Fore Flight / weight and balance

[wannafly]

Just working at setting up the weight and balance on Fore Flight for my Kitfox IV. In the forward and aft CG limits it has 2 spots to fill in. So my forward CG limit is at 10.2 inches and aft CG at 16 inches. Empty weight at 700 lbs and Max at 1200.
So for forward CG limits do I enter 10.2 in at 700 lbs, and 10.2 in at 1200 lbs.
for aft CG limits do I enter 16 in at 700 lbs and 16 in at 1200 lbs.

Am I understanding this right? Anyone familiar with the app let me know how you filled it in so the graph is accurate.

[t j]

I'm not familiar with foreflight but I'll see if I can get myself in trouble. I made a weight and balance CG envelope graph using your numbers to find the 4 corners and it appears it works for a Model 4 1200 Kitfox.

I would try it and see if the program builds the correct graph.

[wannafly]

it builds the graph but just a square box. It then alerts you for anything outside of the box. Yours has a different shape to it so not what to think of that. Would they both work the same?

[t j]

If the box is square the program probably has the length of the CG arm on the horizontal axis instead of the moment (arm times weight). I should have labeled the horizontal axis "Inch pounds".

[Mcslamma]

I just entered W&B in Foreflight for my Kitfox IV and get a square box, as a CG envelop. In the IV POH, they have a C of G Moment envelope as shown below and is the same shape, but both are valid, as long as CG falls within, Foreflight plots fuel used for flight as well, if you enter and shows new CG, and also 0 Fuel CG projection, Seems very well done, I have skiis and floats, and entered both and at is accurate in my estimation:):)

[kmach]

This is how I have my model 5 setup

[t j]

The CG envelope I hand plotted has weight on the vertical axis and Moment on the horizontal. The slanted left side of the box is forward CG limit and the slanted right side is the aft CG limit.

This type of graph eliminates the step in the calculations of dividing loaded moment by loaded weight to obtain the loaded CG location. Computers will probably make it extinct.

It looks like the Foreflight program uses CG Arm on the horizontal axis, thus the vertical sides on the box.

[HighWing]

Sorry and very likely showing my age, but I wonder the practical value of this much data on a Kitfox. When I worked as a SOR at United Airlines - don't know what SOR stands for, but we sat in front of a computer received all the passenger seating data, baggage and freight weight and location then calculated a MAC (Mean Aerodynamic Chord) for each departing flight out of SFO. I once miss-positioned 2000 lbs. aft of the CG on a 747 and confessed it to a pilot friend. His response "No Problem". They set elevator trim based on the calculated MAC but it's easily adjusted if in error. - except, I guess in extreme cases that result in a tail strike on departure. We would often restrict seating for W/B on take off, but once airborne people flocked to the empty rows, again No Problem.

I sometimes think I am driving (flying) a Model T rather than a Model IV when these topics come up. I rarely trim for departure, my departure trim is determined by ASI and A;);).