RCU Review: Seagull Zlin Z50 .75-.91 ARF

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    Contributed by: Geoff Barber | Published: December 2011 | Views: 28355 | email icon Email this Article | PDFpdf icon
    RCUniverse.com Review of the Seagull Zlin Z50 ARF
    Geoff Barber

    Email Me

    4105 Fieldstone Rd.
    Champaign, IL 61822
    Phone: (217) 352-1913

    In the fall of 1973, Moravan Otrokovice decided to develop a new aerobatic airplane. The design team, headed by Jan Mikula, decided to use the 260 HP Lycoming AIO-540 and a three-blade Hartzell constant speed propeller.

    Flying just 18 months after the project was started, the test-flights proved to be very successful. The all metal design was a low-wing, single engine airplane called the Zlin Z50L (the L is for the Lycoming powerplant). The "50" as those who know this plane well have come to call it, is able to withstand gravitational forces from +9 G to -6 G.

    Seagull Models, distributed in the U.S. by Horizon Hobby, has added the Zlin Z-50 to its line-up in a .75-.91 size ARF.

    Let's get the box open and see what we've got!

    • Nice Scale Appearance
    • Balsa and Ply Construction
    • UltraCote Covering
    • Rivet and Panel Detailing
    • Fiberglass Cowl and Wheel Pants
    • Electric Conversion Parts Included!

    • Battery Access is Limited for Electric Conversion.

    Skill Level:

    Time Required to Build:

    Frustration Level:

    What do these ratings mean?

    Name:Seagull Zlin Z50 .75-.91 ARF

    Price: $229.99
    Stock Number: SEA5125
    Wingspan: 67.5 in (172 cm)
    Wing Area: 780 sq in (50.3 sq dm)
    Weight: 8.6-9.7 lb (3.9-4.40 kg)
    Length: 49.0 in (124.5 mm)
    Airfoil: Fully-symmetrical, low-wing
    Center of Gravity: 3.75 " (95 mm) Back from the wing's leading edge at the Fuselage
    Radio Used:Spektrum DX7
    Motor Used: E-flite Power 60
    ESC Used: E-flite 60-Amp Pro ESC
    Battery Used: E-flite 5000 mAh 22.2V 30C LiPo
    Channels Used: 4 total - Aileron, Elevator, Throttle, Rudder

    Control Throws:




    Low Rate

    Up: 3/8" (10mm)
    Down: 3/8" (10mm)

    Right to Left: 1.5" (40mm)

    Up: 1/2" (12mm)
    Down: 1/2" (12mm)

    High Rate

    1/2" (12mm)
    1/2" (12mm)

    2 3/8" (60mm)

    5/8" (15mm)
    5/8" (15mm)

    The Zlin arrived in a nicely adorned, sturdy cardboard box. All of the contents were bagged and taped together to prevent shifting (and damage) during shipping. My plane arrived with a clean bill of health!

    As I unpacked this unique airplane, my first impressions were good. I liked the three-color trim scheme - I even found images of a full-scale Zlin that has a very similar paint job!

    Some of the features that I really liked were the rivet and panel lines printed on the covering, the fiberglass cowl and wheel pants, and the detailed instrument panel. The painted pilot figure was definitely a big plus as well, due to the large, clear canopy.


    The instruction manual leaves just a little to be desired, but if you've put together a few ARFs, you can get through assembly without any problems. I read a manual, cover-to-cover, at least twice before I start a project - which helped me a lot with the Zlin.

    Control Surface Hinging

    Assembly started with hinging the control surfaces - ALL of them! After inserting a "T" pin into each hinge, the hinges were installed.

    When I was satisfied with my hinge gap and control surface location, thin CA was used to secure the hinges in place.

    Control Horn Installation

    I liked the control horns Seagull used for the Zlin. It consisted of a threaded machine screw and nut, a pair of washers, and a plastic "horn". This set-up was easy to install and rugged - just be sure to add a drop of thread locking compound to the bolt before tightening the nut.

    Motor Box, Motor And ESC Installation

    As I reviewed the Zlin set up for electric power, I was happy to see the included electric conversion kit. After marking the center lines on the firewall, the instructions showed the conversion mounting box epoxied in place using the included tri-stock for additional support. While I'm sure that would work, I decided to use the machine screws and blind-nuts (for the glow engine mount) to secure the motor box. Again, I applied a drop of thread locking compound on the screws before tightening.

    The blind-nuts for mounting the motor were then installed.

    After the motor was installed, I measured the correct distance from the propeller hub to the firewall, marked the position of the adjustable motor box, and epoxied the mount in place. Once the epoxy had cured, the motor was reinstalled, along with the ESC and receiver power switch.

    I opted to make a small bracket from some scrap wood, so the power switch was accessible through one of the openings in the cowl. I also added three screws to each side of the motor box for additional security - while the epoxy would surely handle the load from the motor, I do tend to be over-careful on the power end of my planes.

    Main Landing Gear Installation

    The main landing gear came next, and I was a bit surprised by the wheel pants - there were no axle holes! Per the instructions, I marked and drilled the axle holes, and added the axle and wheel assembly. Since I have become accustomed to attaching the wheel pants with bolts and blind nuts, this method seemed to be awkward - though it did work fine.

    I slid the axle through the hole in the landing gear leg, and secured it with another washer and nut with a drop of thread locking compound.

    Each side of the main gear is held in place by two bolts and washers, and was very easy to install.

    Battery and Elevator and Rudder Servo Installation

    The last piece of the electric conversion kit was then installed. The original servo tray (the larger of the two in the first image) was removed from the fuselage. Seagull made this easy by using two bolts and a slot on each side of the interior to secure the servo tray!

    With the servo tray removed, there is now access to add the battery pack and removable plate. The pack was first attached to the plate with hook-n-loop tape, and I added two hook-n-loop straps to hold the battery tight. The front of the plate has a tab that slides into the back-side of the firewall, and two screws hole the other end in place.

    The smaller, electric servo tray was then installed and secured, and the elevator and rudder servos were installed.

    REVIEWER'S NOTE: With the servo tray bolted in place, I was unable to remove the battery pack with the plate attached, so I trimmed the rear end of the plate so it could be removed easier.

    Cowl, Propeller and Spinner Installation

    After marking and drilling the holes in the firewall, the cowl was slid in place and secured using the included screws. I did have to trim a small section of the cowl to allow the clearance for the landing gear.

    The propeller and spinner were then added to complete the nose of the plane.

    Aileron Servo and Pushrod Installation

    Installing the aileron servos is standard procedure, and presented no problems at all. The pushrods were bent at a 90 degree angle for the servo arm, and then secured with the keepers. I did like that the metal clevises had jam nuts.

    Wing Assembly

    I slid both wing panels on the aluminum tube, then drilled a hole in the tube at the pre-marked locations by the servo hatches.

    The included screws were then tightened in the wing tube, the wing bolt discs were glued in place and the decorative tube was glued into the pre-drilled hole in the left wing.

    Horizontal Stabilizer Installation

    After installing the wing, I marked a center-line on the horizontal stabilizer and the fin base.

    The covering was then removed from the stab mount and the top and bottom of the stabilizer, and the stab was epoxied in place. I used a large cordless drill battery to weight down the stab while the epoxy cured.

    Vertical Stabilizer Installation

    The covering was removed from the base of the fin before it was epoxied to the stab. I used masking tape to keep the fin square to the stab as the epoxy cured.

    The stabilizer braces are attached with CA hinges and thin CA. Getting the three hinges into place can be a bit of a job, but they hold everything tight!

    Final Touches

    I centered the elevator and rudder servos and their respective control surfaces, and attached the pushrods to the servo arms. The tail wheel bracket was installed - I really liked the way the steerable tail wheel was attached to the rudder!

    The pilot, instrument panel and canopy were then installed, followed by the antenna. The antenna is really cool, because the base is a threaded rod that is screwed into a blind nut in the fuselage. This is a great idea, because the antenna can be removed for transporting the plane to avoid damage to the antenna and the fuselage.

    As assembled, the plane came out a bit tail heavy, so 3 ounces of lead were added to the firewall to balance Zlin perfectly neutral.

    We were nearing our winter up here in Minnesota, so to have a half-decent day in early November was good enough for me. The sun was shining brightly, and the temperature was pretty good, so the fact that the wind was blowing at 10-15 MPH wasn't enough to scare me away. I figured that the Zlin could handle the breeze, so I called my buddy Mike and we were headed to our local abandoned airport to fly.

    The rudder and steerable tail wheel did an OK job for taxiing, but they may have been hindered a bit by the wind. I got the nose of the plane lined up into the wind and pushed the throttle stick forward. Down the runway the Zlin went with very little effort - I must say that when I first got the plane and an E-flite Power 60 motor, I was concerned about the power-to-weight ratio. My concerns were 'tossed to the wind' as the Power 60 motor pulled the Z50 skyward with authority!

    After a lap around the field to check the trims - no trim changes were needed - I climbed up a ways and checked out the stall characteristics of the plane. The Zlin has such a large wing that as the plane stalled, the nose simply dropped. Once a little speed was gained, she was flying again. At that point, I felt very comfortable with her, so it was on to high speed testing. With the Power 60 in the cowl, I was definitely not going to be winning any pylon races with the Z50, but she did move along very nicely.

    OK, let's talk about aerobatics. The full-scale plane was designed to perform aerobatics, and the Seagull model will keep right up with its bigger sister. If you can think of a maneuver, the Zlin will do it with ease. Loops and rolls are effortless, and Immelmans and Cuban 8's are pure fun! Anything else you want the Z50 to do? DONE - and done with style!

    Approximately 10 minutes after taking off, I decided to bring the plane in. Landing into the breeze was more than easy - the Zlin slowed nicely, and sat down gently. I do believe that on a nicer day, this plane would be even more fun to fly than I had on the maiden flight!

    Check out the video to see the Zlin Z50 ARF in action!

    Seagull Zlin Z50 ARF

    The Zlin has been assembled and flown. There are a couple of minor things that I didn't care for - the instruction manual left a little to be desired, and the wheel pant attachment was less than ideal as well. With that said, I forgot all about the minor inconveniences when the plane took to the air. Any short-falls in assembly were more than righted when it came time to fly. I'd give the assembly part of this review a 7 out of 10, but the flying part will get a 9.5 out of 10. Good job, Seagull, and a big thank you to Horizon Hobby for bringing such a unique plane to the masses of our hobby!

    4105 Fieldstone Rd.
    Champaign, IL 61822
    Phone: (217) 352-1913

    Spektrum Radios
    Distributed by:
    Horizon Hobby

    4105 Fieldstone Rd.
    Champaign, IL 61822
    Phone: (217) 352-1913

    Comments on RCU Review: Seagull Zlin Z50 .75-.91 ARF

    Posted by: Kostas1 on 12/21/2011
    I'd like to know if a Saito FA-72 will be ok for mild aerobatics and smooth sport flying.
    Posted by: Sessholvlaru on 12/22/2011
    The FA-72 is going to be marginal; this is a 60 class plane. Mine is also electric and instead of trimming the radio tray I flipped it 180 degree and just shortened the pushrods. This makes a whole lot more room to get the battery in and out.
    Posted by: flyalot on 12/26/2011
    Not flown yet/ OSfs90. I felt the pushrods too thin and soft, replaced with 4-40. The plastic horns are not long enough. The pivot points are not over the hinge line, resulting in differential throw. The rudder pushrod rubs on the stab brace. I used a nosewheel control arm for the rudder control horn. This gave me equal throe and cleared the stab brace. Other than that a beautiful well built airplane. Looking foward to flying it in the spring.
    Posted by: flyalot on 12/26/2011
    Not flown yet/ OSfs90. I felt the pushrods too thin and soft, replaced with 4-40. The plastic horns are not long enough. The pivot points are not over the hinge line, resulting in differential throw. The rudder pushrod rubs on the stab brace. I used a nosewheel control arm for the rudder control horn. This gave me equal throe and cleared the stab brace. Other than that a beautiful well built airplane. Looking foward to flying it in the spring.
    Posted by: albsurfer on 12/28/2011
    It looks to me like you have to take the wing off in order to change the lipo pack out. Is that correct?
    Posted by: G.Barber on 12/29/2011
    Yes, the wing has to come off to remove the battery. Fortunately, there are only 2 wing bolts, so it is a quick job to remove the wing.
    Posted by: gmeyer-RCU on 12/29/2011
    I saw the elv. linkage pushrod setup on this plane and I have the same joiner for the pushrods on a different model what I did though is put a 1/16 wheel collar on both sides of the joiner in case of failure in your case I would use 6
    Posted by: kittykatjaz on 04/03/2012
    On mine I replaced all the rods/fittings with quality hardware as the supplied are too soft. Originally it was fitted with a Super Tigre 90 which was a nice match but now it has a DLE30 installed with a substantially beefed up engine box. Now that makes the plane fly with authority!
    Page: 1
    The comments, observations and conclusions made in this review are solely with respect to the particular item the editor reviewed and may not apply generally to similar products by the manufacturer. We cannot be responsible for any manufacturer defects in workmanship or other deficiencies in products like the one featured in the review.

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