[NSRCA-discussion] triangulation trimming

Thu Mar 13 14:33:19 AKDT 2008

Hi Chris,

Send the pictures.  I'm not promising to do it but if it's easy I  
probably will.

Jim O

On Mar 13, 2008, at 2:29 PM, krishlan fitzsimmons wrote:

> Jim,
>
> Putting wing adjusters in the Abbra was super easy.. I can send you  
> pics of what I did if you'd like..
>
> Chris
>
> James Oddino <joddino at socal.rr.com> wrote:
> Bryan,
>
> Thanks for your effort. I agree with you almost completely on fix
> #1. I'm not sure you can fix the down line. My Impact was pulling to
> the canopy in both up line and down line. I kept adjusting the wing
> positive until I fixed the up line. I had some remaining pull in the
> down line and put in a small amount of down trim with low throttle to
> take care of that. I'm not sure if I had gone further it would have
> fixed the down line without screwing up the up line. I analyzed this
> as increasing the down thrust. I didn't want to change the motor
> angle so I changed the wing. Make sense. The wing was going to fly
> at the same incidence with respect to horizontal but the motor would
> be more negative in level flight, Right? The Impact didn't need any
> serious mix for knife edge and I'm not sure one could prove anything
> with it because the wings were like a propeller. Anyway that plane is
> now a test bed.
>
> My Abbra seems to fly great with the factory settings in up lines and
> again I use a small amount of down trim with low throttle to fix the
> downlines. I have the cg ahead of the factory recommendation but not
> near as forward as Jerry Budd. I'm guessing that he has more positive
> in his wing from the factory. I do fly with a little down trim at
> neutral. The bad news is it takes lots of up mix to fix the knife
> edges. I guess your solution would be to move the cg forward which in
> turn would require more positive incidence? I hesitate to modify the
> airplane to make the wing adjustable until I'm pretty sure I can
> improve it.
>
> Thanks again for making us think about this stuff, Jim
>
>
>
>
>
> On Mar 11, 2008, at 8:05 PM,
> wrote:
>
> > triangulation trimming,
> > this is going to be long winded,
> > I want to preface this discussion by saying I have learned a great
> > deal from Dean Pappas one of my hero`s in the sport,,Jim Oddino I
> > read these guys all the time ,,Nat Penton ,,I learned a great deal
> > about painting from Mike Harrison who is always willing to tell you
> > what he knows and
> > I have looked up to Earl Haury as an all around Teacher and
> > appreciate those guys for their hard work in the sport ahead of
> > me and willingness to share what they know.
> > Now let me say I am no flight engineer or aerodynamic Guru , I`ll
> > leave that title to Nat Penton as he deserves it, But the two guys
> > that started this flying madness were,, by cycle mechanics,as we
> > all know .
> > so I`m in good company
> > After trimming over 15 of my own designs and trimming and building
> > two or three airplanes a year for about 20 years I have a lot of
> > practical knowledge on this subject matter and have kept notes. to
> > verify my observations I hope this will help.
> > A better Flyer with more experience will be a better trimmer because
> > he demands more from his airplane ,,but being a better trimmer will
> > earn you better flying skills .
> > so here we go
> > Mike ,Keith, Jim and Don, thank you for your patience
> >
> > For the purpose of this discussion tail heavy nose heavy is relative
> > to the recommended C/G and not always an extreme position just a way
> > to example it.
> >
> > If you are using a 0-0 setup things may- be alittle different as to
> > what I say and what you see on your airplanes as you fly them
> > my set up and your set up are not to be equated with each other.
> > and I think that's where some of the confusion comes in you having
> > only experienced your set ups.
> > However ,,left rudder tuck is a symptom of the airplane being tail
> > heavy on all pattern models no matter the set up, as long as the
> > stab and elevators are accurately adjusted , Extreme tail heavy will
> > mean both knifes will tuck to the belly. it is just a symptom that
> > tells me the cure and allows me to diagnose trim problems
> > reply to Chad>
> > Jim O,
> > Any wing has to produce lift, to fly and there are two ways to do
> > it, add pos inc to the wing according to the datum line on the fuse
> > My Method or,, add pos inc to the fuse, the 0-0 method ,,,by this
> > I mean , flying the airplane a little tail heavy to achieve pos
> > inc ,, there is no way around it ,the wing has to have a pos angle
> > of attack to produce lift and fly level and lift 11 pounds of balsa
> > and Glass.
> > vertical c/g has no factor on this discussion I don`t understand
> > enough about it to discuss it,{G}
> > The stab does not induce the lift ,,it controls the lift of the wing
> > and steers the wing and fuse. {no arguments here please I`m trying
> > to make the bigger picture I know it does contribute lift and share
> > the lift load,}
> >
> > A ,0-0 or sub 1/2pos set up will cause some or all of these
> > problems ,,for you guys set up 0-0 ,, check um off ,,,
> > A tuck to the belly on left rudder {or both depending on how tail
> > heavy} more tail heavy more tuck ,,pull in both up and down
> > lines ,,,So now we add down thrust to fix one problem upline pull
> > { as as Jim and others observed and suggested } and it magnifies
> > the others. like Nat explained to Chad ,,,and now it may give a
> > differential problem . so we address that with the radio.by mixing
> > and this occurs,,
> > stalls may be hard to do because,, "mix dont go away ", Snaps and
> > spins are hard to perform correctly start,,stop consistently ,and
> > they wander off line in the uplines,and 4/5`s so you see flyers
> > using opposite rudder to lead before, and after to keep them on
> > line , and even more apparently worse in a upline ,,, you can`t
> > convince these guys that it`s possible to do a snap without
> > displacing or tucking ect, because they have never experienced it.
> > and it supports their lack of trimming skills
> > or a poor design ,Sorry Guys!!
> >
> >
> > ,,BTW contrary to popular belief nose heavy airplanes {weight
> > forward } snap better, lands the snap cleaner, and is perfectly
> > consistently ,stays on line way better , { do you have an
> > airplane you have to lead to stop ,,its because it does not recover
> > from the stalled condition its probably tail heavy } a nose heavy
> > { weight forward} set up stops instantly . providing you have the
> > right inputs.
> >
> > In windy weather the 0-0 or sub 1/2 Pos. airplane moves all over
> > the place and is not solid at all. its not directionally stable ,
> > because of the tail weight needed to induce the pos inc in the wing.
> > a positive set up will actually weather vein into the wind by itself
> > and you will need opposite rudder to maintain the line
> > sometimes ,,in other words it will self correct in the wind ,,this
> > makes it much easier to fly in windy weather.
> > now ,,,
> > every year designers go back to the drawing boards and play with
> > airfoils, tail moments ,,tail size ,,,hocus pocus ,,ect all in an
> > attempt to fix a trim problem.,, not a design problem.
> >
> > Now to this,,, to correctly trim a model you need three tools,
> >
> > #1 an incidence meter no matter what kind dig. may be better,,
> > #2 honesty without it you will deceive yourself into believing it`s
> > trimmed
> > #3 patience ,,,,I know I just lost some of you But ,
> > there is only one of these three you can do without ,,, it`s the
> > inc. meter,, the other two will guide you if you stay at it till
> > it`s right.
> >
> > Now the Hebert triangulation Method
> > assuming everything else is perfectly straight and aligned
> > correctly ,,, this is a big assumption , but,set your c/g according
> > to the design spec on the drawings for your design as a starting
> > point ,,,if you don`t have a C/G spec contact Nat Penton, he will
> > give you a great formula he has worked up.
> > # 1 set motor at 1/2 deg down ..neg inc.
> > wings at 1/2 pos to start ,,,this is not a hard deck
> > stabs at 1/4 pos because this is about where you will end up.
> > Line up all your control surfaces get them even, because we are
> > going to let the airplane tell us what to do to fix it later
> >
> > #2 fly the airplane trim hands off level flight,, don`t cheat ,,{I
> > know a lot of guys use a little down trim in upright flight to help
> > with upline pulls} it has to be hands off perfect then fly
> > inverted to see if you like the inverted elevator and the airplane
> > feels solid and easy to hold on a line . and then take notes.
> > #3 pull a vertical line see what it does
> > #4 put it straight down see how long it takes to pull out to the
> > canopy
> > #5 do a left rudder knife edge ,see if it`s straight no pull the
> > entire length of the field don`t cheat,,
> > #6do a right rudder knife edge see if it`s straight same as above.
> > This is the triangulation method I use to diagnose all trim problems
> > with any airplane I-MAC to pattern ,,wings are wings.
> >
> > #7 now land and see where the elevator wound up ,,,never mind the
> > stabs right now, we will adjust them later.
> > take notes of what the airplane did in all these three maneuvers,
> > you will see you can triangulate a common input fix, I find it help
> > full to have a buddy to help remember whats happening in the air.
> > Look at the elevator trim and see what it has in it, if we are
> > lucky and your airplane is 10 pounds you are "all over it" and it
> > just may take a little c/g to give a click or two one way or the
> > other.
> > #1 But, if it pulls in the up lines and downline you need more
> > pos inc one turn at a time on the adjuster ,,
> > As an aside ,,,,if you have rear adjusters take them out and put
> > pins and donuts make sure they do not move at all as this will mess
> > with the trim process ,,I find the rear adjusters being a different
> > distance for the wing tube take different amounts of turns to be
> > equal and the wings have to adjust perfectly and lock exactly. no
> > warp in the root., yes it happens and gives you a false reading.
> >
> > #2 if it goes to the belly in left rudder move the c/g
> > forward{ your tail heavy} untill it stops pulling to the belly
> > regardless of the inc.
> > if it goes to the canopy in both knifes #1 will probably
> > fix it but
> > refer to the inverted flight part of you notes and see if you
> > think the elevator was mushy ,hold able but mushy and you might
> > require tail weight. and pos inc. to fix both problems canopy
> > pull downlines and knife edge flight.
> >
> > Because we are on the edge of trim perfection now in all wing
> > loaded, and unloaded ,positions now we can adjust c/g by using the
> > earlier mentioned bullet points for fine tune feeling
> > Remember most of the time one fix will fix 3other things and bring
> > it all together because they are all related, thats why a well
> > trimmed airplane rolls with ease and 4 points with ease. because we
> > are not fighting any adverse trim issues in any axis. or wing load
> >
> > Now do the adjustments and leave the trims on the airplane like they
> > are
> > make another flight your adjustments should Jive with the reverse
> > of what you trimmed on the first flight and make your trims work ,,,
> > if you have to increase the trim you already have in there from the
> > first flight LAND you went the wrong way with the adjustments and
> > make your corrections again
> >
> > < on another side note > for my designs since I know where they
> > should be set ,a quick method is to do the triangulation method this
> > way ,, trim the airplane to fly the down lines,,, leave this trim
> > in and land ,,
> > then adjust the wings to get the trim out and all three Maneuvers
> > are now happy,,,
> >
> > The closer you get to the end, the finer the tuning will need to be,
> > and it can try your patience
> > make sure the tank is centered on the c/g or you will have trim
> > changes during the flight as the tank drains
> >
> > don`t get mad at me if you cannot fix your favorite airplane Just
> > buy a better design ,,,,Mine preferably
> > there is so much more that I could add But I`ll leave it alone for
> > another post.
> > However I would like to add this ,,
> > I agree with Nat that add on T wings are smoke and mirrors However
> > who is going to argue with the word Champion ,,
> > yes it does work ,,somewhat, it reduces the required rudder angle
> > needed to hold knife edges which will in fact reduce mix ,,less
> > rudder less mix ,, A POS setup needs none of this.
> > Hope this helped ,,you may need to read it twice to absorb it all
> > thanks for your interest ,However Brian Clemons is mad at me because
> > I was supposed to be painting his airplane tonight LOL
> > Bryan
> >
> > Chris F. if you Like you can clean this up and include it for a k-
> > factor issue
> >
> >
> >
> >
> >
> >
> >
> >
> > ---- Don Ramsey wrote:
> >> I'm with Jim in not understand the reason some of the incidence
> >> changes
> >> work. Consider increasing the incidence for adjusting the push to
> >> the belly
> >> in knife edge. My reasoning would be; increase the incidence, put
> >> in some
> >> down elevator to fly straight and level. Roll to knife edge and
> >> the model
> >> would then push to the belly more severely. What am I missing?
> >>
> >> Don
> >>
> >> -----Original Message-----
> >> From: nsrca-discussion-bounces at lists.nsrca.org
> >> [mailto:nsrca-discussion-bounces at lists.nsrca.org] On Behalf Of
> >> James Oddino
> >> Sent: Tuesday, March 11, 2008 10:59 AM
> >> To: NSRCA Mailing List
> >> Subject: Re: [NSRCA-discussion] the joy of trimming , left rudder
> >> tuck
> >> downline pulls
> >>
> >> Bryan,
> >>
> >> I'm trying to figure out how increasing the wing incidence, I  
> assume
> >> with respect to the fuselage, will get rid of a pull to the  
> canopy on
> >> a vertical downline. Is it because you need to crank in some down
> >> trim to make it fly level? Or is it because the tail flies higher  
> in
> >> level flight and the higher vertical cg creates a couple pushing  
> the
> >> nose down during the vertical downline?
> >>
> >> I assume that if one could achieve a good vertical downline with
> >> power
> >> off, he could then adjust the thrust to get a good vertical upline?
> >> It would seem that the thrust is part of what made it fly level and
> >> you would get into an endless loop chasing things around. What is
> >> the
> >> sequence for getting what you want?
> >>
> >> I adjust the relation between the downthrust and wing to get a good
> >> vertical upline and trim out the pull in the downline like Chad.
> >> Tell
> >> us how we can get a combination of vertical up with power, level  
> with
> >> power (less power?) and vertical down without power that are all  
> good
> >> without throttle to elevator trim.
> >>
> >> Jim O
> >>
> >>
> >> On Mar 10, 2008, at 5:31 PM,
> >> wrote:
> >>
> >>> Chad having a small tuck to the belly on left rudder only,,
> >>> is always a result in a little too much tail weight ,,providing
> >>> the stab halves and elevator halves are correct.
> >>> thats whats happening in your wandering 4/5`s
> >>> the tail weight as is ,,is making you add a little down elevator
> >>> trim because the wing is flying a little more positive.
> >>> You want to create the pos angle of attack with the wing only use
> >>> the tail weight only to adjust the feel for rolls and inverted
> >>> flight.
> >>> engine thrust is contributory But ,not doing anything in the left
> >>> knife edge.
> >>> it would be happening in the right rudder too.
> >>> sorry Nat..
> >>> approach it like this, before you reset the down thrust ,,,because
> >>> we want to know what really fixed it
> >>> increase the wing inc 1/32 " more positive or till it stopps
> >>> pulling in the downline , some airplane require the wing more than
> >>> 1/2 deg depending on weight and airfoils 1/2 pos. is not a hard
> >>> deck and you will have to move the cg forward to remove the left
> >>> rudder knife mix ,,move it till you find a sweet spot , between
> >>> downlines and both knife edges.
> >>> , Always remember tail heavy makes the elevator and rudder
> >>> sensitive and nose wweightmakes them a little numb but much more
> >>> effective
> >>> your spins,snaps entry and exits ,, up and downline,45`s will be
> >>> corrected
> >>> you will also see improvement in the wind due to the forward c/g  
> and
> >>> pos inc. add pos wing inc till it stops pulling to the canopy in  
> the
> >>> downs
> >>> and let us know what happens
> >>> Bryan
> >>> darn now I have given away the family secrets ,And
> >>> I have just made it harder to beat Chad
> >>>
> >>> ---- Nat Penton wrote:
> >>>> Chad
> >>>> Your problem is caused by the large difference between T/L and
> >>>> wing. Reduce
> >>>> the downthrust by 1 deg and reduce the wing incidence by 1 deg ,
> >>>> and test.
> >>>>
> >>>> We will go from there.
> >>>>
> >>>> Your excess downthrust requires up elev trim when under power.  
> You
> >>>> need to
> >>>> adjust wing and T/L to avoid other problems. If you just lower  
> the
> >>>> wing inc
> >>>> it will go to the belly in knife. If you just reduce the D/T it
> >>>> will go to
> >>>> the canopy in
> >>>> knife. Nat
> >>>>
> >>>> ----- Original Message -----
> >>>> From: "Chad Northeast"
> >>>> To: "NSRCA Mailing List"
> >>>> Sent: Monday, March 10, 2008 4:57 PM
> >>>> Subject: Re: [NSRCA-discussion] the joy of trim
> >>>>
> >>>>
> >>>>> Ok you trim masters, here is a tricky one for you.
> >>>>>
> >>>>> Bryan and I have been through this a bit last year but I ran out
> >>>>> of time
> >>>>> before the Worlds to fix it and just flew with what I had.
> >>>>>
> >>>>> On my Twister I have this pesky problem, the setup is like so,
> >>>>>
> >>>>> wing = 1/2+ Bryans suggestion and I like it
> >>>>> stab = 0
> >>>>> motor = factory claims 2.5 down, have not measured but could if
> >>>>> asked, I
> >>>>> have added more to cure a problem see below
> >>>>> CG = has been anywhere from 275 to 300mm from TE mostly with the
> >>>>> same
> >>>>> result. Currently its around 285-290 and it feels good at that
> >>>>> point. 45
> >>>>> ups inverted track almost hands off if under enough power.
> >>>>>
> >>>>> Symptoms,
> >>>>>
> >>>>> Plane flies well, at this setup I need 0 mix right rudder to ele
> >>>>> in knife,
> >>>>> and about 2% up ele with left rudder in knife,
> >>>>> about 1/32" down elevator with idle to fix a downline
> >>>>> Added downthrust as the increase in wing inc. and more forward  
> CG
> >>>>> really
> >>>>> helped the mix in knife and made rollers easier, but forced an
> >>>>> increase in
> >>>>> downthrust as the plane started pulling to the canopy on  
> uplines.
> >>>>> Downline mix remained the same.
> >>>>>
> >>>>> The big problem I cannot resolve is this, a 45 deg down upright
> >>>>> (motor at
> >>>>> idle) the plane pitches to the belly and will not track on its  
> own
> >>>>> for any
> >>>>> length of time. If I switch the idle-down mix off its rock solid
> >>>>> on that
> >>>>> line.
> >>>>>
> >>>>> I am open to all suggestions now that I have a bit of time to  
> play
> >>>>> with
> >>>>> this, I hope Bryan chimes in some more as I would like to  
> continue
> >>>>> where
> >>>>> we left off last fall. If you suggest something I will do my  
> best
> >>>>> to give
> >>>>> it a go and let you know how it works (provided it doesn't  
> snow!)
> >>>>>
> >>>>> The plane is basically super locked in with this setup, except  
> for
> >>>>> the
> >>>>> silly 45 down upright, which is a problem in cubans and such.
> >>>>>
> >>>>> Comments and thoughts from the masters are most appreciated :) I
> >>>>> consider
> >>>>> myself one of the, cant really trim that well but can fly  
> through
> >>>>> it just
> >>>>> fine types :)
> >>>>>
> >>>>> Chad
> >>>>>
> >>>>> _______________________________________________
> >>>>> 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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> >>
> >> _______________________________________________
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>
> === message truncated ===
>
>
>
> Chris
>
>
>
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