph of a LE, but most are heavier.   I have flown
side-by-side, not a serious test, but the performance was as similar as
another LE and mine, side-by-side.

Bill Freeman

I'll believe it when I see a serious top speed test. Top speed has little to do
with weight.

Here are the percentages for a Me109. Lots of evidence to support these percentages.
Dave Anders and Tracy Saylor are going so much faster than other
RV's mainly because they pay close attention to cooling drag.
there is little else you can do to a stock RV wing.

I highly recommend getting a new or used copy of Hoerner Bill.

Paul Lamar
 
The AirCraft Rotary Engine NewsLetter.              Powered by Linux.
ACRE NL web site.
http://home.earthlink.net/~rotaryeng/            http://www.linux.org