Moving the cg forward

[Extra260]

As most of you know I am building a compy 260 3m after christmas. I have heard of a lot of problems with the cg being to aft. I was going to mount 2 5955's in the tail for rudder for better resolution but now I am second geussing. I also was wondering how much of a difference it would make to put a carbon tube in the tail. Whats the weight of the stock tube and what size of the tbm carbon tubes fit??? I have a da 150 with a 28.5x12 with a standard truturn spinner. I am also running greeves. I will mount everything forward but is there anything extra I can do??? What is the optimum cg for imac. Thanks a ton guys.

[Extra260]

Anyone???

[rcdart]

Dude, I am today just finishing my second, both are identical, single 5955 on each elevator, 3 on the rudder in a SWB tray, mounted off the back of the tank tray, BMB pipes, DA 150, all my batteries are on a tray up the front, CG is 95mm from LE at the tip. Originally I had 4 servos in the tail, and removed 2. I only fly IMAC, so I dont need large throws and run the elevator arms at 1". I would advise against putting the rudder servos in the rear. See my build thread for my layout.
Composite ARF 260 KIWI

[Extra260]

What was your cg when you had 4 in the tail??? I only fly imac also. Could I get away with 2 servos in a tray or should I get three??? I dont skimp on anything so just tell me.

[Extra260]

Do the 1 inch arms even give you enough throw for imac???

[Extra260]

Or would a seiko work well??? It would be cool to have that much power but it would weigh more.

[Extra260]

Since this is a strictly imac plane do you think I could use just 2 servos on the rudder in a tray???

[Downhumpty]

8611's or equivalent why not. 8411's would probably be fine.

KP

[Dan767]

The one inch arms will give you just enough for IMAC. I use 1 1/2" in mine. My setup is similar to Rcdart, except I still have all the servos in the tail (5955's) for the elevator. I would consider the SWB self adjusting tray, that's what I have. I should have mounted it a little more forward than it is. My cg is 95mm also. Everything that you can put in the motor dome helps. You will need to reinforce the landing gear mount. I had to cut a lot of the gear mount out for my cannisters to fit, so does everyone. I used coarse fiberglass and West systems epoxy on the gear plate and the joints. Use a mask when you sand/grind Carbon fiber or fiberglass. In order to get the servo trays and servos mounted in the wing and stabs using the supplied screws, you will have to use JR servo hardware (grommets and eyelets), nothing else works. Pics later.

[Dan767]

Pictures. Hope this helps.

[Extra260]

I am using greeves so they are alot less wide. My only question is if I could get away with 2 servos in a tray for the rudder. I will probably use 1.25 inch arms. But do I absolutly need 3 5955's in a tray for the rudder??? If I do I will get them.

[Dan767]

I think you have a few choices here. You can use 3 of the Futaba 9152's you have for sale, or 2 JR 8711's in SWB self adjusting trays. You don't need to use 5955's if you don't have them. The setups I mentioned will give you over 800in.-ozs. of torque.