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Old Jul 25, 2008, 12:04 AM
Onward & Upwards
Blayne Chastain's Avatar
Joined Sep 2004
101 Posts
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gabby 2 meter cg / incidence setup

Ok... just finished a Gabby 2 Meter. Flew her today and she's clearly not flying right. I've read most of the posts on her here. I'm about to check incidence / decalage as soon as the coffee kicks in but was wondering if there is anyone on the board that has their gabby REALLLLLLLY dialed in and if so, where are you running cg and did you have to change wing incidence at all. I tend to go for just forward of cg neutral (in a high speed dive I like it to slowwwwwly pull up) I've got her at 90mm back and she's still pulling up in dives though she's unstable at low speeds which makes me suspect incidence/decalage issues... I've tried going extremely forward cg in the range of 75 - 70mm and still not happy. So... Anyone got one that truly dialed in?

All the best,

B
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Old Jul 25, 2008, 12:40 AM
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Blayne Chastain's Avatar
Joined Sep 2004
101 Posts
-3

Just measured. The stab is -3 in relation to the wing. This is needless to say too much. I've heard folks say that the Gabby wants to pull up no matter what the CG... this is no doubt why. I'll set to 0 and see what happens. Anyone else hacked a gabby to get her to fly right?

Cheers,

B
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Old Jul 25, 2008, 07:04 PM
LSF 1359
sailfree's Avatar
Northwest Florida
Joined Dec 2006
220 Posts
Blayne,

I have a Gabby 2M. It flys great. I had to jack the trailing edge up 5/32nds inch to get the down trim out of the elevator. I have the CG were I want it. I use lead tape on the tail boom to adjust the CG at the field. Haven't measured yet but will let you know. It themals very good. It will also cover a lot of sky with very minimum sink to search for thermals. The first time I launched it after changing out flap servos, got over a 12 minute flight. That was before the CG was adjusted.

Sailfree
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Old Jul 25, 2008, 08:07 PM
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Blayne Chastain's Avatar
Joined Sep 2004
101 Posts
Cool. Thanks for responding. I did some tweaking to get the decalage at around 0 and it flies a TON better... Still a 2 meter but at least a decent 2 meter Sal called me today and we talked through things. Mine is a bit of a strange one... Came in much heavier than it should have (wet layup me thinks)... At any rate... had some success. The decalage was way too much... especially if you factor in the fact that you'll normally run the foil cambered.

I think I have my CG around 94mm now and she just barely want to pull out of a dive... just the way I like it... now to move the hook even further back.

Thanks again... she's now starting to look promising.

Best,

Blayne
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Old Jul 25, 2008, 09:58 PM
LSF 1359
sailfree's Avatar
Northwest Florida
Joined Dec 2006
220 Posts
Current weight of Gabby is 35 & 1/8 ounces. Should be lighter when lead tape is removed from tail boom and weight is removed from nose to achieve right CG. However, flies great at this weight.

Sailfree
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Old Jul 26, 2008, 02:23 AM
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Blayne Chastain's Avatar
Joined Sep 2004
101 Posts
Mine is about that as well. I just did a bit more tweaking tonight... Hopefully she'll perform even better tomorrow... Dialed in my vtail settings and such...
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Old Jul 26, 2008, 05:37 PM
LSF 1359
sailfree's Avatar
Northwest Florida
Joined Dec 2006
220 Posts
Flew The Gabby today. Great little sailplane. I have the CG just where I want it. I'll measure it this weekend and let you know where mine is.

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