Castor oil aircraft fire preventative

[HagarTheHorrible]

So, there I was reading an article about WW1 aero engines.  When describing rotaries it obviously mentions the castor oil mix and describes the well-known fact that oil would be liberally sprayed around the aircraft and over the pilot. 

 

Given that Castor oil was specifically chosen because of its ability to not catch fire, usually, and given that much of the cockpit and rear fuselage of a rotary engined aircraft would have been clarted in accumulated oil the question I have is.  Would a rotary powered aircraft have had an unintended ready-made fire inhibitor, offsetting the natural flammability of the dope ?

 

If above is in any way potentially true, would the mineral oil used by the Germans, later in the war, have been as effective ?

[Chill31]

11 minutes ago, HagarTheHorrible said:

So, there I was reading an article about WW1 aero engines.  When describing rotaries it obviously mentions the castor oil mix and describes the well-known fact that oil would be liberally sprayed around the aircraft and over the pilot. 

 

Given that Castor oil was specifically chosen because of its ability to not catch fire, usually, and given that much of the cockpit and rear fuselage of a rotary engined aircraft would have been clarted in accumulated oil the question I have is.  Would a rotary powered aircraft have had an unintended ready-made fire inhibitor, offsetting the natural flammability of the dope ?

 

If above is in any way potentially true, would the mineral oil used by the Germans, later in the war, have been as effective ?

Nope.  At the time, they used EXTREMELY flammable fabric covering materials on the aircraft.  The rotary powered Dr.1s I've seen are indeed smeared with oil, but no where near enough to stop a fire.  The biggest source of fire in WWI was a punctured fuel tank, and Richthofen mentions it in his autobiography...seeing the white mist was a sure sign of impending fire. 

[AndyJWest]

I don't think castor oil could be described as a 'fire inhibitor'. It is less flammable than mineral oils, but will still burn given enough heat. https://www.aromantic.co.uk/technical-documents/msds/castor-oil-msds.aspxhttps://www.aromantic.co.uk/technical-documents/msds/castor-oil-msds.aspx

[=TBAS=Sshadow14]

Castor oil does indeed burn.
Have you ever seen an RC plane smoking (thats Castor oil)
Or smelt an RC plane Running (thats castor oil)

Basic Radio control plane engines run like 40-60% Nitro with 10-25% Methanol and 25-30% Castor oil.
Once run in (rings bedded) many run 80-90% Nitro and castor oil only.
Like a 2 stroke lawn mower or brushcutter could also run it mixed with fuel.
 

[HagarTheHorrible]

 

 

Indeed castor oil does burn but not as readily as petrol or maybe dope.  I'm not suggesting castor oil clarting was anywhere near perfect at preventing the fabric catching fire just that it might have unintentionally helped.  As Chill points out though, many, if not most fires would have been petrol leaking, probably in a fine white mist.

 

At a time when everybody smoked, flying must have been a right royal pain in the arse.

Edited July 24, 2018 by HagarTheHorrible

[unreasonable]

9 hours ago, Chill31 said:

Nope.  At the time, they used EXTREMELY flammable fabric covering materials on the aircraft.  The rotary powered Dr.1s I've seen are indeed smeared with oil, but no where near enough to stop a fire.  The biggest source of fire in WWI was a punctured fuel tank, and Richthofen mentions it in his autobiography...seeing the white mist was a sure sign of impending fire. 

 

Even a punctured fuel tank was only a sure sign of impending fire after everyone started using incendiaries as a matter of routine, and not just on balloons, sometime in mid 1917. Before that fires were very rare, surprisingly so for aircraft that were sometimes riddled with bullets, afterwards they happened more often than not.  MvR mentions fire in 10 of his last 13 victory reports: before that he had only mentioned it in 9 cases out of 67!

 

Edited July 25, 2018 by unreasonable
dyslexia getting wrse.

[HagarTheHorrible]

Chill31 has said he doesn't think there would have been enough of an accumulation to have had much effect either way which is probably quite right.  I suppose one factor might be whether the doping allowed, or prevented absorption of the oil.  If the fabric absorbed the oil and the oil had a lower flash point than the dope then it may have hindered ignition. On the other hand, if it just produced a film and an insignificant one at that then I doubt it would have had much effect.

 

Contrary to my earlier thought, maybe the oil increased the risk of fire.  I just remembered that oily rags can self combust.  I can't say I've overly worried about it, in my job (furniture restorer) but after using furniture finishing oil, it is recommended to lay rags out flat on the ground to dry, rather than scrunched up in the bin. Self generating heat can set them on fire.  I expect linseed oil, as typically used in furniture oil, has a far lower flash point than castor oil though.