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<DIV><FONT face=Arial color=#0000ff>IMO ~ one reason is you don't have your
planes trimmed aerodynamically neutral ... One of your choices is to
either fly slight down stick in your up lines as needed adjusting to slowing
dynamics or move your CG so you aren't trimming for a slightly nose heavy model.
Of course their are other forces at work here also but I think you will find on
many planes moving the CG aft will help cure that.. course that is a compromise
many don't like as they model don't track or groove the same and elevator input
can become twitchy if you move it to far back. Everyone has a
different feel for what they like and what works best for them. I have yet to
find two top level competitors have identically trimmed models.. Close and maybe
similar but not truly identical in every dimension. </FONT></DIV>
<DIV><FONT face=Arial color=#0000ff> </FONT></DIV>
<DIV><FONT face=Arial color=#0000ff> Del</FONT> </DIV>
<BLOCKQUOTE
style="PADDING-RIGHT: 0px; PADDING-LEFT: 5px; MARGIN-LEFT: 5px; BORDER-LEFT: #0000ff 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=mwickizer@msn.com href="mailto:mwickizer@msn.com">Michael
Wickizer</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> Friday, March 07, 2008 11:18
AM</DIV>
<DIV style="FONT: 10pt arial"><B>Subject:</B> Re: [NSRCA-discussion] YS
Questions+more - Rolls</DIV>
<DIV><BR></DIV>Bryan:<BR> <BR>I agree that the plane doesn't know which
direction it's flying, but then why will a plane fly straight and level then
pull to the canopy in uplines? This has been driving Brett and me crazy
for over a year. Admittedly, it a much shorter drive for
me:)<BR> <BR>Mike<BR><BR><BR><BR><BR>
<HR id=stopSpelling>
<BR>> Date: Thu, 6 Mar 2008 23:13:48 -0500<BR>> From: <A
href="mailto:shinden1@cox.net">shinden1@cox.net</A><BR>> To:
nsrca-discussion@lists.nsrca.org<BR>> Subject: Re: [NSRCA-discussion] YS
Questions+more - Rolls<BR>> <BR>> Chris ,, the airplane does not know
it`s flying horizontal or vertical <BR>> the wings are still lifting
whether up or down that s why we can use the vertical up or down to test this
problem ,<BR>> Bryan<BR>> ---- krishlan fitzsimmons
<homeremodeling2003@yahoo.com> wrote: <BR>> > Lance, <BR>> >
<BR>> > 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.. <BR>> > <BR>> > Chris
<BR>> > <BR>> > Lance Van Nostrand <patterndude@tx.rr.com>
wrote:<BR>> > 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" <BR>> > To:
"NSRCA Mailing List" <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 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: <BR>> > >> To: "NSRCA Mailing List" <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 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" <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 , 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>> > >> >
--------------------------------------------------------------------<BR>>
> >> > ----------<BR>> > >> ><BR>> > >>
><BR>> > >> >
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> <BR>> > <BR>> > Chris <BR>> > <BR>> > <BR>>
> <BR>> > <BR>> > <BR>> >
---------------------------------<BR>> > Never miss a thing. Make Yahoo
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