[NSRCA-discussion] the joy of trim
rcmaster199 at aol.com
rcmaster199 at aol.com
Fri Mar 7 19:56:45 AKST 2008
Bryan,
I respectfully disagree on the upline, full power issue. The downline is a totally different trim situation because the vectors involved are different
MattK
-----Original Message-----
From: Nat Penton
To: NSRCA Mailing List
Sent: Fri, 7 Mar 2008 7:16 pm
Subject: Re: [NSRCA-discussion] the joy of trim
I'm thinking, I'm thinking ----- Original Message ----- From: shinden1 at cox.net> To: "NSRCA Mailing List" nsrca-discussion at lists.f3a.us> Sent: Friday, March 07, 2008 1:53 PM Subject: [NSRCA-discussion] the joy of trim > Matt, I refer back to my earlier post > thrust is not the issue. > wing inc. will always trump thrust,, in power and influence over vertical > lines. > thrust is a" very fine tune" issue it should not be used to adjust > tracking issues > > jump in Nat ,, why do you not need down thrust on your design?? > Bryan > ---- rcmaster199 at aol.com wrote: >> If the model pulls to canopy on a�FULL POWER�vertical upline and you >> reduce downthrust, the problem will worsen. You need to add downthrust >> (about 1 degree initially, and more if needed). I would not mess with CG, >> at least not yet. >> >> >> � >> >> >> Horizontal flight places quite a load on the wing....the wing must lift >> the load accordingly. Vertical flight removes the load therefore whatever >> trim was found in horizontal flight will affect the vertical flight. The >> simplest fix is downthrust addition for the condition Mike references, >> but assumes that the model is close to begin with. >> >> >> � >> >> >> Downline flight (NO POWER) is a totally different trim scenario and may >> indeed require wing/stab inc adjustment and CG adjustment. >> >> >> � >> >> >> It should be understood�that it is an iterative process to get "perfect" >> trim. >> >> >> � >> >> >> MattK >> >> >> >> >> >> >> >> >> >> >> -----Original Message----- >> >> From: J N Hiller >> >> To: NSRCA Mailing List >> >> Sent: Fri, 7 Mar 2008 11:33 am >> >> Subject: Re: [NSRCA-discussion] YS Questions+more - Rolls >> >> >> >> >> >> >> >> >> >> >> >> The airplane may be flying with positive trim. Try reducing the down >> thrust or move the CG back. >> >> >> If it doesnt help put it back. >> >> >> Jim Hiller >> >> >> � >> >> >> -----Original Message----- >> >> From: nsrca-discussion-bounces at lists.nsrca.org >> [mailto:nsrca-discussion-bounces at lists.nsrca.org]On Behalf Of Michael >> Wickizer >> >> Sent: Friday, March 07, 2008 8:19 AM >> >> To: NSRCA Mailing List >> >> Subject: Re: [NSRCA-discussion] YS Questions+more - Rolls >> >> >> � >> >> >> 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 >> >> > > >> > 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 >> >> > > >> >> > > _______________________________________________ >> >> > > NSRCA-discussion mailing list >> >> > > NSRCA-discussion at lists.nsrca.org >> >> > > http://lists.nsrca.org/mailman/listinfo/nsrca-discussion >> >> > > >> >> > > >> >> > > >> >> > > Chris >> >> > > >> >> > > >> >> > > >> >> > > >> >> > > >> >> > > --------------------------------- >> >> > > Never miss a thing. Make Yahoo your homepage. >> >> > _______________________________________________ >> >> > 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 > _______________________________________________ NSRCA-discussion mailing list NSRCA-discussion at lists.nsrca.org http://lists.nsrca.org/mailman/listinfo/nsrca-discussion
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