rmh

LIBBY is now 8 yrs old a bit prematurely grey but otherwise fine.

UStik

Indeed that's pointless since it's trivial, and it wasn't my point. That Brushfire/Integral thing is not an exception that proves the rule but a counter-example. Do you really mean the Integral as kitted and set up as recommended by Jason Shulman won't be competitive? So I'd be taken for a fool as an innocent customer, fall victim to clever marketing? And do you really think that Brushfire did not fly knife-edge hands-off without mixes (as Dick said)? Even though it had a bit dihedral as a mid-winger, and even though Integral is not a true mid-winger but has no dihedral? Wow! I'm screwed up again. Still awaiting the rationale...

rmh

I didn't mention the Brushfire's hands off character
BUT
Any of our old fashioned overweight models could be trimmed for a nice straight knife edge
Why? they flew fast and that provided the lift needed for predictable flight in knife edge
Sometimes we had to re do dihedral but basically -getting the cg sorted out , did what was needed
Trimming is just a common sense approach and doing each fix -one at a time
No mystery
My ZLINS had 3" thrust line to wing cl spacing - yet they rolled as well as any model and were extremely easy to setup for pattern.
A Cap is another example of wide spacings -yet can be setup for very smooth , predictable aerobatics

MTK

Add the Arrow to that list. Not as wide a spacing as the Zlin but wide enough at around 2". Many of yesterday's models placed the wing much lower on the fuse than current models, as I stated before. Intgeral is one exception with its wing lower.

It's no big deal and in fact a lower wing offers an increase in effective side area, good for knife edge. Wing vertical placement is no biggie regardless of where it is placed

And FWIW, Shulman's Integral was no different than anyone else's....it had a small adverse roll couple as all the other, unmodifeid Integrals do. Remember talking with him about that 3 or 4 years ago at the US Nats. Bryan helped him fix the problem (I think)....same fix I suggested to him. Some Integral owners now go straight for a new set of wings with added dihedral and it's done.

This isn't rocket science

rmh

I once did a model with a tube going fore and aft at the center of the wing ( Jason had two of these)

rmh

I once did a design (Jason had two of these) with a tube for and aft at the center of the wing
The tube dia was same as max wing thickness -
Anyway - the wing dihedral OR relative panel incidence could be altered by simply slicing and rejoining the top of the tube.
The tuned pipe went thru the tube
Tho it all worked - I found that most users found getting the pipe installed was just too much fiddling
Going to seperate panels was ultimately more popular.
The advances in kits RTF is now such that some purchase a model with servos installed and all you do is add a few bits n pieces .
It's no wonder trimming has become a chore for some - they never had the chance to learn the basics.
To me- learning by doing was a great part of flying

DagTheElder

Very interesting debate this thread, however, can manufacturer of pattern planes accomodate the specifications mentioned herein. Example, 25% CG and 25%static margin. My experience with purchased planes is that a rebuild is neccesary. Some have too large stabs and some are too heavy in tail to obtain balance at 25%. Even when the stab area corresponds to the static margin at 25%. Hence CG will go forward and static margin will increase and loosing parts of its agility.

Guys excuse me, but i think parts of the trimming prosedures published need a tiny rework to add in some of this. The worst cases re. CG and SM will be impossible to remedy without rework.

Best wishes to all!

DagTheElder

rmh

For years - many ARF products wer very tailheavy - a matter of quick n dirty construction
You buy em - YOU fix em
recent products are much better
afte you are certain the plane is STRAIGHT and solid
setup a zero zero zero as a baseline - then balance to aprox 25% and fly -it - THEN make adjustments .
Some guys never check to find exact angles in the ARFS and get frustrated trying to trim em
I "put together " ARFS for people as the occasion needs and the new stuf is MUCH better.

flyncajun

Dag,
Be carfull of the advise you get on this Thread
If you set it at 0-0-0 you wont be able to set the c/g at 25%
Because,you will be nose heavy your airplane will pull like a beast in a upline,and downline!
however, you won`t pull to the belly on knife edge ,,that would be cool HUH!

Dick ,you crack me up
Bryan

DagTheElder

In my previous post I mentioned that purhased planes had some defects, attached you find my design criteria/rebuild spec for Qigris C1. By flying it no adjustment was nessary staight from table, however, the fuselage and the modified tail is still to heavy so another stab and rudder are made approx 50gr lighter than the current one.

If all goes well details in attached pics.



rmh
setup a zero zero zero as a baseline - then balance to aprox 25% and fly -it - THEN make adjustments

Iguess you have a procedure you follow to make adjustments. Can you share this with us?

Best wishes to all!

DagTheElder

Sorry, but gren dot=CG red dot=Static margin, Green diamond=CG at MAC.

rmh

Procedure I use is same a 90% of the successful aerobatic guys use -

1 get it straight - really straight -first
Then determine how much built in incidence /angles were done -on purpose or accidentally
Then using standard technique for derermining MAC- setup a CG of about 25% don't worry if it isn't exact but get close .
Some self appointed experts claim certain angles will work for all planes - they won't.

Fly n try for an easy to handle upright / inverted flight .
adjust nothing but cg to get this
Depending on your speed tastes -you may find a bit of elevator trim is necessary
You may also find that your radio setup is just too sensitive or too dull to get this feel correct.
Again make sure that everything measures zero zero for roll and yaw -
This takes a bit of watching for spiralling in loops or a yawing in perfectly level zero wind flight.
The business of hands off thrust line setting thrust offset can now be played with
Use which ever "expert" advice you want to determine this .
I usually find nothing but a bit of right thrust is needed in a good design.
Friends who are national winners over the years all have different preferrences here - really -
Having built planes for these guys -I have gotten lots of feed back on what works - and the opinions are quite varied.
You can not ever get perfect hands off up n down at same power speed settings
Close but that's it ( laws of nature prevent this .)
gravity is the reason here.
anyway find the compromise which feels good for you .
Just because yoursetup is not what someone else likes - don't worry -
You will have your own feel which is most comfortable for you.
I don't do trim charts - etc too much opinion here - not enough fact.
Years back -I found some trimming problems were simply the radio- vague response , looseness etc..
I am glad I crack up some guys - at least they are happy.

DagTheElder

rmh,
Thank you for detailed answer!
One ting thou, how do you trim for zero pitching when deflecting rudder?

Regards

flyncajun

Dag,
I`m the so called expert Dick is refering to- and yes I`m happy all the time
Please,
Start with Dicks methods, which is really a "cop out " But you wont be happy, no specifics as usual because I have cornered his replys , after they don`t work And BTW you just got Dicks" trim chart", the only one he ever used. except he left out down thrust for uplines.

Please report back to the list,But.
This is what you will find with Dick`s methods.
A pull to the canopy in the uplines ( no matter what speed).
A big pull to the canopy in the downlines requiring 15% mix.
A pull to the belly on left rudder knike edges.
The right rudder might be ok but prob pull to the belly as well.
And Up elevator trim requiring you to adjust negative in the stab to level the elevator halves to the stab (basicly Up elevator)

(WHere do you think the up line pull comes from )

Next he will advise you to move the c/g back a little ,,or adjust negative thrust in the engine to compensate for the upline pull, fine.
This will make all unloaded wing flying worse ,,except for up lines ( the thrust helps only here) requiring more mix every where else.

Dag.
Go read My #13 post and set the airplane up correctly.
Then if you want to trim like a World Team Member and, if you want further trimming ,use my complete method for perfection here.
http://hebertcompetitiondesigns.com/triangulation.aspx

BTW I am the one responsible for trimming the Xigris through helping the "Canadian National Champion" and Multi time World Team member,Chad Northest I also helped him trim his ZN line Twister, and his Integral you can read about it on my website here.
http://hebertcompetitiondesigns.com/triangulation.aspx
ZN line now sets there Xigris up at the factory Close to my Spec.

Go Ahead,waist your time and use Dicks Method or,
get it right the first time ,But please report back to the list your findings.
You will find dick will be out of advise when his method above does not fix your problems however ,
(other than the two this I already told you he will say) these Are the only adjustments he uses.

Bryan

rmh

How Bryan knows how I ultimately set up a model is a mystery to me .
As I noted - there are many opinions and what is good for some is no good for others
"waist" your time as it suits .
Dag -how do I trim for pitching when rudder is applied ?
This is related to CG setups so watch out!
Some models will NOT trim out of this characteristic
Some will do it increasingly as more rudder is applied
Some are very good at doing litle pitching as rudder is applied
The reason why the pitch with rudder is applied is pretty simple
A yaw (away from straight flight ) , sets up a loss in in the balance of the stabilizing forces which hold the wings at the desired angle of attack .
Usually -this is because the horizontal stab develops less downforce during the yaw.
Sometimes this is due to blanking of one side of the stab.
Redoing the hinge line of the rudder is sometimes used as a band aid - not too effectively
Perhaps others have a fix
I don't
I found that lateral area placement and the vertical location of area in the fuselage really affect this
Of course -I found this thru making various foam fuselages and prooving what force layouts really did what in yawing maneuvers
other self appointed experts may have a fix for this issue on any design - I don't

flyncajun

Dick I noticed you did not say ,,(thats not what I would have told him) or, offer advise on how to get his airplane from yawing with rudder application.

I know because we have been debating this between the two of us since 1998 I have them all,
you can also just look on RCU and see what you have already said ,however you have changed your oppinions on some things
and have leaned in my direction.

it`s easy to deflect and say "some planes just can`t get rid of it" it`s ,,blame it on spiral airflow ,down wash,slip stream, or design.
Experiance tells how to fix it.

I also know from Many years of experiance fixing airplanes set up with the 0-0-0 method how to fix um ,it`s why I can predict what will happen with your method. ,,Dick just try my method and to prove me wrong and learn.
Dag,
To get the yaw out use my method, the "so called expert"

Bryan

rmh

Bryan - -you apparantly have the answers to this problem - let's see them
As for me following your approaches?
Gee -Idid not know that anyone had the authorship to any trimming setups - I always just did what was needed or used which compromise gave the best results
By they way - it is all compromise - unless you are working in a zero gravity field.

da Rock

Both approaches have been covered. And covered again. And again.

You two undoubtedly could go on forever, but not here.

talk the torque

Hi Bryan

I have read you article before and it is a very interesting read. I have not read all of this thread but just a few of the posts. I hear what you are saying about trimming and agree with pretty much all you say.

I have another way of trimming and am not saying its better and am not trying to debate that or argue it. I would like you to give me some of your opinions and even suggestions if you like. I started pattern many years ago and was from a small club and had no outside input from the larger more competitive clubs. Personally I think this was an advantage for me as I looked at trimming planes from a different perspective rather than what goes on with the everyday pattern pilot.

Ok here goes, firstly I have been trimming my planes to fly as accurate as I could for about 18 years now. I realised not having to fight the plane allowed me to focus on complex maneuvers and also had this interest to see if I could succeed with trimming my planes. As I had no input from anyone else I really felt I needed planes that are as symmetrical as possible and that my flying style should be as well. By this I mean I hold as much up to fly level as I do down to fly inverted. I dont trim the plane to fly level as most pilots do and I think its because thats how they are taught. I changed my trimming style when I got interested in aerobatics, might sound weird but its actually very comfortable flying like this. I fly close to 25% CG and is where I start off with my CG. I totally agree a fwd CG is the way, gives better directional stability, better in turbulent weather and recovers better from spins and snaps. Ok now here is where it gets tricky... I fly 0 - 0 - 0.... now before you start throwing things at me hear me out I have got plenty of planes trimmed out really well, up lines, down lines, slow and fast KE, power off, power on etc.

Firstly I always try get a mid wing plane or as close as possible (not always possible with pattern planes but the wind S pro looks nice for me), it suits my style of setup and I prefer them. Preferably motor, wing and stab in line. I know guys will say what about the wing turbulence on to the tail but I have never had any issues with that. I think the secret here is that I'm not trying to make the plane fly level with a 0 - 0 - 0 setup but rather produce no lift when I release the sticks. Another way to think of it is my wing produces 0kg of lift where as if it flies close or level at hands off then it is producing around 4 - 5kg of lift on a patternship. My plane will drop off in similar fashion whether its upright, inverted or KE until an input is given. Now when it comes to KE, up lines and down lines I have no lift to counter as I'm producing no lift. I think this is also why my setup works best with mid wing type planes where the drag, thrust and vertical CG are in line. I think that the lower wing designs have evolved because of the average way pilots trim their planes to fly straight and level. The asymmetrical shape from a KE perspective helps to compensate the trim given for level flying lift.

Some advantages I feel I have is. If I alter CG fwd or back or fly at different altitudes I dont have to re trim the plane again for level flight which will change all other trims. I very seldom use any differential for ailerons (Mid wing planes that arent trimmed to produce any lift will roll very axially).

I am most certainly up for using your trim methods, especially if it is not a mid wing plane. The high engine low wing type of plane designs I do trim those similar to how you have described.

Regards TtT

pimmnz

Bryan, I'm interested in how you would remove yaw when using rudder...
Evan, WB #12.

MTK

Geeeeeezzz,

You two boys still at it

speedracerntrixie

My Feedback: (29)

Tell me about it Matt. I do have to say that it seems that with Rich's approach he realizes and is telling us that all airplanes are going to trim slightly different, to listen to the airplane and let her tell you what she needs and that it is all a compromise. In my 34 years of flying just about everything I have to say I agree with that approach rather then the " Do it my way or else it will fly like crap" brow beating.


Truth be told 90% of R/C pilots are flying poorly set up airplanes.

talk the torque

I dont understand.... this is my first post ever? [X(]

charlie111

You really have to set the trim ounce in flight.If your plane is not flying straight and levelOr you'll have your hands full just flying it never mind manuevers.You can get it close with a straight edge running from stabilizer and over the control suface.Everything should be nuetral.Good Luck

speedracerntrixie

My Feedback: (29)

Didn't take long to get my last post confirmed LOL

protectedpilot

Just wondering, what was the last pattern plane you trimmed? What were the symptoms, what were the results?


Libby isn't watching me, she's licking herself. And you.