August 2007 Feature Story:
Flying the Yak

Story by Ryan Ferguson

I flew a Yak-55M recently. The opportunity arose quite unexpectedly — I had finished my aerobatic practice for the day and went over to hang out with some other pilots when the offer to fly the plane came. Of course, I took it!

For those of you not familiar with this kind of aircraft, it is a large Russian-built monoplane with a supercharged 360HP radial engine — a 9 (!) cylinder M14P Vendenyev — swinging the prop to the left instead of the right. It’s a taildragger (most aerobatic aircraft are), it’s big, it’s basic, it’s a tough and reliable airplane. One other thing…It’s a single-seater, so you get to learn how to fly it by flying it. No dual checkout, unless the instructor wants to hang onto a wing.

Getting to know the Yak
The pre-flight includes draining the oil from the bottom cylinders to prevent hydraulic lock when starting. Then, just to make certain that there is no hydraulic lock, you pull the prop through, about 12 blades. Crawling up into the thing is an interesting feat to begin with — you’ve got to sort of climb backwards up the tall landing gear struts to sit on the wing, then you can walk over to the cockpit. You get the feeling of sitting very high up in a Yak.

There are a few interesting facts: 1) there is no mixture control, 2) there is no trim control, and 3) it starts with a pneumatic air system (not electric). Oh, and the gauges are in Russian, there are leather straps to keep your feet attached to the rudder pedals, and it is as un-ergonomic a seating position as you can imagine. I’m a middle-sized guy, about 185 lbs. and 5'9", and my knees were poking up towards my chest — slightly uncomfortable (the awkward position, however, did not impede my ability to get to all the controls). I’m sure that if I flew the plane a few times I’d get used to it.

I had a “five-minute checkout” on the ground with the owner. We covered the gauges: Prop is in percentage of RPM, ASI (airspeed indicator) is in kilometers per hour (KMH), MP (manifold pressure) is in millimeters of mercury (but the 30" Hg. setting was straight up at 7.5 (755 mm/Hg) with the engine off, and the owner explained that, with supercharger full power, it would be at about 8.5.). Downwind and approach were to be flown at about 200KMH, and short final at 150. I fretted about this a bit during the ground checkout but it later turned out to be unnecessary. It was very easy to “feel” the proper airspeeds. Of course, we discussed emergency procedures, how to cut off the fuel, and jettison the canopy. It’s all fairly straightforward. I did a few sweeps of the panel to start memorizing where everything was. Placards were all Russian except for MP, oil press/ temp, and altimeter! The CHT was color-coded by some thoughtful individual, making it easy to keep an eye on the temps.

Starting procedure
Checklist for starting a Yak:

1. Air Pressure – Check (40 - 55 Kg/cm2)
2. Air Valve – Open (CCW, then 1/2 turn CW)
3. Fire Handle – Forward
4. Landing Gear – Down
5. Flaps – Up
6. Friction Locks – 2 Release
7. Oil Cooler & Cowl Claps – Open (set friction lock)

Starting Engine “Clear Cylinders” before starting engine
(DANGER: DO NOT pull prop through by hand unless cylinder head temp is below 80 degrees Centigrade, and mags are off)

1. Brakes – Set
2. Oil Cooler & Cowl Flaps – Closed (cold start only)
3. Carb Heat – Cold
4. Panel Switches 1, 2, 4, 6 (from left) – On
5. Battery – On
6. Generator – On
7. Ignition – On
8. Warning Lights – Test
9. Prop – Forward
10. Throttle – Crack open
11. Primer Cold Start
    a. Left – Fuel Pressure 0.4
    b. Right – 4 or 5 Strokes
12. Primer Hot Start
    a. Left – Fuel Pressure 0.4
    b. Right – 2 Strokes
13. Starter – Engage (confirm CCW prop rotation)
14. Mags – On (1 + 2)
15. Throttle – Decrease rpm to 39% – 41%
16. Oil Pressure – Check
17. Panel Switches – On
18. Engine Warmup
    a. Oil Pressure (>1) – 39% – 41%
    b. Increasing Temp – 41% – 44%
    c. Warmup at – 44% – 48% (51% max)
19. Oil Cooler and Cowl Flaps – Open
20. Brakes – Release

Generator, instruments, radios, and compressor are then brought online. The compressor recharges air pressure for your next air start. (It builds slowly so you watch a small air pressure gauge installed for this purpose as you taxi. Prior to “red-line” on the gauge, the compressor is shut down).

Taxiing was no big deal. I’m used to a Pitts, and the forward visibility in the Yak was far better than in my little rocket ship. Even though the tailwheel only swivels 30 degrees in either direction, taxiing is quite straightforward. I made small S-turns out to the runway. You get a lot of attention when taxiing around in this strange-looking bird.

I memorized the sight picture to the left and right of the plane as I taxied into position on the runway; I would use this to gauge my flare height for the landing later. I applied full power — there’s a little lag there at low power settings — and boy, was this baby roaring! It’s a pretty loud ride. I immediately sensed the need for left rudder then, as I raised the tail, eased off the rudder just a bit. I had been warned not to pop the tail up smartly as is customary with the Pitts – the tail arm is quite long in this airplane and the empennage is also heavier. Also, even with the extra long landing gear struts, there’s less prop clearance than in most taildraggers. It was no big deal; some gentle forward pressure brought the tail up nicely. The controls which felt heavy on the ground became extraordinarily light. (I should note that the control surfaces are HUGE. The ailerons, for example, span nearly the entire wing. The rudder is nearly as thick as the leading edge of a C-172's airfoil.)

Cleared for takeoff
There was a pretty decent crosswind from the northeast (taking off runway 9L at SFB, winds from 050 at 14 knots gusting to 19). The big rudder made it easy to track the centerline on the takeoff roll. A slight aft pressure on the stick, and… I was airborne! Time to have some fun! I got out from under the class Bravo shelf around MCO (Orlando International) and headed for my practice area northeast of the airport. I made a few turns and immediately noted significant adverse yaw caused by the huge ailerons. It was harder to “feel” the uncoordinated turn as I was sitting directly above the main wing spar, but after a few turns I got a feel for how much rudder was needed. In short order I worked up to high-G turns and was able to nail the altitude without so much as a burp from the altimeter. Preliminaries out of the way, it was time for some rolls and inverted flight.

The Yak takes a lot more top rudder on the slow rolls, probably due to the roundness of the fuselage. My little Pitts’ fuselage acts more like an airfoil on knife-edge. I rolled the plane inverted and did some shallow and steep banked inverted turns. Still very stable; I didn't need nearly as much forward (stick) pressure as I do in my Pitts. (Not to say I need a lot in the Pitts either, but the Yak would practically fly inverted hands-off.)

I mentioned earlier that the Yak has no trim or mixture control. The airplane is always automatically in trim. Russian simplicity — they built it into the very design of the aircraft. It was slick — the controls never felt heavy. Mixture is managed by a device which automatically compensates for altitude. The airplane was built for the harsh environment of the former Soviet Union, and it shows. Everything is rugged and built to be simple as possible.

Getting intimate with the Yak
Time for some vertical maneuvers. The plane seemed pretty docile so far. It was about to show me some quirks in its behavior. I made a 3.5G pull-up to the vertical with the intention of a hammerhead turn to the right (left-swinging prop, hammerhead to the right — opposite my usual routine.) As I pulled up I had the immediate sensation of flying a spinning gyroscope — which I quite literally was. I used rudder to compensate for the fast rate of pitch change and started easing into left rudder as I drew my vertical upline. The plane started rolling in the vertical and I felt unable to stop it! I did a pretty ugly hammerhead (I hesitate to even call it a hammerhead) and tried to draw a nice vertical downline. Same thing on the pullout: Right as I reached the 45-degree point the plane started wobbling again and then threw me somewhat violently into a quarter snaproll to the right. Cute! I called the owner on the radio to confirm the entry speeds — he told me anything over 250 KMH. I noted the “25” mark on the altimeter and decided to try a loop, entering at 300 KMH (“30” on the ASI.) This time I passed the vertical without any problems (although I was much more careful with the rudder.) Right at the three-eighths mark of the loop as I was nearing inverted flight, it did it again, although this time the snap was a good three-quarter of a roll ending with the nose pointing downward and the telltale start of a power-on spin setting in. I simply reduced power and the plane flew right out of it with no recovery needed. I tried the loop three more times, finally getting it right the last time. In the Pitts the required rudder input is very easy to sense, probably because the pilot sits so far behind the wing spar. In this plane, I really had to fine-tune my senses. I imagine it would be pretty easy to fly an “avalanche” (loop with a snap roll at the top) in the Yak! This plane is truly a flying gyro. Every pitch change requires the pilot to be cognizant of precession and torque, probably due to the immense power generated by the engine and the size of the propeller.

Round and round she goes, where she stops, nobody knows…
Finally, it was time to try what I call a “tumble”. This is a maneuver which should only be attempted in an aircraft approved for such maneuvers, which the Yak is. My Pitts is very resistant to my “tumble” maneuver — probably due to the bi-wing and the drag of the flying wires — so I was really looking forward to giving it a try. I made sure I had plenty of altitude and slowed down to 220 KMH, the recommended entry speed. I mashed the right rudder pedal to the floor, followed instantly by full forward elevator and full right stick deflection. Wooooo-hooooo! Better than Mr. Toad’s wild ride. I probably did some combination of somersault and cartwheel. I have no idea how it looked from the ground, but that’s how it felt in the air. Recovery was simply neutralizing the controls. VERY easy airplane to fly in that sense — get in trouble? Just let the plane fly itself out.

I came back for landing and wouldn’t you know it, the tower asked me to provide my airspeed on downwind. I was following (and catching up to) a Seminole in the pattern. I guesstimated my speed at about 100-105kts and told the tower so, and was told to make a short approach inside of the Seminole and a 727 on final. Okay, nothing like a little pressure on my first landing in a Yak.

I slowed down to 185 KMH on base, 175 for final, and pretty near 150 (remember — KMH not knots) for very short final, which the airplane seemed to like. It was an extremely easy airplane to land (but just remember how high this airplane sits off the ground for the flare!) I am sure that anyone with tailwheel experience could easily land this airplane. The crosswind was still present but I simply needed to dip the right wing into the wind a bit and apply a bit of rudder pressure to track the centerline. I came down on the tailwheel just an instant before the mains gently touched down and didn’t bounce — almost satisfactory on my first try! I taxied back and shut down.