Zlín/Let Z-37 Čmelák – The Winged Tractor

Z-37T Agro Turbo performing at Čáslav, Czech republic in 2015.
Z-37T Agro Turbo performing at Čáslav, Czech republic in 2015.

Agrarian from the Outset

The Z-37 Čmelák (Bumblebee) prototype first flew in 1963 and was the first specifically agricultural aircraft designed in Czechoslovakia.

The result of a 1960 competition for a completely new, purpose designed agricultural aircraft. The Z-37 was a combined effort of the Zlín and Let aircraft companies. As both companies were based in the heavily agricultural Moravian region of the country, it was not at all difficult for them to consult directly with those who would be using the end product and tailor it very closely to the needs of projected customers.

Aerial spraying and seeding had been practiced in the former Czechoslovakia since the mid 1920s, but until the arrival of the Z-37 it had been an exercise in improvisation with aircraft not specifically designed for the task. Accordingly, the success of such improvisation was mixed.

The Z-37 put agriculture first in every aspect of its design from the rugged fixed landing gear which allowed operations from rural grass airstrips to wings designed for optimal low speed performance only a few meters above the ground.

The baseline Z-37 features full metal wing construction and a fuselage built of fabric on steel tube. The aircraft’s cockpit provides excellent outward visibility for the pilot; immediately behind the pilot is a hopper which can be filled with liquid, powdered or granulated chemicals for spraying. Directly behind the hopper is a rearward facing passenger compartment which was typically used for transporting farm mechanics to rural areas.

Z-37A-3 at Pardubice in 2014
Z-37A-3 at Pardubice in 2014

An Able Hand

As the prototype XZ-37 had taken several awards at international exhibitions, export success came with relative ease to the production standard Z-37 and it found use in roughly a dozen countries. While the largest export customer by a wide margin was the former East Germany, the Bumblebee also found users in Bulgaria, Finland, Great Britain, Hungary, India, Iraq, New Zealand, USA and the former Yugoslavia.

The aircraft’s usefulness was not limited to farm work, it also found use in forestry, advertising, research, light transport, aerial survey work and as a glider tug.

Eventually, owing primarily to increased fuel costs, aerial spraying lost popularity to land based spraying methods in many places where the Z-37 operated. Many examples of the aircraft were simply left to deteriorate while others found their way into the hands of flying clubs where their powerful engines made them popular as glider tugs capable of taking more than one glider aloft at a time.

A Z-37A seen at Brno in 2014
A Z-37A seen at Brno in 2014

A Look Inside the Beehive

Initial production of the original piston engine Z-37 ran uninterrupted from 1963 to 1977 and was briefly resumed in 1983 and 1984. In 1985, a turboprop powered variant was added to the Z-37 family.

Approximately 700 examples of the Z-37 were built in seven variations:

Z-37:
This was the initial production version, built from 1963 to 1971.

Z-73A:
A strengthened version of the Z-73 introduced in 1971. It was built between 1971 and 1975 and was briefly put back in production between 1983 and 1984.

Z-73A-2:
A two seat training version converted from the Z-73A.

Z-73A-3:
A light transport conversion of the Z-73A with accommodation for three passengers in rearward facing seats behind the pilot.

Z-37T Agro Turbo:
Turbo prop version introduced in 1985. The Z-73 T featured an extended rear fuselage as well as reinforced wings with winglets at the tips. The Z-37 T also had an internal hopper of increased capacity and stronger landing gear with larger wheels.

Z-37T-2:
Turbo prop conversion of Z-37A-2 training aircraft.

Z-37TM:
A one-off conversion of a Z-37T in the mid 1980s to test the type’s suitability for the military close support role. The aircraft was found unsuitable and returned to agricultural work.

Z-137T:
Slightly improved version of the Z-37T

Z-37A under restoration at Kunovice in 2014
Z-37A under restoration at Kunovice in 2014

The Z-37 Today

By most indications, the bulk of airworthy Z-37s at the time of writing is split between the Czech Republic and Slovakia. The type does still see some use in its original agricultural roles, particularly in Slovakia.

Some examples of the type have found their way into museums while those that have not are either very well cared for by their owners and remain airworthy or have been left derelict and deteriorating in the elements at the peripheries of airports.

As the Z-37 is neither glamorous or common, your chances of seeing one may be quite limited.

While there is no dedicated internet resource for the Z-37, these two articles from Czech online publications contain some good information. The translation to English is not ideal, but workable:

http://translate.google.cz/translate?hl=en&sl=cs&u=http://technet.idnes.cz/praskovaci-letadlo-cmelak-09a-/tec_technika.aspx%3Fc%3DA130628_132746_tec_technika_kuz&prev=/search%3Fq%3Dzlin%2Bz-37t%2Bcmelak%26rlz%3D1C1FDUM_enCZ483CZ483%26espv%3D2%26es_sm%3D122

http://translate.google.cz/translate?hl=en&sl=cs&u=http://letistecr.cz/zajimavosti/nebesky-traktor-z-37-cmelak.aspx&prev=/search%3Fq%3DLet%2BZ-37%26rlz%3D1C1FDUM_enCZ483CZ483%26espv%3D2%26es_sm%3D122

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