by MikeL » Mon Apr 20, 2015 9:31 am
Hi Nigel
Like you, I have tried many times to get the correct figures to produce an acceptable polygon, and hope that I have now cracked it.
SkyDemon is a brilliant piece of kit, but the weight & balance instructions are pretty opaque -the figures they give are not backed up by an explanation.
First, these are my SPL's Weight & Balance figures: Empty weight 260 kg @ CG 1586
With trial & error I have found the following will produce a polygon:
Going around the polygon (clockwise starting from the X/Y axis junction) in order:
1 1601.0, 260.0, ( 1601= CG minimum limit. The 260 = my empty weight)
2. 1601.0, 315 ( Most Fwd CG calculated with 55 kg pilot & no fuel-315 kg)
3. 1650.0, 450.0, ( Most Rearward CG calculated with 2 x 86 kg crew & no fuel. Max Weight allowed )
4. 1695.0, 450.0 (Most Rearward CG limit) & Max Weight Allowed)
5. 1695.0, 260.0 (Most Rearward CG & my SPL's empty weight)
If your set-up figures under “Aircraft” use the Pilot position 1688, Fuel/baggage position 2215 & you put your own weight in as pilot default weight & zero default for the other items, the graph populates itself waiting for you to add the relevant passenger/fuel/ baggage (if you are lucky) weights.
You must, of course, enter your A/C empty weight & CG in the top panels initially.
I found that you need to keep switching SkyDemon off/on every time you enter different polygon figures & also that the “flying weight” figure which comes up on the graph deducts the figure you have entered initially for taxiing, which is confusing at first, but actually very helpful.
I don't claim that these figures are “cast iron” because I am no expert in this matter, but they seem to work graphically & I hope they might stimulate further testing/verification by others who have been confused by SkyDemon's instructions.
Perhaps you can let us know how you get on?
Mike L.
Pc 1601.00,260.0, 1601.00,315.0, 1650.00,450.0, 1695.00,450.0, 1695.00,260.0