Hellcat exhaust streaking colour

[Work In Progress]

Good post.

 

From a modern-day perspective, in case anyone cares, what used to be known as 100/130 is now known simply as AVGAS 100. It is green, and is very rarely available in the normal aviation world. 100LL is what you normally get: it is blue, meets the same 100/130 spec as AVGAS 100 but uses only half the lead. However, even 100LL uses a phenomenal amount of lead compared to any road car fuel.  

 

There have been a number of attempts over the last couple of decades to bring unleaded aviation fuels to market in significant quantities. They are technically perfectly feasible but as the whole of the global AVGAS industry is such a tiny niche product compared to road fuels and jet fuels they have proven to be difficult to market at prices that work for both manufacturers and operators. 100LL soldiers on for the time being.

 

You can run any of the old warbird or post-war airliner big pistons on 100LL, but in many cases you will have to limit boost and accept reduced power. Not a problem in the real world as such aircraft no longer fly at the original military weights.

[72modeler]

@303sqn,

 

Thanks for the post- it was very interesting and informative- especially Cline's article! Obviously you got an 'A' in organic chemistry in school!

Mike

[303sqn]

At the end of WWII the US developed 115/145 grade gasoline to provide extra power on take-off from the big multi-banked radial engines. It became available about VE-Day. It continued after the war but the military were virtually the only customer. When they stopped using the refineries stop manufacture. There were only some ageing freighters and warbird owners that wanted it.

 

Postwar 100/130 grade differed somewhat from that of WWII. No aniline for a start. Refineries would add lead until it passed the lean mixture requirement at which point the the rich mixture rating would usually be well above the the required 130. Typically they would be around 100/137. For 100LL most refiners add the allowed amount of lead and then add toluene to meet the 130 rich mixture rating. Typically 100LL will be about 104/130. When the market moved from 100/130 to 100LL there was a significant increase in knocking complaints.

[Work In Progress]

31 minutes ago, 303sqn said:

At the end of WWII the US developed 115/145 grade gasoline to provide extra power on take-off from the big multi-banked radial engines. It became available about VE-Day. It continued after the war but the military were virtually the only customer. When they stopped using the refineries stop manufacture. There were only some ageing freighters and warbird owners that wanted it.

 

Plus the major airlines who were running the likes of the DC-7 and Super Constellation as their principal transatlantic flagships until the very late 50s. They used either 115/45 or in some cases 108/135, for take-off, often also with ADI