Flight Impressions – Sukhoi Su-29

The Sukhoi is also very strong. The main spar is carbon fibre and has a phenomenal limit ‘g’ loading of +11 to -9 ‘g’. Near full span ailerons are attached to the wing with hinges that would seem more at home on a tractor and the main undercarriage A-frame and tail wheel bracket is solid Titanium. The Sukhoi is pow- ered by a nine cylinder radial air cooled piston engine developing 360 horsepower (268kW). This drives a geared three bladed 2. 5 metre diam- settled into a thundering idle. Pretaxi warm up was at 40% revolutions, the tachometer being calibrated in percentage of maximum revolutions per minute, no rpm. That makes a lot of sense.

Directional control on the ground and general ground handling is excellent for a tailwheel aircraft, especially compared to a Pitts which is shorter coupled and loses direction easier. The solid titanium undercarriage frame absorbs any bumps with impunity. Visibility directly forward while taxying is similar to all tail wheel aircraft, ie non existent.

I never had a good go at using the brakes but hopefully they would be better than on the Extra 300, which has pathetic brakes. Run-up was to 80% revolutions, during which time the usual checks of propeller control and magnetos were made. (The magnetos are a massive work of art, and apparently are exceptionally easy to work on). Pretakeoff checks complete, and we are cleared for takeoff on Camden’s runway 06, with an unrestricted climb of course.

Acceleration at 100% power was a bit better than a Pitts S-25, and similar to an Extra 300, even with two people aboard, a fair bit of fuel, and a warm day. Climb angle was a sustained, 30-35 degrees, and the Sukhoi had no trouble maintaining it’s climb speed of 80kt (150kmh) up through

The Sukhoi mushed down slightly, then flew away level accelerating from its fully stalled state. Some party trick.

eter propeller which enables more thrust to be produced than would normally be developed from a 360hp engine. This aircraft gives the impression that it will be able to sustain a lot of hard core aerobatic work.

After a brief walk around and rundown on the aircraft, Nigel put me in the front seat. This is where a major difference between this aircraft and other aerobatic machines I have flown became readily apparent. It wasn’t that the instruments were decorated with Russian symbols, and calibrated in a more sensible metric system, it was the seat. Or more correctly the seating position. You do not sit in a Sukhoi Su-29, you damn near lie in it. I do not know what angle the seat reclines at, but, because the tail wheel was on the ground, I thought I was near horizontal and initially felt uncomfortable. I like to be able to look rearwards to ‘check-six’, however this was awkward at the angle we were at. The adjustable rudder pedals are also positioned high in relation to the pilot, and you feel as though your feet are about your ears.

The reason for this seating position is to give a higher ‘g-z’ tolerance. It became noticeable when we did fly that the effects of high ‘g-z’ were greatly reduce, and subjectively, I feel that +8. 5 ‘g’ in this aircraft feels like about 5-6 ‘g’ in a Pitts. A similar effect negative ‘g’ wise.

In the front cockpit there are no controls to start the engine, so I can only give a rough run down on the starting procedure. Nigel had to prime the engine with fuel using a hand operated mechanical pump and then use a compressed air starter. The radial started almost instantly and 300m where the power was reduced to 90%.

Nigel handed over at this point and immediately I took over, I could sense that this machine had a ‘different’ feel to other aircraft I have flown. The stick force in pitch was very light, in roll it was comparatively heavy, while the rudder force was also quite light. Control around all three axes was exceptionally powerful.

The aircraft gives the impression of being near neutral in static stick-fixed longitudinal stability. (ie Stick movement per Angle of Attack change). While this is necessary to achieve the incredible pitch rates of this machine, it did/will take getting used too. The light pitch stick forces, combined with the small movement required to effect large angle of attack changes, led me to quite often exceed the critical angle of attack and stall whilst pulling into some manoeuvres. However, once the pitch control is mastered, I can see the potential to execute some very tight’ constant radius comers. In fact, +8. 5 ‘g’ was easily achieved and sustained, which enabled any vertical or 45 degree lines to be reached quickly leaving more time and energy for the pilot to ‘think’ and execute other manoeuvres.

Roll rate is awe inspiring and must be over 360 degrees per second, although I never achieved full stick deflection, as the lateral stick force required was too high. (These relatively high lateral stick forces are to be reduced by the inclusion of larger aileron ‘spades’ and will be ‘trimmed’ to match whatever the pilot desires). I haven’t rolled like that since I stopped flying Mirages about six years ago.

The aileron roll rate is about the same as it’s snap roll rate and leaves a Pitts S-2 with symmetrical ailerons for dead and may even out roll the Extra. But since my brain was left behind by both the Extra and Sukhoi roll rates I cannot be sure. The relatively high lateral stick force means that rolls are much easier to stop without the wobbles. This compares to the Extra, where the light lateral stick forces lead to a ‘wobbly’ roll stop, unless you know precisely where the stick neutral position is. In the Sukhoi, it is just a matter of letting the stick find the neutral position itself, and bang the roll stops, dead still. The only thing the pilot needs to do is ensure she/he stops the roll at the correct position.

The aircraft has a very high power to weight ratio, which enables steep climb angles to be maintained. The Sukhoi is not very fast in straight line speed, nor does it accelerate past about 135 to 160kt (250 to 300kmh) if you commit the nose down and reduce the power. This is to its advantage. The last thing you need when manoeuvring in a 1km aerobatic box is a machine that accelerates through warp speed, especially when trying to maintain a vertical or 45 degree down line.

The Sukhoi chugs along, the big three bladed prop churning away dragging the aircraft through the air with ease at a fairly constant speed, no matter what the attitude is.

The aircraft will fly away from approximately 22kt (40kmh) and maintain height. A handy feature if ever you get a bit slow at the top of a vertical roll and have to fly away. Nigel reinforced this by demonstrating a manoeuvre that left me shaking my head. He pulled the aircraft into a vertical climb, reduced power to idle, started a stick hard forward together as the nose fell through the horizon. The nose pitched down through the vertical to a level inverted attitude and then stayed there. The Sukhoi mushed down slightly, then flew away level accelerating from its fully stalled state. Some party trick.

My flying was a bit embarrassing as the aircraft took getting used to. All rolling manoeuvres were easily accomplished, and pitching to 45 degree and vertical lines is very fast, as long as you don’t stall it. Stall turns are also simple, providing you use a right foot stall turn, as the propeller rotates anticlockwise as seen from the cockpit. The aircraft is also very capable when it comes to rolling circles, again, once you get used to it. The powerful rudder caught me out as I over controlled it.

Snap rolls demand a special technique. You cannot slam full back stick and rudder, then unload the stick forward slightly like in a Pitts. First you must pull the stick straight back, followed a fraction of a second later by full rudder, then push the stick well forward, and then give full aileron in the roll direction. These steps occur in less than a sec- ond, and if followed accurately, will give a very clean rapid snap roll. If not, well, the snap goes all yucky. Nigel got sick of my wobbles after a short period and demonstrated some of the more basic things the aircraft can do. Such as pulling up to 45 degrees, executing three rapid aileron rolls left, then snap rolls right until the nose was vertical down after following a ballistic path. I gave up counting the snaps after I reached five. I thought I had died and gone to aerobatic heaven.

After about 30 minutes, Nigel let me fly it home. The aircraft is stable on approach and little sideslip is needed to see the runway. As far as the landing goes, it’s simple. Just flare and hold off to the landing attitude, and the big titanium undercarriage absorbs any misjudgement with ease. The aircraft rolls straight down the runway, with none of the ‘tap dancing’ on the pedals that a Pitts demands.

The Sukhoi does the job it was designed for superbly. To perform unlimited class aerobatic training, airshow displays, and compete at national and international aerobatic contests.

That said, the aircraft is no toy. To master and fly it to it’s limits will take pilot’s with a lot of skill who are able to practise regularly. And it would be a long time before they could fly this aircraft to it’s full potential. But once the pilot does get a good handle on the Sukhoi, they would be almost unbeatable in the competition aerobatic arena. +