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Old Jun 11, 2011, 03:58 AM
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Originally Posted by m_beeson View Post
Everybody likes to watch carnage these days. Enjoy

http://www.youtube.com/watch?v=DV36hjJciDk


If you watch the ailerons, you can see that I hold them in the right-bank position for about 5 seconds before I get any response.

Then I hold them in the left-bank position (trying to level it out) and it remains in a right bank.


Mike


p.s.

I'm settled down now a little, and not clouded with anger & frustration any more.

I'd like to figure it out though before I chuck this thing in the air again.

Has anyone else experienced these symptoms?

Does anyone have a stall-speed on this airframe?

I am wondering if I just tip-stalled d/t insufficient thrust & speed. I'm thinking about purchasing a more suitable motor.
If I were betting, I'd bet you had an aft CG. Where exactly is your center of gravity?? Looking at your video, if the CG was correct, even an underpowered motor will give you adequate flight control response assuming you are above stall speed (and I think you were well above stall speed.) I noticed as soon as you hand launched, the Skywalker took off nose high.

One other thought, make sure your wings and tail are parallel (same angle of incidence, if they aren't, that can mess up controllability too.
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Old Jun 11, 2011, 04:06 AM
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Netherlands, NH, Edam
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M_beeson,

Do you have any means of stabilization running? On the OSD, or maybe a gyro installed? Either way it helps to just make the plane nose heavy, give her lots of uptrim on launch and apply full throttle. Then with subsequent flights you can move the CG further back and hone in on the correct position for CG. A nose heavy plane will fly, a tail heavy plane is bound to crash.

Cheers,

Sander - ImmersionRC
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Old Jun 11, 2011, 04:22 AM
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Eastern side of Australia
Joined Jan 2007
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What is the agreed CoG position on a Skywalker?
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Old Jun 11, 2011, 04:23 AM
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Firatp's Avatar
Turkey, Istanbul
Joined Dec 2010
413 Posts
Hello
How weight is your Skywalker?

My one is 2,3kg with
4S 5000ma
3S 1800ma
2 extra flap servos
36-42 turnigy motor
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Old Jun 11, 2011, 04:33 AM
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Quote:
Originally Posted by Cralis View Post
What is the agreed CoG position on a Skywalker?
On the slots where the servo cable is inserted into, that's 80mm from the leading edge (front of the wing). Typically for these kind of straight wings CG can easily be calculated as being 33% of the width of the wing.

Cheers,

Sander - ImmersionRC
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Old Jun 11, 2011, 04:42 AM
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takeoff2's Avatar
Romania
Joined Jan 2009
244 Posts
After many attempts I reached the following conclusion about CG;


With CG at aileron wires:


takeoff:catastrophic

horizontal flight:good,whole range of throttle

landing:good



with CG 30mm behind aileron wires


takeoff:good

horizontal flight:good,30/100% throttle

landing: poor,seems tail heavy


Landing with no engine or motor less.

So,the truth is somewhere in between,depending on the particularities of each model.
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Old Jun 11, 2011, 05:00 AM
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cmanley_nl's Avatar
The Netherlands
Joined Jul 2010
500 Posts
Quote:
Originally Posted by Cralis View Post
What is the agreed CoG position on a Skywalker?
I have the CoG on the servo wire slot. I maidened mine recently with the elevator trimmed neutral and it flew perfect without any need for trim adjustments. I wouldn't place the CoG behind the servo slot (or behind 1/3 from the leading edge) and especially not during the first flights. It's good to have a reasonable amount of control throws on all the surfaces, especially aileron and rudder (perhaps in combination with 30% expo). You could also use rudder instead of just aileron next time to save it if it banks towards the ground. The yawing effect of rudder will also let you know if you have control or not.

Launching it with this CoG presented no problem at all in contrast to the "catastrophic" mentioned above.
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Old Jun 11, 2011, 07:03 AM
Chris R
United Kingdom
Joined Dec 2009
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Quote:
Originally Posted by Cralis View Post
What is the agreed CoG position on a Skywalker?
Got mine at 40mm back from servo wires, so 120mm back from leading edge.

Flights great and cruises at 5amps

BEVRC FPV Skywalker (8 min 36 sec)
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Old Jun 11, 2011, 09:25 AM
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m_beeson's Avatar
United States, UT
Joined Jan 2011
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Quote:
Originally Posted by ssassen View Post
M_beeson,

Do you have any means of stabilization running? On the OSD, or maybe a gyro installed? Either way it helps to just make the plane nose heavy, give her lots of uptrim on launch and apply full throttle. Then with subsequent flights you can move the CG further back and hone in on the correct position for CG. A nose heavy plane will fly, a tail heavy plane is bound to crash.

Cheers,

Sander - ImmersionRC
Sander,

I have the FY20A, and it was in the off postition, so no stabilization.


I found a Aileron hinge that was pulled from the right wing. Maybe it was there from the crash of the previous day.

One thing is for sure though, I will not fly it again, until I get the Thrust situation resolved

Mike
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Old Jun 11, 2011, 09:29 AM
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United States, UT
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Quote:
Originally Posted by thekubiaks View Post
One other thought, make sure your wings and tail are parallel (same angle of incidence, if they aren't, that can mess up controllability too.
Thank you kubiaks, I'll look at it.


I'm also thinking that it was too tail heavy for being underpowered, I think you are right.

I used to fly a trainer with a .25 nitro, and that had plenty of response, so I couldn't believe it when I got no response out of this

one. It has to be due to the aileron hinge that I found pulled out. It had to be from the previous test flights.

Mike
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Old Jun 11, 2011, 10:51 AM
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Quote:
Originally Posted by m_beeson View Post
Thank you kubiaks, I'll look at it.


I'm also thinking that it was too tail heavy for being underpowered, I think you are right.

I used to fly a trainer with a .25 nitro, and that had plenty of response, so I couldn't believe it when I got no response out of this

one. It has to be due to the aileron hinge that I found pulled out. It had to be from the previous test flights.

Mike

Priority one
if it were my Skywalker would be to make sure the CG (balance point) is on the servo wire channel. The plans call for the CG to be 75mm behind the leading edge, the forward edge of the servo wire channel is 78mm back on my Skywalker. I see that people are able to fly at up to 120mm back so there is a wide "envelope". In general, a more forward CG is more stable but a little less efficient. I would put the CG on the servo wire channel, get everything trimmed up, and then you can start moving the CG back in small increments if your really want to experiment. Since the Skywalker is molded EPO, I think that the wing/tail angle of incidence issue is not likely unless there was some gross building error.
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Old Jun 11, 2011, 11:09 AM
Whats the wrst that can happn?
AdamChicago's Avatar
Chicago, IL USA
Joined May 2010
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Here's one of my favorites so far...a little somber, but good

http://www.vimeo.com/24961942
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Last edited by AdamChicago; Jun 11, 2011 at 12:19 PM.
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Old Jun 11, 2011, 11:53 AM
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Originally Posted by AdamChicago View Post
Here one of my favorites so far...a little somber, but good

http://www.vimeo.com/24961942
Did you use a GoProHD mounted right out on the front of the platform near the nose?? Great video !!
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Old Jun 11, 2011, 12:18 PM
Whats the wrst that can happn?
AdamChicago's Avatar
Chicago, IL USA
Joined May 2010
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That's what I did...I actually cut the nose clean off in front of the canopy, mounted the GoPro to the top of the part that was cut off, then re-attached the nose but with layers of vibration deadening material (foam and moongel) in between.

Originally I was a little worried about having it on the nose where it could get damaged, but its in its protective case and probably 4-5 inches up from the ground on landing, and I haven't had any problems/damage yet...except for crashing into the lake but that's a whole other story

Quote:
Originally Posted by thekubiaks View Post
Did you use a GoProHD mounted right out on the front of the platform near the nose?? Great video !!
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Old Jun 11, 2011, 01:55 PM
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rsowder's Avatar
San Francisco
Joined May 2009
1,098 Posts
Keychain cam on Skywalker

I mounted a friends #11 keychain cam to the tail of my Skywalker with some velcro. The winds were gusting to 30mph, so it really shaky at first until I could get above the turbulence. Worked pretty well

#11 keychain camera test (4 min 31 sec)
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