Avia BH.1 – Cutting Teeth at the Cutting Edge

Avia BH.1 replica at Prague in 2014.
Avia BH.1 replica at Prague in 2014.

Avia: Born Running

Established in 1919, the Avia company has remained a strong player on the Czech industrial landscape to this day. Making its name in both aircraft and trucks over the years; the company continues to make trucks and aircraft propellers today.

Avia built full aircraft from its founding until the early 1960s and became one of the best known names among early Czecholsovak aircraft manufacturers producing a range of successful interwar aircraft and license producing several foreign types in the post World War Two period.

If there is any truth to the old proverb that one must crawl before they can walk and walk before they can run, then Avia needed very little crawling or walking time before they could truly run. Their first aircraft design, the BH.1, which was introduced in 1920 was a radical departure from aircraft design of the period and certainly not what one might expect of a first product from a new manufacturer.

There was very little conventional or conservative in the BH.1’s design. It was a streamlined monoplane in an era still dominated by slow biplanes. In a time where fabric on frame was still the standard method of construction, the BH.1 made extensive use of wood in its design. In its day, there was very little about the BH.1 that couldn’t be called revolutionary and pioneering.

The Minds Behind the Machine

BH.1 performing at Prague in 2014.
BH.1 performing at Prague in 2014.

Aircraft designers Pavel Beneš and Miroslav Hajn were two of Avia’s four founders. Both men had designed sailplanes in the years prior to Avia’s founding and so certainly were not newcomers to aviation. Both men also admired and were inspired by the design philosophies of Germany’s Hugo Junkers and the Dutch designer Anthony Fokker.

Rather than working with existing wing designs, Beneš and Hajn designed an entirely new wing of largely internal bracing; this did away with the myriad drag inducing bracing wires so typical of biplanes, and even some monoplanes, of the day. Initially, the wings were wooden frame construction covered in canvas though later variations replaced the canvas partially with plywood.

They also chose to use full wood construction for the aircraft’s fuselage, this resulted in the aircraft being much stronger and robust than many of its contemporaries which used more traditional fabric on frame construction methods for their fuselages.

Beneš and Hajn both left Avia in 1930. They developed a series of aircraft during their tenure in the company which could trace their origins back to the BH.1 and firmly secured Avia’s, and Czechoslovakia’s, place as world class producers of aircraft.

Good from the Start

BH.1 seen at Prague in 2014.
BH.1 seen at Prague in 2014.

When the BH.1 took to the air on October 14, 1920, a day after it’s first flight, it showed itself to be very responsive in handling and quite maneuverable in spite of its ungainly, boxy appearance. the only real problem early on in its development was that the pre World War I vintage Daimler engine initially fitted to the aircraft was not powerful enough to carry the aircraft aloft with two people aboard.

The engine issue was overcome when the aircraft received a great deal of attention while being exhibited at an international aviation exhibition in Prague shortly after the first flight. So impressive was the BH.1 that it not only was judged the best exhibit of the show but also won Avia a generous development grant for the aircraft from the Czechoslovak president, T.G. Masaryk.

The aircraft made its final flight under the Daimler engine’s power in April of 1921, after which it was extensively rebuilt. The new modifications included a much more powerful French built Gnome radial engine and most of the canvas wing covering replaced with thin plywood.

Following the modifications, the aircraft was given a new designation; what had initially been known as the BH.1(exp) was renamed BH.1bis.

A Point Proven and a Legacy Born

Avia BH.1 replica at Pardubice, Czech Republic in 2013.
Avia BH.1 replica at Pardubice, Czech Republic in 2013.

The BH.1bis flew for the first time in May of 1921 and went on to participate in many competitions across Czechoslovakia and promotional events for Avia.

The aircraft proved itself as competitive and often finished ahead of more powerful aircraft. Through 1921, many pilots tried their hand at flying the BH.1 and were impressed with its performance and handling. The BH.1 was proving beyond a doubt that the monoplane was the way forward in aircraft design.

The BH.1 took its final flight in spring of 1922 and was determined to be not worth repairing after being seriously damaged in a landing accident. However, the BH.1 had proven itself worthy enough of development that Avia already had more refined variations of it underway at the time of the crash.

Beneš and Hajn developed an extensive family of aircraft based on the design principles of the BH.1. Some, like the BH.1, were simple one off machines intended for development or competition purposes. Most notable among these was the BH.5, a much refined design that won Czechoslovakia its first international aviation prize in the Belgian Touring Aircraft Contest in 1923.

Another development was the BH.3, a military variant of which only 14 were made. The BH.3 proved temperamental in flight and was not popular with pilots, most of whom were more accustomed to biplanes. Attempts to make the BH.3 into a credible monoplane fighter ultimately ended in failure and the Czechoslovak military instructing Avia to provide them with a more conventional biplane fighter instead.

The resulting biplane fighter, the BH.21, borrowed heavily from the experiences of the BH.1. It was built largely of plywood and its boxy fuselage echoed the BH.1. The BH.21 served in the militaries of both Belgium and Czechoslovakia and was popular with pilots, acquitting itself well as both a credible fighter and racing aircraft.

The BH-1 Today

BH-5 replica at Pardubice in 2010
BH.5 replica at Pardubice in 2010

While the original BH-1 does not exist intact, since 2004 a faithfully reproduced full scale replica of the aircraft has been a regular performer at airshows across the Czech Republic. In 2007, the BH.1 replica was joined on the Czech airshow circuit by an equally faithfully replicated BH.5.

In 2008, the BH.5 replica was flown from Prague to Brussels in a re-enactment of the original’s prize winning flight in 1923.

Learning More

A condensed history of the BH.1 can be found here:

http://avia.vyrobce.cz/doc/2index.htm

A news story from 2008 about the BH.5’s Prague to Brussels flight can be found here:

http://www.radio.cz/en/section/curraffrs/replica-avia-bh-5-to-fly-to-brussels-in-re-enactment-of-1923-air-race

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