CG Machine
 

Every time I ask you guys for some ideas you never cease to amaze me with your ideas and inventions.

Tell me the different types of equipment you use to balance your jets to adjust the center of gravity.

Pictures would be great too.

Seems like when I think I have a way worked out to do something....someone here has a better idea.

Let's see some "CG MACHINES"!

Don

RE: CG Machine
 

This is what I use for KingCats, Boomerangs, etc. It's handy if you don't have any help with the bigger aircraft. And it's adjustable, just unscrew one of the dowel rods and place where needed. It's crude but it works

RE: CG Machine
 

An inverted chair, with some protection on the leg for the airplane

RE: CG Machine
 

Oh my god, of course ![X(]

Doh! That's so stupid-simple that it's brilliant ! The best ideas are always ridiculously simple and make me ask why I didn't think of that.:eek:

RE: CG Machine
 

What's so simple about it? I couldn't get it to work.[:o]

RE: CG Machine
 

Nice chair Mark!!!
Don

RE: CG Machine
 

I've decided I prefer to hang them. In the pic here, I just make a plywood plate (2, identical), that slips around the wingtubes, and fits between the model and wing. Your model configuration may or may not allow for that. The nice thing about the plates, is you can then drill locations that correspond to various %mac, so you know exactly where your CG is (25% mac, or whatever.) Or if its a kit, just drill the plates where it needs to balance, and maybe 1/4" fwd and aft of that, whatever... You can then retract your gear, and check that CG. Then you can write it all down and store it with the plywood plates, till the big ol' repair job comes, and you hafta do it all over again!... :)

RE: CG Machine
 

Same here but in this case I'm hanging the airplane from screws that are located at the CG point on the wing root . Pretty slick way . A 32 lb airplane is a little too heavy to lift up with your fingertips !

RE: CG Machine
 

Thanks guys.

Great ideas.

Keep 'em coming. I bet many pilots will be helped by these ideas.

Don

RE: CG Machine
 

as simple as it seems, I purchased one of the Great Planes CG Machines a few years ago.

It handled the weight of my Yellow Twin Hornet with no problem.

if the base is too narrow for your project, all you have to do is acquire a pair of larger rods to widen the support structure.

RE: CG Machine
 

Heres my offering, uprights 30inches on sliding base to accomodate all jets balanced so far.

RE: CG Machine
 

yeahbaby , what is the weight of your twin Hornet? I have that same Great Planes CG machine but I have never used it for a big or heavy plane.
Don

RE: CG Machine
 

Amigo

it weighed aprox 32lbs.

RE: CG Machine
 

yeahbaby ,
Wow, I would not have thought it would support that much weight. Thanks...

RE: CG Machine
 

no sweat amigo.

unless you widen the support base, some of the larger models can be challenging to balance. I ended up inverting the big bird, so you can imagine this quote from my son.... "Dad is this a good idea?" when we balanced the beast, the fins cleared the ground by mere inches

Silence.....I Keel You:D

RE: CG Machine
 

You gotta love Achmed! :D

RE: CG Machine
 

Stop Touching Meeeeeeeeeeeeeeeeeeeeeeeeeeeee

RE: CG Machine
 

I bought 3 digital scales for 30 bucks apiece and find CG the way they do on full scale aircraft. Visit the Jet Pilots Organization web site for the spreadsheet with all the formulas. Takes three measurements and then three weights ... one on each wheel. Works with any size aircraft with no hanging.

There are several spreadsheets out there for various planes.

www.jetpilots.org pick the members tab and then weight and balance from the sub-menu. I am getting ready to post more spreadsheets this evening.

RE: CG Machine
 

You can do it with one digital scale and to a high degree of accuracy.

Change the below file extention to .doc and open in Word.

Have to make a few measurements. Nicest thing is you can sit on the scale all day and move things around until you have it dead on.

RE: CG Machine
 

I prefer the hanging method also except I use a plumb bob to find the c.g.

RE: CG Machine
 

I have used this one in the past, works fairly well.
http://home.mindspring.com/%7Ethe-pl...%20Machine.htm

RE: CG Machine
 

I used the Great Planes C of G machine to set up the Flash after I'd seen someone from that thread use it. I wasn't sure it could hold that weight, but it was fine. It can take up to 40lbs!!

Thanks for the pointer to the jetpilots website pilot28, some great info on there!

Chris

RE: CG Machine
 

These are GREAT ideas guys!

RE: CG Machine
 

Anyone else? Anything different from these listed?
Don

RE: CG Machine
 

I concur w/Keith (pilott28): The weight/moments method with the spreadsheet is the cat's meow. Why lift, hoist, bang your jet around? Just slap it on the scales, make the measurements (which you only need to take once) and plug in the weight(s) - just like the big boys do it - and VERY accurate too. You'll soon be asking yourself why you hadn't done it this way before!