What fuel is best to use?

[David Dunlop]

Robert. Interesting comments on AVGAS.

In the past 10 years, a couple of B-17's have dropped by at the local aviation museum for visits. Sally B was one, I cannot recall the other at the moment. In chatting with both crews about the rising costs of gas and oil and the availability of parts these days I was surprised by their comments. Both stated their was still enough interest and support from the general public to continue funding operating expenses each year with no problem. Also, there are apparently enough spare parts sources still around to keep the existing global fleet of B-17's flying for many decades to come.

What had both groups a bit nervous about the long term future of flying vintage piston powered military aircraft, was the slow and steady decline in octane rating for avgas. Something which I had not thought of at all. These great engines can still run on today's avgas, but they are not able to produce the power levels they were designed for during the war. With that handicap, there performance is a lot less, which directly affects what the aircraft can do in certain flight situations. Both crews felt that any further decline in octane ratings may soon result in these aircraft no longer able to fly/perform safely.

I could be wrong, but I think wartime avgas ratings were up around 130 to 140. When I was a kid. BA Oil sold premium automotive gas with a rating of 98. Things have definitely changed.

David