[NSRCA-discussion] YS Questions+more - Rolls
J N Hiller
jnhiller at earthlink.net
Fri Mar 7 03:03:33 AKST 2008
Interesting discussion; differential aileron trimming is right where I left
off last fall. I have had airplanes that needed differential travel and some
that didn’t. I find the imbalance most noticeable when flying to or away
from myself watching the nose walk around the opening of an invisible cone
as if one wing is rotating over the top of or tucking under the other. At
the 90 degree point the nose is either above or below the flight path and at
180 degrees the flight path or heading is off either left or right. The
heading change may indeed be different for each 90 degrees of rotation and
in-flight correction may become. Late last season the roll axis became
unacceptable and as I began to evaluate the probable cause (improper
differential travel) it dawned on me that I increased the endpoints on one
channel (1) and not the other (6). I have used “Y” connectors in the past
and adjusted the linkage and the day I adjusted the travel it didn’t occur
to me that I needed to adjust both. Yes I know old guys with old solutions
for old problems from a simpler time. After returning all endpoints to 100%
to get back to square one and found that all 4 deflection angles were
different. Setting equal deflection made differential aileron much more
difficult to identify and then it got cold. I will need to revisit this when
it warms up. Thanks for the reminder.
Jim Hiller
-----Original Message-----
From: nsrca-discussion-bounces at lists.nsrca.org
[mailto:nsrca-discussion-bounces at lists.nsrca.org]On Behalf Of Ken Velez
Sent: Thursday, March 06, 2008 8:13 PM
To: NSRCA Mailing List
Subject: Re: [NSRCA-discussion] YS Questions+more - Rolls
Gorge Nat is correct, think about it this way. The down deflected control
surface produces more lift. lift = Drag. Lift is the force that's opposes to
gravity"
Ken
----- Original Message -----
From: Nat Penton <mailto:natpenton at centurytel.net>
To: NSRCA Mailing List <mailto:nsrca-discussion at lists.f3a.us>
Sent: Thursday, March 06, 2008 6:08 PM
Subject: Re: [NSRCA-discussion] YS Questions+more - Rolls
George, I believe the down aileron produces the most drag ( re adverse
yaw ), but, over half of our rolls occur in verticals.
----- Original Message -----
From: Del Rykert <mailto:drykert2 at rochester.rr.com>
To: NSRCA Mailing List <mailto:nsrca-discussion at lists.f3a.us>
Sent: Thursday, March 06, 2008 2:11 PM
Subject: Re: [NSRCA-discussion] YS Questions+more - Rolls
The general consensus has been that the faster moving molecules over the top
surface don't require as big as a deflection as the aileron that deflects
towards the bottom of the plane. What one tries to achieve is the plane
tracks as purely straight on a string as possible while one rolls both
directions without introducing any yaw.
Del
----- Original Message -----
From: < glmiller3 at suddenlink.net <mailto:glmiller3 at suddenlink.net> >
To: "NSRCA Mailing List" < nsrca-discussion at lists.nsrca.org
<mailto:nsrca-discussion at lists.nsrca.org> >
Sent: Thursday, March 06, 2008 2:49 PM
Subject: Re: [NSRCA-discussion] YS Questions+more - Rolls
> Nat and all you other aerodynamicists,
>
> I thought that the rational for "aileron differential" was that upward
deflection causes more drag than downward deflection so to equalize drag and
prevent yaw with aileron deflection, aileron differential is needed. It
seems that you guys are now saying that ain't so. Please elaborate.
>
> George
>
> ---- Nat Penton < natpenton at centurytel.net
<mailto:natpenton at centurytel.net> > wrote:
>
> =============
> IMO center hinged or top hinged is OK. With top hinge, to achieve equal
vertical travel of the trailing edge requires different angular travel, up
vs down. The objective is zero aerodynamic differential.
>
> Ron I don't think a fairing would prevent separation but, how are you able
to fair the gap using the top hinge ? Nat
> ----- Original Message -----
> From: ronlock at comcast.net <mailto:ronlock at comcast.net>
> To: NSRCA Mailing List
> Sent: Thursday, March 06, 2008 7:20 AM
> Subject: Re: [NSRCA-discussion] YS Questions+more - Rolls
>
>
> And while your at it, I'd appreciate some discussion of the impact of the
top hinge system as seen on Viavat, and Prestige birds - (top hinged,
with fairing that eliminates the gap at deflection)
>
> Thanks, Ron Lockhart
>
> -------------- Original message --------------
> From: vicenterc at comcast.net <mailto:vicenterc at comcast.net>
>
> Nat,
>
> Could you explain why the differential should be different for
non-center hinged? I understand that the mechanical configuration of
non-center hinged requires differential to obtain same travel in both
directions. However, the travel up and down should be close to equal.
>
> Thanks,
>
> --
> Vicente "Vince" Bortone
>
> -------------- Original message --------------
> From: "Nat Penton" < natpenton at centurytel.net
<mailto:natpenton at centurytel.net> >
>
> Tom
> It's just something that is peculiar to the Southern Hemisphere.
>
> Changing wing incidence will not help. Unless things are really
screwed up <G>, at our roll rates, centrifugal forces are too low to cause a
problem. You want zero differential, aero speaking ( same up/down if center
hinged ).
>
> I find the best check is the fast half-roll in the vertical up.
Regards Nat
> ----- Original Message -----
> From: Koenig, Tom
> To: NSRCA Mailing List
> Sent: Wednesday, March 05, 2008 7:24 PM
> Subject: Re: [NSRCA-discussion] YS Questions+more
>
>
> Hi Troy!
>
> Thanks for the info. I thought you would be toiling away on the
next developmental stage of these engines!!
>
> Hopefully soon, I can find the time to get flying again. I am
looking forward to running this little beast. I am still a little concerned
in keeping it quiet though.
>
> Four blade props? I have some of the 18.1 x 12 two bladers but I
just cant see how I'll shut the thing up with these paint stirrers??
>
> Also-one more question to any of you out there in pattern land.
>
> I have struggled with aileron differential for years. I am just not
happy with the rolls. I have tried various design fixes-but about the only
one that seems to work is to get the wing back to 0-0 ( which can be
achieved by a few ways, design, mix or thumbs) Differential itself does not
seem to work if the wing is POA ( well...it works for half the roll !)
> Another black magic fix appears to be to run parallel ailerons-but
this only 'sorta' seems to fix it. I like the feel of equal% chord ailerons
however.
>
> I am frustrated with it-I like my planes to roll as if they had a
string up its ...........well you know!
>
> OK-any 'secrets' I need to know??? Very good elevator work fixes it
( hence my 0-0 comment)
>
> Tom
>
>
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