Engineer Federico Cantero Villamil was mainly devoted to public works.

-But his main hobby was aviation, to which he devoted time and financial resources for his invention of a helicopter in two versions. The one with the double contra-rotary rotor was called "Libelula".

-And the other one was called "Viblandi" taking the first syllables of two other co-builders.

-From the latter there are taken two photographs at Cuatro Vientos (Madrid), perhaps during the test periods in the early 1940's.

“Photographs of Cantero's Viblandi”

-With a 130 hp? Pobjoy engine showing below thanks to the superimposed reduction gear and a fan that was necessary for powerful stationary flights. Subsequent information gives the engine only 90 hp.

-These works have been unknown until today, when a family member has published a book about his interesting biography, titled with his name.

-For our publication we are interested in other patents on propulsion systems that were advanced for its time:

"Cantero's patent, no 156551"

-By his patent number 156551 from March 1942, we have a means to gain power (today PTO) through propellers installed in the gas flow of turbo-reactors (incipient at that time).

-On November 5 the same year he requested patent for an axial-flow turbojet (the Germans would still not have an operating equivalent -BMW or Jumo- until 1944).

"Cantero's, number 159178"

-In 1944 (March) he was granted patent number 167813, for a nozzle with ejectors to "create spinning vortexes" to produce a better mixing with the exhaust gases in turbojets.

-Actually it is the booster principle that half a decade later was used by Melot.

"Cantero's patent number 167813"

-There is another patent on propulsion, with the number 170018 that we are looking for.

-Don't forget that Federico Cantero had previously obtained many patents on helicopters and their devices. He was contemporary of Sikorsky and the German FW-61, who made his first flight in WWII.

-However, the Libelulas were pioneers in Spain. Remember that Cierva made autogyros, with different principles, they could not hover.

From appendix 9: At the Spanish patent office they have located more works on jet propulsion by indefatigable engineer F. Cantero .

-In the main text it comes to his more visible work, the helicopters called "Libelula" and "Viblandi".

-The illustrations below are copies of original documents provided for the patent.

"Gas turbine"

"Gas generator"

-The "free piston" type gas generator could be used to drive a turbine or directing pressurized gas to the blade tips of a helicopter rotor. Like in the illustration below.

-This generator is similar to Pescara. (see)

"Patent for a jet driven rotor"

"Rotor driven by gas"

-As it is an incipient turbine, we need to study the accompanying text to assimilate its operation. A simpler system would be the one shown below.

"Spinning caused by gas flow "

-First the simplest form and after that the one shown in the figure above. The first one clearly makes the propeller spin with the gas from the free piston generator.

"Realistic turbojet from 1945"