Feb 26, 2013, 08:03 PM
radian 4700
francoishaha's Avatar
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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Feb 26, 2013, 08:48 PM
What goes up, must come down
crazy1pilot's Avatar
Should add a canard!I hope it flys as good as it looks

Crazy1
Feb 26, 2013, 09:12 PM
AP-stick
ggtronic's Avatar
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!
video
Feb 26, 2013, 10:59 PM
Crashaffinity on youtube
CrashAffinity's Avatar
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!
Feb 26, 2013, 11:37 PM
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.
Feb 27, 2013, 07:38 AM
radian 4700
francoishaha's Avatar
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.
Feb 27, 2013, 08:12 AM
Registered User
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!
Feb 27, 2013, 09:03 AM
radian 4700
francoishaha's Avatar
Quote:
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...
Feb 27, 2013, 11:10 AM
2^p - 1
signflyer's Avatar
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.
Feb 27, 2013, 11:21 AM
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!
Feb 27, 2013, 11:36 AM
radian 4700
francoishaha's Avatar
Quote:
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.
Feb 27, 2013, 11:42 AM
Mini Obsessed
Shadrack's Avatar
Quote:
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.
Feb 27, 2013, 12:02 PM
Waypoint Collector
TNug's Avatar
Quote:
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?
Feb 27, 2013, 01:08 PM
Mobius Cables... I got em'
chanyote66's Avatar
Quote:
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.
Feb 28, 2013, 06:42 PM
Psalm 37:4
HawkHunter's Avatar
Quote:
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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