Boomerang1

Yep, the're too big & heavy to balance on sticks or fingers.

I've read a lot about the Vanessa CG rig.

http://creswellrcflyers.org/Text/Vanessa_CG_Machine.pdf

http://www.rcuniverse.com/forum/m_70..._1/key_/tm.htm

http://www.youtube.com/watch?v=h57T8OXH4qk

Have many of you guys built one, use one, like them, hate them?

I know some guys use the weight on the wheels & spreadsheet method but
I'm a bit old school & like to keep it simple. - John.

wfield0455

My Feedback: (7)

I used to use a similar contraption. Now I just level the plane, take the weight at each wheel along with the distance from an origin point and calculate the CG.
It provides an accurate CG and also gives you an accurate all up weight of the aircraft. All you need is an accurate shipping scale which are pretty inexpensive these days.

Square Nozzle

My Feedback: (1)

I use the Vanessa exclusively and find it's easy to use and accurate. The only issue I find, is lifting a heavy plane off the ground and securing the lifting rope to suspend the plane when I don't have help.

Pepperpete

I used to use the scale system and then a vanessa rig. I didn't mind the vanessa rig but found it to be a bit of a pain in the rear. Everytime having to re-adjust the aircraft, move stuff around, re-string it, lift it back up yadda yadda. And if you don't keep the cross member perfectly straight, you get false readings. I've switched to the EZ Balancer and would NEVER go back. The fact you can place the plane and it can't fall over, do as many adjustments as you want, and have it perfect in no time is worth the price and then some.

I know there are a ton of people who see the price and think "not a chance". I sympathize but I'm not in that camp and it's the best balancer I've ever used. I'm just SUPER picky when it comes to the setup on my aircraft.

http://dreamworksrc.com/catalog/ez-b...ii-p-1415.html

ww2birds

My Feedback: (14)

I've always had great results with a device that works similarly to the Vanessa rig, I got the idea from a post here on RCU but I regret that I cannot recall whose idea it was.

You start with a hefty 36" or 48" wood dowel, 1" or even 1-1/4" dia. Drill a hole in the center for a large eye bolt, 1/4" to 3/8" dia threads are good. Hang the dowel from the ceiling with a hook attached to the eye bolt, and make sure the dowel hangs level .. trim the heavy end if not. For the hanging strap, I like to use the fabric straps you get at HD or Lowe's, meant to strap down loads in a pickup truck .. then it's easy to adjust the hanging height since they have a nice adjustment mechanism built in.

Next make two loops of soft rope, one goes around the nose of the aircraft, just forward of the wing, one just aft of the wing. Set the airplane to be balanced on a table, hang the strap and the long dowel above the plane. The dowel runs parallel to the fuselage. Then loop each soft rope loop around the plane, and over the dowel. You can make a 1/2 twist at the dowel to make a figure 8 loop .. this will hold the rope loop on the dowel more securely. Some guys add foam tube padding to the ropes (the stuff meant for pipe insulation).

Next position the dowel above the plane so the eye bolt on the dowel is just above where the CG should be, and gently lift the dowel by the hook hanging from the ceiling .. slide the rope loops forward and back along the dowel until the plane sits level. At this point the CG of the plane is directly below the screw eye. You can hang a plumb bob on the dowel if you like. Same physics as vanessa but sliding the rope loops back + forth is much easier for me than the vanessa method, especially with larger and heavier planes.

If you add one of the cheap suitcase or fish scales between the hook on the ceiling strap and the eye bolt you also can easily weigh the plane. It's also very easy to see CG changes with gear up + down, UAT or fuel tanks full or empty, etc .. just slide the rope loops slightly to restore the plane to level and measure the new CG position with the plumb bob.

Dave McQ

Boomerang1

Thanks for the feedback guys, I'll give Vanessa a try! It won't take long to make one.

The guy that owned my house previously put a fixture in the garage (concrete) ceiling
which I used to lift my lathe onto the bench so it should handle my models!

I have a few motorcycle tie downs, I'll suspend the whole shebang from one of those,
just hook it on & pull it to raise the model. - John.

Boomerang1

It didn't take too long to make & was a simple job.

This has to be one of the simplest, safest ways to balance a model ever.

I started off on the floor, looped the rope over the fuselage &
just pulled on the tie down to lift it off the floor. The key seems
to be get the spirit level parallel with the zero incidence line from
the plan (was told it's usually the tailplane angle although not
mentioned on the BVM plan). - John.

Crazy Legs

I built a Venessa Balancing Rig because I'm by my self in my house and find that with the Venessa Rig I have the convenience of being able to have the airplane rest in suspension while I add a little weight at a time to get it to balance. I don't know exactly how precise the machine needs to be built, but I would think it isn't too critical. Have a look at my photo and let me know if you think it would suffice. The Dowel that supports the 1/4" Rope is a little lop-sided, so that's my concern. I used a laser level on a tripod to establish / determine when the Fuselage was "level".


The Laser Level's beam is lined up with a feature on the Fuselage that parallels an imaginary Datum Line. The bottom of the Rudder is also known to be a good reference for determining when the airplane is level.

Viper1GJ

My Feedback: (20)

My value and use of a CG checker is just to see if a plane is safe to fly. If it is in the safe to fly zone then go fly it. After flying the CG is adjusted to get the flight performance and feel that I want. After that I really don't know exactly where it is unless I want to share it with someone.

Gorm73

This is the best tool for measuring CG.


Of course, it takes up some space when it is in rest mode...