Cyclicscooby Posted April 26, 2014 Share Posted April 26, 2014 Hi Guys... Just a quickie, regarding C of G calculators... Ive looked at a few and used the Adamone one... Thing is, they all show a swept LE wing.. Ive built a 1200mm W/S Sbach-ish plane which has a straight LE and swept TE. Ive entered the figures and got numbers out, but knowing the swept bit is back to front.. Will the calculated CoG be correct from my straight LE (calc assumes LE is swept remember) or will i have to measure it forward of the swept TE...? I presume the calculation doesn't take into account the direction of flight, just the physical CoG of the wing shape.. ?! Luv Chrisie.. xx Quote Link to comment Share on other sites More sharing options...
Stefan Hafner Posted April 26, 2014 Share Posted April 26, 2014 As long as you set the sweep value (S on the calculator) to zero the CoG will be correct. I'm guessing you could even use a negative in as the S value to calculate a forward swept wing, assuming the script could handle it. You're right in saying that the CoG calculations don't take into account, they are only geometric solutions to find the neutral point, and then you choose your static margin to find your centre of gravity, as the static margin will determine how stable your plane is, the bigger it is the more stable the plane will be. Quote Link to comment Share on other sites More sharing options...
GrahamC Posted April 26, 2014 Share Posted April 26, 2014 I think, on the calculator in question, the drawing is just a guide to the figures you put in. It's shape is to help the user understand which figure is which. For the wing you describe, 'S' will be zero, and the mathematical model accounts for the swept traing edge because 'A' is greater than 'S' Does the value you get out look about right? Quote Link to comment Share on other sites More sharing options...
Chuck Plains Posted June 14, 2014 Share Posted June 14, 2014 Hi CCS. I use adamone's calc all the time. But I have tried several others and fwcg.3dzone.dk flying wing calc shows a varying image of your wing profile each time you update your dimensions. Put in a zero sweep and it shows a straight leading edge. I think this works on adamone's one. Although the image doesn't change, I believe the calculated cg will be ok. I tried it just now and then changed the sweep distance to the same value as the tip chord and the recalculated cg moved back quite a bit. Hope this helps. After that, I guess we just have to suck it and see. Quote Link to comment Share on other sites More sharing options...
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