After the last visit of Martin Fisher to the Musée de l’Air et de l’espace in Le Bourget (Paris), it was impossible not to save memory of the following ingenuity, typical of a science fiction movie.
The author of such curious machines is the French engineer and aircraft builder René Leduc (April 24, 1898 – March 9, 1968), who was satisfied with his passion for thermo-propulsion in 1938, designing and manufacturing The Breguet Aviation the first prototype of thermo-propelled aircraft: the Leduc 010, the first basic development of the stator-reactor.
While the first studies on the subject can be traced back to the year 1908 by the French René Lorin, Leduc was the first to bring out the ideas of Lorin several decades later.
World War II prevented him from carrying out the flight tests, which were not made until the year 1950.
Leduc built four prototypes of his “birds”: the 010, 016, 021 and 022, which increased their speed progressively, from 0.85 Match of 010 to the 1.15 Match of 022.
The reason of these developments was the commitment of Leduc for lighting the Match 2 Supersonic Ramjet…but the appearance of machines like the Dassault Mirage III back in 1956 that easily reached these speeds “without breaking a sweat and without new inventions”, that made definitely his project almost be forgotten, reserving the “almost” for all those who do not have stopped to surprise us with such inventions…
For those who want to dig a little deeper, continue reading…
How does the ramjet work?
A ramjet is the simplest of the jet engines that exists, as it does not have the main elements of the turbomachinery: compressors and turbines… and it doesn’t need them!, because the compression is performed by the high dynamic pressure due to the speed that is needed to print the ramjet so it works.
The air after it is compressed by the effect of the high dynamic pressure in the diffuser inlet, is subjected to combustion in a chamber in which atomized fuel is injected, to finally expand into an exhaust nozzle.
Its operation mode is a true “flying pipe”, which operates on a continuous mode once the initial power-up is activated due to a spark plug.
The only mobile mechanical element that it has is the fuel pump.
It is simple:
Both the diffuser inlet and the exhaust nozzle have different settings, according to the ramjet is designed for subsonic speeds (in this case we talk about Ramjet), or supersonic (Scramjet).
Up to here the ramjet seems to be the perfect ingenuity: high speeds, a very simple maintenance, a very high performance…but… it has a great disadvantage; it needs a mother aeroplane to put it in motion or, in other words: start it. We have to say that the performance of ramjets is obtained at high speeds (>1000 km/h).
In case of the Leduc 010, it was launched by an aeroplane Sud-Est Languedoc, which we can see in the picture below:
To conclude this article, it should be noted that today, the main applications of ramjets are the additional aircraft Propulsion (after acquiring the additional propulsion that the ramjet need to start up), the propulsion of helicopters (through small ramjets at the edges of the rotor blades) and Propulsion for rocket launching.
Here there is a photograph of the impressive Lockheed SR71, whose engines Pratt & Whitney J58 are a composition of turbojet + ramjet, which allow to reach speeds higher to Match 3.