In 1990, RJL Industries obtained the HP Model Engine product line as well as the HP name and HP logo used in the hobby industry as trademarks in an agreement with Hirtenberger AG,  Austria. HP model engines are no longer associated with Hirtenberger Patronen munitions company, Austria. Hirtenberger is quite a historic company and is still a leader in Munitions production in Austria.  
Hirtenberger Patronen Since 1857

Hirtenberger has quite a history. Located in the town of Hirtenberg south of Vienna, Austria, HP's primary business as an ammunition factory dates back to 1860. The word Patrone in their name means cartridge.

Initially, HP produced hand made hunting cartridges but steadily expanded to manufacture a full range of ammunition.

At its peak, during the Austro-Hungarian monarchy, the factory employed over 4000 workers.

By 1937, one million cartridges per day were being manufactured to supply the axis powers. However, following World War II and the postwar occupation period, the factory was left an empty ruin until 1955. Production recommenced during 1957 under the guidance of the former president, Fritz Mandl.

With his interest, the model engine department was started in the early 1960's to develop a twin cylinder military drone engine. Then development of a .15 and .61 engine for the consumer market followed. Only the .61 went into full production.

The first model of the .61 had a bell type rear rotary valve and Schnuerle porting design, both were unheard features of in the 1960's. Soon the .61 evolved into a front intake version which proved to be more suitable for conventional model airplanes.

With the success of the .61, the HP .40 soon followed and gained a wide following which its descendant today still carries.

Throughout the 1970's a full line of engines soon to be known as the most advanced and highest quality were in full production.

In the early 1980's the Austrian government took ownership of the munitions factory. During this time development began on a series of 4 stroke engines with a unique rotary valve designed by Leopold Habsburg. These proved to be the quietest and most fuel efficient engines ever produced.

During the late 1980's the engine production was neglected as it was such a small portion of Hp's business.

In 1990, after years of negotiation, RJL was able to purchase the model engine department from Hirtenberger and move the engine production to Southern California.

Hirtenberger AG, Austria is still in the business of manufacturing ammunition and munitions and is no longer affiliated with the model engine production.

The HP engine line, name and HP logo were obtained in 1990 from Hirtenberger AG,  Austria. HP model engines are no longer associated with Hirtenberger Patronen munitions company in Austria.


Interesting Fact: The designer of the 2 stroke HP engines left the company in the early 1980's and joined WEBRA. You can see the similarity between the WEBRA Speed line and the HP Gold Cup and Silver Star engines..