I have a beautiful kit built Arrow 40 with a YS45 RE which I can't get to perform as it should. Everything has been checked but don't have the precise CG info. I'm thinking it might be tail heavy and will fly it this weekend with new CG, but would appreciate expert advice on this plane.

Just a note: I also have an Atlas 60 with a Novarossi 75 that flies awesome. I suppose the little Arrow should be just as good.

Thanks!!

Ed

Ed,

The MK Arrow 40 is indeed a beautiful little classic. I want to build one as well with the exact same engine on a Hatori 400 pipe.

Is the problem with the model, the engine or both?

Wing and stab incidences correct?

The wing is very wide at the root and is double tapered so the CG should be in the 30% wing chord range. I'll check at home.

David

Everything seems to be perfect, but I can't get it to fly adequately. It tracks perfectly well most of the time except on certain maneuvers (stall turns, knife edge). The plane I got from a guy in Ca. Seems expertly built. The engine pulls it extremely well, achieving speeds of 135 mph after a dive, using a 10x8 APC.

How far back from the LE is the balance point on your model? I built one from the MK kit back in the late '80s powered with an OS .40VF and it was a rocket. Mine was very light (all monokote). There is not much room in the fuselage for equipment; so it is difficult to move anything (like the battery) around. The YS .45 is heavier than the OS 40 VF so I'm a little surprised that you think it is tail heavy. Specifically, what does it do that makes you think the CG is wrong?
Please post a photo of your Arrow, if you can - thanks

Yak,

it sounds like there isn't really anything wrong with your A40 other than some trimming. They aren't perfect sphere's but dynamic machines... ;-)

Anyhow, I've got the data:

CG: 5.18" from wing LE at fuse side
CG: 5.41" from back of F3 at fuse side
Wing incidence: +0.5 deg
Stab incidence: 0 deg
Engine thrust: 1 down, 1.5 right

Do you have a 270 cc MK oval tank in her? Just wondering what kind of flight time you are getting on the piped YS45 FR. What pipe are you using? Also, what's she turning on the APC 10x8?

Oh yes, what Will said, some pics of her! I'd be interested in seeing the expert build innards and some 3-views if possible as well as the pipe setup.

David

Thanks guys. I'll take some pics and post them.

The YS45 RE is doing 14,300 on the APC 10x8. 10% Nitro, 20% oil.

Arrow 40