Henri Coandă’s enigma and the Coandă Effect

Henri Coandă’s enigma and the Coandă Effect

Today is the anniversary of Henri Coandă’s birthday from 1886. I looked up the Wikipedia article on Henri Coandă to look into the story of his aviation ventures, especially with regard to jet engines and all just a few years after the Wright Brothers first powered flight. Why was a jet powered aircraft in 1910 not more well known?

Well, in short, it’s quite a lengthy story and one researched by premier aviation historians which reads like a Rockford file. The Romanian born inventor — who did most of his work in France, Belgium and Germany — did not succeed with his 1910 vintage aircraft (Coandă-1910) — but make no mistake, this aircraft was prescient. It was a sesquiplane (a biplane with a much smaller lower wing) as Coandă likely saw a monoplane to be the more aerodynamic design and was powered by a ducted fan. Yes, a ducted fan back in the year 1910!

He also ran in good company — rooming and co-designing with Giovanni Caprioni.

Alas, the aircraft was underpowered and made (possibly) just one bounding type of flight for an abbreviated distance. Decades later, when jets came into the fore, Henri Coandă credited himself with the first jet engine. Witnesses to his flight also came out to testify though they had not done so more than 40 years earlier. Recently modified drawings were also produced to indicate a jet engine but it appears the design was that of a ducted fan if one inspects the original drawing.

It is doubtful that Coandă created the first jet engine, though if fuel had been injected and ignited in the stream from the fan there would be room for argument. Nonetheless, the aircraft and propulsion design are both  remarkable and a reproduction of the aircraft resides in the Romanian National Military Museum (Muzeul Militar Naţional) in Bucharest.

Another, and much more documented achievement of Coandă is his description of fluid flow close to a surface and how the stream can be attracted to and then flow along that surface — the Coandă Effect. This effect is significant in modern aviation as it is an important reason for the efficiency of ducted fans. The Boeing C-17 Globemaster III makes use of this as well. Blown flaps enable its spectacular short field performance with engine exhaust deflected downwards against the flap lower surfaces while directed engine exhaust is blown along the flap upper surfaces (Coandă Effect) creating an enhanced Bernoulli Effect.