Quote:
Originally Posted by Skoshi Tiger
Just as an aside, What was the storage life for the fuel, (both 100 and 87 Octaine)? Less than a year? Modern fuels degrade over time (visibly noticable by the gums and varnishes that seperate from the fuel and discolour it) and would cause all sorts of issues in use. The Fuel companies advise not keeping fuel stored for any great length of time.
I would assume they would have used some sort of rolling reserve system that as new shipments of fuel would be put into storage and the older stock sent out to be used. Does anyone know how they managed their fuel reserves?
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I found this pdf file
Collective Knowledge on Aviation Gasolines which, if you scroll down to pages 21 & 22 says:
"A petrol researcher named Charles F. Kettering and his assistant Thomas Midgley, and later Midgley‘s colleague Thomas Boyd, did about ten years of research on various fuel formulations and additives to both address the pinging noises heard in engines and to find a way to elongate the petroleum crude oil reserves (Kovarik, 1994/1999).
Shortly after its discovery, tetra-ethyl lead became ―‘Kettering‘s magic anti-knock fluid‘ (Kovarik, 1994/1999) that would provide the anti-knock margin necessary for engines to be designed both more efficiently to burn the fuel more fully in the combustion chambers and to generate more horsepower (Kovarik, 1994/1999). Lead was added to lower quality petroleum in low percentage volumes and this in combination with more effective combustion in the engines was recognized as an effective method for stretching the usage of refined crude oil products to help address oil shortage issues (Kovarik, 1994/1999).
Without going too much into detail about its advantages over other fuel additives to reduce knock, tetra-ethyl lead did not have a high freezing point, did not gum while in storage, did not lower the overall energy content or BTUs, and very little of it was needed to provide the benefits it was designed to deliver (Kovarik, 1994/1999). Tetra-ethyl lead did attack parts of the engine if too much was left behind after combustion, thus the need to use a scavenger such as bromide which achieved market dominance to meet this purpose (Kovarik, 1994/1999). Overall, tetra-ethyl lead became the low percentage additive of choice to help alleviate demands on oil reserves and to prevent knock even though health concerns over its manipulation had already been brought to the public‘s attention from its onset (Kovarik, 1994/1999)." This is wrong in that TEL didn't stop gumming altogether, but probably helped reduce it to manageable levels over a longer storage life.
The current shelf-life for 100 Octane (100LL)
is about a year. There's also an article
here.
The Air Ministry produced books called the Aeroplane maintenance and Operation Series No. 16
"Aeroplane Fuel and Oil Systems" which had a chapter on Testing Aeroplane Fuel. While this does not specify a shelf life it describes the testing regime to ensure that aviation fuel is able to be used: for 87 Octane fuel it specifies "(a) Existent gum = not more than 100 milligrams per litre, by evaporative glass test (b) Potential gum = not more than 100 milligrams per litre after heating at 35° C. for 20 hours." Presumably testing was carried out from the fuel storage facilities all the way down to Squadron level.