View Full Version : Phil Aero / Aircraft CG Calculator
12-08-2011, 10:46 PM
Easy simple way to weight and locate your balance point ( CG ) .
No need to lift the plane by the wingtip, no need for a second set of hands.
Make battery and equipment location easy.
Only requires Microsoft Excel and 3 Scales.
Available directly from me or from:
For only 30$
PDF instruction will be available for viewing on MR Aerodesign website.
12-08-2011, 11:32 PM
Phil, what kind of scales?
12-09-2011, 12:06 AM
Phil, what kind of scales?
weigh scales - probably digital (for ease) - I bet. The kind that you might weigh food on in the kitchen (for those of us who actually venture in there other than for eating - unlike me, totally an eater ;-)).
I think the idea of the Excel and physical geometry is to measure the pressure (weight) imposed by the plane on each wheel, use that plus the dimensions to compute basic F=ma type calcs to reverse calculate the balance points. Ie. using the available info one can calculate how much the plane is leaning to the left, right, forward (or back). That weight differential can be used to determine how 'off' the CG is or where it should be.
Way cool and simple (at face value) idea!! Kudos to Phil Aero & co ;-).
12-09-2011, 10:58 AM
I have build this system from the tool i use at work for full scale helicopters.
Works really well, giving you your aircraft total weight, CG and also lateral CG (span wise).
Basically any scale will work...
Digital add to the measurement precision of course, and also you have to be aware of your scale range... Most kitchen scale stop at 5 to 8 pounds, not enough for large scale airplane.
I was able to find some good quality scales on e-bay for 12$ each plus shipping and they are good for up to 35 pounds.
12-09-2011, 02:11 PM
This is a great idea.
Heck I just remembered they used to do this at the flying school I was at.
12-09-2011, 03:19 PM
Feel free to send me an e-mail if you wish to see the instruction manual...
It was too big to be posted here...
12-12-2011, 11:22 AM
I've done this before without the Excel spreadsheet. Would deffinitely make it easier but shouldn't you just be using one scale and blocks? The reason I ask is if you use 3 different scale they are not all calibrated to each other. With one scale even if the scale is out a bit it is out the same for each of the measurements. JAT
12-12-2011, 12:38 PM
Yes, your scales should be all calibrated for accurate reading, which i did with my scales, using a known weight i have ensure that they all have the same reading.
The other thing that can done is move the scales around from each position and use the average reading at each position, this is something we do for real aircraft.
But you do need 3 scales for the best result and most efficient way to do it.
I didn't invent anything here... I have build the Weight & Balance system that we use here for all our aircraft (we operate a fleet of 11 Helicopters). What i did is make it more user friendly and adapted for RC planes.
I fly large scale planes and i always find it hard to accurately balance your plane, but this is thing of the past now that i have that system. With my lap top on the bench i can have the plane sitting on the scales and play with my equipment location until i find the proper placement.
12-13-2011, 05:20 PM
I now have my website going...
Its very simple but give you access to some picture and instruction...
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