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Old Jul 14, 2012, 07:07 PM
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subsonic's Avatar
Sydney, Australia
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Quote:
Originally Posted by brifa View Post
I have a problem with my new skywalker v4... when i fly it with the .cg 25 mm behind the servo wire (my 4s lipo is near the nose - no fpv stuff at moment) well the model goes with the nose up, with throttle and without.. elevator perfectly centered.. using the fy 31 balanced mode keeps it levelled but when in rc manual model it goes with the nose up.. i don t understand..
Did yo trim the model? As Daemon explaned before, with the CG in the correct position (105 to 115mm from the LE) you will need some down trim in the elevator. Sounds like your model is plain old out of trim?

Sub
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Old Jul 14, 2012, 07:08 PM
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Lakewood, Colorado
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Yes, as I just got done explaining in quite some detail, twice, if the CG is back where it is closer to
optimal you need to add some visible DOWN TRIM to counter the natural negative incidence
angle of the horizontal stab. You'll actually see the elevator surface below center.
If you don't, then it will pitch up quickly as the airspeed increases, including and especially
when you're on the throttle (blowing more air over the tail). The way to get the trim correct is
get it up high, throttle off, and push it into a moderate dive (not too steep), and then take your
hand off the stick. If it pitches up quickly, dial in some down trim. Repeat until it doesn't pull
up quickly. If it always pulls up going fast, and drops the nose going slow, then you need
to move the CG back more and repeat trimming steps.

ian
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Old Jul 15, 2012, 02:44 AM
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brifa's Avatar
ITALY
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Thank you
but using the radio trim... which effec will i have on the fy31 behaviour??

Quote:
Originally Posted by Daemon View Post
Yes, as I just got done explaining in quite some detail, twice, if the CG is back where it is closer to
optimal you need to add some visible DOWN TRIM to counter the natural negative incidence
angle of the horizontal stab. You'll actually see the elevator surface below center.
If you don't, then it will pitch up quickly as the airspeed increases, including and especially
when you're on the throttle (blowing more air over the tail). The way to get the trim correct is
get it up high, throttle off, and push it into a moderate dive (not too steep), and then take your
hand off the stick. If it pitches up quickly, dial in some down trim. Repeat until it doesn't pull
up quickly. If it always pulls up going fast, and drops the nose going slow, then you need
to move the CG back more and repeat trimming steps.

ian
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Old Jul 15, 2012, 02:58 AM
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Lakewood, Colorado
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Quote:
Originally Posted by brifa View Post
Thank you
but using the radio trim... which effec will i have on the fy31 behaviour??
Firstly you should be doing the trimming with the FY unit turned off with the mode switch.
Otherwise it will get in the way.
Secondly, once you trim and re-power everything, FY unit will treat power-on trim as center.
However, what's even better is to trim it in the air, land, measure how much elevator
deflection you have, then center the radio trim, and move the position of the elevator mechanically
by screwing in the clevis, till it matches the deflection you measured.

ian
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Old Jul 15, 2012, 03:22 PM
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Thanks Ian
coming back from the field... i did what you said and this is the result:
i moved the position of the elevator mechanically by screwing in the clevis
now when i fly with rc manual model it flies well at a moderate speed, if i take off my hands from the stick it has a little nose up, but just a little...
with fy31 ap in ABM mode it flies really well at moderate speed but when i give throttle it pitches down, goes with nose down..
any advice??
(cg at 30 mm behind servo wire - moved from 25 to 30 mm)
thanks

Quote:
Originally Posted by Daemon View Post
Yes, as I just got done explaining in quite some detail, twice, if the CG is back where it is closer to
optimal you need to add some visible DOWN TRIM to counter the natural negative incidence
angle of the horizontal stab. You'll actually see the elevator surface below center.
If you don't, then it will pitch up quickly as the airspeed increases, including and especially
when you're on the throttle (blowing more air over the tail). The way to get the trim correct is
get it up high, throttle off, and push it into a moderate dive (not too steep), and then take your
hand off the stick. If it pitches up quickly, dial in some down trim. Repeat until it doesn't pull
up quickly. If it always pulls up going fast, and drops the nose going slow, then you need
to move the CG back more and repeat trimming steps.

ian
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Old Jul 15, 2012, 04:26 PM
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It should pitch down if you throttle up hard, because thrust line is above center of mass
but should be able to increase it gradually and stay level. If you're over powered (pushing
say 60mph) then you'll have to move the CG back forward a little and take out some of that downtrim, as at
high speeds this airfoil will always want to pitch forward and you need more st. If you're flying that fast, it's going
to suck the battery down quick though.

ian
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Last edited by Daemon; Jul 15, 2012 at 05:22 PM.
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Old Jul 15, 2012, 05:09 PM
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Ok thanks
just last question: a turnigy plush 60 amp is good for a skywalker with 4s and fpv stuff (bevrc motor)??


Quote:
Originally Posted by Daemon View Post
It should pitch down if you throttle up hard, because thrust line is above center of mass
but should be able to increase it gradually and stay level. If you're over powered (pushing
say 60mph) then you'll have to move the CG back forward a little, as at high speeds this airfoil
will always want to pitch forward. If you're flying that fast, it's going to suck the battery down quick though.

ian
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Old Jul 15, 2012, 05:22 PM
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Should be more than enough, but I don't fly 4S (lower current, but may be pushing motor harder).

ian
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Old Jul 16, 2012, 02:45 AM
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rcimports's Avatar
South Africa
Joined Oct 2005
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Quote:
Originally Posted by brifa View Post
Ok thanks
just last question: a turnigy plush 60 amp is good for a skywalker with 4s and fpv stuff (bevrc motor)??
I use the Turnigy Plush 60A under the wing with no heat issues, seperate BEC

Cheers
Dion
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Old Jul 16, 2012, 04:18 AM
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Quote:
Originally Posted by brifa View Post
Ok thanks
just last question: a turnigy plush 60 amp is good for a skywalker with 4s and fpv stuff (bevrc motor)??
depends how many amps u r pulling

running a 9*6 i ran high on amps on full throt with 4s, so went with a 70a esc

but then i proped down and only ran 40a

if u have a wat meter, you'll b able to determine

but i do like a higher amp esc, as it doesn't have much aeration in that little cavity ;-)

it can take the payload anyway ;-)

..
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Old Jul 16, 2012, 04:20 AM
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Originally Posted by subsonic View Post
Could it be your wing bands are too loose causing the wing to lift out of the saddle at high speed?

What is your experience like as pilot? Were you flying FPV?
i dont use the stock bands, but when i did... i put 2 knots in them...

they are just too lose for the SW ;-)


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Old Jul 16, 2012, 04:26 AM
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Originally Posted by liteglow View Post
first flight with my Skywalker today:



Not what I had expected :\

Did some more flights and I got it in the air flying perfectly..
But there is a bug!!

Maybe to sensitive aileron, but also when I give full throttle and use my aileron the skywalker goes straight UP and stall, then fall straight down again !!!

Any ideas?
hang in there mate

its a great air frame. just work your basics and it'll be working fine soon.

check all your elecs etc..

trust me... she flies great...

FPV'n Around - Kill tha Bixler .... (2 min 19 sec)


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Old Jul 16, 2012, 07:11 AM
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Brasil, CE, Fortaleza
Joined Jun 2011
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Quote:
Originally Posted by PMRfly View Post
hang in there mate

its a great air frame. just work your basics and it'll be working fine soon.

check all your elecs etc..

trust me... she flies great...

http://vimeo.com/44973487

.
Nice hit, are you using GoPro2 and with mode wide, normal or zoom? Nice clear colors!!!!

Mauro
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Old Jul 16, 2012, 07:13 AM
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Brasil, CE, Fortaleza
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Quote:
Originally Posted by brifa View Post
Thanks Ian
coming back from the field... i did what you said and this is the result:
i moved the position of the elevator mechanically by screwing in the clevis
now when i fly with rc manual model it flies well at a moderate speed, if i take off my hands from the stick it has a little nose up, but just a little...
with fy31 ap in ABM mode it flies really well at moderate speed but when i give throttle it pitches down, goes with nose down..
any advice??
(cg at 30 mm behind servo wire - moved from 25 to 30 mm)
thanks
I had the same issue and what I did is a little mix with throtle and elevator, so when you give throtle the elevator make the adjustments, just a very little percentage will do the job. This is my 2 cents ideia.

Mauro
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Old Jul 16, 2012, 03:17 PM
wep
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"crashed" my skywalker.......

Well, it actually made half of the flight totally on it's own cause I lost all (read ALL) power...
Think the main accu connection was loose.... (not sure yet)

Crash skywalker ..... Lost all power but nice gliding but then..........bad bad luck. (2 min 15 sec)


99% land.....1% water in the neighbourhood....AAHH
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