BMW 801D engine compared to 2CV engine

Visited the Museum of the air battle over the Ore Mountains fought over that area in September 1944 when 60 Luftwaffe fighters (Me 109s and Fw 190s) intercepted a formation of 36 USAF B-17s shortly before they rendezvoused with their P-51 Mustang fighter escort.

They had the wreckage of a BMW 801D engine from a Fw 190A-8/R2 Sturmbock of II.(Sturm)/Jagdgeschwader 4.  As this is an air/oil cooled engine of the same vintage as the 2CV the similarities are striking.

Whilst the size is significantly different (2.9l per cylinder as opposed to 0.3l) the cylinder and head assemblies are very similar with a ferrous cylinder and finned aluminium head:

Cylinder and head from a BMW 801 engine  2CV head and cylinder

Likewise, inside the head, the domed combustion chambers are very similar with one intake and one exhaust valve, hardened valve seats and the spark plug situated in the same place.

Cylinder head from a BMW 801 engine showing combustion chamber

2CV cylinder heads showing combustion chamber and push-rod tubes

Known as Black Monday, on 11th September 1944 the USAF launched a large number of bombing raids into the Reich.  The Luftwaffe put pretty much every available fighter into the air to intercept.

The FW190s involved in the action over the Ore mountains had extra armour and 30mm cannons.  They attacked the B-17 boxes in a tight formation known as Sturmbock (battering ram) opening fire at under 200m. The Me 109s were there to mop up any B-17s that were forced out of formation (Herausschuss) and to deal with the Mustang fighter cover which, in this case, arrived after the Surmbock attack.

The Museum is typical of a volunteer only effort:  there are a large number of items in very dense displays with very detailed and comprehensive notes.