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<DIV><FONT face=Arial size=2>Lance, I am taking a private pilots ground
school class, and the aerodynamics portion if it says that the lower aileron
produces lift, and a byproduct of lift is drag. The higher aileron dumps
lift and therefore has less drag. This condition creates yaw. So,
what we are doing in pattern, is to add differential between the ailerons
by raising the ailerons in the upward direction to increase it's drag to
match the lower ailerons drag so we don't get or minimize the yaw. Hope that
helps to understand what is going on.</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<BLOCKQUOTE
style="PADDING-RIGHT: 0px; PADDING-LEFT: 5px; MARGIN-LEFT: 5px; BORDER-LEFT: #000000 2px solid; MARGIN-RIGHT: 0px">
<DIV style="FONT: 10pt arial">----- Original Message ----- </DIV>
<DIV
style="BACKGROUND: #e4e4e4; FONT: 10pt arial; font-color: black"><B>From:</B>
<A title=homeremodeling2003@yahoo.com
href="mailto:homeremodeling2003@yahoo.com">krishlan fitzsimmons</A> </DIV>
<DIV style="FONT: 10pt arial"><B>To:</B> <A
title=nsrca-discussion@lists.nsrca.org
href="mailto:nsrca-discussion@lists.nsrca.org">NSRCA Mailing List</A> </DIV>
<DIV style="FONT: 10pt arial"><B>Sent:</B> Thursday, March 06, 2008 9:59
PM</DIV>
<DIV style="FONT: 10pt arial"><B>Subject:</B> [SPAM]Re: [NSRCA-discussion] YS
Questions+more - Rolls</DIV>
<DIV><BR></DIV>
<DIV>Lance, </DIV>
<DIV> </DIV>
<DIV>Just a thought though, if going straight up, up straight down, aren't the
up and down ailerons both inducing equal drag, no lift? I've often
wondered if our straight up test is actually a perfect test for this. It is
for our up and down lines, but what about our 45's or horizontals where we do
indeed have lift on the low aileron and drag on the other? This would create a
different condition I'm guessing.. Probably small, but still a little
different because as I mention, both create drag on the up or downline..
Still, it's the best test we have I guess.. </DIV>
<DIV> </DIV>
<DIV>Chris <BR><BR><B><I>Lance Van Nostrand
<patterndude@tx.rr.com></I></B> wrote:</DIV>
<BLOCKQUOTE class=replbq
style="PADDING-LEFT: 5px; MARGIN-LEFT: 5px; BORDER-LEFT: #1010ff 2px solid">This
thread is timely because I've been experimenting with differential
<BR>recently on a new design that seems to need it. Never needed it before
on a <BR>pattern plane but now I might. My test is to fly very high, point
the nose <BR>directly at the ground and roll pure aileron. Plane should be
axial, but <BR>remember that axial is along the vertical CG, which may not
be a line that <BR>pierces the wing LE/TE. You need to do it a few times to
be sure that their <BR>is an axis that everything rotates around and that
line is straight. If it <BR>wobbles, then we have an issue. Another way to
determine this is to do <BR>unlimited rolls while flying straight up. If the
airplane consistently arcs <BR>off its vertical line, you have a
problem.<BR><BR>Aerodynamics suggests two contributors. One is that the
lowered aileron <BR>increases the lift of the airfoil and lift creates drag
so this wing may <BR>pull the plane off axis. the other is that the spiral
slipstream of the prop <BR>is pushing down on the right wing and up on the
left so up/right aileron is <BR>more effective than up/left and down/left is
more effective than down/right.<BR><BR>The overall effect for most pattern
planes is minimal and usually ignorable, <BR>but on IMAC style planes these
factors can be significant and the resulting <BR>differential corrections
may need to be adjusted with something as simple as <BR>a prop change (from
3 blade to 2 for example).<BR><BR>the correction of course is to start
playing with aileron differential. <BR>Given the contributors I've
suggested, its not a given which way you go with <BR>the differential to
correct the problem and the answer might not even be
<BR>symmetrical.<BR><BR>Note that contributor #1 above will change if you
are flying upright or <BR>inverted, so it would seem that a correction for
upright flight would simply <BR>exacerbate inverted flight, but contributor
#2 is the same for any flight <BR>mode but is throttle
dependent.<BR><BR>--Lance<BR><BR>----- Original Message ----- <BR>From:
"Koenig, Tom" <TOM.KOENIG@ACTEWAGL.COM.AU><BR>To: "NSRCA Mailing List"
<NSRCA-DISCUSSION@LISTS.NSRCA.ORG><BR>Sent: Thursday, March 06, 2008 4:45
PM<BR>Subject: Re: [NSRCA-discussion] YS Questions+more -
Rolls<BR><BR><BR>> My head is spinning!!! The more I think about this,
the more questions I<BR>> have.........rather than
answers!<BR>><BR>> Maybe the contra rotating prop set up on a Voodoo
X( Nat??) maybe the<BR>> answer??<BR>><BR>> I still 'feel', that
the best rolls I get are with a 0 differential set<BR>> up-BUT- somehow I
'drive' that wing to 0 ( or should that be some sort<BR>> of
equilibrium??) during the rolls. Certainly in my case, it seems to
be<BR>> Pilot dependant!!!<BR>> I'm starting to think that my rudder
control has turned to the<BR>> proverbial trying to micro analyse what's
happening!<BR>><BR>> Tom<BR>><BR>> -----Original
Message-----<BR>> From: nsrca-discussion-bounces@lists.nsrca.org<BR>>
[mailto:nsrca-discussion-bounces@lists.nsrca.org] On Behalf Of<BR>>
shinden1@cox.net<BR>> Sent: Friday, 7 March 2008 9:15 AM<BR>> To:
NSRCA Mailing List<BR>> Subject: Re: [NSRCA-discussion] YS Questions+more
- Rolls<BR>><BR>> what happens on a 4piont?<BR>> Bryan<BR>> ----
Del Rykert <DRYKERT2@ROCHESTER.RR.COM>wrote:<BR>>> The general
consensus has been that the faster moving molecules over<BR>> the top
surface don't require as big as a deflection as the aileron that<BR>>
deflects towards the bottom of the plane. What one tries to achieve
is<BR>> the plane tracks as purely straight on a string as possible while
one<BR>> rolls both directions without introducing any
yaw.<BR>>><BR>>> Del<BR>>><BR>>> ----- Original
Message -----<BR>>> From: <GLMILLER3@SUDDENLINK.NET><BR>>> To:
"NSRCA Mailing List" <NSRCA-DISCUSSION@LISTS.NSRCA.ORG><BR>>> Sent:
Thursday, March 06, 2008 2:49 PM<BR>>> Subject: Re: [NSRCA-discussion]
YS Questions+more - Rolls<BR>>><BR>>><BR>>> > Nat and
all you other aerodynamicists,<BR>>> ><BR>>> > I thought
that the rational for "aileron differential" was that<BR>> upward
deflection causes more drag than downward deflection so to<BR>> equalize
drag and prevent yaw with aileron deflection, aileron<BR>> differential
is needed. It seems that you guys are now saying that<BR>> ain't so.
Please elaborate.<BR>>> ><BR>>> > George<BR>>>
><BR>>> > ---- Nat Penton
<NATPENTON@CENTURYTEL.NET>wrote:<BR>>> ><BR>>> >
=============<BR>>> > IMO center hinged or top hinged is OK. With
top hinge, to achieve<BR>> equal vertical travel of the trailing edge
requires different angular<BR>> travel, up vs down. The objective is zero
aerodynamic differential.<BR>>> ><BR>>> > Ron I don't
think a fairing would prevent separation but, how are<BR>> you able to
fair the gap using the top hinge ? Nat<BR>>> > ----- Original
Message -----<BR>>> > From: ronlock@comcast.net<BR>>> >
To: NSRCA Mailing List<BR>>> > Sent: Thursday, March 06, 2008 7:20
AM<BR>>> > Subject: Re: [NSRCA-discussion] YS Questions+more -
Rolls<BR>>> ><BR>>> ><BR>>> > And while your at
it, I'd appreciate some discussion of the impact<BR>> of the top hinge
system as seen on Viavat, and Prestige birds - (top<BR>> hinged, with
fairing that eliminates the gap at deflection)<BR>>> ><BR>>>
> Thanks, Ron Lockhart<BR>>> ><BR>>> > --------------
Original message -------------- <BR>>> > From:
vicenterc@comcast.net<BR>>> ><BR>>> > Nat,<BR>>>
><BR>>> > Could you explain why the differential should be
different for<BR>> non-center hinged? I understand that the mechanical
configuration of<BR>> non-center hinged requires differential to obtain
same travel in both<BR>> directions. However, the travel up and down
should be close to equal.<BR>>> ><BR>>> >
Thanks,<BR>>> ><BR>>> > --<BR>>> > Vicente
"Vince" Bortone<BR>>> ><BR>>> > -------------- Original
message -------------- <BR>>> > From: "Nat Penton"
<NATPENTON@CENTURYTEL.NET><BR>>> ><BR>>> > Tom<BR>>>
> It's just something that is peculiar to the Southern<BR>>
Hemisphere.<BR>>> ><BR>>> > Changing wing incidence will
not help. Unless things are really<BR>> screwed up <G>, at our roll
rates, centrifugal forces are too low to<BR>> cause a problem. You want
zero differential, aero speaking ( same<BR>> up/down if center hinged
).<BR>>> ><BR>>> > I find the best check is the fast
half-roll in the vertical up.<BR>> Regards Nat<BR>>> > -----
Original Message ----- <BR>>> > From: Koenig, Tom<BR>>> >
To: NSRCA Mailing List<BR>>> > Sent: Wednesday, March 05, 2008 7:24
PM<BR>>> > Subject: Re: [NSRCA-discussion] YS
Questions+more<BR>>> ><BR>>> ><BR>>> > Hi
Troy!<BR>>> ><BR>>> > Thanks for the info. I thought you
would be toiling away on<BR>> the next developmental stage of these
engines!!<BR>>> ><BR>>> > Hopefully soon, I can find the
time to get flying again. I am<BR>> looking forward to running this
little beast. I am still a little<BR>> concerned in keeping it quiet
though.<BR>>> ><BR>>> > Four blade props? I have some of
the 18.1 x 12 two bladers<BR>> but I just cant see how I'll shut the
thing up with these paint<BR>> stirrers??<BR>>> ><BR>>>
> Also-one more question to any of you out there in pattern<BR>>
land.<BR>>> ><BR>>> > I have struggled with aileron
differential for years. I am<BR>> just not happy with the rolls. I have
tried various design fixes-but<BR>> about the only one that seems to work
is to get the wing back to 0-0 (<BR>> which can be achieved by a few
ways, design, mix or thumbs) Differential<BR>> itself does not seem to
work if the wing is POA ( well...it works for<BR>> half the roll
!)<BR>>> > Another black magic fix appears to be to run
parallel<BR>> ailerons-but this only 'sorta' seems to fix it. I like the
feel of<BR>> equal% chord ailerons however.<BR>>> ><BR>>>
> I am frustrated with it-I like my planes to roll as if they<BR>> had
a string up its ...........well you know!<BR>>> ><BR>>> >
OK-any 'secrets' I need to know??? Very good elevator work<BR>>> >
fixes it ( hence my 0-0 comment)<BR>>> ><BR>>> >
Tom<BR>>> ><BR>>> ><BR>>> >
--------------------------------------------------------------------<BR>>>
> ----<BR>>> ><BR>>> ><BR>>> >
_______________________________________________<BR>>> >
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NSRCA-discussion@lists.nsrca.org<BR>>> >
http://lists.nsrca.org/mailman/listinfo/nsrca-discussion<BR>>>
><BR>>> ><BR>>> >
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> ----------<BR>>> ><BR>>> ><BR>>> >
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<DIV><STRONG><EM><FONT face="comic sans ms" color=#0000bf size=3>Chris
</FONT></EM></STRONG></DIV>
<DIV> </DIV>
<DIV> </DIV>
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