[NSRCA-discussion] triangulation trimming
Ron Van Putte
vanputte at cox.net
Wed Mar 12 04:28:23 AKDT 2008
Me too.
Ron Van Putte
On Mar 11, 2008, at 11:54 PM, <shinden1 at cox.net> wrote:
> I`m all for it
> Bryan
> ---- Matthew Frederick <mjfrederick at cox.net> wrote:
>> Chris and Bryan,
>>
>> I'd be happy to help edit this for a K-Factor issue. Since I fly
>> with Bryan
>> I have a good insight to his thought process, and it would be easy
>> for me to
>> clean this up.
>>
>> Matt
>> ----- Original Message -----
>> From: <shinden1 at cox.net>
>> To: "NSRCA Mailing List" <nsrca-discussion at lists.nsrca.org>
>> Sent: Tuesday, March 11, 2008 10:05 PM
>> Subject: [NSRCA-discussion] triangulation trimming
>>
>>
>>> 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 <G> 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 <see my 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 <G>
>>> 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 <donramsey at gmail.com> 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, <shinden1 at cox.net> <shinden1 at cox.net>
>>>> 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 <G>
>>>>>
>>>>> ---- Nat Penton <natpenton at centurytel.net> 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" <chadnortheast at shaw.ca>
>>>>>> To: "NSRCA Mailing List" <nsrca-discussion at lists.f3a.us>
>>>>>> 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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