ORIGINAL: Popriv
I started the original post questioning what part of the plane should be level when balancing.
I see where you have put your level, I dont really have anything flat like that on my tiger fuse to go by.
Really, any part of the plane that's at 0 incidence will do. That's why i mentioned the string level earlier...if you know the wings to be at 0 incidence, then simply put the string level on...well...a piece of string *heh*, and then tape the string to the wingtip, with the string running through the centerline of the wing (presuming a symmetrical wing). or through the chord line if not. It's ok to be a tad off.
Other places I've used include the tail, the bottom of the fuse (hang the airplane upside down), the top of the vertical stab, or even pinstriping on the side of the fuse.
While it may not be exactly "perfect" you can, ime, use pretty much any line that "looks straight" through the long axis of the airplane.
So I was putting a small level on the tail (supporting it with my hand because of the weight of the level)
This, imo, is probably not the best way to go about it. Others may disagree, but I feel that I can't be precise enough "supporting something with my hand" to accurately offset the weight of a level. Instead, when i've used the level at a point well away from the intended CG, I do a bit of very simple math:
W*A=M
Weight * Arm = Moment
Basically, all that formula says is that for a 50 lb kid to balance a 100 lb kid 10 ft away from the middle of the see-saw, the 50 lb kid must sit 20 feet from the middle.
Weight is exactly that. The weight of the item in question, in this case your level.
Arm is the distance of the weight (measure to the CENTER of the item in the case of something long like a level) from the balance point, or CG in this case.
Moment is the product of multiplying the two. So, if you have an 8 oz level, and it's 25" from the CG, you have a moment of 200 oz-in
Let's say you have the level on the tail. Fine. To balance it, you need an equal moment somewhere FORWARD of the CG.
Perhaps there's a spot by the motor, for example, that you can set something. But the motor is only 10" away from the CG, perhaps. Ok, do the math. You need some as yet unknown weight * 10" arm to equal 200 oz-in.
Viola. A 20 oz weight will do the trick.
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While we're on the subject, one of the handiest things I have in my shop is a big tray of old wheel balancing weights. Just go up to any tire shop near you, and tell them you'd like to take a few handfulls of old, used wheel weights off their hands. They'll be happy to give them to you. The weights come in sizes from 1/10th of an oz all the way up to 5 oz or more, and are usually clearly marked. They're small, and many are easily bent. They're GREAT for offsetting unwanted weight like the level in the example above, or for simulating weight you haven't yet installed, like future servos or batteries.
Also, My canopy will be over my CG so I guess I'll put masking tape on it to make any marks... But I'll lose them as future reference points when I remove the tape. Why do they say to balance low wing models with the canopy down.
Taping the canopy for marks is fine...or you can tape or mark out on the wings if you wish. With something like the vanessa, you can easily get out at the wingtip, and sight down the line to see where the plumb bob is pointing. Take a look at the second picture in my post for an example.
As for balancing canopy down, there's a couple of things there. The major thing is that if you're balancing on fingers or dowels, you want the mass of the airplane BELOW the wings, so it's acting like a pendulum. It's not that the CG is "wrong" done the other way...it's just considerably easier to be more precise.
Like I had posted, I still think I'm nose heavy but dont have enough flying experience to tell for sure.
And that's much of the fun of this sort of thing, imo.
As you fly more, you become better adept at identifying the subtle (or sometimes not so subtle *heh*) changes a small shift in CG can make to an airplane's characteristics in the air.
Perhaps you ARE "nose heavy"...but so what? Just remember...as several have pointed out, this is a VERY subjective thing. Given an airplane that does X with the CG at some point Y, then there are, indeed, some fairly predictable changes that will occur if you move the CG forward ("nose heavy") or rearward ("tail heavy"). But these aren't necessarily "bad" or "good" things (within reasonable limits, of course)...they just are what they are. See below.
I was talking to some of the guys about doing flat spins ( watching them do it ) And got as high as I dared and tried a couple. My nose always pointed down, It was more of a spireling dive down than a flat spin.
Here's exactly that example. You're probably right...moving the CG back a bit would quite possibly flatten those spins out. It'll do a few other things too.
The tail surfaces will likely become a bit more responsive to inputs, the plane may "float and thud" (floating to a near standstill, and then suddenly falling out of the sky) a bit more on landings, turns may require a bit more rudder...all kinds of neat things. Some changes may be so subtle you don't see them, others very pronounced.
Are any of these things "good" or "bad"? Not really. They're simply what they are. What makes them good or bad is whether YOU like them. YOU want the airplane to flatten out a bit in spins...so if you can move the CG a bit, and get it to do that...then that's as "good" as it needs to be.
All you can really do, as Minn suggested a while back...is play around.
When the airplane does what you want, and you enjoy flying it, then it's "right"...regardless of what some manual or "expert" may say to the contrary.
I'm going to add 1/4 oz weights to the tail ( 1 at a time ) and see how it flys.
Nothing wrong with that. There's all kinds of ways to play with the CG. heck, there's multiple ways to THINK about it. As i said above...perhaps you're a "X amount of weight in the tail" guy...or maybe you're a "Move the CG X distance" guy. Whatever works, man.
You might even consider just moving some things...perhaps slide a battery back a touch, or relocate a servo. Those impact CG as well, and have the advantage of not adding "dead weight" to the airframe.
All just stuff to play with.
I'll use the venessa to see how I balance before and after adding weight. If I like the way it flys I'll then go in and move my equipment around.
And this, exactly, is why I consider the tool so valuable. It provides means to do all sorts of things, including just what you said. You can use it to see what kind of impact ANY change makes to the CG, and then also use it to 'record' that change, and recreate it later using another method.
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In any event, Steve, I probably should echo again what I believe Minn's original point was...
All this stuff is well and good...and for some of us odd-balls, it's actually an enjoyable part of the hobby to play around with weight and balance to some insane level of precision. There are, however, a million ways to skin this cat, and ultimately, "close enough" will, indeed, get the airplane in the air and flyable...and from there it's all a big pile of subjective preference anyway.
In other words...don't forget to have some fun in all of this.