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ZN Twister Building

Old 02-23-2006, 09:35 AM
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can773
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Default ZN Twister Building

Just thought some of you might like to follow along as I finish up my new ZN Twisters. Electric of course

http://www.rccanada.ca/bb/viewtopic.php?t=21543
Old 02-23-2006, 09:58 AM
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MHester
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Default RE: ZN Twister Building

Nice thread Chad!!!!! Excellent work, I can't wait to see them. Will you be bringing them to the US Nats this year?

-Mike
Old 02-23-2006, 11:28 AM
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olivierq
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Default RE: ZN Twister Building

Hello

beautiful construction !!!
I have also Twister (ZN line) visible here http://oquellier.free.fr/twister.html

By
Old 02-23-2006, 11:29 AM
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olivierq
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Default RE: ZN Twister Building

.
Old 02-23-2006, 12:30 PM
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Rune
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Default RE: ZN Twister Building

Hi you Twister builders and fliers!
i have about 10 fligths on mine at this time.
i have some trimming difficulties .... it goes to the belly in knife e. and the CG is placed at ca 31 cm from the T.Edge that is 4 cm in front of the place that zn has placed it .
it also dive pretty hard when i give it rudder at level fligth and climb in inverted.
i have the onepiece wing version so the wing should have the rigth angel off attack I also have to trim some down elevator (the elevartor is also wery sensetiv).
maybe i'm stupid but the down trim, elevator senesetivity and the K.E problem tells me to move the CG more forward but .
any thoughts or experience on this plane someone????
Rune
Old 02-23-2006, 02:09 PM
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Adamg-RCU
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Default RE: ZN Twister Building

Climbs inverted? That is _way_ tail heavy. You are trimmed with lots of down elevator to hold the tail up in level flight, so it climbs inverted and pushes in knife edige.
Old 02-23-2006, 02:30 PM
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can773
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Default RE: ZN Twister Building

ORIGINAL: Rune

Hi you Twister builders and fliers!
i have about 10 fligths on mine at this time.
i have some trimming difficulties .... it goes to the belly in knife e. and the CG is placed at ca 31 cm from the T.Edge that is 4 cm in front of the place that zn has placed it .
it also dive pretty hard when i give it rudder at level fligth and climb in inverted.
i have the onepiece wing version so the wing should have the rigth angel off attack I also have to trim some down elevator (the elevartor is also wery sensetiv).
maybe i'm stupid but the down trim, elevator senesetivity and the K.E problem tells me to move the CG more forward but .
any thoughts or experience on this plane someone????
Rune
Hi Rune

I would double check your incidences with the stab set to 0....something doesnt seem right...CG at most should be 270-280 from the TE.

How much downtrim are you carrying?
Old 02-23-2006, 02:41 PM
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Rune
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Default RE: ZN Twister Building

well i just back from checking indiences!
so i had ca -0.5 -0.75 deegreds at the stab ..here i must have made i wrong at the fisrt .......ehhhhhh
but ...Adam ...its not tail heavy...the cg is in front off the recomended and also in front off the normal 33-35 % at the middel off the wing,dont relly know how to say it i english(mean cord??)that should give it a dive and + elev.trim (as it had) and climb in inverted..well i give it a try tomorrow after work!
and Chad ..i had ca 3mm down trim ..not much but enough to notice it when model was standing on the ground!
Rune
Old 02-23-2006, 09:03 PM
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Default RE: ZN Twister Building

Double check the wing incidence also. You can always shimmed the wing saddles.

Adrian
Old 02-23-2006, 09:43 PM
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can773
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Default RE: ZN Twister Building

ORIGINAL: Rune

well i just back from checking indiences!
so i had ca -0.5 -0.75 deegreds at the stab ..here i must have made i wrong at the fisrt .......ehhhhhh
but ...Adam ...its not tail heavy...the cg is in front off the recomended and also in front off the normal 33-35 % at the middel off the wing,dont relly know how to say it i english(mean cord??)that should give it a dive and + elev.trim (as it had) and climb in inverted..well i give it a try tomorrow after work!
and Chad ..i had ca 3mm down trim ..not much but enough to notice it when model was standing on the ground!
Rune
Hi Rune

No you are right that should not be tailheavy balanced that far forward. Use your incidence meter to set the stab to 0, then check the wings...they should be slightly positive (0.25-0.5 is what the plans say)...and the motor should be -2.5 degrees. For reference the tailpost in this condition is inclinded back at 6 degrees, that is another way to get everything leveled out.

My guess is that the incidences are way off.
Old 02-23-2006, 09:44 PM
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can773
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Default RE: ZN Twister Building

ORIGINAL: MHester

Nice thread Chad!!!!! Excellent work, I can't wait to see them. Will you be bringing them to the US Nats this year?

-Mike
Of course! Already registered and vacation booked
Old 02-24-2006, 08:30 AM
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Default RE: ZN Twister Building

Hi, together with Nathan of Znline france we came up with these angles....

Good starting point....

Winfried
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Old 02-24-2006, 10:13 AM
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jamesjoneill
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Default RE: ZN Twister Building

This is all good stuff! Thank you!!! I will be doing the final set up on my Twister this weekend before covering the wings to complete the plane, so knowing the angles is very helpful.

James
Old 02-24-2006, 11:40 AM
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Rune
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Default RE: ZN Twister Building

hi again !
first thanks for good help answering!
was out had 4 pretty nice flights weather was sunny and just over zero ..didn't even get cold on the fingers!!life is great!
well..i didn't get any drawings with my Twister but i see now that my stab was way off ...pretty stupid i should done better but !
the K.E is much better but still needs some mixing rudder to positive elevator ,no rudder to ailerons so fare.
this indicates for what i learn many years ago that (in the Curare age) we should move the cg forward so we could trim more positive ..OK?
but when i let it dive vertical it has a tendency to pitch out towards the cockpit..that tells me to move it back to get more negative trim ?
is there any one else out there that have flown the Twister and experience the same thing?or has any solution...know that someone talking about Imulse from BM models has the wing to high in the fuse and that can give the same effect,some kind off aerodynamic unbalance in the layout off the fuse
Old 02-24-2006, 11:54 AM
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jamesjoneill
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Default RE: ZN Twister Building

Rune,

it seems to be a common behaviour of many of the modern f3a planes that they pitch down in knife edge, my Alliance does it and I have heard of quite a few other people who have experienced it. If you are now happy with the incidences, I would set the cg by flying it inverted, and also in a vertical dive. When you are happy with that then just dial out the rudder-elevator coupling with the radio.

glad to hear you are getting there with your plane, give me a week and hopefully I will have flown mine too!!

James
Old 02-24-2006, 12:09 PM
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Rune
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Default RE: ZN Twister Building

James!
if you just flies it its shes delight to fly .
I just thoght that when you buy a kit like this it should not had this problems..even my old Temptation hanst ..only a few % to correct it !
but i have to move the cg back wards again to prevent this other things.
but to get planes like this to fly as you wish takes some fligths and sometimes your change things even after many flights!
Old 02-24-2006, 07:22 PM
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Default RE: ZN Twister Building

Rune,

Almost all fixed gear planes pulls to the belly, the landing gear is doing the pulling. Also, on a long straight down line, most plane pulls to the canopy also, the thrust no longer plays a role. And if you have slight pos wing incidence, it should pull to the canopy.

Just dial in a little rudder to ele, and off throttle to down ele mix. As long as it is not excessive, no big problem there.

Adrian
Old 02-24-2006, 10:08 PM
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Default RE: ZN Twister Building

ORIGINAL: riot3d

Double check the wing incidence also. You can always shimmed the wing saddles.

Adrian

It's a 2 piece wing - not a one piece wing.
Old 02-24-2006, 11:11 PM
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Default RE: ZN Twister Building

Derek, the Twister is produced in both two piece and one piece wing versions.
Old 02-24-2006, 11:55 PM
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Default RE: ZN Twister Building

Rune has the one piece wing version
Old 02-25-2006, 11:34 AM
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Rune
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Default RE: ZN Twister Building

hi!
yes i have the one piece wing type!
could a counter balanced rudder fix this problems with rudder to negative pitching?? both my Temptaion and my old Onyx(Focus 1) didn't had this much mixing as i can recall!
well i have reduce some off the weight i the nose not sure exact where the cg is now but closing in to 28 cm from LE i think...and also add some negative ele. to idle!
so if possible i fly again after work tomorrow[>:]
Old 02-25-2006, 11:57 AM
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Default RE: ZN Twister Building

ORIGINAL: Adamg-RCU

Derek, the Twister is produced in both two piece and one piece wing versions.

Oops... I saw the pics - made an ass"umption" out of me. [8D]
Old 02-26-2006, 01:31 AM
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Default RE: ZN Twister Building

Rune,

What is the percentage on your rudder to elevator mix? Anything within 5% is nothing, up to 10% is not that big of a deal. Over 13% then you starting to notice some other problems.

Using counter balanced rudder will definitely reduce the workload of the servo, but not necessary will reduce your rudder to elevator mix. I don't know how much rudder throw you are using, and whether you have duel rate on your rudder.

I programmed a duel rate on my throttle stick, when it hits right below half throttle, the rudder duel rate kicks in. My full rudder under duel rate will barely holds the nose of the plane in knife edge flight, and usually only needs 4% to 6% of down elevator mix.

I suggest you start everything from scratch. Make sure your stabs are zero, and wings are slightly positive (between 0.25% to 0.5%). Also, ensure the CG is correct, not just on the ground but also in the air for both upright and inverted flight. Do some trim path to ensure all moving surfaces are flush, otherwise, either adjust the stabs or shim the wing saddles. Usually, problems are relatively easy to fix. If it persits, then, it might be the design of plane - location of canopy, landing gear, or difference between wing and stabs location.

Good luck, keep us posted.

Adrian
Old 02-26-2006, 12:00 PM
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Rune
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Default RE: ZN Twister Building

One more time, thanks for helping and answering!
this should maybe not be under this tread at all but my hope was that maybe other Twister owners\flyers also had some experiences with the plane,but it seems that i is one off the first that have flown it!
Been out today after work ..not really a good trimming day some wind but tried the plane one flight anyway!
yesterday i adjust 1\2 turn more on my stabs not really sure how much thats influence on the agels but it should be closing in to 0,25 compare to the wing soon(the wing is also 0,25 positive) maybe i can give it a 1\2 turn more.
So to the trows on the plane i have 13 mm up and 15 mm down elevator , ca 35 degreed rudder and ailerons..not sure ..but thats not an issue here ..( they suits me!)all this is low rates and the snap roll mode has the same rudder but a bit more elevator and so much ailerons that is possible!
I have put on 4% down to idle(used curved mix mode and only on the lowest point) that helped a lot on the down line , on rudder to elevator also a curved mix and its 5 % , 10%, and 15% this seems to be right with the cg the planes holds now.
i have at this point added 50 gr in the nose (under the engine an OS 140 rx so you with YS will not experience this if you build as heavy or light as me) the 2300Mah 5 cells Nmh battery is placed on a plate that runs from the front wing support to the firewall.
My plan with the plane is to repaint the fuse (not happy with the scheme)and build a new rudder (frame up one)and save a few grams that maybe let me remove the lead in the nose.
so for you that are planning to use a OS in the Twister that is no problem with the power off the engine , i have a Greve pipe and use a 18x10 apc sport , nice combo, only thing its not very good room for the carb. in the Twister .
Old 02-26-2006, 01:20 PM
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Default RE: ZN Twister Building

Rune, is the Twister more power hungry than the last plane you flew with the 140RX?

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