I have one of these 59" Yaks unopened with the recommended Turnigy nano-tech 4S 3300mah pack (also unused) beside me here in the UK if anyone would like it?
I have finally conceded that I have too many 45"-65" foam planes and am now infatuated with helicopters too




Can be posted within 24 hours and at your door in 48


(can be done via ebay for security and piece of mind if you so wish)

Unfortunately, I also have one of these gorgeous YAK airframes powered by a cheap piece of garbage ESC and motor. Since so many people were having problems with the motor I decided to bench test mine with no load --- no prop and no cowl to see how hot it would get in an optimal situation. Ya.. it cooks! ... as in hot enough to cook eggs. After 4 minutes with no load (no prop), and varying speed it is very hot to touch, and does not turn easily either. Seems the bearings are crap. ALSO. If I advance the throttle one click at a time... very slowly.. I can advance it to 100% and he motor will never start. The motor makes a knocking sound at low throttle when running. -- both of these are caused by the ESC. I put a Castle Creations Phoenix ICE 75 on it and it runs fine at low throttle, and starts every time on the second click no matter how slow I advance the throttle -- even with the trim.

I'm sick of cheap crap. I'm (think I'm) going to replace the motor with a Rimfire .55 42-60-480. I'll have to slightly modify the cowl because the ID of the cowl is exactly the same as the OD of the motor. I also cut out the cowl under the facade air scoop and blocked the leading side of the scoop inside so air will exit through the scoop from the cowl. I'm going to use the Castle Phoenix ICE 75. I'd change to Futaba digital servos too, but that ESC and motor will pretty much tap me out.

I'm sick and tired of these dealers -- regardless of origin -- who will not sell the airframe unless it has their crap electronics. The reason is clear -- that's where they are making their money.

In the drive thru restaurant business the money is made from soft drinks and fries. burgers don't bring much profit -- but the burgers bring the customers and THEY CHOOSE if they want the soft drinks and fries. Sure their are value meals -- but they are not the only way to purchase the burger.

As far as I'm concerned -- Hobby King and any other dealer that will not sell the burger without -- oops.. I mean the airframe without the electronics should be flogged. It's dishonest business in my opinion. At least they could advertise it as "a great airplane with crap for electronics" and then be honest about it.

So, I'm not going to maiden the Yak tomorrow as planned. The bench test failed too miserably to risk it. Maybe in a week if Tower cans ship the motor here fast enough.

Well I think getting everything done in one night was a bit ambitious. I've definitely got my work cut out for me lol. The motor wasn't plug and play so I'm going to have to find a good way to get this thing mounted to the motor housing. Will not be maidening it tomorrow.

Will update as I get closer.

Originally Posted by flythreedee

I have one of these 59" Yaks unopened with the recommended Turnigy nano-tech 4S 3300mah pack (also unused) beside me here in the UK if anyone would like it?
I have finally conceded that I have too many 45"-65" foam planes and am now infatuated with helicopters too




Can be posted within 24 hours and at your door in 48


(can be done via ebay for security and piece of mind if you so wish)

How much? I'm in Southampton

I agree that the electronics are crap. I burnt up my motor. Then ordered a new one, but after hooking it up the ESC smoked when I just checked the turning direction of the motor. Absolutely worthless. I can't believe I paid this much for a piece of packing styrofoam. It is dishonest business as scott page said. Especially when the dealer, HobbyKing will not acknowledge THEY shipped a faulty product and can't step up to the plate and admit it, even with so many of us with failures. Poor business practice and cowardly if you ask me. This plane has more than doubled in value with the replacement parts and shipping I have purchased. I have shelved this plane. Too close to the end of the season to get sucked into a money pit.

That's why yo take a risk buying from HK, they are cheap because they do not refund and don't spend money on customer support. They just focus on getting as many units out and sold as possible which will help keep the prices down.

my bad...

See motor : I am thinking either this

http://www.hobbycity.com/hobbycity/s...idProduct=5204

OR

http://www.hobbycity.com/hobbycity/s...idProduct=2139

Originally Posted by ukgroucho

That's just an index link - does not show a specific motor.

Originally Posted by chessgame

my bad...

See motor : I am thinking either this

http://www.hobbycity.com/hobbycity/s...idProduct=5204

No... that's only 270Kv. Gonna need a HUGE prop to get the required thrust on 4S.

Originally Posted by chessgame

http://www.hobbycity.com/hobbycity/s...idProduct=2139

And that is a bit 'hot' (1100Kv)... you really want something in the 700 - 900Kv range in order to be able to run a 13 / 14 inch prop.

Trexid - Did you maiden the Yak with your new setup. Interested to hear how it performs...

Can we buy these planes ARF instead of PNP with the cheapest crap they can throw in them. Looks like an awesome flying plane but would rather put high end electronics and motor in it. If they don't sell them ARF they need to start I'm sure they'd sell A TON

-Chevy

Originally Posted by AgonyOfDefeat

Trexid - Did you maiden the Yak with your new setup. Interested to hear how it performs...

Hey Agony, no I haven't maidened yet. I still need to figure out the best solution to mount the motor to the firewall / motor housing on the Yak because the 50-55b mounting holes aren't plug and play with the default holes.

I'm also going to cut the prop shaft down with a dremel and then use the prop shaft adapter it came with to run it. I estimate that I might have it RTF by this Saturday depending on how much free time I can muster to work on it this week.

I did get the following results with MotoCalc that a friend helped me out with to figure out that a 12x6 prop should be perfect for my setup.

12x6 on Flightmax 5S 3000 mAh numbers.

MotOpinion - Yak54 1.5m Monster 3D Brushless

315ft above Sea Level, 29.92inHg, 58°F


Motor: Turnigy 50-55B 600kv Outrunner; 650rpm/V; 3A no-load; 0.0205 Ohms.

Battery: Flightmax (20C); 5 cells; 3000mAh @ 3.7V; 0.008 Ohms/cell.

Speed Control: Turnigy Brushless ESC 85A; 0.006 Ohms; High rate.

Drive System: 12x6 Electric Prop; 12x6 (Pconst=1.31; Tconst=0.95) direct drive.

Airframe: Yak 54 1.5m Monster 3D Brushless; 680sq.in; 81.3oz RTF; 17.2oz/sq.ft; Cd=0.038; Cl=0.2; Clopt=0.43; Clmax=1.07.

Stats: 141 W/lb in; 122 W/lb out; 21mph stall; 33mph opt @ 74% (23:31, 116°F); 48mph level; 1642ft/min @ 34.8°; -369ft/min @ -7.4°.


Warning:


MotoCalc was unable to determine a throttle setting for hands-off cruise airspeed, so the best lift-to-drag ratio airspeed and throttle setting will be used instead.

Inability to determine a throttle setting for an airspeed usually means the model is not capable of reaching the required speed with the given power system, or the airfoil information has not been specified correctly.


Possible Power System Problems:


The full-throttle motor current at the best lift-to-drag ratio airspeed (33.4A) is lower than the motor's maximum efficiency current (49.8A). A higher current level would improve system efficiency.

Current can be increased by using more cells, a larger diameter or higher pitched propeller, a lower gear ratio, or some combination of these methods.


Power System Notes:


The voltage (16.5V) exceeds 12V. Be sure the speed control is rated for at least the number of cells specified above.


Aerodynamic Notes:


The static pitch speed (57mph) is within the range of approximately 2.5 to 3 times the model's stall speed (21mph), which is considered ideal for good performance.

With a wing loading of 17.2oz/sq.ft, a model of this size will have trainer-like flying characteristics. It would make an ideal trainer, for use in calm to light wind conditions.

The static thrust (99.4oz) to weight (81.3oz) ratio is 1.22:1, which will result in extremely short take-off runs, no difficulty taking off from grass surfaces (assuming sufficiently large wheels), and vertical climb-outs. This model will probably be able to perform a hover or torque roll.

At the best lift-to-drag ratio airspeed, the excess-thrust (46.7oz) to weight (81.3oz) ratio is 0.57:1, which will give steep climbs and excellent acceleration. This model should be able to do consecutive loops, and has sufficient in-flight thrust for almost any aerobatic maneuver.


General Notes:


This analysis is based on calculations that take motor heating effects into account.

These calculations are based on mathematical models that may not account for all limitations of the components used. Always consult the power system component manufacturers to ensure that no limits (current, rpm, etc.) are being exceeded.

Has anyone tried on 6S yet. I just bought one and am going to run it on 6S with this motor.

http://www.hobbyking.com/hobbyking/s...idProduct=7069

Be interested to see how that fits... could be a bit of work as I think it is bigger than the stock motor.

Originally Posted by erozion

Has anyone tried on 6S yet. I just bought one and am going to run it on 6S with this motor.

http://www.hobbyking.com/hobbyking/s...idProduct=7069

I'm simply amazed at the number of people who after buying a piece of garbage from a dealer, "correct" the problem by buying replacement gear from the same source.

Hobby King was at fault when they shipped these defective Yak motors and ESC's -- why should they profit AGAIN??!!?

I'm DARN sure not going to buy my replacement parts from Hobby King. That is why they sell us garbage in the first place, because they know we'll spend more to get it into the air. Even if I have to spend more than the Yak54 cost in the first place, I'm going to put a quality motor and ESC from any other dealer other than Hobby King.

Wow. Break the cycle.

Would need some work the stock motor dims:
Physical Specs are: Weight (g) 147.4 Max Current (A) 60 Shaft A (mm) 5 Length B (mm) 45 Diameter C (mm) 37 Can Length D (mm) 35 Total Length E (mm) 65

So will need to maybe do some work to the cowl.

I changed the motor to handle the 6S Scott.