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FT Mini Arrow CG Question

JasonK

Well-known member
#1
I am building a Mini Arrow for my first wing (have been flying a Tiny Trainer for a while) and am running into a problem. I have the main wing put together, but haven't mounted the electronics. I checked CG the motor (A pack), ESC, Receiver, & battery (3C 650mAh) , and I had to hand the battery out the front of the section about 1" to get it to balance on the CG points. (Servos are basically right on the CG marks front/back, so I didn't worry about those for the quick test)

Is it normal to have to add some dead weight to the wing to get it balanced (or an even bigger battery then what I have there)? or am I perhaps missing something?

ArrowCGQuestion.jpg
 

Merv

Well-known member
#2
I have not built the Arrow, I have built many Versa’s.
I avoid adding dead weight if at all possible. I build the plane, then tape all of the components in place & test the CG. I will continue to move things around until I can achieve the CG without adding weight. With a Versa pusher, I move the motor forward 2-3 inches from the stock position, just like they did on the Arrow.

A small nose to move the battery forward would be very easy. If you don’t like the look of a nose, I would move the motor forward or use a heavier battery before I would add dead weight.

Don’t attempt to fly it tail heavy, wings are very sensitive to CG.
 

JasonK

Well-known member
#3
A small nose to move the battery forward would be very easy. If you don’t like the look of a nose, I would move the motor forward or use a heavier battery before I would add dead weight.
This was one of my thoughts, it just suprized me that I might have to extend it.
 

mrjdstewart

Well-known member
#5
what is your AUW?

i have built more Arrows than i can count. most with a 2205 but a few with 1806. try a 3S-850 and your problems may be solved.

good luck,

me :cool:
 

JasonK

Well-known member
#6
my AUW is ~245g (I don't have my control horns glued in yet and a few things aren't attached, just sitting on the scale). I don't have a 850 3S, the biggest thing I have is a 650 3S.
 

Keno

Well-known member
#7
Ah, when building a wing the CG is very important, even then you have to add reflex (Up Elevator) when you get these two in balance you will have a excellent flyer.
So anyway Happy Flying.
 

danskis

Well-known member
#8
Yours looks great. I've just gotten my arrow flying great after ripping a wing off (they're tough). I've got a 2204 2300kv motor with a 700mah battery. I've modified the pod and my battery sits just at the front of the wing (point). The 30A esc is as far forward as I can get it internally. if you need more nose weight you can put the esc on the bottom of the wing further forward. Set it up the way they tell you with expo, reflex and rate and you will reduce your pain. The launch is a wing launch of course. Angle of launch is about 75 degrees. You shouldn't have to throw it just guide with your arm. Launching a wing takes practice.
arrow2.jpg
 
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sprzout

Knower of useless information
Mentor
#9
With my Versa Wings, I usually add some pennies and hot glue to the nose. I KNOW this is not standard or recommended, but all the Versas I've built are meant for Combat. Having a reinforced nose and weight to it makes it a little easier to do damage to the other wings when flying.

That said, I'm probably the exception to the norm on that, and I definitely wouldn't recommend adding weight on the Arrow - its small size is much more susceptible to added weight than the Versa Wing.
 

Aireal Anarchist

Well-known member
#11
With my Versa Wings, I usually add some pennies and hot glue to the nose. I KNOW this is not standard or recommended, but all the Versas I've built are meant for Combat. Having a reinforced nose and weight to it makes it a little easier to do damage to the other wings when flying.

That said, I'm probably the exception to the norm on that, and I definitely wouldn't recommend adding weight on the Arrow - its small size is much more susceptible to added weight than the Versa Wing.
I have to add weight to all my versa wings in "pusher" config, but thats understandable I dont run a gopro on the nose as the FT crew did in their video
 

danskis

Well-known member
#12
@JasonK - that's the right thing to do. Don't worry it probably won't look that good for long. Balance and elevon angle (reflex) are the keys to getting a wing to fly. The CG has to be in the right place for it to fly at all. Good luck with maiden!
 

mrjdstewart

Well-known member
#13
CG is very important obviously but with the Arrow the reflex is just as vital. once i get mine flying, i rarely worry about CG, i roughly know where the battery goes and place it pretty liberally. one thing i always check though is the reflex.

to set proper reflex, set the wing on a flat surface and then adjust servo sub trim so that you can just put a piece of foam board under each elevon. do this to both sides and you are golden.

as for launch, a side arm toss works great. doesn't take much. or, if you want to have fun, make sure when you instal your wing tips that you can set your wing down vertically. then you can just launch straight into the air without even holding the wing. this one get's everybody's attention.

good luck,

me :cool: