<... Do you have any references ...>
No I don't offhand. I heard about it from the speed merchants
in the canard community. They do some pretty slick (no pun intended)
stuff. It might have been written up in the Central States Association
newsletter. A lot of the discussion was on the Canard Aviators email
list which I left a couple of years ago. Anyway, you should be able
to minimize the effect by forming your louvers such that the air exits
the traveling in a direction parallel with the air stream (flag against
the fuselage).
Oh - another example of rooster tail drag is the aileron hinge gap.
Rutan planes have the ailerons hinged at the top surface of the wing, so
it's easy to seal the gap. Most dramatic result is low speed roll
authority, but air on from the lower (high pressure) side of the wing squirting
up through the aileron hinge gap to the upper (low pressure) side not only
compromises the aileron, but makes a rooster tail. These guys even
take extra care sealing the cowl to prevent plenum air from squirting out
from where the cowl joins the wing and fuselage.
Hope this helps. I'll try and find references if I can ... Jim
S.
Ed Anderson wrote:
That
is interesting, Jim.
My RV has louvers on both sides of the cowl, so if I understand what you
are saying, I might pick up less drag due to the turbulence created up
front that flows back over the entire fuselage. Do you have any references
about this effect other thanthe one already mentioned? Ed
Anderson
RV-6A N494BW Rotary Powered
Matthews, NC
eanderson@carolina.rr.com
----- Original Message -----
Sent: Sunday, October 12, 2003 9:06
AM
Subject: [FlyRotary] Re: solo's &
Delta T... no more emergencies
<... I've
considered adding a set of louvers on the right side of the cowl and ducting
the right rad outlet to exit the louvers ...>
If you try this,
you might want to take care to avoid "rooster tail" exit drag. Studies
have shown that is a real significant component of drag. Canard folks
have picked up significant airspeed by making them go away.
Best ... Jim
S.
--
Jim Sower
Crossville, TN; Chapter 5
Long-EZ N83RT, Velocity N4095T
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