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[Ric Gillespie]

Current research suggests the artifact we found in 2021 may be the cap on either the coolant filler neck or coolant drain plug for the W12 Lorraine Dietrich engine of l'Oiseau Blanc.
Unfortunately, neither the Lorraine Dietrich manual nor the parts manual for the Levasseur PL-4 aircraft (from which the PL-8 l'Oiseau Blanc was derived) shows those features.  We need a surviving PL-4 with a Lorraine Dietrich W12 engine but we can't find a museum or collection that has one.

[Kurt Kummer]

I imagine you've already seen this Ric, but just in case...  https://www.skoda-storyboard.com/en/press-releases/skoda-museum-presents-an-extraordinary-exhibit-the-w12-aircraft-engine-by-laurin-klement/

[Ric Gillespie]

Lorraine Dietrich engines are not hard to find, but just an engine does not show us what we need to see. We think we might have the cap from the filler neck of the water reservoir (aka header tank) that sat on top of the engine.

[Arthur Rypinski]

Ric-

Note the sealing mechanism on a World War II jerry can.  Fancy glass beer bottles use a similar mechanism.  The latch exerts pressure along the centerline of the lid.  Gasket around the periphery of the lid. Holds pressure, No vapor leaks, at least in principle.  No threads on the lid.

adr

[Arthur Rypinski]

here is the jerry can.
adr

[Christophe Blondel]

Unfortunately, the website https://www.avionslegendaires.net/avion-militaire/levasseur-pl-4/ says unequivocally that no PL 4 has survived their decommissioning (except the one that may still be sitting on the floor of the Mediterranean ...). But the French ministry of Armed forces (even though they do not know in what circumstances) has salvaged 195 blueprints from the Levasseur company, which are available online at https://www.memoiredeshommes.sga.defense.gouv.fr/fr/article.php?larub=407&titre=plans-de-constructeurs-aeronautiques-sur-des-appareils-civils-et-militaires-xxe-siecle-
Just in case you did not notice, one is the side view of the internal arrangement of a PL 8 (apparently not l'Oiseau blanc, but the second "postal" PL 8, which, according to Wpd, "was built [in 1928 and] equipped with a Hispano-Suiza 12M 375 kW (500 hp) engine. Flown in 1928, the PL.8-02 was intended as a long-range record breaker but modified as an air mail carrier"): https://www.memoiredeshommes.sga.defense.gouv.fr/fr/ark:/40699/s0062cad8b3f3722/62cad8b400a1d
That may give some ideas. However, the caps (or lids) do not seem to be other than an ordinary type... Sorry I do not find how to make a reduced image suitable to be included here, but someone will soon find how to do that, if showing this blueprint appears of some interest.

[Arthur Rypinski]

Very interesting. thx.
adr

[Arthur Rypinski]

One can hope that there are more drawings done by M. Soulier
adr

https://gallica.bnf.fr/ark:/12148/bpt6k6568023j/f29.item.r=LevasseurL'Aeronautique

[Renaud Dudon]

I own a copy of the following books:

"Pierre Levasseur et ses avions " TMA 2002;

"Les avions de Pierre Levasseur" LELA PRESSE 2004.

There are two interesting photographs inside which reveal a little of the cap that covers the water reservoir at the head of the cylinders.

I'll try to scan them tomorrow at work. For what it is worth. From what I've been able to measure, the cap is about 8 cm in these photos, and the pipe it covers about 6 cm.

[Kurt Kummer]

That's very interesting Renaud!  Thank you for remembering Ric and Tighar and offering your help.

[Renaud Dudon]

First one, hoping it will be uploaded....

[Renaud Dudon]

And the second one... Knowing that the fuselage at engine mount level measures 120 cm, we can measure that the cap in question is 8 cm or thereabouts... Of course, we'd need to know the depth of field to correct the perspective somewhat...