Daimler-Benz Cold Weather Start Feature
 

Does anyone know exactly what method was used and how it was accomplished, to assist in cold weather starting of DB 601 or DB 605 engines? I have heard it could have been anything from "glow plugs" to acetylene but my information may be wrong or applicable to other engines of other nations.

Hal

Re: Daimler-Benz Cold Weather Start Feature
 

Finns used the petrol method for DB 605. The amount of petrol mixed with oil ranged from ten to twenty percent of total weight. [*]
[*] http://digi.narc.fi/digi/fullpic.ka?kuid=2904386 and http://digi.narc.fi/digi/fullpic.ka?kuid=4594811.

Re: Daimler-Benz Cold Weather Start Feature
 

Thank you for your curious information. But how could the Finns justify mixing lubricating oil with aviation fuel knowing this procedure would seriously degrade the lubricating qualities of the oil and thus seriously shorten engine life? To me it just doesn't make any sense. I must be missing something critical, but what?

Hal

Re: Daimler-Benz Cold Weather Start Feature
 

Hello Harold
not so, very cold oil lost its, what was the English term, maybe viscocity, and had to be diluted just to ensure its lubricating qualities, when engine and oil get warmer, the aviation fuel evaporats and so the warmer oil maintain its lubricating qualities.

One other possibility is to warm the oil before the start but that takes more time.
Juha

Re: Daimler-Benz Cold Weather Start Feature
 

Absolutely. From the first link: "We did not warm the oil but used 10% cold start instead." The second link remarks that many [oil] radiators were broken before the squadron moved to 15-20% cold start.

Re: Daimler-Benz Cold Weather Start Feature
 

I've seen this technique described as something established within the Luftwaffe prewar.

Re: Daimler-Benz Cold Weather Start Feature
 

Juha, Martti and Graham,

Thanks to each of you for your instructive comments. As explained, it seems clear the process of mixing aviation fuel with engine oil, in the right percentage, worked when needed and it may very well be true that engine life was not compromised. I cannot help but wonder if American and British air forces relied upon the same remedy. But that is a question for another day and another forum.

Hal

Re: Daimler-Benz Cold Weather Start Feature
 

Hello Harold
at least the Pilot’s Flight Operating Instructions for P-39Q-1 mentioned the system and explained it, in fact there was a inbuilt system in winterised P-39Q-1s.

Juha

Re: Daimler-Benz Cold Weather Start Feature
 

Hello,

Perhaps of some interest concerning mixing fuel on Bf 109 E-1.
Sorry I am not able to post a picture. Here is a sketch:

95 % Benzin 50 % Benzin
5 % Oel 45 % Äther
5 % Oel

Best regards.

ClinA-78

Re: Daimler-Benz Cold Weather Start Feature
 

Hello,

as nightfighters on Me 110 we used the cold weather procedure in wintertime 1943. In my papers I found an old "Kaltstart-Karte" for As 10 Engine (in FW 58) which is attached, probably the same we had for Daimler-Benz. Enlarge scan if necessary.

The mixture with Benzin varied with outside tempertature:

+ 5° C - 10° C 7,5 per cent
- 10°C - 30° C 15 per cent
- 30°C and colder 20 per cent

very important was to watch the maximum oil temp during taxiing and take-off:

+ 65° C at 7,5
+ 50° C at 15
+ 35° C at 20

we had fatal accldents at or after take-off when the oil temp was not observed, so called "Kolbenfresser".

regards
Peter

Re: Daimler-Benz Cold Weather Start Feature
 

Many thanks to Herr Spoden and all other gentlemen who responded with hard evidence to support the use of fuel mixed with oil for cold weather starts. Happily, we are now so informed.

Hal

Re: Daimler-Benz Cold Weather Start Feature
 

Hi Harold,

That is not the case at all. In fact, it extends engine life. When the temperature drops below a certain point, the higher viscosity oils used in aircraft such as 100W become extremely thick.

This causes a number of problems. First the oil pressure is so high that it would damage the engine. Most airplane engines over come this by bypassing the oil pump by returning a portion of the oil directly to the sump until the oils viscosity reaches a point it will flow properly.

During this time, the wear and tear on the engine is higher than normal.

One of the ways to overcome this is to blend a multi-viscosity oil. Today we have several blends to choose from the most common being 15W-50.

http://aeroshelldirect.com/aviation_oil.asp

http://www.skygeek.com/48250.html

This is what is being done using the properties of fuel in the winter starting systems. Thinning the oil allows the oil pressure to remain within limits that will not damage the engine. The oil system is then able to circulate the oil from the start and as the engine warms up, the fuel evaportates returning the oil to its higher viscosity required at the higher operating temperatures.

It extends engine life and reduces maintenance.