ok here is a 'not to scale' but all measurements are accurate representation (all be it very crude) of a glider i have built.
i am having a prob with the cg location, i have gone for the thickest part of the kfm wing and the i get the cg at 75mm from leading edge, but it just dont look right?
i have tryed the online cg locator gives me a cg location near the trailing edge??
can someone please advise if they can.
Many thanks in advance RCT

wingspan is 1603 not 1630 sorry my bad

It looks like it's about 38% of wing chord which would be too far aft for me if I was setting up a plane. I likek to start at 25%, Now that's just me, and lots of guys like cg at 30% of chord. This all for a conventional type plane like yours. I don't know why the calculator might say otherwise. Generally with a KFM2 or 3 and the 50% top step, cg will be foreward of the step.

OK. Going by the old Rule of Thumb the testing CG should be at 25% of the wing cord, that is 30mm from the leading edge. The CG can then be moved back to around 1/3 of the cord to 65mm.
Or: Using a calculator I get testing at 33mm and final at 52mm.
That'll get you going.
Good luck with it all.

Hah! My bro got in first!

thanks to you both that has helped loads, now to get back to building.
RCT
P.s. its a kfm9 foil
P.P.S. made a mistake in the wingspan it should read 1603 not 1630.

Originally Posted by Whiskers

OK. Going by the old Rule of Thumb the testing CG should be at 25% of the wing cord, that is 30mm from the leading edge. The CG can then be moved back to around 1/3 of the cord to 65mm.
Or: Using a calculator I get testing at 33mm and final at 52mm.
That'll get you going.
Good luck with it all.

Hah! My bro got in first!

Bingo-correct! Whiskers hit the CG on the head!

now AUW so far is 900g ish so i was looking at either of these two motors what do you think?


http://www.giantcod.co.uk/epower-gt2...-p-405956.html because i need some extra weight up front, still might need say 40g extra on the nose i think.

or this one...

http://www.giantcod.co.uk/221720t-86...-p-402409.html but will need to add extra weight for this one.

i am leaning towards the first one but not to sure, will want to put a nice big folding prop on it as well.
can i please ask for everyones advice on this matter please?
many thanks RCT