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Jeesh, another balanceing problem

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Jeesh, another balanceing problem

Old 08-22-2009, 01:11 PM
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outdoorhunting
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Default Jeesh, another balanceing problem

Finishing up on a Nitro Plane Zlin 50. I've got the motor as far forward on the mounts as it will go. The battery is mounted on the firewall just in behind the muffler. I have hung14 oz. of lead on the very front of the cowl & it still isn't enough.I don't like putting any weight on the cowl,let alone that much on a small plane. Has anybody else had this problem? I guess the next step is to move the rudder & elevator servos forward with the throttle servo. That'll be a pain in the butt !!! Also, anybody else have one? How does it fly. With all that control surface it has. I think it will be a handfull. Any & alll help will be appriciated !!!
Old 08-22-2009, 03:24 PM
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freeair
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Default RE: Jeesh, another balanceing problem

something doesn,t sound right with your balance . 14 ounces of lead weight [ almost a pound ] is heavy, you should remove the lead weights and start with all radio / servos set up closer to the front , check the c.o.g at 1/3 back from the leading edge.
Old 08-22-2009, 04:25 PM
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outdoorhunting
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Default RE: Jeesh, another balanceing problem

Yeah, I just came in from the shop. I moved rudder & elevator servos up with the throttle servo. I did a rough check on the balance machine. It takes right at 8 oz to balance now. My next step is to get rid of the plastic spinner & go with a weighted one ( I'll have to order it) Hello, Tower !!! I figure I can get it down to 3 or 4 oz., maybe less. I can live with that. I said this before ( many times)"on my next project I'll check the balance BEFORE I start fastening stuff down" !!!!!!! It absolutely amazes me how much diference moving stuff around can make !!!!!!!!!
Old 08-22-2009, 05:34 PM
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Default RE: Jeesh, another balanceing problem

Where did you put you battery and what size is it?
Old 08-22-2009, 06:38 PM
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Default RE: Jeesh, another balanceing problem

Where are you trying to balance it? Also, use heavier prop like APC if you haven't already.
Old 08-22-2009, 07:02 PM
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outdoorhunting
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Default RE: Jeesh, another balanceing problem

To begin with I had 4.8 battery on top of fuel tank &I moved it to the firewall right behind the muffler. CG is dead center of sweet spot. Inst. says 80mm I'm using APC prop.
Old 08-22-2009, 07:15 PM
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Default RE: Jeesh, another balanceing problem

What engine are you using? Maybe going slightly larger and turning led into power would be something to look into on this plane.
Old 08-22-2009, 07:29 PM
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Default RE: Jeesh, another balanceing problem

Humm, ya got me thinking. It seems I forgot the slogan at the bottom of my posts.. I think I've got an OS 61 under the workbench.If I don't have to butcher up the cowl too much. I think you've solved my problem. Back to the shop I go.
Old 08-22-2009, 07:41 PM
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Default RE: Jeesh, another balanceing problem

a guy at our flying site had one of those. he had a four-stroke on it and it required no balance at all. he did some fantastic 3-d flying with it. i agree 14 ounces seems a lot.
Old 08-23-2009, 08:13 AM
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Default RE: Jeesh, another balanceing problem

What size 4-stroke ??
Old 08-23-2009, 09:49 AM
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Default RE: Jeesh, another balanceing problem

Sounds like the CMP 50 size zero POS I had...I put like a pound of lead in the nose plus mounted the battery in the cowl..It flew like a brick and crashed on maiden
Old 08-23-2009, 04:38 PM
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Default RE: Jeesh, another balanceing problem


ORIGINAL: outdoorhunting

What size 4-stroke ??
Something like a Saito 72 would probably be a nice size for it.
Old 08-23-2009, 09:49 PM
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Default RE: Jeesh, another balanceing problem

Thanks, I needed to hear that !!!
Old 08-25-2009, 09:57 PM
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Default RE: Jeesh, another balanceing problem

I've got Nitro Planes Zlin 50's too, and having a tough time getting it right. I've flown it, but it's a handful to say the least! It's got a Saito 56, still have the servos in the rear, battery mounted as far forward as I can get it. With that setup, the CG comes out at about 110mm from the leading edge. I've flown it that way. It flies fairly well until you start to get aggressive with the inputs, then things get really wild. For instance, pull up into a tight loop, and it will just pancake or snap out of it. Same thing with a tight bank and yank turn. It's like the wing blocks the elevator causing it to lose effect. When landing, you have to come in hot, for it'll fall off the wing in a heartbeat. I just finished mounting 14oz of lead to the front edge of engine mount. That brought the CG forward to about 90mm. I plan to try that tomorrow or the next day and I'll let you know if that improves it. If it does, I'll move the servos like you did.

Old 08-27-2009, 09:17 PM
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Default RE: Jeesh, another balanceing problem

Well, I tried just about everything I could within reason to tame this bird and it's bad habits. I added 14oz of weight to the engine mount which brought the C of G to 90mm from the leading edge. Flew the plane and the elevator performance was worse! In fact with full up at the recommended 25mm of throw, it could barely pull the nose up at all. Inverted took a bunch of down to hold level....obviously nose heavy to the extreme! I removed the weights and flew again. Inverted flight was good with little input needed, but still problem with an inside loop. Pull up to hard, and it's like you intended to do "the wall" instead of a tight loop. Tried doing some outside loops and it performed them well. To me, this indicates that for sure, the stab and elevator is covered up by the wing when the nose is raised to about 25 degrees or so. So how in the heck are you supposed to fly this thing, much less fix it?

I knew this plane was toast sooner or later. It came sooner than I intended when I did some fairly tight "bank and yanks", and it pulled one of it's snaps, went into a roll and never recovered.........

I don't think I'll miss it much. Time to move on.

I certainly wish you better luck with yours than I had.
Old 08-28-2009, 07:21 AM
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Default RE: Jeesh, another balanceing problem

Thanks for the heads-up. I think as soon as I get back home,( out of town for a week due to ALMOST forgetting 46th anniversary) I'm on the motel's computer.Gotta keep the wife happy so I can be happy !!! I'll do some extensive surgery on the tail feathers. I'm going to move the rear stab to be in-line with the wing. I guess the incidence should be set at zero. It's gonna be a major pain, but it sounds like I'm not going to be able to fly it if I don't.
Old 08-28-2009, 06:54 PM
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Default RE: Jeesh, another balanceing problem

outdoorhunting I to thought about relocating the stab/elevator, but really wasn't to thrilled about it even though I love to build. I did quite a bit of searching for articles from anyone with this plane, and from what I could see, most were having problems with it resulting in it becoming a "lawn dart" either on maiden or shortly after. I think yours will fly, just be aware that you'll want to take it real easy until getting about 3-4 mistakes high. Don't make any sudden elevator inputs and it should be okay. But I wouldn't be surprised if it did the same thing mine did once you get a little aggressive with it. I've watched the video that Nitro has on their website of someone flying it....didn't see them doing any real aerobatics there either.

Ah well, good luck with it. Let us know how it did.....or didn't!
Old 08-28-2009, 07:16 PM
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Default RE: Jeesh, another balanceing problem

honstly do not know what size four stroke was on it. i know it had a lot of power. he could hover the zlin 50's tail just above the ground and walk it (he called it the "walk the dog")from left to right and vise versa while doing rolling circles. amazing! wish i had my camera that day to shoot a movie
Old 08-29-2009, 07:02 AM
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Default RE: Jeesh, another balanceing problem

I've seen guys do that kinda stuff. I'll try it at about 1000' elevation & still can't do it.!!! I think some people are magical!! They must be, how else can you explain some of the stuff David Blaine does??

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