Pico-J3-S CG Question
06-25-2003, 10:46 AM
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Pico-J3-S CG Question
I am new at this and am building a Pico stick. I have the following gear:
ICS50 ESC
R4P receiver
GWS Pico Servos
7.2V 270MAhr battery pack
I built it according to the instructions. I spaced the front wing mount at 55mm from the back of the IPS and the receiver mount 25mm behind the front wing mount. I have the battery holder forwarded as far as possible against the front wing mount and the battery is as far forward as it can go in the holder. The CG per the instructions needs to be 130mm from the back of the IPS. With this setup the CG is a lot further back. So I moved the wing mount forward along with the battery holder. After moving everything forward to get the CG at the 130mm point I noticed the center of the wing is now over the CG. This doesn't seem correct. I maybe wrong. BTW, the servos attach to the battery holder so their position is fixed, cannot be moved separately.
Can anyone give me some guidance on this? Thanks in advance.
DIck
ICS50 ESC
R4P receiver
GWS Pico Servos
7.2V 270MAhr battery pack
I built it according to the instructions. I spaced the front wing mount at 55mm from the back of the IPS and the receiver mount 25mm behind the front wing mount. I have the battery holder forwarded as far as possible against the front wing mount and the battery is as far forward as it can go in the holder. The CG per the instructions needs to be 130mm from the back of the IPS. With this setup the CG is a lot further back. So I moved the wing mount forward along with the battery holder. After moving everything forward to get the CG at the 130mm point I noticed the center of the wing is now over the CG. This doesn't seem correct. I maybe wrong. BTW, the servos attach to the battery holder so their position is fixed, cannot be moved separately.
Can anyone give me some guidance on this? Thanks in advance.
DIck
06-25-2003, 12:24 PM
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Pico-J3-S CG Question
From what I remember on mine (I'm at work), that is not too far off.
Depending on the size of your batteries, you may want to use some foam rubber "spacers" to keep the battery from shifting forward or back.
The kit comes with (2) sets of dihedral braces to hold the wings. Use the one with more Dihedral. It helps indoors, and outdoors you are pretty much a pawn to the wind anyway so it doesn't matter that you don't use the "outdoor" wing brackets (with less dihedral).
When flying, the plane will turn with the nose level and better with it pointing down, but you will be hard pressed to get it to turn with the nose pointing up. Ask the gym wall at Red Bank Regional High School if you don't believe me!
This plane cat get ratty looking fast, but it is infinitely repairable and because of the way things mount on the boom, fairly resilient to electronics/servo damage.
If you want to make it easy on yourself, use the micro E/Z connectors (Dubro) on the servo control arms instead of z bends on both ends of the control "rods". They make trimming a whole lot easier, especially if you are using a non-computer radio!
Depending on the size of your batteries, you may want to use some foam rubber "spacers" to keep the battery from shifting forward or back.
The kit comes with (2) sets of dihedral braces to hold the wings. Use the one with more Dihedral. It helps indoors, and outdoors you are pretty much a pawn to the wind anyway so it doesn't matter that you don't use the "outdoor" wing brackets (with less dihedral).
When flying, the plane will turn with the nose level and better with it pointing down, but you will be hard pressed to get it to turn with the nose pointing up. Ask the gym wall at Red Bank Regional High School if you don't believe me!
This plane cat get ratty looking fast, but it is infinitely repairable and because of the way things mount on the boom, fairly resilient to electronics/servo damage.
If you want to make it easy on yourself, use the micro E/Z connectors (Dubro) on the servo control arms instead of z bends on both ends of the control "rods". They make trimming a whole lot easier, especially if you are using a non-computer radio!
06-25-2003, 01:44 PM
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Pico-J3-S CG Question
Check your instructions again. As I remember it, the LE of the wing should be about 130mm from the IPS and the CG should be between 50 and 60mm back from the LE.
06-25-2003, 01:49 PM
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Pico-J3-S CG Question
I don't have a J3 no more just sticks 4 the wing mount you do have to slide back and forth with everything mounted I made
a mount to go into the wing cradle to do this with a hole drilled
into the mount about 30% back then a string to get the CG. CU
a mount to go into the wing cradle to do this with a hole drilled
into the mount about 30% back then a string to get the CG. CU
06-26-2003, 10:42 AM
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Pico-J3-S CG Question
Thanks for the help. I went back and rechecked everything and found out the new bifocals I get last weekend was the cause. I was misreading my metric to inches converter. Took my glasses off held it to my face and it said 5 inchs not 3. Now the CG is correct.
Gave it a quick try at dusk when the wind died down and it climbed out nice from a ROG and was nice and level. Landed it and am now ready for an indoor fly in at the sports dome in Cleveland.
Dick
Gave it a quick try at dusk when the wind died down and it climbed out nice from a ROG and was nice and level. Landed it and am now ready for an indoor fly in at the sports dome in Cleveland.
Dick
