Franz Friedrich Kruckenberg (* 21 August 1882 in Uetersen, Germany; † 19 June 1965 in Heidelberg) was an engineer and pioneer of high speed railway systems. He designed several high speed trains. His most famous train was the Schienenzeppelin.
Kruckenberg was son of an old Hamburg merchant family. He made his diploma as a ship building engineer. Before World War I he constructed combat aircraft and airships. Already at that time he criticized airships because of their explosive hydrogen filling and the civil use of aircraft because of the high fuel and maintenance costs.
After the first World War he opened an engineer bureau in Heidelberg. First he invented a hanging monorail, but he did not get the fortune for a prototype. Later he founded the Flugbahn-Gesellschaft mbH together with Hermann Föttinger to build a high speed propeller driven train, the "Schienenzeppelin". The first test runs were made 25 September 1930 on the track Braunschweig-Paderborn between Kreiensen and Altenbeken.
On 21 June 1931 his Schienenzeppelin made the first run on the track Hamburg-Berlin. Between Ludwigslust and Wittenberge, achieving a world record for trains of 230,2 km/h. It was the fastest railcar of the world for more than 20 years. A major problem was the propeller, causing noise and wind. Kruckenberg rebuilt the Schienenzeppelin to a hydraulic driven car, which still made a top speed of 180 km/h with only 441 kW.
The Schienenzeppelin was revolutionary for this time, since the aerodynamic streamline profile and the light weight construction was proven usable for high speed railways. His ideas influenced the high speed train constructions until today (ICE, Acela, TGV). The Schienenzeppelin was scrapped in 1939.
After the Schienenzeppelin Kruckenberg designed the DRG Class SVT 137 155 in 1934. This prototype of a three unit DMU had a diesel-hydraulic transmission and was ready in 1938. On a test run, on 23 June 1939, this train made a world speed record for diesel trains of 215 km/h between Hamburg and Berlin. Parts of the SVT 137 are still preserved in Dresden.
Based on this prototype Kruckenberg constructed the DB Class VT 10.5 ("Senator" und "Komet") as talgo technique fast running daytime (7 parts) and night (8 parts) trains after World War II. They were famous for their unreached light weight (0.92 t/seat), but had disadvantages in maintenance due to their six motor concept. So they were taken out of service in 1959 resp. 1960.
Also the famous DB Class VT 11.5 ("TEE") und DR Class VT 18.16 ("Vindobona") were derived from Kruckenbergs SVT 137 155.