P51p

Hi all
I have a Katana S 140 from Nitro Models and I am unclear about the CG location. The instructions state 110-130mm back from the leading edge and 150mm out from the fuselage. I tried balancing by measuring back from the leading edge near the fuselage then out 150mm, but the the plane required way too much of nose weight to balance which leads me to think maybe the instructions mean to measure out 150mm first than back 110-130mm from the leading edge. The leading edge of the wing is tapered back so I am not sure which is the correct way to locate the CG location.

Any help would be great.

Thanks
Graham

MinnFlyer

My Feedback: (4)

Yes, out first, then back

P51p

Great,
thanks for the info.

RCVFR

My Feedback: (7)

I have just completed and maidened my CMP Katana S version 2. The CG numbers in my manual are different from what you are showing. Mine shows to measure 242mm from the center line of the fuse and 100-120mm back from the leading edge. I think this is an unnecessarily goofy way to do it, but mine lines up to just in front of the wing tube, and it was a good setting for the initial flights.

Good luck with yours.

P51p

My problem is I don't have to original manual for the plane. But I did try measuring out first then back 110-130mm and the plane seems to balance much better. I hope to have a successful first flight. I have balanced it a little nose heavy for the first flight or until I get use to it.

sportrider_fz6

a rule of thumb I learned here that hasn't failed me yet is set the CG at 25% of the cord and adjust it from there.

jp928

My Feedback: (5)

jIM,

Did yours require much weight to balance it please? I have a Moki 135 with BCM muffler, alloy spinner, 2oz nut, battery on side of engine box, elevator servos in front of wing tube, 8oz of lead on engine box, and its still tail heavy....
I will check your 242mm out from centre and see if its the same as Iam using. The 100-120mm back is the same as my book.
thanks
jp

Mr67Stang

That works well on a constant chord wing and you might be able to get away with it on some tappered wing like the Katana but try it on a Delta and you will be vey nose heavy.

RCVFR

My Feedback: (7)

I didn't add any weight to mine: I have a CRRC 26cc gas engine at around 1100 grams up front. I did put the batteries forward, under the gas tank, however.

jp928

My Feedback: (5)

Well, with my Moki 135 etc (1350gm), ele servos up front, battery on engine box, throttle servo on engine box, a 66gm brass prop nut, its going to take 350gm on the engine box and 130gm on the mount (lined up with cylinder centreline) to balance it. Thats a total ballast (ie deadweight) of 546gm or 19.5Oz. Better than some, but still a sign of something wrong in the design or build. The stab halves seem to be foam/balsa, with maybe glass over it, and the fin also seems to be similar, which will add a lot of weight where its worst.
Curiously I have an ESM Katana (78"span, 2m), with a Moki 210 in it, servos in the centre, but behind the cg, and it needed a moderate amount of tail ballast. Its tail end is very lightly built though.
jp