304.904.3850=0A=0A=0A=0A=0A________________________________=0AFrom: Glenn C
rowder <gcrowder2@hotmail.com>=0ATo: europa-list@matronics.com=0ASent: Mon,
April 12, 2010 9:36:43 PM=0ASubject: Re: Europa-List: Effects of Flaps and
er <gcrowder2@hotmail.com>=0A=0A=0A=0APeter Zutrauen <peterz@zutrasoft.com>
wrote:=0A=0A>Hi Glenn,=0A>=0A>that was my understanding as well - but when
trimmed for cruise, wouldn't=0A>the anti-servo/trim-tab be required to por
trude *downwards* to drive the=0A>trailing edge of the tailplane *up* to re
sult in the equivalent of pulling=0A>back on the stick,- to have the tail
plane produce the required downward=0A>force on the tail?=0A>=0A>All the pi
cs I've seen show the trimtab portruding *up*, ie, trim- = foward=0A>st
ick..... no?=0A>=0A>Still confused,=0A>Pete=0A>A239=0A>=0A>=0A>=0A>On Mon,
Apr 12, 2010 at 2:41 PM, Glenn Crowder <gcrowder2@hotmail.com>wrote:=0A>=0A
=0A>>=0A>> The airfoil of the wing of any aircraft with a non symmetrical s
ection will=0A>> produce a negative pitching moment (-cm) around the aerody
namic center of=0A>> the wing.- This means that without the tailplane pro
ducing an equal but=0A>> opposite moment the acft will pitch over into a ve
rtical dive.- The all=0A>> flying tailplane on the Europa has no fixed an
gle of incidence so to produce=0A>> an opposing positive torque moment to t
he wings negative one the trim tab=0A>> must be held out of plane.- At hi
gher speeds then the tailplane must provide=0A>> greater downforce then req
uiring even more trim tab offset.- We have to pay=0A>> a small drag penal
ty to achieve a level trim condition in cruise flight.=0A>> This penalty ca
n be reduced somewhat by loading the acft towards the aft cg=0A>> limits re
quiring less trim tab offset reducing the downforce the tailplane=0A>> must
produce to maintain level flight.=0A>>=0A>>- The tailless flying wing de
rives it's pitch stability due to the outer=0A>> portions of the wing being
reflexed up to produce that necessary positive=0A>> pitching moment but al
so introduces that small drag penalty again.- There is=0A>> no free lunch
in aerodynamics!- Every desireable aerodynamic quality (like=0A>> pitch
stability) has a price that must be paid.=0A>>=0A>>- - - - - -
- - - - - - - - - - - Glenn=0A>>=0A>> Fred Klein <fkl
ein@orcasonline.com> wrote:=0A>>=0A>> >=0A>> >On Apr 12, 2010, at 6:24 AM,
david miller wrote:=0A>> >=0A>> >> I think that for most efficient flight t
he incidence of the wing and=0A>> >> tail should be such that at cruise the
re is no up or down trim on=0A>> >> the elevator or all flying tail.=0A>> >
=0A>> >Fascinating discussion...as a non-aerodynamicist, I can't resist the
=0A>> >temptation to add a comment...=0A>> >=0A>> >I've always understood t
hat the elevator or an all-flying tail=0A>> >(horizontal tail plane) has a
"job"...namely, to exert a force, either=0A>> >up or down, in order to bala
nce the lift of the wing and stabilize the=0A>> >flight path of a normally
configured aircraft (i.e., not a canard=0A>> >type). To do this "job" requi
res "work"; the tail plane is never=0A>> >neutral.- And w/ our Europae...
with it's trim tabs acting in=0A>> >opposition to the all-flying tail plane
thru a direct mechanical=0A>> >connection...whenever the tail plane is doi
ng its job (at whatever=0A>> >angle of incidence), the trim tabs will be do
ing their job as well=0A>> >(that of counterbalancing forces on the tailpla
ne), and will=0A>> >necessarily be raised or lowered w/ reference to the ta
ilplane.=0A>> >=0A>> >Of course if this explanation is correct, one might p
onder the=0A>> >aerodynamics of my tail-less biplane...pix below.=0A>> >=0A
>> >Fred=0A>> >=0A>> >=0A>> >=0A>> >=0A>>=0A>>=0A>>=0A>>=0A>>=0A>>=0A>=0A>
=0A>-- =0A>"A man is not old until his regrets take the place of his dreams
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