d554d9058dfbb6bdeae47891b2b6a24eae64f1377c6dfdcabd02cf5819a80e84 Section "Cruise" item count differs between passes (5 vs 3); verify nothing was dropped. Section "Landing" item count differs between passes (2 vs 3); verify nothing was dropped. Section "Starting" item count differs between passes (10 vs 7); verify nothing was dropped. Section "Take-off" item count differs between passes (2 vs 3); verify nothing was dropped.

General A four-seat tourer-cum-aerobatic trainer, the 18T was designed by Yuri Yankyevich and first flew in 1967. More than a thousand have been produced and delivered, mainly to Eastern Bloc countries. The manufacturing licence was subsequently bought by TechnoAvia in Moscow. Nine-cylinder supercharged Vedeneyev 360hp M-14P radial engine. At 27 1/2 feet long and 36 1/2 feet span, the Yak is nearly four feet longer and a foot wider than a Piper Warrior. Construction Riveted alloy panels form the main structure. The rudder, double-braced tailplane and elevator are fabric covered. The split elevator has an adjustable trim-tab on each side, while the rudder carries only a fixed tab. The wing centre-section carries an oil radiator in the starboard wing-root and a large metal single-position plain flap-cum airbrake across its span, plus the inward-retracting main gear legs. The battery is mounted on a hinged tray in the port wing-root, released by three Camlock fasteners, and may be dropped down for service. External power connector behind a small access door near the port wing-root. Wings and Fuel The wing dihedral starts at the break point just outboard of the main undercarriage. The outer wing panels are fabric-covered and can be removed. The port wing carries a long barber's-pole-striped pitot tube, the stall warning vane, and a large-diameter landing light. The Frieze ailerons are also fabric-covered, while tie-down rings are provided near each wingtip. Each wing contains a 95 litre (21 imperial gallon) fuel tank, of which four litres are unusable. Undercarriage On each of the three gear legs is a small, forward-facing white light for the benefit of the flight dispatcher to confirm undercarriage down at night. Three small mechanical plungers protrude — one from the top surface of each wing and one just in front of the windscreen — to act as a belt-and-braces method of checking the undercarriage position. Main wheels are 5.00 x 500. Long anti-static wicks trail from each main wheel assembly. Cockpit and Equipment Each door is individually jettisonable via a prominent red handle below the panel. The aircraft can be flown with both doors removed. The front seats are fore-and-aft adjustable. Four-point harness is fitted; no central fifth g-strap nor second aerobatic security strap is provided. The hinged rudder pedals have leather stirrups but no brake pedals. The pedal assemblies are adjustable. Rear passengers have a wide bench seat behind which sits a large yellow-painted auxiliary fuel tank holding 95 litres, which drains automatically into the wing-tanks. The cockpit trim and rear seat materials are reminiscent of an early 1960s aeroplane. The rear side windows boast sliding curtains, also fitted above the two front seats. Two smoked plastic sun visors hinge down from the top of the screens. A pull-cord arrangement unrolls a miniature window-blind in front of the pilot's screen to facilitate IMC training. A two-speed, self-parking windscreen wiper is fitted, but no washers. The panel is dominated centre-stage by a huge electrically-driven and non-toppling artificial horizon. A gyro-magnetic compass is adjustable for north or south hemispheres and individual latitudes. Fuel System A single fuel gauge with a selector switch shows total litres in both tanks on the outer scale, and the contents of the selected tank on the inner scale. The fuel is controlled by a prominent red T-handle on the panel left of the quadrant. Push for On, pull for Off. Electrical System A combined single ammeter/voltmeter is fitted; press its switch for amps, release for volts. Controls Each yoke sports two PTT buttons; the left-hand one opens the air-ground transmission circuit, the right-hand one activates the cockpit intercom. The pneumatically-operated brakes work through a pull-handle on the back of each yoke. The P2 position has an override button to allow the instructor to release the brakes. The park brake is a small button under the yoke; pull the lever and press the button. No nose-wheel steering: to turn on the ground, press the appropriate rudder pedal and squeeze the brake lever. The pitch trimmer is a small handle on the left-hand cockpit wall, low-geared taking five turns from full aft to full nose-down trim. A light indicates neutral trim. Annunciation and Warning Lights Annunciation lights show Fuel low and Gen. fail. Two red lights flash Slow and Stall as the aircraft approaches stalling speed. Undercarriage and Flap Controls The undercarriage lever is set low down on the left-hand end of the panel, pressed firmly before operation, with a slide-across safety bar. The two-position (Up and Down) flap lever is on the central quadrant with the cowl gills control, carb heat, oil cooler selector and throttle friction lever. The prop lever actuates a microswitch which, at anything less than full throttle in fully fine setting, illuminates the landing gear warning light.

The big radial requires to be thoroughly warm before flight. For really cold climates the engine oil can be diluted by a button next to the starter, feeding neat petrol into the sump, up to twelve per cent dilution. Primer SEVERAL PUMPS Primer selection LINE OR CYLINDER Starter button outer ring UNLOCK — TURN UNTIL TWO RED DOTS ALIGNED Master switch and almost all the double row of switches ON Starter PRESS After two or three blades have passed the vertical, magneto switch TURN ANTICLOCKWISE TO 1+2 Throttle (to get all nine cylinders on line) JUDICIOUSLY PUMP Engine idle AROUND 30 PER CENT

Taxying requires a degree of initial concentration, at least until the braking system is mastered for turning. No nose-wheel steering: to initiate a turn requires differential braking by pressing the appropriate rudder pedal, then squeezing the brake lever.

The pre-flight run-up only differs slightly from that of a Lycoming or Continental.

Initial pitch-up overcome by FIRM PUSH FORWARD IMMEDIATELY AFTER LIFT-OFF Lift-off speed 130 kph

Best climb speed 170 kph Rudder CONSIDERABLE BOOT REQUIRED AGAINST TORQUE AND P-FACTOR

Cruise setting 59 PER CENT CRANKSHAFT SPEED Manifold pressure 6 ON DIAL (600mm OF MERCURY) Fly at almost equal settings on the two gauges, e.g. 80/80, 60/6. Throttle and prop levers are well-matched and can be treated almost as one. At 6,000 feet the 59 per cent setting produces 150hp and fuel consumption of eleven gallons an hour at 205kph (110 knots). The M14 radial has a rather irritating harmonic in cruise; both prop and throttle levers vibrate sufficiently to blur their handles.

Ailerons and elevator are light and responsive, though the rudder is heavier. Full aileron requires only about forty degrees deflection either way. The test aircraft had no inverted oil system, so no negative manoeuvres were permitted. An inverted oil system is an option. G limits are +6.4/-3.2g.

Stall speed (depending on all-up weight and power settings) 100 kph (54 kt) TO 123 kph (65 kt) The stall is signalled by a horn, flashing lights and a pre-stall buffet. Roll authority remains present throughout. The Yak is cleared for spinning; a three-turn spin and recovery consumes about 2,300 feet loss of height.

Gear and flap extension BELOW 200 kph Approach speed 150 kph Trim (with two occupants) FULL AFT Threshold speed 140 kph Touch-down speed AROUND 115 kph In the last stages of final approach and flare, the airfield disappears under the nose; look peripherally to judge height and keep directionally straight. There is little float; touchdown occurs about six inches before one expects it. Unless the yoke is right back at contact, the nose-wheel drops with a thump.

Aft trim UNWIND RAPIDLY TO NEUTRAL Prop and throttle PUSH FIRMLY FORWARD Flaps UP Undercarriage RETRACT Shoulder harness (before going round) UNLOCK Pitch-up is accentuated if flaps are still down or trim hasn't reached neutral by lift-off.

Brakes MUST NOT BE USED OVER 110 kph Deceleration after landing is noticeable, even without brakes.

Length 27 ft 6 in Height 11 ft 2 in Wing span 36 ft 7 in Wing area 202.36 sq ft

Max AUW (utility) 3,637 lb Max AUW (aerobatic) 3,307 lb Empty weight 2,683 lb Useful load (utility) 954 lb Useful load (aerobatic) 624 lb Fuel capacity (as tested) 62.7 imp gall Wing loading (utility) 17.97 lb/sq ft Wing loading (aerobatic) 16.34 lb/sq ft Power loading (utility) 10.10 lb/hp Power loading (aerobatic) 9.18 lb/hp

Cruise at 59% crank speed 110 kt Max speed in level flight 156 kt Vne 161 kt Stall (clean) 64 kt Stall (with flaps and gear) 55 kt Take-off roll (firm grass) 370 m Landing roll (firm grass) 390 m Take-off (firm grass, to 50 ft) 690 m Landing (firm grass, from 50 ft) 790 m Range (as tested, with reserves) 485 nm Rate of climb at s/l 1,082 ft/min Service ceiling 18,000 ft

Engine Vedeneyev M-14P supercharged single-row air-cooled nine-cylinder radial, 360 hp at 99 per cent crankshaft speed (2,900 rpm) Propeller B530TA-A35 constant speed, two-bladed, wood, 94.5 inches diameter