flyerdave

My Feedback: (212)

I have an aeroworks 100cc extra 300 that I've been flying for two years. One of the sweetest flying planes I've ever had.I have never had even a prop strike with this one.I don't fly much 3D, though I've been flying for 33 years, I know my limits. I have however changed the servos in the stabilizer to the larger and heavier futaba 9152. The exact weight difference is 1.4 oz. total added to the tail. Aeroworks recommends the CG be 4 1/4" behind the leading edge measured at the wingtips. Before I move my battery packs forward, has anyone tried moving the CG back? How far back can you move it before you get a "dangerous" situation? I have a huge (to me) investment in this one and I don't want to lose it because of an improper CG placement. I appreciate the help.

speedracerntrixie

My Feedback: (29)

Dave, CG is one of those topics that get out of hand quickly so you will no doubt get lots of answers to weed through. With that said here is mine. I have a bit of time on that airplane and in fact a few years ago I took a 3rd place IMAC unlimited finish with a borrowed one. If I remember correctly for my style of flying the factory CG was pretty darned good. These airplanes will tollerate a fairly aft CG and still be perfectly flyable. !.4 oz is not much of a CG shift. I would think it to be 3/8" or less. I would say you are safe to fly as is and then adjust as nesessary.


Things that would indicate an adjustment is nesessary.

1. Having to use down trim in relation to neutral = tailheavy

2. Having to use up trim in relation to neutral = nose heavy

3. Airplane steepens climb while doing an inverted 45 degree upline = tailheavy

4. Airplane excessivly shallows climb during inverted 45 degree upline = noseheavy

5. Airplane pulls to the gear hard during knife edge = tailheavy

6. Airplane pulls toward the canopy during knife edge = very nose heavy. All Extras with the correct CG will have a slight pull to the gear, use a rudder to elevator mix to fix this.


All these are assuming that the airplane has it's engine thrust and incidences correct. You may want to measure and adjust if needed. What you are looking for is stab at zero, engine at zero with 3 degrees of right and wing at +.5 degree.

Hope this helps some.

Ih82crash

As was already stated, bigger planes can handle quite a bit before they are dangerous. As long as you are on the wing tube with the CG you will be good. It is pretty much a preference thing from there. If you are nervous just make sure you have low rates set up and turn them on. That should keep you from too much trouble.