Yak-18 ARF

Model Airplane News, Aug 2001 by Van Tassel, Bob

An easy-to-fly Russian Warbird

Approximately 7,000 Yak-18s were produced in the USSR and Hungary between 1946 and 1957. This aircraft was designed as a primary trainer, and like so many Soviet aircraft, it was built to withstand the rigors of rough-field takeoffs and landings. It had a rugged tricycle landing gear and a powerful, easily serviced radial engine. The airframe was steel tube with a mixture of metal and fabric covering. The full-size plane had a distinctive sharp dihedral.

Hobby People offers a terrific sport-scale ARF model of this legendary plane that comes with nearly everything you need except the engine and radio gear. The instruction manual is complete and provides you with all the necessary information.

The model is constructed almost entirely of lite-ply, balsa and foam and has a factory-painted fiberglass cowl. It's finished with a heat-shrink polyester covering and decals. The manufacturer recommends that you use a .36 to .46 2-stroke or a .40 to .52 4-stroke engine, so I installed a Magnum XL-40A, which performed beautifully with the Yak.

SPECIFICATIONS

Model: Yak- 18

Type: ARF sport-scale trainer

Manufacturer: Hobby People

Distributors: Hobby People and Global Hobby Distributors

Wingspan: 54.5 in.

Wing area: 460 sq. in.

Weight: 5.5 lb.

Wing loading: 27 oz./sq. ft.

Length: 42.5 in.

Engine req'd: .36 to .46 2-stroke or .40 to.5; 4-stroke

Engine used: magnum XL-40A

Prop used: Global 10x6 (included)

Radio used: Futaba T6XA

Radio req'd: 4-channel with 5 servos (engine, rudder, elevator, 2 ailerons)

Price: $124.99

Features: high-quality materials and construction; wrinkle-free, iron-on covering with decals: and factory-painted, fiberglass cowl with forward openings already cut; complete hardware, including wheels, tank, pushrods and a 10X6 propeller; detailed manual cotians over 55 photos and diagrams.

Comments: the Yak-18 is an excellent choice for a first warbird. The kit is complete and very easy to assemble. It took me longer to read the well-written manual than it did to assemble the plane.

Hits

Well-written instruction manual.

Quick and easy asaembly.

Fine-quality construction materials.

Good flight performance.

Complete hardware package.

Misses

Quick connectors do not hold well. (They can be better secured by adding wheel collars to both sides).

FLIGHT PERFORMANCE

Since I broke in the XL-40A on a test stand, it fired right up. I made some minor engine adjustments, faced the YAk-18 into a lymph wind and let it go.

TAKEOFF AND LANDING

I held the Yak on the ground using some down-elevator until it was out about 50 feet, and it accelerated rapidly. With a small amount of up-elevator, it jumped into the air. It needed only a few minor trim changes. I did a number of passes before taking it upstairs to check the stall, but there were no unpleasant surprises.

Gradually reducing power and altitude, I brought the Yak in for a final approach. I kept a small amount of power on and was careful not to over-control it. When it was about 2 feet off the ground, I reduced power to idle, and the Yak settled in on the main gear.

SLOW-SPEED PERFORMANCE

At slow speed, the flight performance was very respectable. Slow passes over the field were straight, and all of the controls were responsive. The Yak flies like any other low-wing sport airplane.

HIGH-SPEED PERFORMANCE

On the first flight, the pushrod became disconnected from the throttle servo at full speed, and the Yak was off to the races. This gave me a great opportunity to check the plane's high-speed performance. With the XL-40A going at full bore, I tried to get it to quit by flying inverted, but I had no luck. It just kept going through 10 minutes of high-speed inverted flight.

I tried to take the Yak from the deck to the heavens, and though vertical performance was not unlimited, it did strain my eyes. All the controls were very responsive at both low and high rates.

AEROBATICS

The Yak can do it all. I was pleasantly surprised by its capabilities, especially given its low cost. Loops were straight and tight at high and low rates and at slow and fast speeds. Rolls were axial at high and low rates and very rapid at high rates and high speed. It also tumbled well. The Yak performed every maneuver I attempted.

ASSEMBLY

I first assembled the wings, which are balsa covered and have foam cores. I attached the ailerons by opening the precut hinge slots with a modeling knife, inserted the CA hinges halfway into the wing and secured them with pins. I pushed the ailerons onto the hinges and checked for deflection. I removed the pins and secured the hinges with thin CA, then I deflected the hinges a few times to make sure that the CA had wicked in and that the ailerons moved freely.

Following the instructions, I attached the two aileron servos to the servo hatches and removed the covering from the servo pockets. I used a simple jig to mark and drill the holes for the screws that hold the hatches in place. Then I routed the aileron wires through predrilled chases to the center of the wings, where they exited through the top. I used 6-inch extensions on the aileron servos.