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Taking off from RAF Wyton's Runway 16, the wind was an undemanding 140º/8 knots, well within the crosswind limitations of 13kts. With a good clearing scan, I lined up and completed the brief take-off checks. Sitting behind the prop' turning in an anti-clockwise direction, I anticipated the swing to the right. With 'T's and 'P's within the green arcs, full power coming on positively and the ASI showing life, I eased the control column forward. Swing was easily countered by a slight deflection of left rudder. She rode straight and smooth and flew herself off at 47kts. I held the aircraft down with no real force against the trim to 65kts, which came quickly, before easing the stick gently back and climbed out at 70kts. I delayed raising the undercarriage until there was no longer any useable runway ahead.

The Zlin settled into a comfortable climb, the ASI showed 75kts 3kts higher than the best rate of climb speed. I adjusted attitude and re-trimmed, then tried a few varying gentle pressures on the rudder and rocked the wings in anticipation of what was to come. She promised good handling and a lot of fun.The haze layer rested on the horizon at 3,000ft QFE (QFE set for aerobatics) and had a pink and purple hue away from the sun. Blue sky was above so we continued the climb to 4,000ft. Once there, with 2,350 rpm set and 97kts indicated, I had a superb view, particularly with the low nose attitude. Trimmed out, she flew hands and feet off with the wings level and the ball in the middle. A good start.

The Bedford Levels appeared beyond and beneath our leading edges. We were clear of clouds, crowds, cities and controlled airspace, with fields below should we need to put down in a hurry. I had memorised the best glide speed of 65kts and completed the ingrained Hasell checks. First, I examined the aircraft's stability. With the stick free, control column induced phugoids died within two short cycles. The release of cross controls from banked and level attitudes demonstrated both longitudinal and directional stability.

With height held and the area cleared, the stall characteristics were explored and proved what a mild-mannered machine the '526 really is. No wing drop is present
when the airframe is clean at 61kts and there was only a slight tendency for the right wing to drop with full flap (40º) and undercarriage down at 59kts. Even then, just as one might expect, the wing could be held with opposite rudder. There is no aural or light warning of the impending stall, other than the undercarriage warning bell when the gear is up. You just feel it through the stick, upright or upside-down. It was in the stall we had identified one of the great benefits of such a low wing loading and wing section. With its docility we could promptly fly away from the clean stalled condition with complete control and no appreciable height loss.

A later marque of the Zlin (the Z.526AFS Akrobat Special) had 5ft 9in truncated from its overall wingspan. This undoubtedly increased its rate of roll but it lost its 'forgiving' ability at the slow end of the envelope. Apparently, the shortened wing was stressed for a higher 'g', but with the increased wing loading and now lower aspect ratio wing, the induced drag increased dramatically when 'g' was pulled. So much so that the whole feel and performance of the marque was degraded.

AEROBATICS
Time to enjoy a different perspective of the Zlin. Aileron rolls left and right from cruise (2,350 rpm) at 97kts are completed without height loss; slow rolls from 118kts, both left and right, so as not to become handed. The break-out force in roll is very light with the underwing spades. The wing can be rolled to the angle of bank and promptly stopped and held there. Their feel is marvellous but the rate of roll is just 60º per second, similar to a Bücker Jungmann or Beagle Pup. The wing does not have a great deal of inertia and it is possible to arrest the roll at a quarter, half, three-quarters and wings level for a precise four-point or hesitation roll. Aileron drag is not pronounced and easily countered with the correct rudder footwork.

And herein lies the real character of the Zlin Z.526; through its controls, light wing loading, crisp response and power. The roll rate is slow enough to be familiar and not too far removed from the everyday ordinary A-to-B machines, but it is perhaps partly the precision of control that endears you to this machine. G-loads are not inordinately different from a Chipmunk, (which has less power and weighs almost the same). Its upright seating position shows its vintage. Today, some 30 years later, a dedicated aerobatic aeroplane's seat would be inclined for the pilot to accept maximum 'g'. However, the Zlin is restricted to 3g and manages all of its manoeuvres within that envelope, so perhaps, the seating is fine for such low 'g' values.
The stall turn to the left against the engine, left us hanging on a knife-edge having used the upper POH figure of 65kts. I felt sure a reduction towards the lower figure of 59kts would be better. With a small amount of vertical sideslip she pivoted around cleanly. Next, with a stall turn to the right, holding her vertical and feeling as if we are slightly on our backs, the right rudder introduced positively at 37kts lets the right wing drop and the left wing slide over 180º so that we were heading down hill, opposite rudder required with lead to prevent the pendulum effect. We had the vertical down line and with in excess of 108kts up for a loop, then a roll off the top. The Zlin is a clean machine and picks up speed downhill noticeably quickly. A couple of Cubans, all completed with a minimum of control forces and low poundage (stick forces), a cleanly and well flown slow roll off the top continued to show her nice, well mannered character in classic, gentle aerobatics.

APPROACH AND LAND
For type conversions, the circuit is the most obvious place where all the exercises of flight are condensed into a short period and high relative workload. Again, similarities with the Chipmunk spring readily to mind when considering the circuit manners of the Zlin. Remember to lower the gear (check for two green lights and the external undercarriage stalks projecting above the upper wing surfaces) although the low-speed warning bell will sound upon reducing power on finals if you forget. PUFA checks on finals; propeller pitch, undercarriage, flaps and altimeter set, the normal constant speed prop lever would be forward and fully-fine but once again, treat this system as fixed-pitch and just throttle back.

Slipping speed is between 70-75kts. The flaps are effective and the slight change in attitude further adds to the view forward. Engine revs are kept a little lower than expected, at 1000rpm, from base leg. The recommended flare height commences at 23ft, somewhat higher than my 'double-decker front seat' standard flaring height, and then level at 1.6ft. Either way it didn't bounce (much). There was a small tendency to float but this would have been considerably more had I used the initial figures determined from the stall information and multiplied by 1.3.
Landing roll on Wyton's long 9,800ft runway was a short 820ft with little or no braking, although a short field landing should be accommodated within 650ft on grass. A gentle, weaving progress to the hangar was followed by a short cooling down pause. Shut down involves turning off the electrics, fuel and magnetos, in that order.

The Zlin has so much pure capability with such a long wing and little horse power, but things have moved on. The Z.526 was capable of flying all known manoeuvres of the day with acknowledged ease in a 3g airframe without the loss of height, plus its pilots introduced the lomcovak to the world at large. For the observer on the ground watching the aerobatics, the size and shape of the aircraft help its viewing, having good visual density. I hadn't realised the length of the wings until I later saw some of Keith's air-to-air photographs of November Oscar. This, coupled with its engine's low, rather melodic note, echoing and sounding not too far removed from a much larger V-12, adds well to the flavour and its acceptance locally.
Competition aircraft now have higher wing loadings and greater power-to-weight ratios, higher rates of roll and climb performance, more grunt, more zaz! The Z.526 has been eclipsed, it is true, and it certainly had its day holding centre stage. Yet it is still an aircraft to fly and enjoy the sky in marvellous, curving, light, dancing flight.
Thank you Alan.

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