pwm2txlhopper From United States of America, joined Jan 2004, 1413 posts, RR: 1 Posted (2 years 2 days 15 hours ago) and read 4305 times:
After reading the Thread about Connie engines, I had a question.
My mechanical knowledge of piston engines is limited to small GA aircraft and their powerplants. I know very little about the operation of larger scale piston engines found on early generations of airliners such as Connie's and other airliners of the era. Or even WWII era fighters and bombers engines.
However, I am aware the that these types of aircraft used a leaded high octane aviation gasoline. I think somewhere between 125-130 octane, if memory is correct? That compared to the 100LL that's refined for avgas these days.
With relatively so few of these types of large piston engined classics flying today, my question involves their source of fuel.
With the original leaded high octane fuel they were designed to run on no longer produced by refiners, what do current operators use to run these planes? Can they be converted to run on 100LL, much as small GA planes can be converted to use auto gasoline with a lower octane rating than 100?
Lufthansa has been restoring a Constellation for about four or five years at an airport near where I live in Maine. They even built a hangar for the project. When completed, the aircraft will be flown to Germany. Also, I'm curious to know where all the fuel will come for the flight assuming it's not normal 100LL? How much fuel does it take to fuel a piston of this size for a trans-Atlantic flight. .
kalvado From United States of America, joined Feb 2006, 567 posts, RR: 0
Reply 1, posted (2 years 2 days 14 hours ago) and read 4260 times:
I remember discussion on the topic here a while ago - and the answer was that once in a while a small custom refinery run of those very high octane, lead-filled fuels is done for those historical engines. I assume there is some exempt for production of those for historical purposes - and as long as there is a demand, there will be supply.
g38 From United States of America, joined Oct 2009, 229 posts, RR: 0
Reply 3, posted (2 years 2 days 12 hours ago) and read 4163 times:
I used to work at an air museum... we'd have B-25's, -17's, etc come in every now and then. They'd always use 100LL.
You say you live near the Lufthansa C-121... Whats the current status of it? When are the projecting completion? The last thing I read was from 2012, projecting 2014 completion, but I realize that probably means 2015-16 with a project of this size.
BlueJuice From United States of America, joined Jun 2010, 312 posts, RR: 0
Reply 4, posted (2 years 2 days 11 hours ago) and read 4135 times:
As g38 has posted, historic WWII planes are fueled with 100LL today. My understanding is 87 and 100 octane avgas were used in piston engines during WWII. I read somewhere the RAF credit 100 octane fuel and engines designed to use the fuel as a contributing factor to winning the Battle of Britain. The RAF fighters were able to squeeze just a bit more performance out of their engines to give the edge over Luftwaffe fighters running on 87 octane.
pwm2txlhopper From United States of America, joined Jan 2004, 1413 posts, RR: 1
Reply 5, posted (2 years 2 days 10 hours ago) and read 4099 times:
Quoting g38 (Reply 3): You say you live near the Lufthansa C-121... Whats the current status of it? When are the projecting completion? The last thing I read was from 2012, projecting 2014 completion, but I realize that probably means 2015-16 with a project of this size.
Yes, I live about 25 miles south of restoration at Auburn-Lewiston Municipal airport. This aircraft has sat idle and failing into disrepair there for most of my life since it last flew into the field in 1984. I hope to watch it depart one day in the not so distant future. First flight is now projected during the later part of 2014.
The restoration has been going on for years now and pretty far ahead, although you can't see the aircraft because it is always in the hangar. They don't update the project website often, and the link below is the most recent update that I can find.
boeingfixer From Canada, joined Jul 2005, 563 posts, RR: 0
Reply 6, posted (2 years 1 day 23 hours ago) and read 3911 times:
Quoting BlueJuice (Reply 4): My understanding is 87 and 100 octane avgas were used in piston engines during WWII.
This statement is true for earlier in the war but 100/130 and 115/145 were the norm by the end of the war for the allies.
Quoting BlueJuice (Reply 4): The RAF fighters were able to squeeze just a bit more performance out of their engines to give the edge over Luftwaffe fighters running on 87 octane.
Bit of a misconception regarding the fuels used early in the war by the Luftwaffe. The Germans listed the lean octane rating for their fuel whereas the British listed the rich rating which is higher than the lean rating.
Quotes from an external source:
There are two octane numbers for each fuel, one for lean mix and one for rich mix, rich being greater. The misunderstanding that German fuels had a lower octane number (and thus a poorer quality) arose because the Germans quoted the lean mix octane number for their fuels while the Allies quoted the rich mix number. Standard German high-grade 'C-3' aviation fuel used in the later part of the war had lean/rich octane numbers of 100/130. The Germans listed this as a 100 octane fuel, the Allies as 130 octane.
100 octane fuel, designated either 'C-2' (natural) or 'C-3' (synthethic) was introduced in late 1939 with the Daimler-Benz DB 601N engine, used in certain of the Luftwaffe's Bf 109E and Bf 109F single-engined fighters, Bf 110C twin-engined fighters, and several bomber types. Some later combat types, most notably the BMW 801D-powered Fw 190A, F and G series, and later war Bf 109G and K models, used C-3 as well. The nominally 87 octane aviation fuel designated 'B-4' was produced in parallel during the war.
L-188 From United States of America, joined Jul 1999, 30176 posts, RR: 58
Reply 7, posted (1 year 12 months 4 days 16 hours ago) and read 3373 times:
Confirm on the use of 100LL in this day and age.
At the risk of oversimplifying things Octane is a measure of a fuels ability to resist detonating under pressure. If this happens too far before the cyliner gets to top dead center youbhave detonation in the engine and a loss of power. This is why generally speaking the height the compression ratio of your engine the higher octane fuel you need. That is why it was developed for fighter planes and later used on transports, the hegher compression ratio engines produced more power.
But that is why you can run lower octane fuels if you don't run the none as hard. The reduced settings also prevent the fuel from detonating
I remember a couple of guys found some 130 when I was living out in the bush one time. A Chevy 350 runs real good on it.
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