Rechliner cold start procedure

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The computing Liner cold start method was an improvised method for cold starting of piston engines required at low ambient temperatures that no complex heating devices for preheating and only a small lead time of the motor to the flight starts. The procedure, which was used by the German Air Force during the Second World War, was developed in the Rechlin test site before the war .

The basis was the admixture of fuel to the engine oil , which reduced the viscosity of the lubricant and it remained thin even when cold. After the engine was started, the fuel was heated to operating temperature and evaporated, so that the engine oil regained the viscosity required for load operation. The time it took to warm up to the point in time at which the full engine output ( starting output ) could be called up was around three to six minutes, depending on the mixture ratio and the outside temperature. After around 30 minutes of flight operation, the fuel content in the lubricant was around four to five percent, after around one to two hours the fuel had completely evaporated. Motor gasoline with 80, 87 or 100 octane was used for the admixture ; diesel fuel was generally not used.

The fuel was added after landing and cooling the engine oil to a temperature of around 20 to 40 degrees Celsius . In older aircraft, this was done by directly filling the aircraft's oil tank with fuel followed by a brief mixed run of the engine; newer aircraft models were equipped with a permanently installed mixing system. The mixing ratio was dependent on the type of engine, the previous flight duration (in relation to the remaining residues from the previous cold start) and the expected outside temperature at the time of the next start. Depending on the oil level of the oil tank of the dry sump lubrication , a mixer tap had to be kept open for a defined time, which can be taken from the mixing table, when the engine was idling, whereby the admixture took place. Corresponding tables have been developed for this purpose in series of tests by the Rechlin test center. The investigations at the test site did not show any damage to the engines as a result of the use of the procedure; rather, in many cases, even lower engine wear was found.

literature

  • Starting aircraft engines in winter. Device manual. Printing specification D. (Luft) T. 3870. Published by the Reich Aviation Ministry, September 1942 (Title of the previous editions: Cold start process using lubricant thinning )
  • The Rechliner cold start process. In: Kyrill von Gersdorff, Kurt Grasmann: Aircraft engines and jet engines: Development history of German aviation engines from the beginning to the international joint developments. Series: German aviation. Volume 2. Second edition. Bernard & Graefe, Koblenz 1985, ISBN 3-76-375283-8 , p. 179/180.
  • The forerunners of the Berlin Airlift: Stalingrad. Section: Cold start of the engines. In: Wolfgang J. Huschke: The Raisin Bomber: The Berlin Airlift 1948/49, its technical requirements and their successful implementation. Second edition. Berliner Wissenschafts-Verlag, Berlin 2008, ISBN 3-83-051485-9 , pp. 36–38.
  • Stefan Zima: Engine pistons: types, operation, damage. Vieweg + Teubner Verlag, Wiesbaden 2005, ISBN 3-52-803986-8 , p. 249.