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Mixing for KE help.

Old 06-03-2007, 07:46 PM
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Backwing
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Default Mixing for KE help.

I need to do a little mixing for better knife edges, but won't it always mix everytime I use the rudder which could mess up other maneuvers?
Old 06-03-2007, 07:58 PM
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folker
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Default RE: Mixing for KE help.

what radio do you have?

you should be able to assign your mix to a switch so that you can turn it off and on
just like you do for low and high rates

i have found that i dont like using mixes for helping with KE and such
i think its better to just fly it issues out
makes you a better pilot because you have to react to what the plane is doing
also you run the risk of forgeting to turn the mix off

hope this helps

jim
Old 06-03-2007, 08:08 PM
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folker
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Default RE: Mixing for KE help.

also i find that if i spend the time to trim my planes out for hands free upright and inverted flight
many of the issues with KE go away
i allways expect to have to input a little aleron in KE, but find if the plane is trimed out and balanced properly
that i have to use very little if any elevator


jim
Old 06-03-2007, 09:59 PM
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Backwing
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Default RE: Mixing for KE help.

I've got a Futaba T6XAs. I figured I could put it to a switch, but I see what you mean about forgetting to turn it off.
Old 06-03-2007, 10:31 PM
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tIANci
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Default RE: Mixing for KE help.

Backwing - I used to think of that too ... so it means I need a to be able to switch the mix on and off, recently in Fly RC magazine they stated that if you plane needs mix in KE then you will need it each time you execute a manuever with the rudder, seemingly its very obvious. Hence, if Fly RC is correct then there is no need to use a switch. BTW, what happens when you use the rudder in a KE, is it only a pitch issue? If so you can always play with the CG to sort it out before you mix it.
Old 06-03-2007, 11:18 PM
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Default RE: Mixing for KE help.

Your radio isn't good enough to do KE mixing either.
Old 06-04-2007, 08:16 PM
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Longaly
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Default RE: Mixing for KE help.

RYGUY,

Sorry, but you are incorrect about the 6XAS not being able to mix. I just did a mix on mine for KE pitch coupling, but in order to accomplish this, you need to asign the aileron, elevator and rudder dual rates to the Ail D/R switch. In doing so, you free up the Elev. D/R switch for 2 more programable mixes, PMx2 and PMx1.

BACKWING,

If you have the 6XAS manual( mine is fairly old so I'm not sure if the page #'s will match yours ), page 39 details combining the Dual Rate switches, and pages 35 & 36 detail the programable mixes. I also have a good link to the Futaba FAQ section for the 6XAS.

http://www.futabarc.com/faq/faq-6xsuper.html

It takes a little experimentation to get the mix just right, i.e. right amount of elevator input, but it can be done. Believe me, if I can do it, you should have no problem. If you have any questions, just reply and I'll run through it with you as best I can.


Longaly

p.s.

With the mix being assigned to a switch, it is selectable as in ON or OFF. Also, my aircraft was pushing HARD to the belly, yet my mix percentage was quite low, -7 & +7. Make sure you move the rudder stick full in each direction to see and change the percentage of mix. I hope this doesn't confuse you, I was at first, but look at the manual and the above referenced web site and all questions should be answered.

p.s.s.

FOLKER is right, a properly set up aircraft should take care of most coupling problems. Get with a pattern guy in your club and he will be able to help you with the sometimes tedious and lenghty process of properly triming your plane.
Old 06-04-2007, 11:17 PM
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Default RE: Mixing for KE help.

Sorry, I was looking at the wrong radio on Tower. I thought you meant the 6EXAS. I can't find a 6XAS.
Old 06-05-2007, 01:29 AM
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andy86na
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Default RE: Mixing for KE help.

Removing pitch or roll KE coupling will improve fying characteristics of the plane for all maneuvers.

What happens in KE in your case? Most likely your plane pitches to the belly. What happens if you apply rudded in the straight level flight? I bet is starts diving, doesn't it? Removing KE coupling will help with that unwanted 'dive' with pure rudder input. Beginnign to see the picture?

You should generally shoot for 'pure innuts'--e.g. left rudder input turns plane left, without seeing the nose dive, etc. See here for the comprehensive trimming process: http://www.wtp.net/DBEST/trimchrt.html. Follow the chart--don't start mixing out KE coupling right away, it's only a small part of the pricess. It takes time but will result in a much, much better flying plane.

Now, trim on low rates may not be the same as trim on high rates. That is, trimming for IMAC may be slightly different that trimming on 3D rates. However, if you are not competing you probably don't care. Just trim for the type of flying you most often do.
Old 06-05-2007, 03:53 AM
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Default RE: Mixing for KE help.

No problem RYGUY. The 6XAS is an earlier model of the 6EAX. And as stated by folker and andy86na, a properly set up aircraft will fly much better and will most likely take care of any coupling. I chose to take the easier, less time consuming way out. I should however, properly set up my plane!
Old 06-05-2007, 10:45 AM
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Default RE: Mixing for KE help.

Great, thanks for all the help. I did go back and fing that article in Fly RC.
I'll go and do some serious set up flights before I do anything with the radio.
Old 06-05-2007, 11:31 AM
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Default RE: Mixing for KE help.

Backwing - its in the May 2007 issue ...
Old 06-05-2007, 02:28 PM
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folker
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Default RE: Mixing for KE help.

id like to add that it might be a time consuming process of triming and balancing the plane out properly
but when you have a plane that is completely hands off inverted and upright, on up lines and dives ect,

many things that you do with the plane become much easer

such as.. you will find that learning rolling circles or slow rolls are much easer because you only really have to input a little rudder in each direction when the plane is
passing through the KE portion of the maneuver
its much easer to learn this way because you for the most part only have to learn the timing of the rudder at first
then go back later and start using the elevator for the high alfa rolling stuff

the first thing that i do with all my 3D planes is get the CG right
if you roll inverted and the plane climbs than you are tail heavy

also a tail heavy plane will "tuck" to the gear and require up elevator to correct when in KE
nose heavy will "tuck" to the canopy and require down elevator to correct in KE
a tail heavy plane might hover easer but a properly balanced plane will fly almost everything else better

hope this helps

jim
Old 06-05-2007, 02:59 PM
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Longaly
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Default RE: Mixing for KE help.

Well said folker, well said. I guess I had better get busy!
Old 06-05-2007, 03:07 PM
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Backwing
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Default RE: Mixing for KE help.

When checking balance upright and inverted on straight and level flight, where should the throttle be? Half, full, or won't it matter once properly balanced.
If it help's, I'm flying an Airfoilz Yak-54 with a Scorpion 2215-18.
Old 06-05-2007, 03:41 PM
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folker
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Default RE: Mixing for KE help.

it will matter to some degree
for myself its half to 3/4 throttle when triming out
but its up to you
if you fly everything WOT then trim WOT
most areobatics are flown at half to 3/4 on a 3D plane though

also should mention that just because your plane is properly trimed and balanced
doesnt necessarily mean that all your coupling issues will go away
and ive had planes that i couldnt get to trim out in everyway
sometimes this can be accounted for with thrust angle

ive had some airframes that like down+ right thrust, some dead center
when you factor in thrust angle things can become very frustrating
a small change in thrust angle can really change the way a plane flys and trims out for that matter
also changing to a diffrent pitch/ diameter prop can make a big difference in the way a plane flys and or trims out


jim
Old 06-15-2007, 10:49 AM
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jamesjoneill
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Default RE: Mixing for KE help.

A completely neutral plane is almost impossible to get - even the latest greatest F3a models will need some mixing to fly right in all conditions.

If the plane is built straight and the cg is in about the right place, the rest must be done with mixes - this is normal and isn't "cheating" like some people think. If your plane tends to roll left slightly, you re-trim it to the right don't you? No-one would fly around having to hold in trim. Mixes are no different.

James

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