[NSRCA-discussion] [SPAM]Re: YS Questions+more - Rolls

Mark Atwood atwoodm at paragon-inc.com
Fri Mar 7 05:57:45 AKST 2008 

It applies to our wings as well.  The problem is it applies when we¹re
inverted too...  So the correction you put in to go from upright to
inverted, exacerbates the problem when you go from inverted back to upright.


On 3/7/08 9:48 AM, "Jay Marshall" <lightfoot at sc.rr.com> wrote:

> Wouldn¹t that apply more to a ³lifting² wing rather than the symmetrical wings
> we use in pattern?
>  
> 
> Jay Marshall 
> 
> -----Original Message-----
> From: nsrca-discussion-bounces at lists.nsrca.org
> [mailto:nsrca-discussion-bounces at lists.nsrca.org] On Behalf Of Robert Harden
> Sent: Friday, March 07, 2008 9:36 AM
> To: NSRCA Mailing List
> Subject: Re: [NSRCA-discussion] [SPAM]Re: YS Questions+more - Rolls
>  
> 
> 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.
> 
>  
>> 
>> ----- Original Message -----
>> 
>> From: krishlan fitzsimmons <mailto:homeremodeling2003 at yahoo.com>
>> 
>> To: NSRCA Mailing List <mailto:nsrca-discussion at lists.nsrca.org>
>> 
>> Sent: Thursday, March 06, 2008 9:59 PM
>> 
>> Subject: [SPAM]Re: [NSRCA-discussion] YS Questions+more - Rolls
>> 
>>  
>> 
>> Lance, 
>> 
>>  
>> 
>> 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..
>> 
>>  
>> 
>> Chris 
>> 
>> Lance Van Nostrand <patterndude at tx.rr.com> wrote:
>>> This thread is timely because I've been experimenting with differential
>>> recently on a new design that seems to need it. Never needed it before on a
>>> pattern plane but now I might. My test is to fly very high, point the nose
>>> directly at the ground and roll pure aileron. Plane should be axial, but
>>> remember that axial is along the vertical CG, which may not be a line that
>>> pierces the wing LE/TE. You need to do it a few times to be sure that their
>>> is an axis that everything rotates around and that line is straight. If it
>>> wobbles, then we have an issue. Another way to determine this is to do
>>> unlimited rolls while flying straight up. If the airplane consistently arcs
>>> off its vertical line, you have a problem.
>>> 
>>> Aerodynamics suggests two contributors. One is that the lowered aileron
>>> increases the lift of the airfoil and lift creates drag so this wing may
>>> pull the plane off axis. the other is that the spiral slipstream of the prop
>>> is pushing down on the right wing and up on the left so up/right aileron is
>>> more effective than up/left and down/left is more effective than down/right.
>>> 
>>> The overall effect for most pattern planes is minimal and usually ignorable,
>>> but on IMAC style planes these factors can be significant and the resulting
>>> differential corrections may need to be adjusted with something as simple as
>>> a prop change (from 3 blade to 2 for example).
>>> 
>>> the correction of course is to start playing with aileron differential.
>>> Given the contributors I've suggested, its not a given which way you go with
>>> the differential to correct the problem and the answer might not even be
>>> symmetrical.
>>> 
>>> Note that contributor #1 above will change if you are flying upright or
>>> inverted, so it would seem that a correction for upright flight would simply
>>> exacerbate inverted flight, but contributor #2 is the same for any flight
>>> mode but is throttle dependent.
>>> 
>>> --Lance
>>> 
>>> ----- Original Message -----
>>> From: "Koenig, Tom"
>>> To: "NSRCA Mailing List"
>>> Sent: Thursday, March 06, 2008 4:45 PM
>>> Subject: Re: [NSRCA-discussion] YS Questions+more - Rolls
>>> 
>>> 
>>>> > My head is spinning!!! The more I think about this, the more questions I
>>>> > have.........rather than answers!
>>>> >
>>>> > Maybe the contra rotating prop set up on a Voodoo X( Nat??) maybe the
>>>> > answer??
>>>> >
>>>> > I still 'feel', that the best rolls I get are with a 0 differential set
>>>> > up-BUT- somehow I 'drive' that wing to 0 ( or should that be some sort
>>>> > of equilibrium??) during the rolls. Certainly in my case, it seems to be
>>>> > Pilot dependant!!!
>>>> > I'm starting to think that my rudder control has turned to the
>>>> > proverbial trying to micro analyse what's happening!
>>>> >
>>>> > Tom
>>>> >
>>>> > -----Original Message-----
>>>> > From: nsrca-discussion-bounces at lists.nsrca.org
>>>> > [mailto:nsrca-discussion-bounces at lists.nsrca.org] On Behalf Of
>>>> > shinden1 at cox.net
>>>> > Sent: Friday, 7 March 2008 9:15 AM
>>>> > To: NSRCA Mailing List
>>>> > Subject: Re: [NSRCA-discussion] YS Questions+more - Rolls
>>>> >
>>>> > what happens on a 4piont?
>>>> > Bryan
>>>> > ---- Del Rykert wrote:
>>>>> >> 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: 
>>>>> >> To: "NSRCA Mailing List"
>>>>> >> 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 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
>>>>>> >> > 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
>>>>>> >> >
>>>>>> >> > 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"
>>>>>> >> >
>>>>>> >> > Tom
>>>>>> >> > It's just something that is peculiar to the Southern
>>>> > Hemisphere.
>>>>>> >> >
>>>>>> >> > Changing wing incidence will not help. Unless things are really
>>>> > screwed up , 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
>>>>>> >> >
>>>>>> >> >
>>>>>> >> > --------------------------------------------------------------------
>>>>>> >> > ----
>>>>>> >> >
>>>>>> >> >
>>>>>> >> > _______________________________________________
>>>>>> >> > NSRCA-discussion mailing list
>>>>>> >> > NSRCA-discussion at lists.nsrca.org
>>>>>> >> > http://lists.nsrca.org/mailman/listinfo/nsrca-discussion
>>>>>> >> >
>>>>>> >> >
>>>>>> >> > --------------------------------------------------------------------
>>>>>> >> > ----------
>>>>>> >> >
>>>>>> >> >
>>>>>> >> > _______________________________________________
>>>>>> >> > NSRCA-discussion mailing list
>>>>>> >> > NSRCA-discussion at lists.nsrca.org
>>>>>> >> > http://lists.nsrca.org/mailman/listinfo/nsrca-discussion
>>>>>> >> > _______________________________________________
>>>>>> >> > NSRCA-discussion mailing list
>>>>>> >> > NSRCA-discussion at lists.nsrca.org
>>>>>> >> > http://lists.nsrca.org/mailman/listinfo/nsrca-discussion
>>>>>> >> >
>>>> >
>>>> > _______________________________________________
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>>> 
>>> _______________________________________________
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>>> 
>>> Chris 
>>> 
>>>  
>>> 
>>>  
>>> 
>>>  
>>> 
>>> 
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