Rogozarski LVT-1 – The “Hurrischmitt”

How the Hurricane looked with the DB 601a engine installation (Nenad Mukslev)

How the Hurricane looked with the Daimler-Benz DB 601A engine installation (Nenad Mukslev)

The Hawker Hurricane is one of the greats of military aviation. Forever sitting in the shadow of its more famous comrade-in-arms, the Supermarine Spitfire, its unassuming looks hide a fascinating and pivotal role it played in history. While its service with the Royal Air Force and Britain’s allies has been well documented less is known of its equally fascinating story with the Kingdom of Yugoslavia Army Air Force (Jugoslavensko kraljevsko ratno zrakoplovstvo).

YRAF_Hawker_HurricaneWith Europe rearming in the face of an increasingly aggressive Nazi Germany the Yugoslavian government signed an agreement with Hawker in the UK to acquire up to 24 Hawker Hurricane Mk.Is with kits to produce more aircraft locally in the future. Production of Yugoslavian machines was split between the factories at Rogozarski and Zmaj and a total of 100 machines were planned. At the same time the Yugoslavians acquired Messerschmitt Bf109Es from Germany as well as undertake a domestic fighter program and it was these three factors that would conspire to create perhaps the most unique of Sydney Camm’s Hawker Hurricanes.

Rogožarski IK-3 (aviastar.org)

Rogožarski IK-3 (aviastar.org)

The story of this unique machine begins with the development of the Rogožarski factory’s IK-3 fighter. The latest in a series of successful fighters designed and built by the factory for the Yugoslavian Air Force the IK-3 was powered by an Hispano-Suiza 12Y-29 liquid-cooled supercharged V12 engine imported from France. The aircraft consequently bore a strong resemblance to the French Morane-Saulnier M.S.406 and in tests against Yugoslavian Hurricanes and Bf109Es it was found to be a very competent combat aircraft. It was faster than the Hurricane at nearly all altitudes while at the same time being more manoeuvrable than the Bf109E.

Production machines began to reach frontline squadrons in 1940 by which time, with commendable foresight, the engineers at Rogožarski realized that they needed to start work on improved versions to keep it credible in the face of rapidly advancing German technology that was being spurred on by the outbreak of war with Britain and France in 1939. They therefore began to look at alternative powerplants for the IK-3 imported from overseas. Three engines were shortlisted the first of which was the French Hispano-Suiza 12Y-51, an improved version of the engine already fitted to the IK-3 that developed 1100hp. The other two engines shortlisted were the 1080hp Daimler-Benz DB 601A (as in the Messerschmitt Bf109E) and the 1030hp Rolls-Royce Merlin III (as fitted to the Hawker Hurricane). These were all sensible choices as the factory and the air force both had some kind of experience with all three. The Hispano-Suiza engine was seen as the low-risk option and plans were beginning to get underway to start production on aircraft fitted with the more powerful version when the Germans overran France in June 1940.

With France now subjugated gone was any chance of acquiring the engine and neither was importing DB 601s from Germany a possibility. It was suggested therefore that plans should be put in to place to fit around 30 spare DB 601 engines Yugoslavia had for their Bf109Es to the IK-3 but not wanting to burn their bridges just yet it was agreed with the Yugoslavian Air Ministry to continue comparison testing with the Rolls-Royce Merlin engine. Building two prototype IK-3s –  one powered by the DB 601A and one powered by the Rolls-Royce Merlin III – would be a costly and time consuming effort but the Yugoslavians came up with a cunning plan. They already knew how the Rolls-Royce engine performed in the Hurricane so they decided to fit a DB 601A engine in to one of their Hurricanes and see how the aircraft performed.

Hurricane converted to DB 601 A engine

Rolls-Royce Merlin powered Hurricane Mk.I compared to DB 601A powered version (below)

It was decided to undertake the conversion at the Ikarus factory in the town of Zemun just outside Belgrade and Hurricane Br.2301 (c/n L1751) was selected for the purpose. It was hardly a straightforward conversion. For one thing the DB 601A’s 12-cylinders were arranged in an inverted-Vee as opposed to the Merlin’s upright-Vee arrangement. This meant that the nose section had to be redesigned with the propeller mounted noticeably lower down the nose along with the exhausts (see image left) giving the aircraft an almost droopy appearance. The aircraft retained the Hurricane’s standard armament of eight .303 Browning machine guns.

The impressive conversion was completed in March 1941 and testing began immediately of what Rogozarski now designated the LVT-1 (Lovac-Vazduhoplovno Tehnički-1). Air force test pilot Captain Milos Bajagić carried out the first flight and immediately noticed a dramatic improvement in performance over the original Merlin engined Hurricane especially in the vertical plane. Further testing revealed that the DB 601A engine gave the Hurricane/TSV-1 a higher top speed over the original aircraft although it was still slightly slower than the Bf109E given the limitations of the original airframe. The TSV-1 climbed faster than the Hurricane yet maintained the excellent turning circle which gave it a real advantage over the Bf109E. Finally, the direct fuel injection system fitted to the DB 601A meant that the TSV-1 could handle much higher g-forces including negative-g (where the pilot experiences weightlessness) which often left the carburettor equipped Merlin engine struggling to take fuel. The aircraft did demonstrate a somewhat nose-heavy feel however indicating that the weight of the DB 601 did unbalance it somewhat. The tests proved conclusively for Rogozarski that the DB 601A was the superior engine but any hopes of fitting it to an improved IK-3 would quickly be dashed as history intervened and incredibly the sole TSV-1 would have its part to play.

On April 1st 1941, less than a week before the German and Italian invasion of the Balkans, a Messerschmitt Bf110C “Zerstorer” took off from Vienna bound for Romania on a flight path that would take the aircraft through Hungary. The aircrew comprised of pilot Lt. Hans Diehter and navigator Wilhelm Pries and included a mechanic, Eugen Schaufelle. Mid way through the flight the aircraft strayed off course and wandered in to Yugoslavian airspace. At the same time the LVT-1 was being readied for a test flight with Capt. Sinisa Nikolic at the controls from the airfield at Kraljevo. With tensions between Yugoslavia and Germany at an all-time high news of German aircraft over Yugoslavian territory saw pilots scrambling to their aircraft and armourers quickly loading rounds in to their guns. Nikolic was no exception and his DB 601A powered Hurricane was prepared for combat. The aircraft took off with a formation of Yugoslavian fighters to search for the Bf110C and stumbled upon the aircraft trying to make its way to Romania having realized its mistake. The Yugoslavian planes spotted the Messerschmitt and made high speed passes on the aircraft firing warning shots. It is reported that Nikolic too fired his guns during the incident which forced the outnumbered Messerschmitt crew to surrender and land back at Kraljevo.

Bf110 captured Yugoslavia

Messerschmitt Bf100C captured by the Yugoslavians on April 1st 1941 and painted in Yugoslavian markings (wp.scn.ru)

The capture of the aircraft and the internment of its crew did much to improve morale amongst the strongly anti-Nazi Yugoslavian people but only further worsened the situation between Hitler and Belgrade. Yugoslavia was never an intended target for Hitler’s armies but rather it was invaded out of necessity. In March 1941 Hitler demanded that Yugoslavia submit to his wishes to have his forces use the country in the war against Greece. The Yugoslavian Prince Regent turned to Britain for help but when the British couldn’t offer the support he wanted he felt compelled to submit to Hitler’s request. This angered the Yugoslavian people on a large scale and within days Prince Paul of Yugoslavia was forced to abdicate and the agreement was quite literally torn up. Hitler decided to teach the Yugoslavians a lesson and ordered plans for a Blitzkrieg assault to be drawn up. On April 6th 1941 his orders materialised in to a fullscale invasion.

Heavily outnumbered, the Yugoslavians put every aircraft they had in to the air including the LVT-1. On April 7th the aircraft took off with Pantelija Grandić (rank unknown) at the controls to join in an attack on German forces around the Kacanik gorge area. Grandić and his comrades approached using heavy cloud for cover before diving through and strafing German troops and vehicles. As they formed back up the LVT-1 was seen with white smoke streaming from the engine bay. It is unclear whether this was a result of combat damage or simply a mechanical breakdown as the aircraft had previously suffered a coolant puncture during testing that produced a similar result. Grandić flew on for a short while before crashing the aircraft in to a field in modern day Kosovo. Grandić survived the crash and abandoned the aircraft.

In the chaos of a German occupied Yugoslavia and the birth of the Federal Republic of Yugoslavia just what happened to the aircraft afterwards remains a mystery. Sadly, any specific test data or even photographs have also disappeared and we only have pilot notes on how the aircraft looked and handled. A true oddity in aviation the story of the Hurricane with a Messerschmitt Bf109 engine is a tale of a handful of committed and intelligent people making the most of what they had and it is a true testament to the unsung genius of Yugoslavian aviation.

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15 responses to “Rogozarski LVT-1 – The “Hurrischmitt”

  1. I’m surprised that a DB601 would be plainly superior to the Merlin, I would expect more parity except in negative-g maneuvers. Perhaps it had one of the earlier propellers?

    Liked by 1 person

    • I do believe that the Yugoslavian Hurricanes didn’t have variable pitch propellers so maybe that did go some way to explaining why the performance enhancement was so dramatic. However when the Nazis took a Spit V and put an equivalent DB 605 engine in it the performance was enhanced then too so the Merlin seems to have straggled behind the DB series a little.

      Thanks for taking the time to read it Dave

      Liked by 1 person

      • Yeah I would have guessed the DB605 would be closer to the 60 series Merlin of a Spit Mk IX. But they sure did go back and forth there!

        Liked by 1 person

  2. A really interesting article a plane that I in my ignorance, had never heard of. Presumably, during the Battle of Britain, nobody thought of recycling any German engines in this innovative way!

    Liked by 1 person

    • Well to be fair most of the 109s that “landed” in the UK at that time were hardly in prime condition 😀 . The Germans did fit a DB 605 engine to a Spitfire V too

      Like

    • The question would be ‘why?’
      It’s just not a practical proposition in any way.
      there was not a shortage of Merlins, and by the time you had a made new mountings and cowlings, let alone spares and maintenance.

      Hawker did make steps to making a Hurricane powered by a Bristol Hercules though.

      Like

      • Hi Tony

        interesting article.

        A few points, the Yugoslavs made Hurricanes under licence.
        3 captured one ended up being passed on by the Germans to Romania to go with the 12 they already had.
        Yugoslav built aircraft can be identified by their camouflage, and all had fabric wings.

        Early machines had the two bladed Watts propeller, but later ones had the De Havilland two speed unit, if they received the constant speed unit conversion I don’t know. By this I mean DH came up with a conversion set which was used to convert DH two speed units to constant speed.

        The Bf 109E did not ever have a engine mounted cannon, the hole in the spinner was for cooling. Later versions did though.

        Sadly no photos of the conversion exist, so the drawing is speculative.

        this thread on Britmodeller has details about Yugoslav Hurricanes
        http://www.britmodeller.com/forums/index.php?/topic/234951133-yugoslav-hurricanes-recommended-schemes/

        as it’s a modelling site there is discussion on camo and markings, but a lot of info one what was supplied and built under licence as well.

        The Yugoslav partisan airforce received Hurricanes late in the war, both Mk IIc and Mk IV, which served into the lat 1940’s, and there is a Hurricane IV on display in Belgrade to this day.

        Like

      • Thank you Troy for getting back to me with that informative response. Alas after looking back I can see I did indeed make a mistake regarding the gun through the spinner and I will amend the article accordingly

        Like

  3. Pingback: Defence of the Realm – Worldwide | Defence of the Realm

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