JoeAirPort

My Feedback: (41)

I found out that the 5-6 CG recommended by DPM web site is way off. Mine was at around 5 inches for the maiden and WAY tail heavy. It bairly stayed level when inverted and almost wanted to climb. It handled horribly (but PERFECT tight inverted flat spins). I set it to around 4.5 inches and it's perfect. So the 5-6 inches is way off. Luckily I had experience landing tail heavy arf's (some down elevator and some throttle). I did end up breaking some structure holding the landing gear block on a rough landing (minor). Not hard to fix but landing in a cross wind with this aft CG is a bear.

Also, if your tank is in the nose, your flight will start out nose heavy and end with the CG that you set it at (empty tank). If it's on the CG like in my case, the CG will always be the same. So what I'm thinking is that the people with the tank in the nose might never come close to emptying their tank in flight. So their planes can have a little more aft CG and get away with it. In my case if it's aft to begin with, it stays that way. So a plane with the tank on the CG it's more critical that you get it right the first time. You won't have a pound plus of fuel helping you keep that nose down during the first 5 minutes of flight.

So I'd say that 4-5 inches is the correct range. I'd personally start at 4.5 inches. At 5 inches it will fly tail heavy. I did mention this to Dave Patrick on the phone this morning.

Hope this helps someone.

LuvBipes

My Feedback: (4)

I agree Joe, I have mine at 4.5" and it almost needs no push to hold level inverted, which leads me to believe it's on the cusp of being tail heavy. With the Moki 2.1/ BCM pitts muffler combo, I had to put all 3 servos in the tail plus 2 ozs of lead to get the CG at 4.5"

JoeAirPort

My Feedback: (41)

Do you have to push a little inverted at the beginning of the tank or towards the end? I know you have your tank in the nose from previous discussions.

With mine at 4.5 I have to push a little when inverted (I prefer that). But it never changes from empty to full since mine is on the CG. The 4.5 is not exact, rough measurement.

LuvBipes

My Feedback: (4)

Can't really notice change in elevator trim with tank in the nose.

RTK

My Feedback: (1)

You are right, 6" is tail heavy. I had to apply down elevator to be able to land, made the first few flights very interesting.
I put the tank under the tube so no CG changes thru-out flight.

JoeAirPort

My Feedback: (41)

5 inches is tail heavy. 6 inches? Wow that thing must have been a handful to land. I will move mine back later if I feel that it's too far forward. I'd rather have it a little forward than aft on a new plane.

RTK

My Feedback: (1)

Yep it was interesting and it might have been more than 6". I hadn't flown in awhile (I'm not that good anyway) and the first 2 landings had me playing catch up all the way to the ground. Every time I neutralized the stick it would come up! I usually don't carry power all the way down, when I have it made I cut the power. At 6"+ CG, when you cut the power it climbs.