[NSRCA-discussion] YS Questions+more - Rolls

Fri Mar 7 07:38:22 AKST 2008

No gravity??  

I¹m always amazed that they don¹t pull MORE to the canopy in the uplines...
But that¹s a CG and engine thrust issue.  Downlines are harder still...

On 3/7/08 11:18 AM, "Michael Wickizer" <mwickizer at msn.com> wrote:

> Bryan:
>  
> 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:)
>  
> Mike
> 
> 
> 
> 
> 
> 
>> > Date: Thu, 6 Mar 2008 23:13:48 -0500
>> > From: shinden1 at cox.net
>> > To: nsrca-discussion at lists.nsrca.org
>> > Subject: Re: [NSRCA-discussion] YS Questions+more - Rolls
>> > 
>> > Chris ,, the airplane does not know it`s flying horizontal or vertical
>> > the wings are still lifting whether up or down that s why we can use the
>> vertical up or down to test this problem ,
>> > Bryan
>> > ---- krishlan fitzsimmons <homeremodeling2003 at yahoo.com> wrote:
>>> > > 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
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>>>>>> > > >> >
>>>> > > >
>>>> > > > _______________________________________________
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>>>> > > > http://lists.nsrca.org/mailman/listinfo/nsrca-discussion
>>>> > > > _______________________________________________
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>>>> > > > NSRCA-discussion at lists.nsrca.org
>>>> > > > http://lists.nsrca.org/mailman/listinfo/nsrca-discussion
>>> > > 
>>> > > _______________________________________________
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>>> > > NSRCA-discussion at lists.nsrca.org
>>> > > http://lists.nsrca.org/mailman/listinfo/nsrca-discussion
>>> > > 
>>> > > 
>>> > > 
>>> > > Chris 
>>> > > 
>>> > > 
>>> > > 
>>> > > 
>>> > > 
>>> > > ---------------------------------
>>> > > Never miss a thing. Make Yahoo your homepage.
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