Chapter 27 - Section 2

Weight & Balance

 

I went to Marc Zeitlen's site and downloaded his Weight & Balance Excel spread sheet to perform by weight and balance calculations. Before any calculations can be done, I need to take a few dimensions (on the place) such that the W&B calculations are specific to my plane.

 

Determining Moment Arm Lengths

I followed Nat's Pilot Operating Handbook Section 6.1.6. Here's what I did:

1)    I leveled the plane and placed chokes on all three wheels. With the help of plumb lines and lasers, I establish my plane center line onto masking tapes on the floow;

2)    I started with the wing root position with plumb lines and assume they are at 113.9"

3)    With laser triangulation, nose tip position is determined to be -6.9";

4)    Nose wheel axle at 18.95"

5)    Canard leading edge at 18.50"

6)    IP front face at 41.25"

7)    Main gear axle at 109.90"

8)    Fire wall (including fiberax & sheet metal thickness) at 124.4"

9)    Propeller flange at 124.4" + 40.25" = 164.65"

10)  Nose ballast compartment at -2.5"

11)  Second ballast compartment (behind nose) at 6".

 

I fed these numbers (as appropriate) into Marc's spread sheet for the moment arm dimensions. My numbers differ slightly from Marc's, generally no more than 0.1". I considered them good to go. 

 

Weighing The Plane

This is one of those moments that give Cozy builders anxiety attacks.  We all worry that our plane may be too heavy and will end up with a slow airplane. Well, my turn has arrived... Clark Canady was gracious enough to loan me his weight and balance scales and a nicely build ramp for rolling my plane onto the scales. Nicely done Clark - Thank You!

 

I set up all the scales, follow its calibration instructions and line up the ramps to the wheels. Susann and I pushed the plane up to the scales and made the measurements. I have 25 lbs inside the nose compartment, 26 lbs at the front compartment, no fuel & 7 quart oil.

 

 

 

 

My weight came in as follows :

Nose             58 lbs

Right main    593 lbs

Left main       586 lbs

 

Total (plane, 7qts oil, 51 ballast) = 1,237 lbs

Total (without ballast)         = 1,237 - 51 = 1,186 lbs...I am happy...