Castor Oil

[Shooter]

This is a question for the "general pop" since I know that someone out there knows the answer.

It has been stated that the main reason for the demise of the rotary engine in German a/c manufacture/design was the unavailability of castor oil to the German a/c industry.

Question: exactly what was the roll of castor oil in the operation of rotary engines? Was it a general lubricant? If so, why was not a petroleum distallate and acceptable substitute?

Shooter sends

My experiences with the stuff are limited to two-stroke motorcycles in which the lubricant is mixed with racing (aviation) fuel, but I'm not sure that the desription below applies to the WWI rotaries. No doubt someone else will know this.

In terms of lubricity, castor oil offers the best protection. The excessive moving parts in a rotary apparently required the extra protection, given that a problem at 10,000 ft is likely to be one's last. In spite of the better protection, castors are resistent to dissolve in gasoline/aviation fuel. When they do not dissolve, causing the engine to receive only fuel, the engine has a nasty habit of seizure. The only way to overcome this is to use varying amounts of alcohol (methanol) with the fuel/oil in order to keep the oil in solution.

Apparently distillates did not suffice and adequate synthetics were not yet formulated.

[Ron_F]

Castor oil was mixed with the fuel for lubrication, just like in 2 strokes, as i dont believe they had oil passages and a self contained oil tank that recurculated the oil. thus the mixing of castor oil and fuel.

perhaps Dwight Rudder can have more info on it.

not enough in my engine diagrams on these systems per se.

Ron F.

[Darryl]

RonF,

Almost right.By my understanding the oil was sort of put with the fuel, but only during the feed process. There was a seperate oil tank which fed into the cylinders at the same time as the fuel. The Oil was used on a "total loss" basis, not recirculated. The main property that made Castor Oil attractive (necessary) was that it did NOT mix in with the fuel, thus it delivered lubrication at the same time as the fuel combusted. The resultant 'muck' then went through the exhaust.
Conventional oil was used in Inline engines on a circulating system.

The Germans obtained supplies of 'ersatz' castor oil from (my VERY fault memory)Sweeden or Rumania?? It was synthetic and not anywhere near as efficient as 'natural'. This was the main cause of the overheating problems suffered by German rotaries in the hot summer of 1918.

As you say, Dwight will probably fill in the gaps....or correct me.
regards


Darryl

Boy, I didn't know that I was held in such high esteem by you guys. GEE THANKS, Although I don't tout myself a genuine expert, I have been around enough WWI aeroplanes and Motorcycles I think I can answer the question.
The world's best source of Castor bean oil is England, Of course the English aren't going to sell Germany this asset. The Germans did indeed try using inferior petroleum oils which usually over diluted in engine and didn't lubricate as well as Castor. The Americans tried better refined oils and they worked fairly good by all accounts.
Castor oil ( current synthetic oils mimic Castor ) isn't easily washed off engine parts and in fact adheres better to hot parts , thus still lubricates well under extremely hot and strenuous conditions. ( that is why many 2-stroke motorcycle race bikes use Castor based oils when being run flat out for extended periods without failure). Rotary engines are indeed total loss oiling. Meaning you have to fill the oil tank at same time as the Fuel tank.
Oil was fed into crank shaft bearings where then it was slung out into the crankcase where the gas fumes and fuel mixture were being collected. Here it mixed with the fuel and also lubricated the cylinders and rod bearings. The mixture of fuel fumes and atomized Castor oil was then sucked up the intake tubes and throught the intake valves into the combustion chamber by the pistons downward stroke. Then the mixture was compressed by the up stroke and fired by a spark plug. Burning most of the fuel and little of the Castor oil. The Castor oil is then expelled on the exhaust stroke out the exhaust valve and then into the atmosphere where the airstream then blew it back onto the aeroplane ( what a mess to clean up , Only alcohol will remove it off the aeroplane)and into the face of our fearless pilot where he breathed it it making him nauseous and have dirriea (sic). But Castor was the best lubricate the world had in 1916. The oil was more or less injected into the engine much like Suzuki's Crank Case Injection system. I hope this helps.
Cher'o,
Lt. Dwight Rudder, RFC

PS: pass the milk and Brandy, all this castor has my stomach turning.
LOL

[Shooter]

All:

Many thanks for the information. While it only serves to sate my personal interest (I have no pending research papers, or such) it is VERY interesting.

Hell, I didn't even know from where Castor oil was produced until Dwight mentioned it (Castor beans, eh?). All I knew was that a spoonful of it tastes like @#$%e!

While there may be more posts, I think I now have the picture. Domo arigato, goziamas', gang!


Shooter sends

PS: Dwight, your opinion is well respected.

[Vin]

Darryl & Dwight

I imagine that the pilots of rotaries would be in a sorry state after a flight – exhausted from wrestling just to keep it in the air and nauseous/diarrhoetic (?). Was there anything they did to assist, e.g. wear a gas mask or scarf to anything like that ?


Vin

[stevedrew]

Vin,
They just put up with it as a side effect of "the job". Little was often nauseated earlier in his career, yet improved when not flying rotaries.

Steve Drew

Gnome, LeRhone and Oberursel rotary engines carried a small tank of castor oil. In some cases the oil tank and petrol tank were mounted inside the top wing. Some diagrams show an oil tank inside the petrol tank to save space. They were filled separately, and never mixed together as we do today.
The rotary engines at first had the petrol and oil just spilling into the crankcase intake pipe, the flow controlled by a petcock.
Once inside the crankcase, the early Gnome engines inducted the mixture into a cyoinder through a valve in the top of the piston. After many failures of this system (the valve stuck and the crankcase caught fire( the engineers at Gnome et Rhone devised an external intake pipe for each cylinder to pass mixture from the crankcase to the cylinder by the vacuum created on the second (non-firing) stroke as the piston descended.
Early Gnome engines inducted the petrol and oil mixed with air from the atmosphere in a very heavy air/petrol/oil mixture that was almost thin enough to explode. Later engines simply poured liquids into the crankcase and mixed them with air as they were inducted into a cylinder, thus making the crankcase less likely to catch fire during normal running.
These were Otto (4 cycle) engines (hit-and-miss).

Vin:
One system of preventing diaharrea was to make a porridge of half Quaker oats and half portland cement. This would certainly negate the effects of inhaling castor oil fumes.
Collatorally, inhaling the exhaust fumes from an internal combustion engine for several minutes is the only known cure for the common cold.