[NSRCA-discussion] the joy of trim

Sat Jan 19 10:04:18 AKST 2008

Chris,

I have been flying the Abbra for 3 years. What is the problem?

--
Vicente "Vince" Bortone

 -------------- Original message ----------------------
From: krishlan fitzsimmons <homeremodeling2003 at yahoo.com>
> My whole reason for finally joining this list was to learn.. Don't seem to do 
> that much on the forums.. And the funny thing is, that the problem I'm having 
> right now, is the setup on my Abbra.. Therefore making me sell it. I just can't 
> get it right, and I don't know what's wrong.. I know it's an awesome plane, 
> because I've seen all of Jerry Budd's.. And they all fly great.. I know someone 
> could set it up correctly.. Just not me apparently.. I've set up many planes to 
> a decent liking before. But I just can't get this one right.. I've got alot to 
> learn and no teachers around.. I was going to go to the nats for the first time 
> this year, but it makes it difficult to shoot for top 10 in Masters like it is.. 
> If it was properly setup, I think it's achievable though.. I know I have the 
> skills, just not the setup.. 
>   Hopefully I can get with Jerry then at some point.. 
>    
>   Chris
> 
> Lance Van Nostrand <patterndude at tx.rr.com> wrote:
>   Bryan,
> I have been anticipating your response but now it seems it won't be coming 
> soon. Maybe we can take this offline. There's no way anyone could 
> interpret my response as being argumentative and I know your are tough 
> enough to take a few pin pricks without flinching. Certainly I have my own 
> experiences and opinions but those are completely set aside. I believe 
> there are always at least 10 correct answers to any modeling question but 
> each answer is right within its own context.
> 
> In other words, I start from 0-0 and have my trim process advance from there 
> and usually get very good results. I think, if I remember correctly your 
> old KF article and our live discussions, you start from 1/2 degree positive 
> inc in wing and stab and advance from there. Since I know your path is 
> different from mine I am trying to learn from you. this is why I question 
> and ask for deeper explanation. Maybe it's just not there. The answer 
> might be "I never tested in a wind tunnel, can't explain why it works, but 
> it does so just try it and enjoy." But I hate to see you bow out when 
> someone asks for more details. that makes Krishlan's comment seem relevant 
> when, knowing how much you help others and contribute to this sport, it 
> shouldn't be.
> 
> --Lance
> 
> ----- Original Message ----- 
> From: 
> To: "NSRCA Mailing List" 
> Sent: Saturday, March 08, 2008 5:32 PM
> Subject: Re: [NSRCA-discussion] the joy of trim
> 
> 
> > Ok Matt
> > I accept, your probably right ..
> >
> > I will now bow out of the discussion it`s not going anywhere and I`m 
> > waiting my time trying to inform, it seems all the people I`ve helped 
> > accomplish what I`m preaching have quit the sport or they are scared to 
> > write !!
> > I`ll leave you with this ,
> > demand of perfection is different by each persons ability and goals,
> > sometimes we deceive ourselves in thinking we kow it all or
> > we get caught up in out wording every one and talking nonsense ,, then no 
> > one gets anything out of the conversation
> > and then, you die of a thousand pin pricks
> > I can remember sharing pos inc setup with Nat on numerous occasions and 
> > Nat out worded me and proved me wrong on paper and you know he can ,, in a 
> > Popeye Fried chicken House of all places,
> > However I find out years Later he now uses My setup I`m proud 
> > ok ,I`ll stop beating a dead horse I know better than to start this
> >
> > carry on
> > Bryan
> >
> > ---- rcmaster199 at aol.com wrote:
> >> 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 aï¿½FULL POWERï¿½vertical 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. >> >> >> ï¿½ >> >> >> 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. >> >> >> ï¿½ >> >> >> 
> >> Downline flight (NO POWER) is a totally different trim scenario and may 
> >> >> indeed require wing/stab inc adjustment and CG adjustment. >> >> >> 
> >> ï¿½ >> >> >> It should be understoodï¿½that it is an iterative process to 
> >> get "perfect" >> trim. >> >> >> ï¿½ >> >> >> 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 
> >> >> >> >> ï¿½ >> >> >> -----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 >> >> >> ï¿½ >> >> >> Bryan: >> >> ï¿½ >> >> 
> >> 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?ï¿½ This has been driving Brett and me crazy for over a year.ï¿½ 
> >> >> Admittedly, it a much shorter drive for me:) >> >> ï¿½ >> >> 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 
> 
> === message truncated ===
> 
> 
> Chris 
>    
>    
>    
> 
>        
> ---------------------------------
Never miss a thing.   Make Yahoo your homepage.

-------------- next part --------------
An embedded message was scrubbed...
From: krishlan fitzsimmons <homeremodeling2003 at yahoo.com>
Subject: Re: [NSRCA-discussion] the joy of trim
Date: Sun, 9 Mar 2008 01:07:12 +0000
Size: 52191
Url: http://lists.nsrca.org/pipermail/nsrca-discussion/attachments/20080309/e51f825d/attachment-0003.mht 