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-   -   Art Tech Yak 54 from HK. CG? Motor? (http://www.rcuniverse.com/forum/3d-electric-flying-237/11229052-art-tech-yak-54-hk-cg-motor.html)

pcnewman 09-15-2012 12:47 AM

Art Tech Yak 54 from HK. CG? Motor?
Where is the CG on your 36" AT/HK Yak 54? I just flew mine for the first time. Instructions I found online said the CG should be between the leading edge at wing root to 2-1/4" back but NEVER fly with CG further back than that. Well I had to add 3oz of lead to the front of the cowl just to get it to the 2-1/2" mark. Had DX6i @ 30% on low rate all surfaces and 70% on high rate. When I took off I gave it all up elev and was barely able to get it off the gound and wished I hadn't. Had to use high rate just to get it under control. After extensive up elev trimming I was able to get it to fly level, barely. Had to brig it in hot to keep it from drilling the ground. I removed the weights from the cowl and put .75oz on the styrofoam lug just behind (bottom) the cowl. 2nd flight went much better and afterwards the elev was still trimmed up slightly. I think next time will be without any weights.
Thinking about stick mounting a Turnigy 2217 20turn 860kv 22A Outrunner or a park 450, any ideas on these motors with this plane?

Dogbucket 04-16-2013 09:06 PM

RE: Art Tech Yak 54 from HK. CG? Motor?
Hiya pcnewman

I have just bought the yak and also had the same experience as you. I even manually worked out the COG using a spreadsheet for such and it gave the COG as around the same as the manual.
Mine has the brushless out runner motor that uses no gearbox. I believe the earlier ones used an in runner with a gearbox. I put the need for adding lots of nose weight down to the lighter nature of the outrunner.

I actually flew the plane without any added weight as I thought there must be a mistake in the manual. It flew very twitchy and was not a very pleasant first flight for a new plane.
I added the required weight and nearly drove it into the ground just trying to land it straight after the "only just" take off.
I have now halved the weight and are waiting for the battey to charge to see how it goes.

I know this is an older thread but if you are still out there I would love to know how you ended up going with this plane.

pcnewman 04-17-2013 12:56 AM

RE: Art Tech Yak 54 from HK. CG? Motor?
Wound up with no weights at all and it flew fine. Dont remember where that put the cg though. The geared inrunner had plenty of power but the spur gear stripped out where the prop shaft was splined. Put an Eflite 450 in it. Did well until the horizontal stab seperated. One half blew completly off the other half was creased where it had folded and Im sure was on is way too. I would put some CF struts on the tail feathers for sure! Landing gear leaves alot to be desired. Beefed mine up with some piano wire and wheel collers. Inverted filte required UP elev for level flight. Yes I mean UP elev not down as is normal. Also noticed that when trimmed for level flight thet it would dive on excelleration. I think the wing incidence was incorrect or the wing shape was different from top to bottom. Kind of like the wing was on upside down. Good luck with it be sure to reinforce the tail feathers. hope this helps.

millermonsterair 12-22-2013 11:44 PM

I was going to ask this question in a new thread, but I figured someone may know this here. I purchased the Art Tech Yak-54 as a PNP from Motion RC for $79 shipped. It is the brushless outrunner version without the gearbox. I have had it for a couple of months now. I have maidened it and had a few successful flights as an aerobatic plane, not so much 3D. However, I do have a friend who is a pretty good pilot and managed to lock in some pretty good hovers. My question is this: does anyone know the size and kv of the stock motor? I can't find it on the motor, on the wires or online. I'm looking at an Exceed Optima 480size 910kv outrunner as a potential upgrade, but would like to know if it would be the appropriate motor for this model. I have already upgraded the servos to some cheap TowerPro MG90S servos because I didn't trust the stock plastic gear ones. I also put a lightweight 40amp ESC before I even did the maiden because the stock 20amp ESC was just getting too hot with around 1/3throttle on the ground. I didn't feel comfortable, so I put an ESC I had laying around. It doesn't even get warm now, but the motor gets worked hard. I just feel it's a little underpowered. It has no punchout from a hover with the stock motor/prop setup. Anyways, any information anyone has on the motor that comes with the brushless outrunner direct drive Art Tech Yak-54, it would be a big help to me.

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