Seagull Models 20cc YAK-3 ARF Part One

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Does everyone else stock up and put together a whole mess of airplanes over the winter? Well, I know some of you don’t really have winter, and you can fly in nice weather year round – to those of you with this ‘problem’, I say “I’m jealous”! For the rest of us, winter can be cold, windy, and snowy. This is a good chance for us to keep our spirits high by building a kit, or assembling an ARF or two!

That’s the case, for me, in West Central Minnesota. While this winter was anti-climactic in the snow department, it certainly wasn’t good weather for outdoor flying! But, what I lack in good flying time, I make up in building/assembling time! So without further delay, let me introduce this new warbird from Seagull Models – the Yak (Yakovlev) – 3!

The Yak-3 was one of the smallest and lightest Soviet fighters of WWII, and it was liked well by its pilots and ground crew. Some of it’s pilots even boasted that its capabilities were greater than the Mustang and Spitfire – I’m not agreeing with them, only giving you a little background. Over several variations, the Yak-3 had different engines. While this itself isn’t uncommon, it’s much rarer for a fighter to start life with a V-12 engine and then have a radial-engined option later on! The radial engine version, which is a Yak-3U, required many modifications to the airframe, but resulted in a much faster aircraft with a lower potential of overheating the engine.

The Seagull Models Yak-3 is modeled after William Whiteside’s iconic racing aircraft, which set an unofficial speed record, for aircraft under 3,000kg, at 416 mph (670 km/h) over a 3 km (1.863 mile) course back in October of 2011!   Will’s Yak-3 looks quite spectacular, so I’m hoping that Seagull has, once again, hit the mark for a great looking airplane!

Part one of this review will cover the un-boxing, first look, and assembly of the Yak-3 – Let’s get the box opened and find out how well Seagull Models has done!

Specifications

Wingspan: 63 – 1/4 in    (160.65 cm)

Over All Length (Spinner to Rudder): 59.5 in    (151.13 cm)

Wing Area: Approximately 724 sq in   (47 sq dm)

Advertised Flying Weight: Approximately 11.5 Pounds (5.21 kg)

Actual Flying Weight (Electric, 6S 5000mAh LiPo Battery Installed): 10 Pounds (4.53 kg)

Recommended Engine: 20cc gas, 1.20 ci 2-Stroke Glow, 1.50 – 1.80 ci 4-stroke Glow

Electric Setup: 20cc Equivalent, 6-8S LiPo

Radio Required: 5 Channel (Bare Minimum) 6-9 Channel (Optional)

Servos: 6 – 7 Standard Servos, 2 Retract servos (Optional)

Receiver: 5 Channel (Minimum)

Flying Skill Level: Intermediate/Advanced

Time to Assemble: 10-15 Hours

First Look

The Yak-3 arrived double-boxed, shipped directly from the Seagull factory in Vietnam. Unfortunately, this aircraft is not yet a common stock item at Seagull’s US distributor (SIG Mfg.), but can be special ordered through them.

Opening the boxes revealed what appeared to be a well-built airplane with some pretty decent attention to the (scale) details! All of the decals are applied at the factory, and they match Will’s plane closely. The large ’33’ on the port (left) side of the fuselage wasn’t perfectly aligned, but otherwise everything else looked good! The packing job was good, and the Yak survived shipping without a scratch.

The Oracover (UltraCote) covering consisted of light and dark grey with white trim stripes. With all the covering and decals in place, all of the covered parts are sprayed with a matte clearcoat – I love this step, because not many warbirds truly looked glossy – A matte finish looks better in my opinion!

The wing can be assembled in two different fashions – if you desire a one-piece wing, you can epoxy the halves together. If you have a smaller vehicle, like me, you can leave it as a two-piece wing. Either way, an aluminum wing tube helps bear the load!

A large top hatch allows ample room to install a fuel tank or change flight batteries if using electric power, and the inner construction of the Yak is very well done! The firewall is plenty robust, and has pre-cut cooling holes for the electric conversion.

The tail end of the fuselage is very well put together, and gives access to the tail wheel bracket – after the tail wheel is installed, a plastic cover will be added. The Horizontal stabilizer, Elevator, Fin, and Rudder are pre-hinged, and sprayed with the matte clearcoat as well!

There’s a lot of decals on this plane, and Seagull has added another level of realism with a deeper cockpit – this allows for the included inner walls and accessories to be installed! There’s a lot of neat details added to the Yak-3!

The paint lines on the fiberglass cowl are done nicely, and Seagull has included a good spinner, pilot figure, and even the canopy looks great! Personally, I think I may have to add a little more color to the pilot figure though…

Hardware, hardware, hardware – there’s a lot of it included with the Yak-3, and it’s all useable! a set of aluminum/plastic mechanical retracts is even included, and the landing gear looks cool too! The fiberglass control horns have become standard equipment on Seagull’s ARF models, and they are a nice touch. I really like the flap hinges, but I have found that a small piece of fuel tubing adds a great deal of security to them! Seagull also includes a full gas/glow engine install kit, as well as an electric conversion kit – you will need to pick up fuel line, depending on your choice of gas or glow engine.

Items Used for Completion

From the ground, I’ll be commanding the Yak-3 with my trusty Hitec Flash 7 2.4 gHz transmitter. I’ve been using my Flash 7 for quite a while now, and I really love it! A Hitec Optima 9 2.4 gHz receiver will be controlling the Hitec HS-485HB Deluxe HD Ball Bearing Standard Servos. With a brand like Hitec, you just can’t go wrong!

Power on board the Yak-3 will be provided by Hitec Energy Sport 80 Amp Brushless ESC, an Electrifly RimFire 1.20 motor, and a Falcon Beechwood Electric 16×8 Propeller. The battery will be a 6S 5000mAh LiPo, but there’s plenty of room in the Yak-3 to go to a bigger pack if you want!

For all of my kit builds and ARF assemblies, I trust ZAP adhesives. No matter what you need, ZAP has a product that’ll work for you!

Assembly

Though there were only a few, I used my covering iron to get rid of any wrinkles I had found in the covering. While not completely necessary, I like to let a new ARF sit on the bench for a day before I start assembly. That way, all of the parts can be at room temperature and humidity levels before beginning assembly. It’s easier to get rid of wrinkles before the plane is assembled, too!

After the wrinkles had been taken care of, I assembled and installed the six flap hinges. Though this is a relatively simple task, it involved drilling holes for 36 small screws – take your time, and the end result will not only be a perfect alignment, but the flaps will look good and function well! Each wing has one pilot hole marked for each of the three hinges, which greatly aid in alignment.

The ailerons were aligned and attached next, using CA hinges and thin CA. A pair of T-Pins through the center of each CA hinge makes it easy to get half of the hinge in the aileron and in the trailing edge of the wing. When I was satisfied with the aileron spacing (between the flap and the wing tip), I removed the T-Pins and glued the hinges in place with thin CA.

The fiberglass control horns were then installed into the pre-cut slots in the flaps and ailerons. 15-minute epoxy allowed me the working time to install all four control horns on a single mixed batch of epoxy. One thing to note – test fit the control horns prior to mixing the epoxy, and ‘scratch’ the surfaces (with 80-100 grit sand paper) of the horn that will get epoxied into the aileron and flap. I also cleaned the horn with a little denatured epoxy and a clean rag just prior to installation.

 

The aileron and flap servo installation was straight forward, and presented no issues. An 18″ servo wire extension was used for each of the aileron servos, and a 12″ servo wire extension was used for each flap. This allowed for plenty of wiring, later on, when installing the wing to the fuselage. The servo wire extensions I use have a clip on the end that prevents the connection from coming apart. The piece of wood marked ‘Save for servo spacer’ is a small “tool” I made from a piece of 1/16″ aircraft plywood. Its only purpose is to create a space between the servo and the mounting hatch while drilling the servo screw holes, which allows the servo grommets to isolate the servo from vibration from the airframe.

With both the aileron and flap servos installed, the pushrods were assembled and installed. I also trimmed the landing light covers to shape and glued them in place with Formula 560 canopy glue. A word to the wise – when trimming the light covers be careful, because the paint will chip off quite easily. I used a low-tack tape to hold the light covers in place until the canopy glue had dried – about 16-24 hours.

I always like to label my servos – nothing is more frustrating than assembling a model, THEN finding out that the flap is plugged in to the aileron channel!

After removing the covering from the retractable landing gear openings, I had to choose between using the included mechanical retracts or using my Himark electric retracts. The electric retracts won out for ease of installation. Unfortunately, the gear doors included with the kit were warped and didn’t fit correctly, so I opted to paint the gear openings instead – I’ll touch on this a little more later…

The elevator and rudder servos look so small in the cavernous hatch area! The pushrods were slid into their respective tubes to make sure I put the servos in the correct mounts.

Since I’m using the RimFire 1.20, I installed the electric conversion motor mount. A quick mock-up showed me that the adjustable section of the mount needed to be as far forward as possible – this allowed the propeller drive hub to be located close to the proper distance from the firewall. The dimension provided in the manual is 145mm (5.7 in), but there’s a little margin of error that can be allowed. By extending the laser etched marking in the motor mount, I was able to quickly mark the holes for the RimFire’s X-mount. With the holed drilled, the included machine screws and blind nuts secured the RimFire to the mount. My Hitec Energy Sport 80Amp ESC was attached to the side of the mount as well, and a piece of tri-stock was glued to the top of the mount to keep the ESC from sliding around. I also removed the covering from the two cooling holes in the belly of the fuselage, right behind the wing. This should provide ample ‘exit’ airflow from the fuselage to keep the motor, ESC, and battery cool.

To allow inlet air to enter the cowl, I removed all of the fiberglass between the molded engine cylinders with my Dremel tool and a cutting bit. The cowl had pre-drilled mounting holes, so it was a matter of lining up the spinner back plate and the top hatch. There’s plenty of light ply in the front end of the Yak-3, meaning that the cowl can be adjusted if necessary. With the cowl taped in place, I drilled four holes in the fuselage, and permanently mounted the cowl.

With the cowl mounted, I attached the Falcon 16×8 Beechwood electric propeller and spinner. A Velcro strap (included with the ARF) was threaded through two of the holes in the battery mounting area – I added a second piece of Velcro (the blue colored piece) to the battery mount, because all of my batteries have a similar piece. this helps keep the battery secure, in addition to the strap.

Moving on to the tail, The elevator halves were attached to the horizontal stabilizer using CA hinges and the same technique used for the ailerons. When the CA had cured, I mixed up a batch of  ZAP 15-minute epoxy and installed the elevator and rudder control horns.

Using a ruler, I found the center point of the horizontal stabilizer and marker the top and bottom of the stab. I also found and marked the center line of the stabilizer. With the stab centered in its mount, I traced the edged of the fuselage onto the bottom of the stab, and then cut and removed the covering material. This is done to create a good surface for the epoxy to adhere the stab to the stab mount.

At this point, I had to temporarily attach the wing to the fuselage to check the wing/stabilizer alignment. The aluminum wing tube is inserted into each half of the wing as the halves slide together. I was very pleased at how well the parts aligned, so I was on to attaching the stabilizer to the fuselage. Using ZAP 5-minute epoxy, the stab was attached to the fuselage. Normally, I would have used 15 or 30-minute epoxy, but I knew the fit was very good, and the stabilizer would literally drop into place!

The vertical stabilizer and fin followed, and were installed easily – all the parts lined up very nicely, making installation a breeze! After the epoxy had cured for the fin, the rudder was installed using CA hinges and thin CA. The elevator and rudder pushrods were slid into their respective guide tubes, and attached to the control horns,

I taped the elevators in a neutral position, and finished installing the pushrod – this consisted of a ‘barrel’ that attached two long pushrods to a single servo arm connection rod. With the elevator servo centered, I secured the three set screws that make up the elevator pushrod. Now this is extremely important – these three set screws are an excellent area to use some Pacer Z-42 blue thread locking compound, to make sure the screws remain tight!

The rudder pushrod was installed using some of the same technique, but there’s only one pushrod for it. With everything looking really good, a snap keeper was installed on both pushrods to keep the rods securely attached to the servo arms.

The tail wheel assembly was next, and presented only a slight problem – the ‘flat spot’ in the shaft was 180° off. I loosened the two set screws that held the rod in place, and spun the rod. Once again, I added a drop of Pacer Z-42 blue thread locking compound to the set screws – I certainly don’t want to lose my tail wheel in flight! The tail wheel assembly is held in place in the bracket by a steering arm with a set screw, and a second pushrod was installed and attached to the opposite side of the rudder servo arm. A slight bend in the pushrod at the clevis allows nearly full travel of the tail wheel assembly in both directions. With the tail wheel assembly in place, I attached the cover – the instructions said to use epoxy or CA, but I chose to use screws so it could later be removed if necessary.

All of the cockpit interior pieces were trimmed to shape, and readied for installation. Though the digital dash looks out of place in a WWII warbird, I suspect that it might be right at home in the instrument cluster of a racing plane that set an unofficial record in 2011!

Though some final trimming was required to get all of the individual parts to fit together well, the end result was worth the effort. I’m happy with how well the accessories looked once installed! As I mentioned in the First Look section, I decided to add a little extra color to the pilot figure. While he looks better than some pilots I’ve seen over the years, a little acrylic paint and a small detail brush can add just enough to really make the pilot stand out. When the paint had dried, I attached the pilot to the floor of the cockpit with some 5-minute epoxy. Finally, the canopy was set in place and attached. I used a combination of Formula 560 Canopy Glue and a few screws to keep the canopy in place, and some low-tack tape helped keep everything in place until the glue had dried.

I added one final ‘corporate sponsorship’ decal to the fuselage, followed by installing the receiver. Thanks to the ample amount of room in the battery hatch area, finding a spot for the Hitec Optima 9 receiver was easy! A small piece of blue Velcro (not included) and some zip ties secured the receiver and antennas to the inside of the fuselage.

OK, now on to final wing installation! with the addition of the electric retracts, a total of 6 servo wires were now protruding from the center of the wing. Thankfully, there’s plenty of room to stow the servo extension wiring in the bottom section of the fuselage!

With the wing in place, a pair of lite ply washers and nylon bolts keep the wing attached to the fuselage – the leading edge of the wing has a pair of stout dowels to handle the load as well!

OK, OK – I know I said I wasn’t going to install the landing gear covers that came with the kit, and I didn’t. I made replacements out of two layers of 3/32″ aircraft ply – the two pieces were cut and epoxied together cross-grained to add additional strength without adding a lot of excess weight. I covered the outside of the new gear covers with the covering material I removed from the Landing gear openings early on in the assembly, and I painted the inside to match what I had also previously painted. I think it turned out very well! FYI- the ply I used came from the small hobby section at my local home improvement store, and it cost me $11.00. The additional expense was definitely worth the end result!

Assembly Summary

Well, that’s going to wrap up part one of the Seagull Models 20cc Yak-3 review. Stay tuned to RCUniverse.com, both the website and our Facebook page for updates on part two. As soon as my local flying field dries out enough to be useable, I’ll get this war/racebird flown! Thanks for taking a look, and don’t forget to look for part two coming soon!  -GB

Contacts

Seagull Models: www.seagullmodels.com

SIG Manufacturing:  www.sigmfg.com

Hitec: www.hitecrcd.com

Electrifly: www.electrifly.com

Falcon Propellers: www.falconhobby.com

ZAP Adhesives: www.franktiano.com

G.Barber: email – gbarber726@gmail.com

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2 Comments

  1. There were only two Yak-3 radial copies and it NEVER went into production during WWII.

    The Yak-3U was a single seat PROTOTYPE only, constructed AFTER the war. The Lavochkin LA series of fighters was already the premier radial engine fighter so there was NO need for another one much less more demand on engine production.

    The Yak-3UTI was two-seat trainer PROTOTYPE only, that the Yak-11 was based on and produced AFTER the war.

    Several years ago, a Romanian factory found a bunch of parts, tooling, jigs etc for license built Yaks and determined they could build some airplanes to sell so they fired up a limited production run. One of these newer airframes is what all the currently flying Russian WWII types are based on including THIS one.

    NO YAK RADIAL EVER FOUGHT IN A WAR

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