be ready for the national team at the time of

the fifth World Aerobatic Championship in

Magdeburg. The Zlin Z 526 AS did not get the

word "Special" in its name for nothing, it was

indeed special, because it met the requirements of the FAR Part 23 regulations for

the Special category with the allowable loads of +7/-4.5g, while the existing aerobatic

Trainers had to fit into the “envelope” of the

+6/-3g limitation.

The engine mount of Z 526 AS was strengthened for higher loads. In addition, it received a completely new, lighter and sleeker rearward-sliding canopy. The Z 526 AS

was also the first of the Z 26 series aircraft

without flaps, which were removed to save

weight. However, the Walter 6-III carburetor engine with a maximum output of 160 hp

continued to serve as the powerplant.

All of Z 526 ASs prepared for the Czechoslovak representation received a very spectacular livery, which was uniform for all machines except for the lower surfaces, which

were of a different color for each aircraft.

Photo: Stanislav Trnka

HISTORY

Aircraft standing and ready to fly at the aerobatics nationals, which were held in Kunovice, Czechoslovakia in 1969.

In the front, two examples of the „Shorty“ predecessor, the Z 526 AS.

March 2022

OK-ZRB was the first “Shorty” converted to the towing version AFS-V. It was later sold to Germany, where it kept flying

with Czech matriculation. It was destroyed in a crash near the Eberswalde Finow airfield during the Roadrunner's

Paradise Race 61 event on June 26, 2013.

Photo: www.gonzoaviation.com

The M 337 engine was modified in 1969 to

create the 180 hp M 137A. The oil system of

this engine was modified to fully aerobatic

operation with non-restricted reversed flying and snap roll aerobatic figures. The engine also got a modified crankshaft and was

equipped with an injection system to ensure

trouble-free operation even under negative

loads. This was the main problem of the Minor series carburetor engines, where it was

kind of art to tune them for such flight modes. Apart of the Z 526 two-seater, this engine was, of course, also used for the aerobatics specials. These aircraft received their

new engine prior to the 1970 World Championships held at RAF Hullavington, England.

All five Z 526 ASs of Czechoslovak national

team were converted to Z 526 AFs, while the

aircraft received new redesigned fuselage

that incorporated the M 137A engine with

new engine covers. Unlike the exhaust system of the Minor 6-III engine, which had exhaust pipes on the right side leading directly

from each cylinder, the new exhausts were

routed to two exhausts protruding from the

engine cover relatively far apart.

For the needs of the Czechoslovak national team, a Z 526 AFM registered OK-KZA

was later created. The airframe of this version basically corresponded to the Z 526 AF

design, but the wing received landing flaps.

A M 337 engine and a modified V-410 propeller (with propeller blades from the V-503)

were installed. The cowling was taken from

the Z 726 version and its cooling air inlet received louvers . The aircraft had permanently mounted auxiliary wingtip tanks. Due to

the purpose (special towing aircraft), special

equipment such as an oxygen breathing apparatus, two Becker communication radios,

etc. were also installed. This aircraft was

subsequently converted to the Z 526 ASM

(OK-WXA) and sold to Germany, where it is

still flying today as D-EWXA. Later OK-WXB

aircraft gave rise to another Z 526 ASM re-

Photo: www.orlita.net

With an aerobatics engine

OK-ERS parked at the Nitra airfield. This one was manufactured in 1974 and is still airworthy. More to it, the aircraft

keeps the original red-white coloring of all the Z 526 AFS. It is based at the Boleráz airfield, where Aero Club Bratislava is operating it, now as OM-ERS.

INFO Eduard

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