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Old Jul 23, 2012, 05:30 AM
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helichoper's Avatar
Australia, SA, Adelaide
Joined Nov 2006
538 Posts
Quote:
Originally Posted by asaak View Post
Hi guys!! I am planning to buy better pushrods that the stock ones for my new skywalker. Do you think this are going to be good choice?

http://www.hobbyking.com/hobbyking/s...0_mm_5pc_.html

if not, can you recommend me good pushrods/klevis for the control surfaces please?

thanks so much!
Way over kill with 3mm rods --i just use the stock ones and they are fine--HK have some 2mm push rods if you wanted to go that large and you can find linkage stoppers and Clevises there as well.

http://www.hobbyking.com/hobbyking/s...0pcs_set_.html
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Old Jul 23, 2012, 08:55 AM
Whats the wrst that can happn?
AdamChicago's Avatar
Chicago, IL USA
Joined May 2010
2,652 Posts
The 5800 4S goes almost 40 mins.

Quote:
Originally Posted by Cathay Stray View Post
That's quite some weight! Especially for 168 cm wings.
How long does the battery last with this setup?
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Old Jul 23, 2012, 09:03 AM
Outta Sight
Australia, WA, Joondalup
Joined Jul 2008
929 Posts
8000 4S goes over an hour, with a little gliding.
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Old Jul 23, 2012, 11:18 AM
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mauromassari's Avatar
Brasil, CE, Fortaleza
Joined Jun 2011
1,100 Posts
Quote:
Originally Posted by brifa View Post
thanks Mauro
but will it have some effects on fy31??

anyway it really difficult to have cg at 25 mm behind the servo wire with a gopro and a fpv camera on the nose.... (4s 5000mah and 3s 1800 mah for the fpv stuff,..)
Actually this will solve the problem of going down with throtle over 50% and then you can let Fy31 do the job with centered links...

Mauro
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Old Jul 23, 2012, 12:23 PM
Whats the wrst that can happn?
AdamChicago's Avatar
Chicago, IL USA
Joined May 2010
2,652 Posts
IMO the Skywalker is pretty flexible in terms of CG. Sometimes I fly a 3600 4S and sometimes a 5800 4S and while it handles a bit different it flies great and enjoyably so with both. If your CG is somewhere within an inch or so of the servo line don't sweat it. Plus there's always a way to adjust CG later...move the batteries slightly, move equipment, use different size batteries add a weight etc
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Old Jul 23, 2012, 12:29 PM
Whats the wrst that can happn?
AdamChicago's Avatar
Chicago, IL USA
Joined May 2010
2,652 Posts
Here's my Skywalker wish! I wish they would produce a main wing that wasn't so reactive to roll. I watch a lot of Skywalker videos and they have a characteristic constant rolling left and right. I'm no aeronautical engineer but I'd imagine a wing that has a tapering chord and thickness would help...at the same or a shorter length.

The new wings available don't seem to help in these regards since they're just longer and thicker which make them even more reactive to roll than the standard wing.
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Old Jul 23, 2012, 12:40 PM
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Daemon's Avatar
Lakewood, Colorado
Joined Aug 2002
28,488 Posts
It rolls in response to turbulence because it has a lot of effective polyhedral.
In addition to the small dihedral break in each wing, any time
the wing is well above the true center of mass of the plane it
has the same effect as adding polyhedral. Even if you completely
straightened the wing, it would still do it. This is why some
full scale high mounted wing aircraft actually have anhedral,
to minimize this effect. The most roll stable planes have
straight wings, and the center of mass directly in line with the wing,
or a little bit of dihedral and CM above the wing (think warbirds).

ian
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Last edited by Daemon; Jul 23, 2012 at 01:45 PM.
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Old Jul 23, 2012, 12:46 PM
Yeah Baby
bignose13's Avatar
Joined Apr 2006
1,394 Posts
New Pod with pan and tilt here
http://www.rcgroups.com/forums/showthread.php?t=1697449
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Old Jul 23, 2012, 01:55 PM
Whats the wrst that can happn?
AdamChicago's Avatar
Chicago, IL USA
Joined May 2010
2,652 Posts
Interesting, I wondered about how the polyhedral played into it...whether it helped or hurt.

I've actually straightened out most of the polyhedral in my wing so it's probably rolling less than most but still more than I like. But this gives me some direction to work towards...thx.


Quote:
Originally Posted by Daemon View Post
It rolls in response to turbulence because it has a lot of effective polyhedral.
In addition to the small dihedral break in each wing, any time
the wing is well above the true center of mass of the plane it
has the same effect as adding polyhedral. Even if you completely
straightened the wing, it would still do it. This is why some
full scale high mounted wing aircraft actually have anhedral,
to minimize this effect. The most roll stable planes have
straight wings, and the center of mass directly in line with the wing,
or a little bit of dihedral and CM above the wing (think warbirds).

ian
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Old Jul 23, 2012, 05:24 PM
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Joined May 2005
1,185 Posts
Hi, I need some help on the COG.
my cog is 1-3cm behind the servo wires (have been playing around back and forward)

When I fly it now and release every stick and throttle off, the skywalker goes into a stall, and then fall down, up in a stall and then fall down.... this does not happen so fast, it glide pretty well, but not perfect.

Should I add more weight on the back or in the front ?


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Old Jul 23, 2012, 06:01 PM
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Daemon's Avatar
Lakewood, Colorado
Joined Aug 2002
28,488 Posts
Quote:
Originally Posted by liteglow View Post
Hi, I need some help on the COG.
my cog is 1-3cm behind the servo wires (have been playing around back and forward)

When I fly it now and release every stick and throttle off, the skywalker goes into a stall, and then fall down, up in a stall and then fall down.... this does not happen so fast, it glide pretty well, but not perfect.

Should I add more weight on the back or in the front ?


Give it a bunch of downtrim. When it's near optimal CG, the trailing
edge of the elevator surface should be 2-3mm below the trailing
edge of the horizontal stab. This is because the horiz stab is
mounted with negative angle of incidence (leading edge lower
than trailing edge) so it's like it's already flying around with
a bunch of up elevator. This works ok when you've got
a nose heavy plane, but with CG closer to center of lift,
need to counter the stab incidence with some downtrim.
(or shim the front of the stab to change the angle of incidence).

ian
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Old Jul 23, 2012, 06:08 PM
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Joined May 2005
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Quote:
Originally Posted by Daemon View Post
Give it a bunch of downtrim. When it's near optimal CG, the trailing
edge of the elevator surface should be 2-3mm below the trailing
edge of the horizontal stab. This is because the horiz stab is
mounted with negative angle of incidence (leading edge lower
than trailing edge) so it's like it's already flying around with
a bunch of up elevator. This works ok when you've got
a nose heavy plane, but with CG closer to center of lift,
need to counter the stab incidence with some downtrim.
(or shim the front of the stab to change the angle of incidence).

ian
Thank you.

But I`m scared that if I have to much downtrim, it will either go down or straight UP when giving full throttle ? (this did happen in my first flight, but maybe that was because of to much movement on the elevator)
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Old Jul 23, 2012, 06:22 PM
Registered User
Joined May 2005
1,185 Posts
Some interesting interactive java stuff at nasa to play with :
http://www.grc.nasa.gov/WWW/k-12/air...tunnl2int.html

I found it after googling some of the new words from Daemon haha
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Old Jul 24, 2012, 03:57 AM
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rcimports's Avatar
South Africa
Joined Oct 2005
1,570 Posts
Quote:
Originally Posted by liteglow View Post
Thank you.

But I`m scared that if I have to much downtrim, it will either go down or straight UP when giving full throttle ? (this did happen in my first flight, but maybe that was because of to much movement on the elevator)
Just do it

I was allso reading Ian's posts thinking "35mm behind servo wires, that crazy!!"

Until I tried it, some down trim, CG about 32 behind wires, now glides alot better, just limit you're elevator throw, it's much more sensitive like this,

Dion
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Old Jul 24, 2012, 05:13 AM
Foam Snow
South Africa, WC, Cape Town
Joined Aug 2011
1,326 Posts
Quote:
Originally Posted by liteglow View Post
Thank you.

But I`m scared that if I have to much downtrim, it will either go down or straight UP when giving full throttle ? (this did happen in my first flight, but maybe that was because of to much movement on the elevator)
To live in fear, is not to live at all

Besides, you need something to do when the weather is off!
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