[NSRCA-discussion] joys of trimming
Mark Atwood
atwoodm at paragon-inc.com
Fri Mar 7 10:23:06 AKST 2008
Ok Bryan...
Time for the long version of the story then. And please...use english :)
-Mark
On 3/7/08 2:15 PM, "shinden1 at cox.net" <shinden1 at cox.net> wrote:
> Thats where we disagree Matt ,, Sorry
> If you approach it this way you will have to add upp elevator mix on left
> knife edge
> thrust adjustment is only a Band-Aid to a trim issue
> no modern pattern airplane need s more than .5 deg down thrust or right thrust
> fot that matter
> Bryan
> ---- rcmaster199 at aol.com wrote:
>> Mike,
>>
>>
>> ?
>>
>>
>> The pull to canopy on uplines is a fairly simple fix... add?about 1 degree of
>> downtrust to the engine.
>>
>>
>> ?
>>
>>
>> If the model pushed to gear on the upline, you would need to do the opposite
>>
>>
>> ?
>>
>>
>> MattK
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>> -----Original Message-----
>>
>> From: shinden1 at cox.net
>>
>> To: NSRCA Mailing List
>>
>> Sent: Fri, 7 Mar 2008 11:45 am
>>
>> Subject: [NSRCA-discussion] joys of trimming
>>
>>
>>
>>
>>
>> Hey Mike I will give you the short version I will write up a full
>> explanation when I have more time what we do as modelers is put more time
>> in getting our planes to fly level then adjust expo`s for inverted flight
>> feel this should be the last step in the process to properly trim the
>> airplane it has to have 6 critical performance based outcomes that is
>> achieved from 6 different demands from the airframe by performing 6
>> airframe demanding maneuvers. we can mask this by adding fins and wings but
>> it will always raise it`s ugly little head in other demands from the
>> airplane ,,,,,{Nat`s designs excluded } If we as trimmers ,,are extremely
>> honest with ourselves we fall short in this area and use the radio to
>> compensate Short explain.... the reason you can have an airplane fly
>> horizontal great and pull to the canopy in a vertical is we add tail weight
>> or up trim to produce the lift angle for one dynamic and settle for it
>> then we don`t realize t!
> he!
>> uptrim does the same job in the vertical lines ,,up or down what we
>> have to do is use the wing to produce lift by adding inc and then use the
>> weight shift to let the stab elevator steer the airplane in the up and down
>> lines. this cuts across the grain of modern trim practice I know, But I will
>> try to expound later one of the the second to last trim demand that
>> should tell you if your plane is trimmed is the upline one positive or
>> negative snap, when you can do this maneuver without leading with opposite
>> rudder .elevator to mask the out come then your 98% there it should not
>> displace off the line ,,, ofcourse proper input plays a factor in this ,,,,
>> oh the joys of trimming !!!! DEAN P? more later ---- 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 Bre!
> tt!
>> 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 cre!
> at!
>> e drag on the up or downline.. Still, it's the best test w! e 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 !
> lo!
>> wered aileron > > increases the lift of the airfoil and lift creates
>>
>> drag so this w! ing may > > pull the plane off axis. the other is that the
>> spiral slip stream 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 flig!
> ht!
>> would simply > > exacerbate inverted flight, but contributor #2 is the
>> same for any flight > > mode but is throt! tle 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 li
>>
>> sts.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 t!
> ho!
>> ught 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+m!
> or!
>> e - Rolls> > >> >> > >> >> > >> > And while your at it, I'd apprecia
>>
>> te some discussion of the impact> > > of the top hinge system as seen on
>> Viavat, and Prestige birds - (top> > > hinged, with fair! ing 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 t!
> hi!
>> ngs 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
>> che! ck 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 th!
> e !
>> thing up with these paint> > > stirrers??> > >> >> > >> > Also-one m
>>
>> ore 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 va! rious design fixes-but> > > about
>> the only one that seems to work is t o 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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