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Old Oct 28, 2012, 04:40 PM
chuck
santa barbara, CA
Joined May 2009
3,770 Posts
amx cg recommendations.

well i finally got of my butt and finished my amx .

set up is tailerons only , lots of travel. 4cell 1000 40c sky lipo driving stock motor w/ a balanced and clearenced stock 5 blade .

i have read here that the cg can be run a ways back from the stock call out, 3.5 to 4.2" back from the intake lip. 3.5 looks way to far forward? any info on your final cg's would be appreciated. cool little jet.

tia , chuck.
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Old Oct 28, 2012, 04:51 PM
Registered User
Vienna, Austria
Joined Apr 2007
1,801 Posts
Quote:
Originally Posted by chas650r View Post
...
i have read here that the cg can be run a ways back from the stock call out, 3.5 to 4.2" back from the intake lip. 3.5 looks way to far forward?
I just went back w/ CG to the rearward end of the recommended range (some 4.1")
and I found flying characteristics improved a lot - don't start with 3.5", it makes
launching unnecessarily difficult, and landings are a bit hot with the forward CG
You'll like it, it's fast :-)
PS: Will go further back with a lighter RX (half the weight of the ORANGE RX is
the thick plastic case, that has to to now)
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Old Oct 29, 2012, 05:15 AM
we can take off without that
green_flyer's Avatar
London, UK
Joined Nov 2008
695 Posts
I agree too. I maidened my AMX last week, 2 years after I built it (it was waiting for my flying skills to improve). My CG was 10cm from intake lip - thanks to Joe who posted the CG guide.
Despite my extra weight of 352g (50g of plastic sheeting ) it hand launched fine with this CG, and I would probably say a tiny bit nose heavy, so it could probably go back a couple of mm.
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Old Oct 29, 2012, 09:21 AM
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Sunnyvale
Joined Feb 2009
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Quote:
Originally Posted by chas650r View Post
well i finally got of my butt and finished my amx .

set up is tailerons only , lots of travel. 4cell 1000 40c sky lipo driving stock motor w/ a balanced and clearenced stock 5 blade .

i have read here that the cg can be run a ways back from the stock call out, 3.5 to 4.2" back from the intake lip. 3.5 looks way to far forward? any info on your final cg's would be appreciated. cool little jet.

tia , chuck.
I First flew it with the set up that you are using and it went awesome! The CG worked best at the mark that they list in the manual. The same that Joe 1320 says. It is light and nimble with that set up! Tailerons work the best with this plane or like I set it up. Just be careful with the roll rates. Even with the tail only it can spin like a top! I currently fly mine just a hair ahead of where is says in the manual but am using a heavier 55mm AEO 8 blade fan, 40amp esc, UBEC and 3s 25c 1550mah pack. It is heavier but is a bullet! Love the way this thing flies!
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Old Oct 29, 2012, 10:25 AM
chuck
santa barbara, CA
Joined May 2009
3,770 Posts
ok guys now you really have me confused

my book cg works out to the 3.5" back from the lip, so is that what u are saying , 33?

listed in joe's cg info , 3.5- 4.1" ??

thanks for the warning on the roll rate, being taileron only i set some big rates, maybe its not needed. or lots of elevator and easy on the roll?

anyway , cg is the only thing i really worry about , i can mess w/ the rates after surviving the maiden

chuck.
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Old Oct 29, 2012, 10:41 AM
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Sunnyvale
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Quote:
Originally Posted by chas650r View Post
ok guys now you really have me confused

my book cg works out to the 3.5" back from the lip, so is that what u are saying , 33?

listed in joe's cg info , 3.5- 4.1" ??

thanks for the warning on the roll rate, being taileron only i set some big rates, maybe its not needed. or lots of elevator and easy on the roll?

anyway , cg is the only thing i really worry about , i can mess w/ the rates after surviving the maiden

chuck.
I will get the manual and take a pic. I don't measure. I go by the CG mark in the plans. I never measure and all of my planes fly wonderful! LOL But thats just me.....let me measure and get back to you. And I will do it in MM's...
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Old Oct 29, 2012, 10:44 AM
chuck
santa barbara, CA
Joined May 2009
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thanks 33.
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Old Oct 29, 2012, 02:16 PM
Registered User
Vienna, Austria
Joined Apr 2007
1,801 Posts
need help w/ F-16 build

Finally putting my airframe kit together - maybe someone can give me advice
how to strenghten the horizontal stabs, the surface area of the one-sided
glue joint (to the fuse) seems insufficient. Bracing it with a piece of carbon
rod on the other side, e.g.?
thanks in advance
Clemens
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Old Oct 29, 2012, 04:26 PM
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gooniac33's Avatar
Sunnyvale
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Quote:
Originally Posted by mopetista View Post
Finally putting my airframe kit together - maybe someone can give me advice
how to strenghten the horizontal stabs, the surface area of the one-sided
glue joint (to the fuse) seems insufficient. Bracing it with a piece of carbon
rod on the other side, e.g.?
thanks in advance
Clemens
No need for carbon. Just glue it in place. There are some places that don't have glue that could use some. Also you will want to brace the control rods going to the elevator. I will take a pic of how I did it. But I uses a servo arm to do this. Have seen other peoples jet fall out of high speed turns and pull ups because of the rod bowing under load...

I have had mine for almost 2 years and it has been flown a lot! it is doing 90+mph and never once had an issue...
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Old Oct 29, 2012, 05:46 PM
Registered User
Vienna, Austria
Joined Apr 2007
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thanks Gooniac, that was very reassuring! No need for a picture of the control
rod bracing, I have seen that on some pics or videos here on the thread (on
a MiG-15, I think), using control horns glued to the fuse, with the rod going
through one of the holes...
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Old Oct 29, 2012, 09:07 PM
chuck
santa barbara, CA
Joined May 2009
3,770 Posts
or a bit of c/f tubing slipped over the rod works well also.
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Old Oct 30, 2012, 11:37 AM
Registered User
Vienna, Austria
Joined Apr 2007
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Quote:
Originally Posted by chas650r View Post
or a bit of c/f tubing slipped over the rod works well also.
Good idea, should get some tubes! Pretty much done with the build, it was
a lot of work:
Put the Haoye 7-blade rotor in the shroud of a 6-blade 50mm fan, motor is a
Turnigy 2610 w/ 3600kV (around 17 amps on a fresh 3s battery, low timing).
Didn't get it to balance too well, left out the spinner and it's better now. At low
revs there is a vibration howl, but if I am lucky there will be a nice sound at higher
loads - that was the idea at least...
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Old Oct 30, 2012, 01:02 PM
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Sunnyvale
Joined Feb 2009
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Quote:
Originally Posted by mopetista View Post
Good idea, should get some tubes! Pretty much done with the build, it was
a lot of work:
Put the Haoye 7-blade rotor in the shroud of a 6-blade 50mm fan, motor is a
Turnigy 2610 w/ 3600kV (around 17 amps on a fresh 3s battery, low timing).
Didn't get it to balance too well, left out the spinner and it's better now. At low
revs there is a vibration howl, but if I am lucky there will be a nice sound at higher
loads - that was the idea at least...
Down side is weight. A clipped servo horn will be much lighter.
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Old Oct 30, 2012, 01:22 PM
chuck
santa barbara, CA
Joined May 2009
3,770 Posts
Quote:
Originally Posted by gooniac33 View Post
Down side is weight. A clipped servo horn will be much lighter.
alright 33, u started it

the c/f tubes i used weigh 1.5 grams on a ~300 gram auw, for a huge 1/2 of 1 % increase.

the down side of the horn is a huge increase in drag

chuck.
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Old Oct 30, 2012, 07:33 PM
Augermeister
dahawk47's Avatar
United States, TX, Keller
Joined Jul 2011
2,355 Posts
Well,
I gave the Katana a go this evening and it did not go very well. On hand launch, she struggled to gain altitude and went in. Damage is not too bad. Cracked the fuse forward of the intake on the port side. Seemed grossly underpowered. Had a Hyperian 3S 850mah 30C that I use in the F-16. Took her back to bench, plugged-in a 4S and that made a world of difference. With the 3S, she wouldn't even nudge herself along the table. With the 4S, she wanted to fly. Have the Dons RC 4800 with a 4 blader.

Try again Sunday when I return .
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