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Balancing is soo easy [email protected]###[email protected]!!#!

Old 06-28-2010, 01:10 PM
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outdoorhunting
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Default Balancing is soo easy [email protected]###[email protected]!!#!

OK. I built a 60 size Super Hots from plans last year. Everything went together without any major problems. UNTIL, I started balanceing it, I had 17oz. of weight in the nose. ( I don't like putting THAT much dead weight on a plane.) To start from the beginning, I fully sheeted the wings & made a balsa cowel. I also, made the wing detatchable for ease of transporting. Power was a Super Tiger 60. I got it to what I thought was close & maidened & it "pog-goed" like crazy. Maybe I was wrong, but that told me," tailheavy". Brought it back to my shop & went through everything again. Everything is square, battery is under the fuel tank, I moved servos as far forward as possible. I took off the balsa cowel & made another out of ply & lengthened it an inch. I changed motor to a "90 Super Tiger." Tried to balance & couldn't. I got ticked off & hung it up until this year & decided to "have another go at it". It now has about 9 oz. lead in the nose. The plans call for 3 5/16 CG. When I put it on the balancer,I can get it to balance at about 2 degrees down in the front, it will stay there for 5 or 6 seconds & either start falling forward like I have too much weight or sometimes fall back like it's tailheavy. ( It's so touchy I have to keep a hand on the plane at all times when doing the balanceing. It's a mid wing. With the set up that I have, I have to put it on the balanceing machine inverted. I've built quite a few kits, this is my first from plans. Any help greatly appriciated !!!
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Old 06-28-2010, 01:21 PM
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MinnFlyer
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Default RE: Balancing is soo easy [email protected]###[email protected]!!#!

The way you desribe your balancing proceedure, you should be about right. But that is only the first step.

Now fly it and see how it flies. If it still pogos, try adding some more nose weight - then fly it again

Repeat as necessary
Old 06-28-2010, 01:38 PM
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krayzc-RCU
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Default RE: Balancing is soo easy [email protected]###[email protected]!!#!

my balance needs are balance enough to fly and not be tail heavy and then adjust for good inverted flights for my needs that means not applying much elevator.
Old 06-28-2010, 02:16 PM
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Default RE: Balancing is soo easy [email protected]###[email protected]!!#!

ORIGINAL: outdoorhunting

When I put it on the balancer,I can get it to balance at about 2 degrees down in the front, it will stay there for 5 or 6 seconds & either start falling forward like I have too much weight or sometimes fall back like it's tailheavy. ( It's so touchy I have to keep a hand on the plane at all times when doing the balanceing. It's a mid wing.
If the vertical location of the CG is withing the wing profile, you will have problems with a regular balancing machine.
If that is the case, as I suspect, you will need to hang the model from above rather than supporting it from below.

Check posts #8 and #15 of this thread:

http://www.rcuniverse.com/forum/fb.asp?m=9527163

Just do a quick check, before adding more weight and flying it again.

Here is a hanging balancing machine:

http://www.rcuniverse.com/forum/m_70.../tm.htm#708060
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Old 06-28-2010, 02:32 PM
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Default RE: Balancing is soo easy [email protected]###[email protected]!!#!


ORIGINAL: MinnFlyer

The way you desribe your balancing proceedure, you should be about right. But that is only the first step.

Now fly it and see how it flies. If it still pogos, try adding some more nose weight - then fly it again

Repeat as necessary
I'd be REAL careful about doing it that way. Nose heavy planes often fly poorly. Tail heavy planes often fly ONCE.
Old 06-28-2010, 02:50 PM
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MinnFlyer
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Default RE: Balancing is soo easy [email protected]###[email protected]!!#!

Well, when you get right down to it, there IS no other way [sm=omg_smile.gif]

Except maybe to start it a little more nose heavy than it was the last time.
Old 06-28-2010, 03:14 PM
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Dr1Driver
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Default RE: Balancing is soo easy [email protected]###[email protected]!!#!

ORIGINAL: MinnFlyer

Well, when you get right down to it, there IS no other way [sm=omg_smile.gif]

Except maybe to start it a little more nose heavy than it was the last time.
Actually, there is a MUCH better way. A plane with a rectangular wing planform will normally balance between 25% and 33% of the full chord back from the leading edge. The Hots is no exception. I've built and flown several. Start in a "nose heavy" condition, about 25% back, then adjust for your flying style.

If his Hots balances between those parameters, it should fly. The farther back the balance point is, the more squirrely it will be to the point of being uncontrollable.

If his plane balances within that range, and still "pogos", then there is something else wrong. The Hots is a quick little plane, even the large one. It's possible he has too much control throw, or is too "thumb heavy" on the sticks. A defective elevator servo could cause this, as could a flexing or sticking elevator linkage. It could even be loose or too-flexible hinges.

When first flying an untried design, there is some room for guesswork experimentation. With an established design like the Hots series, there's absolutely no reason to risk the plane by guesswork.

OP. go through your elevator linkage from servo to elevator. Inspect everything and determine, ON THE BENCH, that everything is as it should be. Maybe dial in some expo for your next flight. You got lucky with the first tail-heavy flights. Don't tempt it.

As someone else suggested, hang it to balance it. I'm also wondering how it came out SO tail heavy!!! I know it has a short nose moment, but 17 ounces?!?!?! Over a POUND??? I'd strongly look at your balancing method if I were you.

One way I balanced a Giant Hots was to CA a small screw eye in the center of the top of the fuselage at the recommended balance point. Hang it from that and balance accordingly. A small piece of covering covers the hole and is almost not noticeable.

A friendly suggestion: I wouldn't have modified anything on my first "plans" build. Walk before you run.
Old 06-28-2010, 03:22 PM
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Default RE: Balancing is soo easy [email protected]###[email protected]!!#!

Yes, but he said that he already balanced it according to the instructions
Old 06-28-2010, 03:23 PM
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Default RE: Balancing is soo easy [email protected]###[email protected]!!#!

Outdoor,
Check the incidence of the wing and the tailplane if it is straight.
Use one of the many cg calculators on the net and calculate the correct cg. It just sound an abnormal amount of lead you are using.
If the cg on the plans are correct, make weight useful andreplace some of the lead by fitting a bigger, heavier (heavier than the one you've tried)engine and/ or see if you can extend the engine more forward still.
Unless one overlook a very obvious thing ( i.e. glued a pair of pliers by accident in the back of the fuse ) and failing all, toss the plane out
as per the saying "Don't trouble trouble till trouble troubles you"..

Old 06-28-2010, 03:26 PM
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Default RE: Balancing is soo easy [email protected]###[email protected]!!#!

Do a search for "Vanessa cg rig." For $5.00 plus some stuff you've probably got lying around you can make a balancer that will let you balance any model, big or small, high-wing or low wing, by yourself. And it will be easy. Why people pay hundreds for balancers that aren't anywhere near as good is a puzzle.
Old 06-28-2010, 03:29 PM
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Default RE: Balancing is soo easy [email protected]###[email protected]!!#!


ORIGINAL: MinnFlyer

Yes, but he said that he already balanced it according to the instructions
Right. That's why I suggested some other things that might be wrong.
Old 06-29-2010, 10:21 AM
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Default RE: Balancing is soo easy [email protected]###[email protected]!!#!

I'm trying out the new Sig balancer and it is looking pretty good.
Old 06-29-2010, 04:28 PM
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Default RE: Balancing is soo easy [email protected]###[email protected]!!#!

I take balancing seriously and I never use anything but my fingers.

Here's how to do it accurately: cut two thin strips of masking tape, measure where you want the balance point to be on each wing half, and then stick the masking tape to the bottom of the wing at the desired CG with the tapes running spanwise. Then put your fingers on the tapes...you will know instantly if it is tail heavy or nose heavy.

After that initial test, do your maiden flight and then adjust according to how it flies.

Starting very conservatively and adjusting by flight testing alone will work, but why go to all the trouble of getting the plane to balance at a point that is going to be too far forward anyway?

Jim
Old 06-29-2010, 05:36 PM
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Default RE: Balancing is soo easy [email protected]###[email protected]!!#!

The challenge with the "finger tip" technique is that the spinner is in my chest and I can't see if it's nose up or down.  Dowels with erasers on a mid-wing plane is not for the faint hearted. The Vanessa sling requires that you can establish the stab at 0 degrees (or angle of incidence stated by the mfg.) though it works very well on high, mid, low and bi-wing planes - my preferred method of madness.

No matter what approach taken - it's just a starting point. I have found (as well as other posters) that "typically" 1/4 oz. at the tail or 1 oz. at the firewall will move the CG 1/8". Take a bunch of lead with double-sided tape to the field and start your "pitch" trimming. I also create 1 oz. lead bundles that can be quickly inserted behind the FW.

Good luck!

Old 06-29-2010, 07:00 PM
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Default RE: Balancing is soo easy [email protected]###[email protected]!!#!

Yeah, most of my planes are smaller. But I also have windows in my shop, and at night I use the reflection to check out my plane.

Jim
Old 06-30-2010, 07:41 AM
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Default RE: Balancing is soo easy [email protected]###[email protected]!!#!


ORIGINAL: buzzard bait

I take balancing seriously and I never use anything but my fingers.

Here's how to do it accurately: cut two thin strips of masking tape, measure where you want the balance point to be on each wing half, and then stick the masking tape to the bottom of the wing at the desired CG with the tapes running spanwise. Then put your fingers on the tapes...you will know instantly if it is tail heavy or nose heavy.

After that initial test, do your maiden flight and then adjust according to how it flies.

Starting very conservatively and adjusting by flight testing alone will work, but why go to all the trouble of getting the plane to balance at a point that is going to be too far forward anyway?

Jim
I totally agree with everything you said Jim. The only thing I do differently is that I put the tape so that the front EDGE of the tape is on the desired CG so that I have a clear feel for where that "line" is (or I use 1/8" striping tape)
Old 06-30-2010, 08:03 AM
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Default RE: Balancing is soo easy [email protected]###[email protected]!!#!


ORIGINAL: buzzard bait

I take balancing seriously and I never use anything but my fingers.

Jim
I don't trust my fingers, only the CG Machine or the Sig balancer.
Old 06-30-2010, 08:25 AM
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Default RE: Balancing is soo easy [email protected]###[email protected]!!#!

I'm not trusting my fingers, I'm trusting the tapes, which I've carefully measured.
Old 06-30-2010, 09:11 AM
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Default RE: Balancing is soo easy [email protected]###[email protected]!!#!

It is a pretty airplane. WHat I would do is move the engine out 1/2 to 1in and make a new cowl; you have the skill as shown. All the extra stuff added up; I would go for the free weight movement instead of adding that much at first. That is part of experimenting with a design; change one thing will require a change of another. Where did it balance before, because these things should fly ok as far back as 4".
Old 06-30-2010, 09:48 AM
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Default RE: Balancing is soo easy [email protected]###[email protected]!!#!

thats why people hang the biggest engine they can fit up front .
Old 06-30-2010, 11:08 AM
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Default RE: Balancing is soo easy [email protected]###[email protected]!!#!

ORIGINAL: WhiteRook

thats why people hang the biggest engine they can fit up front .

I don't think that the real reason..

But it's one of the justification they come up with.

Kinda like when your wife says she bought those new shoes/dress/purse "because they were on sale."
Old 06-30-2010, 12:34 PM
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Default RE: Balancing is soo easy [email protected]###[email protected]!!#!

O D H
It may not be the CG.
check the incidence on you wing and your tail feathers. A slight missalinement in the h stab will push the tail down in flight making it act tail heavy
Old 06-30-2010, 12:39 PM
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Default RE: Balancing is soo easy [email protected]###[email protected]!!#!

OK., guys, thanks for all the input. I put it back on the GP balancer, added 1oz more of lead,( now I have 8oz in the cowl), reset ALL throws, ( elev was off a little). The wing & stab is set at 0 degress incidence. I took it to the field this AM & it flew a lot better, not perfect but definitly better! After about 2 mins the [email protected]#^%&^% motor developed a stumble I had to dead stick,(into the #$%$ corn.) No damage at all to the plane. However, I learned a long time ago, when things go wrong, don't fight it, (it seems like, THAT'S when I screw up ). I packed her up & came home. I think my engine stumble was from a bad piece of fuel tubing, I'm going to go ahead & check the "O" rings to the needle valve & carb to be safe. I'll post later & let ya know how everything came out. Thanks again, Ed PS. I am going to rig up a " Vanesa balancer.
Old 06-30-2010, 12:48 PM
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Default RE: Balancing is soo easy [email protected]###[email protected]!!#!

Hey, Sir King Livewire. Not seen ya around for a while. Jeesh, 6000 for a score, how do you do it.. I'm totally jealous. Hehehe. I checked the incidence before I flew this AM & it was "spot on". I think last year's deal was I was having a bad day & all of the balanceing stuff just threw me for a loop. I've never had any major problem balanceing before. I got super ticked off & just hung it up for another day !! I had a whole new outlook this AM & thing went a lot easier. Later, Ed
Old 06-30-2010, 01:57 PM
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Default RE: Balancing is soo easy [email protected]###[email protected]!!#!

As far as score some one is having a Hay Day.
Some time you just have to set back , have a cool one and then see what happens. Usually I need another cool one then I don't careMy Waco has been hangeing up for a year and I found radio equipement I thought I lost. It is ready to fly and I forgot about it.
Next I have been in the 1/2A forum pestering the guys there. Postal plane

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