Okay I've pulled out the last pitiful strands of my hair.

I'm at the final stage of assembly and was just balancing to determine where to locate my battery. Much to my surprise my ARF is very very nose heavy at 5" back from the leading edge. Those of you with this plane probably know that the instructions call for 6" back to start, but in another thread it was reported that the plane flies tail heavy at that setting. After testing the same thread reported 5" back was good to go.

I have a few choices if this bird has to balance at 5".

1) Jump up and down on it.... Probably not to rational

2) Replace the Moki 1.80 with my OS .40...Probably poor vertical?

3) Go through the hassle of adding two servos to the tail for elevator. However, even with the servos in the tail the battery (NiCad 6v 1100Mah) will need to be mounted under the leading edge of the horizontal stab.

What I'd like to know is have others with this airplane found 5" to be a good setting?

Thanks,
Mike

I saw one of these at my field this past Sunday. He had an OS 1.60 with an after market canister muffler. Flew great! I ordered one the next day and plan to put a Saito 1.80 on it.

The 1.60, I believe, is about 8-9 ozs less than the Moki. It's ashame that your CG is that far off from what others are recommending because that would be a fantastic engine on that plane.

Did you add anything to the forward part of plane that may have added more weight (i.e. smoke tank, remote glow battery, etc..)?

Good luck with it!

Jon

Do a seach on the ARF/RTF page. There have been alot of posts. Type in DP Edge 540.

I've read many of the posts, but I haven't found anyone reporting very nose heavy.

If you could get it and one of the early DP Extras to mate you might get an airplane that will balance well.

Good Idea! I actually have one of the first Extras. I actually had fewer issues with the Extra...All I needed was a 1800Mah NiCad mounted to the engine box.

MC

The reason the option to put the elevator servo's in the rear was to solve problems like yours. Why not use it?

Doing this would be off setting about 25 ozs. off the nose. Hard to beleive this would not be enough? Hmmmmmmmmm!!!!

Now you have me worried cause I have a DA50 up front with a Slimline smoke system. Thinking I may have to put the rudder servo in the rear with the elevator servo's.

Luckily, that option is also there. Is yours the ARF or ARC version?

Please keep us posted as to how you resolved your problem.

Paul

Hey Paul,

That's what I'm currently doing, but this too runs into a few issues. (FYI - in order to balance my model 5" I had to relocate two futaba 9303 servos in the tail (mock dual elevator setup), the 6v 1100mah battery located just forward of vertical stab, plus 2000Mah "C" cell for on-board glow just foward of vertical stab Aaargh :-()

While mounting the elevator servos in the tail my fears where realized. The pull/pull for the rudder conflicts with the elevator servo location - at least on mine. BTW .. I did mount the rudder horns according to the plans and also took a suggestion in one of the other threads about ensuring the horns are mounted in the hard wood block which is visible through the covering. I then did a bit of thinking and decided to relocate the rudder pull/pull to the bottom of the fuse using a few pieces of ply attached to the fuse stringers. Actually this should work out well since the servo will be further aft and as a result will assist in balance. Of course this also eliminates the pull/pull cable and servo conflict.

I'm pretty sure with this setup will avoid the need for "dead" lead weight.

I was a just a bit disappointed since up to this point my assembly looked excellent. Now I've got to buy additional covering to repair the previous pull/pull slots etc/...

Mike

Mike:
Something has to be wrong as no one else has reported a nose weight problem (unlike the first run Extra's) with this plane and most of the guys flying with the Moki are using the pull-pull elevator.

However, I cannot figure where the problem may be. Perhaps a call to Dave Pratrick would be in order. I wish I was a little further along so that I could check my balance point but it won't happen for a couple weeks.

Good Luck
Paul

I've called and left two messages, but haven't heard back.

I agree seems like somethings wrong....actually that's why I posted hear ... trying to confirm the 'wrongness'.

The great planes CG machine does not lie?

I'll report back on the approx. weight using a pretty accurate bathroom scale. If it's of interest.

Mike

Mike:
I have gotten very eroneous cg reading from the great planes machine due to the fact that the arms are at an angle. I have also seen other posts of eroneous reading and do not trust in on larger planes. I measured my wing and the wing hold down bolt is 6 inches from the leading edge. Try putting your wings on and bolting them on with as large a gap as you can. Then wrap and tie a string on them and hang your plane from the ceiling. This will be far more acurate. You could also drill a small hole in the fuselage side at 5" and run a string all the way through the fuselage. The wing will cover the hole latter anyway.

Stupid question, but I assume that you do not have any fuel in the tank? Guys with much heavier gas engines are not having to put any batteries in the rear, let alone 2.

I quickly calculated that you are tring to offset a couple pounds off the nose with that much tail weight. Hmmmmmmmmmm Something is not right. Hopefully it is the great planes cg machine. I lost a plane because of this machine.

I took the metal arms off the plastic base. I then drilled holes is a 2x4 base at different widths. The arms are now straight vertical and I have not had any problems since.

Paul

Throw away the Great planes CG machine. I have tried these on everything and they just don't work.


You will have better luck using your fingers.

I'll tell you, I have a Brison 2.4, CH ignition, and a 1400mAh ignition NiCad all in the nose of my Edge along with the single pull-pull elevator servo and a fuel tank mounted under the radio/battery tray and mine is now balancing just a shade behind 5". I have both of my servo power batteries mounted in the tail of the plane about 1/2 way back, but I have done nothing else to alter the stock airplane. Mine flies GREAT at this CG location and is just night and day from when I ATTEMPTED to fly at the recommended location.

O.K. I'll bite.

Given the fact that the GP machine has it's balance points on two ball swivels, and the pads are free to float with no interferance from the rods, and given that the only purpose of the rods/arms are to keep your plane off the work surface, exactly what is the difference if they are vertical or angled?

I'm putting one together with a Moki 210 and it's going to need the servos in the tail to balance. At 5" it is nose heavy and it doesn't have a spinner. sevos in the tail and,.....perfect. When I add the spinner it may tip a little forward.

h82crash,

That's what I was hoping to hear...thank you - I feel better.

Thanks for all the replies of assistance.

Mike

Sorry...but if you are getting the CG wrong with a GP CG tool then you are using it wrong. I have used it on all sizes of planes including a 1/5 P40 and 31% Edge and it works great. It would be nicer if the rods were longer ...but it works.
Just my $.02 .

I agree with you BigBird, that's why I asked the question up in post 14.

The problem that I think is wrong with this machine is that the rods are angled. With the larger planes, it is hard to tell if any of the weight is transferred to the spring action created by the angle of the rod.

It seems that every time I got an erroneous reading, it showed it as being nose heavy which correlated to the spring action forcing the plane towards the nose. By having the rods straight vertical, there is no chance of this happening.

I discovered this problem when I tried the GP CG machine then hung the plane from the ceiling on string. The readings were quite different.

I'll bet this is MRC100's problem as his CG reading does not make any sense. I wonder why he has not responded?????

Just my opinion.

Paul

I've balanced the plane in multiple ways and they all come out the same - nose heavy. I really don't want to debat the pros-cons on the CG tool, since I've succesfully balanced no less than 20 planes with my particular device. I didn't respond since I really didn't understand how the device could malfunction since it places the aircraft on a smooth pivot point. Additionally, I didn't want to insult someone who has taken the time to provide me with some ideas to check. Lastly, I can't explain my balance issue...there's nothing at all special about the assembly. BTW - the tank 20oz is empty and my throttle servo is a mini.

Apparently another Edge is coming out nose heavy with the Moki 2.10. I have both engines and they have similar configurations and the 2.10 is only 5oz heavier.

I'm at a loss - I guess there are a few with balance point differences. I'm actually pretty discouraged, because I purchase ARFs to minimize the setup time - now I'm re-engineering.

Anyways, thanks for all of the ideas and feedback.

If anything new comes to lite I'll post ... for the moment I've put it aside to sleep on the issue so to speak.

Mike

I understand your frustration. When I build, I mount the engine, cowl, and prop assy plus all of the control surfaces before cutting or mounting servos. You can then check the CG with servos taped in place. You may still get the CG to come in if you put the battery in the tail. I do a lot of planning and adjusting before committing to a servo location. Not to insult, just a tip for posterity.

No offense taken. Actually I usually do look for the CG prior to permanent placement of electronics etc when straying from the recommended configuration. However, with the Edge DP actually recommends the 1.80 and even illustrates installation of the engine in the assembly guide. The surprising thing to me was how far off the CG actually was and the fact that my rudder cables conflict with rear mounted elevator servos. I expected some issues which might have been resolved with battery placement, oh well.

Anyway, I finished up placement of the electronics today and I'm very happy.

I'd sure like to hear more about actual flights and setup information.

Keep us posted on yours. Any ETCompletion?

Mike

This thing has gone together quicker than any arf I've built before. This is my third evening on it and I only have to install the servos.and fuel tank. I'm waiting for the proper servos and spinner, prop, pump.
Mike, any experience with the Moki? I have a 1.8 on a Midwest Cap and run a Perry pump on it. Tank on CG and very reliable. I had a stumbling midrange before the pump.

Just so I know whats the big deal about sticking the battery near the tail. I've used this method (still do)...just can't stand adding tail weight...which isn't even a big deal in it's self as I have never in over 30 years flown an aeroplane that didn't need it's 'cg moved backwards.

I use an EMS Jomar glitch buster to separate receiver from servo power. For the receiver, I have a little 600 mAh 4 cell up near the receiver and for the servos I have a dual redundant setup of larger 5 cell NiCads that I have mounted pretty far back in the tail on a plywood tray under the pull-pull cables. This balances things out almost perfect in my plane. I figure if I move the receiver battey back, I would go from a tad nose heavy to a tad tail heavy--it's that close. I too refuse to add ballast to a plane like this as wing loading is everything and I already have enough weight in the plane! All this talk about balance makes my head hurt. I say get the thing close using whatever balancing method you use and then go fly the thing! The card from DP that comes with the plane gives you multiple methods of fine tuning your balance in flight and there are even more techniques out there. My first flight was very tail heavy so I adjusted and found that the CG needed to be closer to 5" than 6". This was all determined in flight and then measured on the ground after I made the changes. So far I've seen the plane with a YS 140DZ, Moki 1.80, and my Brison 2.4 all manage to balance and fly well. Good luck to everyone!