weight and balance question

On Tuesday, June 28, 2016 at 2:54:01 PM UTC-5, wrote:

It's not so much a question of empty weight, but where the CG is located, So weighing the glider in a trailer is useless.

Ah, but if you know the total weight of the glider, you can then use a calibrated (or verified) bathroom type scale under the wheel that has the low weight on it, and from that determine the weight on the "heavy" wheel, measure moment arms (or trust factory measurements) and calculate C of G location.

So, I respectfully disagree with your conclusion that weighing the glider in the trailer is "useless". It is just the first step to determining empty weight and C of G.

You could also weigh each part separately, sum them to get total weight, then get the weight on the light wheel with the plane assembled and properly leveled, and calculate C of G location.

But, I agree it is far easier to get an appropriate set of scales, and weigh the assembled airplane!

Steve Leonard

On Wednesday, June 29, 2016 at 10:57:53 AM UTC-4, Steve Leonard wrote:
On Tuesday, June 28, 2016 at 2:54:01 PM UTC-5, wrote:

It's not so much a question of empty weight, but where the CG is located, So weighing the glider in a trailer is useless.

Ah, but if you know the total weight of the glider, you can then use a calibrated (or verified) bathroom type scale under the wheel that has the low weight on it, and from that determine the weight on the "heavy" wheel, measure moment arms (or trust factory measurements) and calculate C of G location.

So, I respectfully disagree with your conclusion that weighing the glider in the trailer is "useless". It is just the first step to determining empty weight and C of G.

You could also weigh each part separately, sum them to get total weight, then get the weight on the light wheel with the plane assembled and properly leveled, and calculate C of G location.

But, I agree it is far easier to get an appropriate set of scales, and weigh the assembled airplane!

Steve Leonard

Further to Steve's point.
A quick and dirty safety check is to level the glider and weigh the tail with an accurate scale.
Comparing the tail weight to what is shown on the last measured weight and balance will show whether there is something to be concerned about from a safety point of view.
This can be done with the bathroom scale we all have.
It is not a substitute for the real thing but it will show if you have a likely problem.
I did this when my first '20 was really hairy to fly after I bought it. This disclosed the 13 pounds of undocumented tail weight.
UH