|Wing Area:309 sq.in.|
|Servos:Towerpro 8 gram|
|Battery:3S1P 2100mAh Lipo|
|ESC:||Castle Creations Phoenix 25|
The prospect of reviewing one of Cermark’s One-Meter Electric 3-D series models was a no–brainer for me. When I was asked to do a review of the new Yak-54, I immediately said YES, I’ll do it! After visiting the website and looking at the model specs and photos, I was even more excited. It sports an unusual color scheme, beautiful line and is an ideal size for small field flying. The series consists of three models, each with a one meter wingspan, thus the name. All are made of built-up balsa and light ply, are beautifully laser cut and professionally assembled and covered. There are two other offerings in the 'One Meter' series, a Katana and an Edge 540.
The box arrived unscathed and included the model pieces, necessary hardware, the recommended Cermark CEM 2820-1200 brushless outrunner motor and prop adapter. I inventoried the box and found that I had been sent two complete empennages.
I eagerly sat down to read through the construction manual. Since the series consists of three aircraft, unfortunately the instruction manual is the same all three. This model is neither marketed to, nor intended for, beginner pilots. It is not difficult to assemble, and anyone with a model or two under his belt would make quick work of the assembly process.
I followed the outlined assembly order and began with heating up my covering iron to shrink up the ever present sags and wrinkles found on ARF models. This was a pleasant task because it allowed me to go over every inch of the model, appreciating the design and the workmanship that went into the framing of the aircraft.
The wing assembly proved to be one of the shortest steps in the process. It consists of gluing in the hinges of the wing with thin CA and using T-pins to hold the hinges in place.
I attached the servo extensions and installed the servos into each wing panel with screws, then assembled and installed the pushrod hardware. The wing halves attach to the fuselage with one bolt per panel, and a carbon spar tube runs through the fuselage into each wing.
The cowling is a nice fiberglass piece that matches the covering scheme beautifully. Mine had a wickedly odd bend in it though, that had me thinking the model had seen some heat in storage or at some point in shipping. I puzzled a bit about what to do with the cowling. I thought about contacting Cermark and requesting another cowling but I just decided that if the bend occurred due to heat, maybe it could be reversed with heat. I carefully heated the inside of the cowling with my heat gun, and as I could feel the cowling warming, I placed it in position on the fuselage and forcefully shaped it to the contour. Once the cowling cooled, it was closer, but still not perfect. I found that my covering iron with a hot sock on it made the cowling pliable in a more controlled area, and I adjusted the shape further. until it was close enough. Next I installed the rudder and elevator servos and connected them to the pushrods, then finally assembled the wheels and wheel pants onto the landing gear and installed them into the underside of the fuselage.
As is the case with most ARFs, the installation of the horizontal stabilizer and elevator was straightforward and simple. The elevator is not hinged until the horizontal stabilizer is glued into the fuselage with epoxy. Before gluing, all that's needed is to trim away a small amount of covering from the vertical and horizontal stabilizers and glue them into place with epoxy.
I then installed the steerable tailwheel and glued the rudder to the vertical stabilizer with thin CA. Finally, the control horns were secured with back plates and screws.
There was ample room in the radio compartment for the receiver, ESC and the 3S 2100mAh pack. With the motor wires routed away from the motor, all the items were secured in place with Velcro. Here's a neat tip a veteran builder gave me that has served me well: I like to spread a thin layer of 5 minute epoxy to the areas where the Velcro will be used for the electronics and let it dry, then affix the Velcro to the dried epoxy. This ensures that Velcro will have a sticky surface to adhere to and never pull loose.
The rudder and elevator servo installation went quickly, and I will add here that Cermark recommends HS 55 servos. I know that those come with fairly long servo leads, but I would still question the ability of the leads to reach from the rear mount position of the elevator and rudder servos to the access area for the receiver. I ended up soldering in 9” extensions to my rudder and elevator servos. Also, unless you plan to mix the two servos in the wings electronically, you will need a Y-harness. Neither a Y-harness nor servo extensions are mentioned in the manual as needed accessories.
Reading the manual, shrinking the covering, and the airframe assembly went quickly. I had the model all assembled and sitting on my work bench in three hours. Including installing the radio equipment and power system, I would estimate that you can have the Yak-54 ready to fly in 5-6 hours.
I guess I only have two other issues with the design or construction of this bird. The first is the motor placement. Again, I am sure this comes about because the basic motor mount design is common to three airplanes, but in the Yak, the Cermark outrunner is mounted behind the firewall. I'm not a big fan of mounting brushless outrunners this way as it greatly reduces the cooling airflow to and through the motor. Since this is a review, I constructed the model as designed, but in my own world I would have modified the motor mount to allow mounting the outrunner in front of the firewall.
The other issue is the method used to hold the canopy in place. I often use rare earth magnets to hold canopies, hatches, etc, but this model uses very strong magnets on magnets and the result is a hold that verges on extreme. This would not have been bad had the balsa frame around the canopy not disintegrated one time when I was trying to remove the canopy. Some CA, accelerator, and canopy glue got it all back together, but it was a frustration.
I set the CG point as per the manual, and the model balanced just slightly nose-heavy. I set the control throws per the manual, with 40% expo on low rates and 70% on high rates. Cermark says to use a propeller of 11” diameter and 5 degrees of pitch. I say, wow! I can’t help but think that is a prop that you would need a strong .46 gas engine to swing, but I can tell you, the Cermark 2820-1200 outrunner spins it with authority.
The Cermark Yak-54 can perform most any sport maneuver that you ask of it. With the recommended Cermark outrunner and 11 X 5 prop installed, the Yak can move through the air at a pretty good clip, but it slows down nicely as well as long as a little throttle is used at all times. I would not recommend it for flying on windy days as it has a fairly light wing loading and gets knocked around pretty easily, but it can handle moderate winds with ease.
Thanks to its powerful motor the Yak-54 takes off in a fairly short distance, I would say less than 50 feet. Because the wheels are fairly small in diameter to accommodate the wheel pants, grass takeoffs are not recommended unless the grass is extremely short, so a long paved surface would be ideal unless you plan to remove the wheel pants and install larger wheels. For smooth landings, I recommend a long, shallow approach with some power applied. Although the Yak never exhibited any bad habits, most aerobatic planes of this type can be prone to tip stall if they get too slow. Just keep the nose up with a little power during the approach, and the Yak will land nicely.
The Yak-54 has large control surfaces that make it an excellent sport flier. On high rates, aileron rolls were blisteringly fast, and loops were a thing of beauty. The rudder is large and so effective that maneuvers such as hammerheads and rudder turns were a blast to try. Inverted flight was also a fun experience, with just a touch of down elevator to keep the plane level. I also tried knife edge flight a couple of times, with only some slight pulling to the gear, and this might be because I balanced the plane slightly nose heavy.
Definitely not. This plane is capable of some exciting aerobatic maneuvers, and as such it requires a good amount of aileron experience but would make a great choice for someone at the intermediate to advanced level.
The Cermark One Meter Series Yak-54 is a great performer and can truly be classified as a “parkflyer”. It's a breeze to build, can be easily disassembled for transport to the park and has a broad flying envelope. Its very well designed and looks great in the air or on the ground. Check it out at your local hobby shop or at www.cermark.com!
C of G on yak
Hi dawnron1 i am new on here...just bought one of these cermark yak,s second hand from a local model shop...it had a small nitro engine in..I bought it to convert to brushless...its in mint condition..I have never flown a 3d model appart from a multiplex acromaster with rates on.. anyway i cant find out any details about it appart from the ones you listed on here..I was going to add a motor similar to the one that comes with it in your reveiw..
RC 1200 KV Outrunner Brushless Motor
Rotational Speed 1200 RPM/V
Free Load Current 0.4A
Working. Current 4A-7A
Input Voltage 8-10V
Max. Efficiency 98%
Motor Dimensions (Diameter x Length) 27.50mm x 27.00mm
Shaft Dimensions (Diameter x Length) 4.00 x 54.00mm
Speed contorller requiement20A
nput Battery Types NiCd/ Nimh/ Li-po Battery
would this motor be ok running a 10 x 7 prop and would it have enough power for the plane...i am not well up on motors you see and need all the help i can get...
Also i need to know the c of g on the model..i set it up with a 2200 mah battery and another motor just to see and it seems very tail heavy, i think it was set up for a nitro engine..the model complete is 850 - 900 grams..
I will be flying it as just a aerobatic plane NOT 3D well not yet..just need to make sure everything is spot on before first flight as i have trashed models that were setup wrong and found out too late...can you help please....
I'll jump in here if you don't mind. I know you were asking Ron. Maybe he will chime in later.
The motor you listed only has a 4-7 amp operating range. The motor Ron used pulled over 20 amps. So the short answer is the motor you selected won't work.
What you would need, as a minimum, is what we call a 480 class motor. Bigger would be better for more 3D.
They're out of stock, but something like this would work.
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