Lumenier RB2205C-12 2400KV SKITZO Ceramic Bearing Motor
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Old Feb 26, 2013, 09:03 PM
francoishaha is offline
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radian 4700
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Still under construction, maiden planned for this week end.
I set the CG 1/2" behind the leading edge of the wing for the maiden... i hope this will be right. I need to make some air intake for the motor and it's ready to go!


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Old Feb 26, 2013, 09:48 PM
crazy1pilot is offline
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What goes up, must come down
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Should add a canard!I hope it flys as good as it looks

Crazy1
Old Feb 26, 2013, 10:12 PM
ggtronic is offline
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AP-stick
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Originally Posted by francoishaha View Post
Still under construction, maiden planned for this week end.
I set the CG 1/2" behind the leading edge of the wing for the maiden... i hope this will be right. I need to make some air intake for the motor and it's ready to go!
video
Old Feb 26, 2013, 11:59 PM
CrashAffinity is offline
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Crashaffinity on youtube
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Quote:
Originally Posted by francoishaha View Post
Still under construction, maiden planned for this week end.
I set the CG 1/2" behind the leading edge of the wing for the maiden... i hope this will be right. I need to make some air intake for the motor and it's ready to go!
damn that is a purdy plane!
Old Feb 27, 2013, 12:37 AM
baconflyer is offline
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cheapskate extroardinairé
oooooh, seeeeeexy! looks like it will be nose heavy tho, maybe some canards are in order? either that or chop the nose down a bit. 1/2" seems pretty nose heavy to me.
Old Feb 27, 2013, 08:38 AM
francoishaha is offline
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radian 4700
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I made a .25 scale of the plane and made gliding test. Yes my plane is nose heavy, but experience tell me that i prefere a nose heavy trimmed up rather than a tail heavy for the maiden. And i go with the flow, i will put a canard.
Old Feb 27, 2013, 09:12 AM
TigerPilot is offline
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The CG is not 'dependent' on the nose length. The CG depends on the wing design. I've never heard of a main wing with a CG of less than ~25% - 33%. At 1/2" from leading edge CG I think you'll need an elevator the size of mount Everest!
Old Feb 27, 2013, 10:03 AM
francoishaha is offline
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radian 4700
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Originally Posted by TigerPilot View Post
The CG is not 'dependent' on the nose length. The CG depends on the wing design. I've never heard of a main wing with a CG of less than ~25% - 33%. At 1/2" from leading edge CG I think you'll need an elevator the size of mount Everest!
I check the funjet cg and it look realy close to the leading edge...
Old Feb 27, 2013, 12:10 PM
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2^p - 1
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Unless your wing is rectangular, it's incomplete to describe 'cg at 25%' or worse 'CG at 2in from LE'.
CG should be described at a percentage of MAC. For typical planes, 25% of MAC is a good estimate. For deltas, flying wings and others, it may not be.
Old Feb 27, 2013, 12:21 PM
baconflyer is offline
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cheapskate extroardinairé
can you give us the dimensions of the wing? then we can help you with the cg. it looks to me like you have about an 8" chord, which means 1" from the leading edge would be a 12.5% cg, meaning you will be using constant up elevator. this will increase drag (reducing both top speed and efficiency) and also you will have to land very, very fast so as not to run out of elevator for the flare. I would recommend 2" back as a good starting place, then move it rearwards from there until it is a little too tail heavy for your liking, then move it forward a little bit. at this point, it should fly level at neutral elevator. good luck!
Old Feb 27, 2013, 12:36 PM
francoishaha is offline
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radian 4700
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Originally Posted by baconflyer View Post
can you give us the dimensions of the wing? then we can help you with the cg. it looks to me like you have about an 8" chord, which means 1" from the leading edge would be a 12.5% cg, meaning you will be using constant up elevator. this will increase drag (reducing both top speed and efficiency) and also you will have to land very, very fast so as not to run out of elevator for the flare. I would recommend 2" back as a good starting place, then move it rearwards from there until it is a little too tail heavy for your liking, then move it forward a little bit. at this point, it should fly level at neutral elevator. good luck!
The wing have 43in wing span 12in root chord and 6.5in tip chord, zero sweep.
Old Feb 27, 2013, 12:42 PM
Shadrack is offline
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Mini Obsessed
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Originally Posted by francoishaha View Post
Ggtronic, awsome video btw.
I remember the nose ripping of ur polaris, in fact i was watching it from my fatshark google hehe, suddently a bunch of tree apear and then we heard a crack in the wood :-)
We were watching from the side. I remember how dark it was when he crashed.
Old Feb 27, 2013, 01:02 PM
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Originally Posted by francoishaha View Post
The wing have 43in wing span 12in root chord and 6.5in tip chord, zero sweep.
This is just one of many CG calculators I found Googling.
http://www.friendlyflyers.org/cg-calc.html
Here's the output from your wing dimensions and a 25% MAC:


I believe 25%MAC is still on the nose heavy end of the typical range. Hope it helps.

Cool looking plane by the way. Any details on construction technique, payload, components?
Old Feb 27, 2013, 02:08 PM
chanyote66 is offline
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Mobius Cables... I got em'
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Originally Posted by TNug View Post
This is just one of many CG calculators I found Googling.
http://www.friendlyflyers.org/cg-calc.html
Here's the output from your wing dimensions and a 25% MAC:

I believe 25%MAC is still on the nose heavy end of the typical range. Hope it helps.

Cool looking plane by the way. Any details on construction technique, payload, components?
25% MAC as nose heavy??? for such a short wingbase that would be light... And create a more sensitive flight characteristic. I personally would start around 20% and work back as desired.
Old Feb 28, 2013, 07:42 PM
HawkHunter is online now
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Psalm 37:4
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Originally Posted by crazy1pilot View Post
Should add a canard!I hope it flys as good as it looks

Crazy1

+1..........A canard would be a good thing!


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