TT2

My Feedback: (13)

I'm (finally) putting the finishing touches on my 31% CA (Columbo Anderson) Extra / ZDZ80. I guesstimated the initial CG to be about 1 1/2" rear of the wing tube and that's about where I'm at. I still have some latitude with battery placement if I need to shift it a bit.

My question to those who fly this plane is: Where does the CG need to be in order for the plane to be pitch-neutral (hands-off upright and inverted level flight)?

Thanks,
-Tom

JB Rekit

My Feedback: (3)

It needs to be just in front of the wing tube.

Tie a string around the tube and it should tilt about 30 degrees nose down. That is where I found this plane to have a very good balance for precision flying. Assuming the incidence is correct, it should require no mixing in knife edge flight and stay almost level inverted (will lose altitude very gradually)

This is with a ZDZ 80, everything except rudder servo is in 6-10" in front of the wingtube and still added 10 oz of nose weight, but it flies the advanced pattern better than my 33% Edge (not my 39% Extra though ).

I definately wouldn't reccomend starting with your C.G. that far back even if you only want to do 3D with it. It would probably end up doing a loop when you rolled inverted b/c there would be so much down trim in it.

There is really no reason for the cg to be back that far even for 3D b/c even though I have all of my planes set up for IMAC, they will still do all the 3D. I did move my cg back about a half inch behind my wingtube for about 30 flights before on my edge and after moving it back to in front of the wingtube, I couldn't tell any difference in the 3D, but there is a huge difference in the pattern.

This is probably long enough and probably told you more than you wanted to hear, but just ask if you have anymore questions

John

TT2

My Feedback: (13)

Thanks John! When I eyeballed it I thought that having the CG at the wingtube was very conservative! It just appeared that way to me...no calculations were done...I just said 'that looks about right'. What you have told me is good news. I will be able to leave my battery packs and receiver on the deck behind the wing tube / tank bay and the plane should balance very close to the wing tube without adding lead. I may be flying this plane next weekend...I can't wait.

What is your servo / receiver / battery setup like? I'm using two HS-5945 for each aileron, two HS-5925 ganged with a tiller arm for the rudder pull-pulls, one HS-5925 in each elevator half, one HS-225 for throttle, one HS-225 for choke. Single JR 9-ch receiver, dual Cermark switches hooked to 5-cell 2150mah NiMh packs.

Any idea what yours weighs? I'm going to try to get mine on some very accurate scales soon...I think I'm under 20 lbs.

-Tom

JB Rekit

My Feedback: (3)

Forgot to tell you the reason I had to add the nose weight was b/c it has the KS tuned pipe. Since the exhaust exits behind the wing, a majority of the pipes weight is behind the cg.

With the added nose weight it came out to 23 lbs.
You are probably going to come real close to your 20 lb goal b/c you will save 1.2 lbs (difference b/w pipe and muffler), the other pound of nose weight and any other lightning mods you might have done. I have some CF gear for it that will save another .5lbs if I ever get around to putting it on. So thats real close to the 20.

Radio gear is 2 - 5945's per wing
1- whatever the 260oz hitec is on the rudder
1 - 5945 each elevator
mini digital on throttle
standard on choke
1 reciever
2 - 2200 lith packs
heavy 1450 Nicad on ign (just had it laying around)

here is a pic of the inside for you

JB Rekit

My Feedback: (3)

Never mind the pic
I guess I don't have any of the 31 % on my hard drive. That is my 39%, didn't realize it when I uploaded it, both planes use a lot of the same colors.

Sorry
I'll see if I can't come up with one later for you.

John