Identification needed

[Varese2002]

Sometimes, all of a sudden an old photograph is discovered which depicts a plane which has not been seen before. This is such a case.







The photograph was first submitted here. The man in front of the triplane / tri-engined machine is Gustave Delabbé, a carpenter-joiner [French: ébéniste-menuisier],who was called in to work on wooden parts of the machine in 1918. Delabbé died in 1960 and the picture is in the possession of his granddaughter.

The machine was constructed just before the armistice and flew succesfully, but after the armistice the whole project was ended. It seems the project was financed by a rich benefactor. This information is from the granddaughter of Delabbé, but cannot be proved till now.

The machine seen on the picture is sort of mini-triplane tri-engined machine, judging by the size of Delabbé. Construction is a classical one, central nacelle with pusher engine and two tailbooms with tractor engines. Engines has not been identified but seem to be radials (no rotaries). Landing gear is special with a large central skid.

As already said, the reference books give nothing on this one. The bringer of this picture on the French site - mimile - has personally browsed the contemporary standard work of de Brunoff (all 735 pages of it !), but to no avail.

Brunoff, Maurice de, and L. Marchis. 1919. L'aéronautique pendant la guerre mondiale. Paris: M. de Brunoff.

So till now nothing has been found to identify this machine. Please help if you can, with any information you might have.

Cheers

Kees

[paolomiana]

Looking at the upper wing, I've noticed that a significant portion of it was suppressed.
Guess was to make room for the crew, but they had removed exactly the portion of the airfoil that generates lift!

cheers

Paolo

[YavorD]

There is very narrow gap too. Gap-to-chord ratio is below unity, particularly for the large chord upper plane. The result should be significant aerodynamic interference and poor lift coefficient. I will be surprised if this design was able to meet expected performance figures.
Regards,
Yavor

[paolomiana]

Quite strange indeed, expecially in consideration of the fact that interaction between pressure fields around wings was well understood in 1918.....

Paolo

[Varese2002]

As Paolo and Yavor have remarked, the design of the wings is below standards as known around 1918. Obviously not an experienced designer or construction firm. The landing gear construction is special too, showing 6 wheels in the picture (two wheels on the central skid and two wheels at either side of the fuselage). A heavy construction, where the machine rested on the ground at the back of the fuselage (tailskid).

Given that from outside M. Larrabé was hired in as a carpenter, there could be challenges with the workforce expertise or strength.

This triplane was most likely the ambitious creation of someone and the first machine built by the construction firm. Given the lower than expected real performance (in combination with the Armistice 1918), the existence of this machine was not released to the public (magazines etc.). Sure the government must have known (and approved) that someone was designing and building a triplane machine in war time, as the construction material and the engines had to be approved for this machine.

It is special that this machine comes up in this picture, while no other data is even known about this machine. The only hope probably lies somewhere in the French SHA archives

Cheers

Kees

[YavorD]

Hi Kees,
It is a bit odd, a dinosaur really, in 1918 when Laboratoire Eiffel was established authority and C.E.P. Caproni's flew combat missions, when large Bleriot designs, if not practical, were far from obvious aerodynamic blunders, as well as Farman Goliath and big Caudrons taking shape, and last but not least several large flying boats flying.

Yavor

[Varese2002]

There is also an 'incision' in the topwing at the back, just above the tailboom. The only rason why this should be done is to give a crewmember / gunner a clearer view above. It could be that there were MG's in the tailbooms operated by crew members in the tail booms.

The machine was possibly devised as a battle ship escorting bomber squadrons. Be aware this is only conjecture, no factual data.

Paolo and Yavor, I presume that the pieces taken out of the topwing at the back are not the best in aerodynamics? Also the wings grow longer from lower, to middle to topwing.

Escorting battle ships (planes) were envisaged at the end of the war in the USA, I think for example by Burgess, but not really built.

Cheers

Kees

As an afterthought. The relatively small size of this three-engined triplane might hint at the fact that the machine is not designed as a bomber, but primarily as an escort battle-ship.

[Rbailey]

The Van den Born F5 was a trimotor that would fit that description,but I don't know if it was a triplane.

[Varese2002]

Originally Posted by Rbailey

The Van den Born F5 was a trimotor that would fit that description,but I don't know if it was a triplane.

Interesting hint, the only reference I could find till now is from the NASM Directory of Airplanes here. At least there exists another trimotor in France, unfortunately no date given.

Charles van den Born (1874-1958) was an early Belgian aviator, naturalized to France. Acquired Brevet n° 37 de l'Aéro-Club de France on March 8, 1910. He did early flying in Indochine, Saigon, Hong-Kong etc.
During the war he was entrusted with the foundation of the Belgian military aviation school (L'École militaire belge d'aviation). No mention about the trimotor named by the NASM.

As we are in the Belgian aviation history area, perhaps Toxisch can help?

Cheers

Kees

[paolomiana]

Originally Posted by Varese2002

Paolo and Yavor, I presume that the pieces taken out of the topwing at the back are not the best in aerodynamics?[/COLOR][/I]

Hi Kees,

here a pic of aerodinamic fields on thin airfoils



and how to arrange multiple wings in order to not lost lift and gain drug



As you can see most of the lift was generated by pression/depression fields in the first 1/3 of airfoil

both of the pics comes from E. Garuffa L'aviazione II ed. 1919 Koloman Mayrhofer collection.

cheers

Paolo