Lnewqban

It seems to me that the problem is in the way the rope is attached to the dowel.
Because it is not symmetrical respect to the center of the rig, a twisting torque (yaw) is applied by the very weight of the model.

Also, that knot next to the trailing edge of the left wing may be affecting the left loop.
I would make two independent loops and two plumbs (plumbs to have a loose loop on dowel, so are not affected by rotation of the dowel by hand).

Tom Nied

Yeah I changed it to "in to out" on both sides and it has made a world of difference. Also reduced the wraps to only 3 on each side, makes it easier for tweaking in the initial lifting. I'm only using one big loop that goes around the fuselage at the leading edge and trailing edge. Seems fine now. Looks like I'll be adding some weight to the tail (moving batteries rearward first).

malitape

My Feedback: (213)

When choosing the bob, which is better, heavier or lighter, in relation to settling the bob? Thanks for any response

ETpilot

I don't think the weight of the plumb bob makes too much of a difference for our modeling needs. More important is to make sure you tie the string properly so the plumb bob hangs centered. Also work in an enclosed space so you do not get any kind of wind movement. I got my plumb bob at Harbor Freight Tools. It probably weighs about 5 oz. Tying the string properly on this plumb bob is key.

Tom Nied

I just used a couple of old pens (I'm using two one on each side) that I cut off the pocket clips making them symmetrical. Drilled a hole at the top axially and used a thread loop making sure they hang straight. Seems to work OK.

malitape

My Feedback: (213)

The reason I ask is that when I watched a video of the vanessa in action, the bob was having a hard time to become still. Could that be fixed by changing the weight of the bob?

ETpilot

Now you you are getting into the Physics of Mass. An object in motion has momentum. The larger the mass the more the momentum. So I would think the heavier bob would take longer to become still. But I could be wrong. Someone may correct me.

The drawback to this rig is you will get motion of the airplane and plumb bob with each adjustment. The key is to minimize the motion. That is why I made the windlass set up in the dowel. I still get motion but not as much as grabbing the dowel and twisting. When I do get movement I just use a finger to counteract the movement on both the plane and the bob. It settles down fast. I do this in my totally closed up garage so wind is not a factor.

malitape

My Feedback: (213)

ETpilot, makes sense, thank you. Hope I'm not going to start a long winded debate.

Tom Nied

Yeah, I just steady and try to stop the plane from swaying and the bob. But my dog "Bart the Wonderdog" has no concept of what I"m doing and will get up or brush past without regard. Thanks Bart.

ETpilot

Yeah, those pesky little pets. They tend to get in the way. I have a few here too but they do not go into the garage. So they are pesky in other areas. You can't win with them. They rule.

Michaelj2k

Cats are the worst.

Fulmic

Good Morning to All of You.
I wrote you from Italy and i would like to have a clarification regarding Vanessa System. If i need to balance a glider Gruapner Grob Twin Acro with 4 Mt wing i need to keep in consideration that the horizontal rudder is completly moveble is not as a regular model with a fix and mobile part.
In this case the main condiction is that between the wings and the horizontal rudder i need an angle of 1,5 Degrees.
My question is the follow
To balance the model with Vanessa in principle i need the Horizontal rudder at 0° and on that position a check the CG on the wing.
But in the case of a completly moveble horizontal rudder i need to start from the wing and in this case i need to put the wings at the angle of 1,5° and later on in such position set to 0° the rudder. It is that correct?
Thanks

Lnewqban

The Vanessa system will show you the vertical line along which the center of gravity of your glider is located.
The inclination of the fuselage or wings respect to the horizontal does not change the fact explained above.

Fulmic

Thanks for clarifications, i agree but any way to mesure the CG is important to fix Horizontal the vertical rudder other way you can not mesure in the correct way

Tom Nied

I agree with Lnewqban. The Vanessa rig will point to where the CG is if properly setup. I was able to use a small bubble level on on my horizontal stabilizer. What is important is that you have the model level. Irregardless of wing incidence or decalage. I have enjoyed revisiting this thread. I still have the Giant Super Sporster.

Fulmic

Tom thanks i agree with you in the case that a model has at least half horizontal rudder fix and half movable, in this case you put the level ball on the fix part and you find the zero position later on you define and set the CG. But on my model the complete rudder is movable and in this case i suppose i need to find the correct zero position of the rudder first and in this case i need to start from the fact that incidence angle between rudder and wing is +1,5°. In this case i start to put wings at 1.5*° and in that position i put on 0° the rudder. From that point i am sure that between rudder and wings i have 1.5° and in that case i can define and fix the right CG. This is my point of view that is connected with the fact that the horizontal rudder is completley moveble. Thanks

scale only 4 me

My Feedback: (158)

You guys always over think things,,

Just set the plane at the angle of attack as it would be in normal level flight, Yes,, just eyeball it,, plus or minus 1 or 2 degrees of incidence is not consequential to where the CG is,,

After all, it's just a toy airplane,, not a swiss watch

jaka54

Guys! How come you bother with that thing when all you have to do is use your two fingers to check the balance on a plane.

Tom Nied

Well my Great Planes Super Sporster is almost 15 pounds. I got over $1000 into it. Do you think two fingers to check the balance on a plane method is appropriate? Maybe for your planes. It's just another method when setup properly will accurately show where the CG is located. It's not for everybody.

scale only 4 me

My Feedback: (158)

LOL,, most mine are well over 25lbs,,, this one clocks in at 35lbs+,, I'd love to see someone hold it up with two fingers,,

Also,, Even with smaller planes, what the rig allows is you to set the plane level,, then move weight or equipment around to find your target CG,, without having to manually lift the plane over and over again

jaka54

Well , I have no problem balancing my 16 pound Yak 54 or my 11 ound GEE BEE R2 with 3 or more fingers under the wing.

scale only 4 me

My Feedback: (158)

You asked,, I answered,

You'll have even less of a problem using a Vanessa Rig,, but since you have never tried it you just don't know how much easier and much more accurate it makes the process,

As you can see from my rig, it can be made very inexpensively,, most that stuff I had laying around the garage,, the only thing I went out and bought was the pipe insulation..

good luck