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Old Jul 22, 2012, 09:13 AM
Whats the wrst that can happn?
AdamChicago's Avatar
Chicago, IL USA
Joined May 2010
2,667 Posts
Haha is that the same physics that allows the peddle on your bicycle to hold hundreds of pounds or is it the same physics that holds the red light poll 50ft out over the road attached to the top of the vertical base poll? Me thinks the physics support the vertical CF rod IMO What is needed however is some epoxy to hold it stable and make sure the CF doesn't grind away as it's being worked.


Quote:
Originally Posted by Daemon View Post
You'll get a lot more rigidity by adding light carbon stiffeners into the surfaces of the stab and/or
boom than you will linking together relatively small diameter round rods along their centerline.
It's basic physics.

ian
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Last edited by AdamChicago; Jul 22, 2012 at 10:12 AM.
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Old Jul 22, 2012, 09:55 AM
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Daemon's Avatar
Lakewood, Colorado
Joined Aug 2002
28,667 Posts
It's the same physics that uses large diameter lightweight thin walled tubes for both bicycle frames
and traffic light poles rather than small diameter heavy or solid ones. The rigidity goes up by the 4rd
power of the diameter or 3rd power of distance between the top and bottom of an I-beam.
On planes it's a lot easier to see the effect in wing spars for foam wings. Install one round carbon tube
the length of the wing in the center of the airfoil, or two small carbon ribbons
embedded edgewise in the top and bottom surfaces and you'll find that the two ribbons usually
produce many times the bending rigidity because of the much larger distance between them (virtual
I-beam) than the diameter of the tube or even a solid rod. The same applies when stiffening the vertical
stab (or any thick structure). We've been strengthening EPP combat planes and DS sailplanes this
way for a lot of years and it's well proven.

ian
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Last edited by Daemon; Jul 22, 2012 at 10:15 AM.
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Old Jul 22, 2012, 10:15 AM
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brifa's Avatar
ITALY
Joined Aug 2006
418 Posts
So are you saying that in my 2 skywalkers, the round carbon tube installed in the vertical stab (joined with the tail carbon tube) is not a great idea??? (Then i have also two external small carbon tube going from the fuselage to the horiz stab)...

Quote:
Originally Posted by Daemon View Post
It's the same physics that uses large diameter lightweight thin walled tubes for both bicycle frames
and traffic light poles rather than small diameter heavy or solid ones. The rigidity goes up by the 4rd
power of the diameter or 3rd power of distance between the top and bottom of an I-beam.
On planes it's a lot easier to see the effect in wing spars for foam wings. Install one round carbon tube
the length of the wing in the center of the airfoil, or two small carbon ribbons
embedded edgewise in the top and bottom surfaces and you'll find that the two ribbons usually
produce many times the bending rigidity because of the larger distance between them (virtual
I-beam). The same applies when stiffening the vertical stab (or any thick structure).
We've been strengthening EPP combat planes and DS sailplanes this way for a lot of years
and it's well proven.

ian
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Old Jul 22, 2012, 10:18 AM
Whats the wrst that can happn?
AdamChicago's Avatar
Chicago, IL USA
Joined May 2010
2,667 Posts
The difference in diameter between the peddle and sprocket arm on a bicycle and the vertical CF rod and boom CF rod are very similar, at least in the rods I have. They are hollow, however when filled and coated with epoxy the rigidity has to go up significantly. It's almost exactly the same concept as the bicycle peddle maybe only a little less efficient, but since IMO the Skywalker's looser tail hasn't been a performance issue, at least that I've detected, it will be a welcome improvement

Quote:
Originally Posted by Daemon View Post
It's the same physics that uses large diameter lightweight thin walled tubes for both bicycle frames
and traffic light poles rather than small diameter heavy or solid ones. The rigidity goes up by the 4rd
power of the diameter or 3rd power of distance between the top and bottom of an I-beam.
On planes it's a lot easier to see the effect in wing spars for foam wings. Install one round carbon tube
the length of the wing in the center of the airfoil, or two small carbon ribbons
embedded edgewise in the top and bottom surfaces and you'll find that the two ribbons usually
produce many times the bending rigidity because of the larger distance between them (virtual
I-beam). The same applies when stiffening the vertical stab (or any thick structure).
We've been strengthening EPP combat planes and DS sailplanes this way for a lot of years
and it's well proven.

ian
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Old Jul 22, 2012, 12:42 PM
Registered User
United States, IN, Carmel
Joined Jan 2008
2,558 Posts
Quote:
Originally Posted by RolandS888 View Post
15mm to as far as 30mm behind the servo wires.
Lose the up elevator trim completely, adjust your elevator throws to a small amount (+/-5mm) for normal rate.
Ian flys at 30mm, I find that a little tail heavy. Personal preference I suppose.
If you had heaps of up trim previously then I suspect you had it balanced too far forward, like on the servo wires.
Most probably it was balanced on the servo wires...

It does climb pretty nice under power though. What I have noticed in many pusher airframes is that if I balanced for level gliding with neutral elevator they tend to dive under power...

So the question is:
1) Do I want an airplane that glides level with neutral elevator and pitches over under power?
or
2) an airplane with positive (up) elevator that climbes under power?

What's best?

/Dimitrios
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Old Jul 22, 2012, 03:55 PM
Whats the wrst that can happn?
AdamChicago's Avatar
Chicago, IL USA
Joined May 2010
2,667 Posts
Ok here's my tail stabilization system...hope it works LOL. For lack of proper language the referred to "screw down" is the wooden piece at the top of the tail that the horizontal stab screws down into

A smaller vertical CF rod is slid through a whole drilled out of the boom CF rod. As this joint may weaken over time/use the inside and outside of the CF rods will be encased in epoxy to ensure solid link.

At the top the horizontal stabilizer has two wood spars going across the top surface. Two alum spaces will be epoxied up into the screw holes on the underside of the horizontal stabilizer. This will give it the ability of the horizontal stab to be screwed down to the solid wooden surface of the screw-down below locking it in tight with little lateral movement allowed.

So now the entire top of the vertical stab needs to be stabilized which will come from the long vertical CF rod that's attached down to the boom CF rod and a shorter CF rod that will be epoxied directly below and snugly up against the horizontal wooden screw-down.
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Last edited by AdamChicago; Jul 22, 2012 at 04:17 PM.
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Old Jul 22, 2012, 04:27 PM
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Shadrack's Avatar
Winnipeg
Joined Feb 2002
5,865 Posts
Is this plane that bad that it needs all this stabilizing and carbon fiber? I get how people want to make it better, but this isn't a 3D plane, or a pattern plane, so why does it need all this strengthening.
Isn't it version 6?
They still haven't gotten it right?
I just want a plane that I can build easily that will carry my fpv stuff.
This is an FPV plane, correct?
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Old Jul 22, 2012, 04:46 PM
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Teamsherman's Avatar
Australia, NSW, Picnic Point
Joined Aug 2011
6,890 Posts
Quote:
Originally Posted by Shadrack View Post
Is this plane that bad that it needs all this stabilizing and carbon fiber? I get how people want to make it better, but this isn't a 3D plane, or a pattern plane, so why does it need all this strengthening.
Isn't it version 6?
They still haven't gotten it right?
I just want a plane that I can build easily that will carry my fpv stuff.
This is an FPV plane, correct?
I totally agree mate!

This will carry your stuff and carry it well. If people want full on hardcore flying with loops rolls and all other G force inducing tricks then why not buy a plane designed for that reason? Its like tricking out a school bus with a huge V12 motor, rims and lowered suspension then trying to race it on a F1 track!!!

Fly it like its meant to carry your gear and see the sights while doing so and it will be fine. I've put some pretty high unnecessary forces on it and it's still flying to this day!
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Old Jul 22, 2012, 05:11 PM
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Shadrack's Avatar
Winnipeg
Joined Feb 2002
5,865 Posts
That is what I thought.
I want to cruise around, up high, and far away.
I don't fly in hurricane conditions so don't need something that strong.
I understand something thin in the wings past the cf rod, but more than that, like all the work on the tail, just has to be unnecessary.
Great analogy Teamsherman...tricked out school bus.
If I want to fly 3d, I'll fpv my Yak 54.
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Old Jul 22, 2012, 10:54 PM
Whats the wrst that can happn?
AdamChicago's Avatar
Chicago, IL USA
Joined May 2010
2,667 Posts
The SW does not need all of this stabilization, this is a personal project for experimentation sake. I currently have an awesome SW with nothing in the tail except a little epoxy around the top and a balsa spar across the horizontal stab. Had an extra SW body lying around for spare parts and since the current one is 3 seasons old and beginning to show signs of wear thought I'd rebuild.

While a slightly floppy tail had almost no negative effects on my flying (check out my videos) it was personally kinda annoying, and since many struggle with the floppiness I decided to take the challenge and try to stabilize it.

My current SW is around 3.7KGs with batts and I like to fly fast and out over the lake, so some extra stabilization in the derriere seemed like a good idea for the new fuse.

And yes it's heavy and much of that is due to full FPV, GoPro in case, 5800 4S, Scorpion 3020, 70amp ESC, CCPro BEC and probably too much glue and tape...but she flies like a corporate jet...smooth!

Quote:
Originally Posted by Shadrack View Post
Is this plane that bad that it needs all this stabilizing and carbon fiber? I get how people want to make it better, but this isn't a 3D plane, or a pattern plane, so why does it need all this strengthening.
Isn't it version 6?
They still haven't gotten it right?
I just want a plane that I can build easily that will carry my fpv stuff.
This is an FPV plane, correct?
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Last edited by AdamChicago; Jul 22, 2012 at 11:14 PM.
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Old Jul 23, 2012, 02:58 AM
The way of being is doing.
IMEIV's Avatar
Italia, Emilia Romagna, Ravenna
Joined Apr 2009
434 Posts
Quote:
Originally Posted by Shadrack View Post
There are a ton of configs on here IMEIV if you search. Probably 2 forums that have the distribution of the fpv equipment on the plane.
Just make sure that you have the vTx far away from the receiver.
That is most important.
Other than that, you are kind of limited as you need the gps on an osd have access to the sky, so that mounts on top.
Thanks but it's a little difficult to search in 1004 pages. Anyway I will search...
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Old Jul 23, 2012, 03:05 AM
Flying Zayin
Cathay Stray's Avatar
China, Guangdong, Guangzhou
Joined May 2012
914 Posts
Quote:
Originally Posted by AdamChicago View Post
3.7KGs
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, 03:07 AM
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joel0407's Avatar
Australia, NT, Lyons
Joined Oct 2010
544 Posts
Quote:
Originally Posted by IMEIV View Post
Thanks but it's a little difficult to search in 1004 pages. Anyway I will search...
Do what I did. While I gathered my parts and saved the cash, I browsed every page right from the begining.

It's also worth while just checking out the gallery.

Happy Days.
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Old Jul 23, 2012, 03:26 AM
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asaak's Avatar
Joined Mar 2012
147 Posts
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!
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Old Jul 23, 2012, 05:17 AM
If it's to be, it's up to me.
subsonic's Avatar
Sydney, Australia
Joined Jan 2007
3,091 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!
Those will be the wrong length. all the pushrods are different lengths around 80mm.

If you don't like the stock pushrods, get these:
http://www.hobbyking.com/hobbyking/s...idProduct=9887
and these:
http://www.hobbyking.com/hobbyking/s...idProduct=8416

You will need to make a z bend at one end. Makes for a very solid connection IMO.

Sub.
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