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Lack Of High Octane Avgas  
User currently offlineBravogolf From United States of America, joined Apr 2005, 539 posts, RR: 1
Posted (8 years 6 months 1 week 5 days 7 hours ago) and read 3431 times:

I read a while ago that 120-130 octane was no longer available now that the military no longer neeeds it. What do the still flying Connies and the like do for fuel? Did they reduce compression of what?

30 replies: All unread, showing first 25:
 
User currently offlineIAHFLYR From United States of America, joined Jun 2005, 4790 posts, RR: 22
Reply 1, posted (8 years 6 months 1 week 5 days 7 hours ago) and read 3427 times:

They head down to the closest NASCAR/INDY Car track!  Smile


Any views shared are strictly my own and do not a represent those of any former employer.
User currently offlineBravogolf From United States of America, joined Apr 2005, 539 posts, RR: 1
Reply 2, posted (8 years 6 months 1 week 5 days 7 hours ago) and read 3426 times:

I can see them flairing on the strightaway, but the first turn must be a bitch!

User currently offlineFLY2HMO From , joined Dec 1969, posts, RR:
Reply 3, posted (8 years 6 months 1 week 5 days 7 hours ago) and read 3420 times:

Quoting IAHFLYR (Reply 1):
They head down to the closest NASCAR/INDY Car track!

I don't think those big radials would like to burn methanol....


User currently offlineIAHFLYR From United States of America, joined Jun 2005, 4790 posts, RR: 22
Reply 4, posted (8 years 6 months 1 week 5 days 6 hours ago) and read 3414 times:

Quoting FLY2HMO (Reply 3):
I don't think those big radials would like to burn methanol....

Hey never know till ya try! lol



Any views shared are strictly my own and do not a represent those of any former employer.
User currently offlineTornado82 From , joined Dec 1969, posts, RR:
Reply 5, posted (8 years 6 months 1 week 5 days 6 hours ago) and read 3397 times:

Quoting FLY2HMO (Reply 3):
I don't think those big radials would like to burn methanol....

NASCAR runs on gasoline still.


User currently offline2H4 From United States of America, joined Oct 2004, 8955 posts, RR: 60
Reply 6, posted (8 years 6 months 1 week 5 days 5 hours ago) and read 3371 times:
AIRLINERS.NET CREW
DATABASE EDITOR




Quoting Tornado82 (Reply 5):
NASCAR runs on gasoline still.

...And here I thought those things ran on coal.




2H4 - Formula One Fan  Wink





Intentionally Left Blank
User currently offlineMrChips From Canada, joined Mar 2005, 927 posts, RR: 0
Reply 7, posted (8 years 6 months 1 week 5 days 4 hours ago) and read 3348 times:

Quoting Bravogolf (Thread starter):
I read a while ago that 120-130 octane was no longer available now that the military no longer neeeds it. What do the still flying Connies and the like do for fuel? Did they reduce compression of what?

If I'm not mistaken, those aircraft can run on either 100 or 100LL gasoline with little or no difficulty. With the earlier of the large piston airliners (DC-3s, DC-4s, DC-6s and early model Constellations), they can run on 100 or 100LL gasoline with no restrictions or modifications, as that gasoline is of an equal grade to what they were designed for.

The later models (DC-7s and late model Constellations) can run on 100 gasoline with only a placard indicating permissible manifold pressures, as they have to sacrifice some power for the sake of keeping the engine intact.



Time...to un-pimp...ze auto!
User currently offlineKELPkid From United States of America, joined Nov 2005, 6371 posts, RR: 3
Reply 8, posted (8 years 6 months 1 week 5 days 4 hours ago) and read 3327 times:

Quoting Bravogolf (Thread starter):
I read a while ago that 120-130 octane was no longer available now that the military no longer neeeds it. What do the still flying Connies and the like do for fuel? Did they reduce compression of what?

I talked to the flight crew of the Commemorative (used to be "Confederate") Air Force's "FiFi", the world's last airworthy B-29, the last time I saw her. Their engines were designed for 130 octane (purple) avgas. They said that they are basically using emergency procedures every time they fly her...(there were operating procedures in the Air Force operating manual [dash-2?] for operating on 100 octane gas, and they use these). They basically can't get the full rated power out of their "corncob" (4-row!) raidals because of the octane limits. The flight engineer handles most of the work related to keeping the engines from detonating. Not sure what he really does, I don't think the flight engineer can handle things like ignition timing...maybe he can, but I don't know.

There is at least one time a year, however that 130 octane is brewed again: the Reno Air races  Cool (and I read this in "Flying" magazine a couple of years ago!).



Celebrating the birth of KELPkidJR on August 5, 2009 :-)
User currently offlineBravogolf From United States of America, joined Apr 2005, 539 posts, RR: 1
Reply 9, posted (8 years 6 months 1 week 5 days 3 hours ago) and read 3322 times:

Wouldn't retarding the ignition timing cause overheating?

User currently offlineKELPkid From United States of America, joined Nov 2005, 6371 posts, RR: 3
Reply 10, posted (8 years 6 months 1 week 5 days 3 hours ago) and read 3315 times:

Quoting Bravogolf (Reply 9):
Wouldn't retarding the ignition timing cause overheating?

I'd imagine, but they can also run the mixture rich of peak, which would keep the engines from detonating...the problem with this is that the plugs would foul with carbon.



Celebrating the birth of KELPkidJR on August 5, 2009 :-)
User currently offlineBravogolf From United States of America, joined Apr 2005, 539 posts, RR: 1
Reply 11, posted (8 years 6 months 1 week 5 days 3 hours ago) and read 3309 times:

How many plugs on FIFI?

User currently offlineKELPkid From United States of America, joined Nov 2005, 6371 posts, RR: 3
Reply 12, posted (8 years 6 months 1 week 5 days 2 hours ago) and read 3305 times:

Oops, FiFi's engines aren't 4 row, only two row:

http://itfp.lps.org/fifi2/b29.html

2x18 cylinders=36 plugs per engine, a mere 144 plugs to clean after a flight  Big grin



Celebrating the birth of KELPkidJR on August 5, 2009 :-)
User currently offlineBuzz From United States of America, joined Nov 1999, 697 posts, RR: 21
Reply 13, posted (8 years 6 months 1 week 4 days 18 hours ago) and read 3197 times:

Hi BravoGolf, Buzz here. We've been using 100LL (the blue gas) on DC-3's and Lockheed Harpoons. 48 inches MP for takeoff is still permitted, and we pull the power back a few times during climb.
Regarding FiFi (the B-29) you shouldn't need to clean sparkplugs very often. Ours run clean, we don't run really rich of peak. The F/E pretty much sets the power (MP and RPM) and mixture, per the left seater's request. I don't think anybody has the engines that adjust the timing anymore, the P+W 1830-75 engines were made to advance the timing for better efficiency in cruise. Most of them are secured to 25 degrees BTC.
I'm not looking forward to the demise of 100LL avgas, it's a concentrated, useful fuel... although rather poisonous.
You can get the STC to run many of the smaller aircraft engines on auto gas, but you need to check the fuel for alcohol before use. Alcohol is good for cars, but a lot of the aircraft hoses / seals soften in alcohol.


User currently offline2H4 From United States of America, joined Oct 2004, 8955 posts, RR: 60
Reply 14, posted (8 years 6 months 1 week 4 days 17 hours ago) and read 3195 times:
AIRLINERS.NET CREW
DATABASE EDITOR




Quoting Buzz (Reply 13):
You can get the STC to run many of the smaller aircraft engines on auto gas

I've always wanted to roll up to an FBO and tell them I need mo' gas...


 rotfl 




2H4





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User currently offlineBravogolf From United States of America, joined Apr 2005, 539 posts, RR: 1
Reply 15, posted (8 years 6 months 1 week 4 days 9 hours ago) and read 3163 times:

Being at the south tip of Lake Michigan we get treated to an airshow of sorts just before Oshkosh. You hear the sound of multiple heavy radials and start looking. The best was a few years ago when two B17s came over in formation. A short time later here comes FiFi. Lets hope that these warbirds and the Connies can keep flying. Nothing else sounds so good.

User currently offlineL-188 From United States of America, joined Jul 1999, 29795 posts, RR: 58
Reply 16, posted (8 years 6 months 1 week 2 days 7 hours ago) and read 3082 times:

We filled up DC-6's and DC-3's tanks with the same 100LL that everybody else was burning.

It has been a while since I have looked at the list, but I think the R1830 and the R985 both have the Autogas STC available to them.

Where I used to work, we we cleaning up some old fuel tanks from the 1950's and found one that has some purple gas in it. One of the guys ran it in his pieced together chevy that he had.....that 350 supposedly ran...real good on it.



OBAMA-WORST PRESIDENT EVER....Even SKOORB would be better.
User currently offlineTod From Denmark, joined exactly 10 years ago today! , 1724 posts, RR: 3
Reply 17, posted (8 years 6 months 1 week 2 days 6 hours ago) and read 3067 times:

Quoting L-188 (Reply 16):
Where I used to work, we we cleaning up some old fuel tanks from the 1950's and found one that has some purple gas in it. One of the guys ran it in his pieced together chevy that he had.....that 350 supposedly ran...real good on it.

You can run high octane avgas in a car, but generally speaking it will produce slightly less power. The higher the octane rating the lower the BTU output. Your best performance comes from running a octane level just high enough to prevent preignition and no higher.

Tod


User currently offlineRkmcswain From United States of America, joined Dec 2000, 222 posts, RR: 0
Reply 18, posted (8 years 6 months 1 week 2 days 5 hours ago) and read 3056 times:

Nice explanation Tod.

I don't know much about aircraft piston engine fuel requirements, but 15 years ago I knew a guy with a jet drive boat. He ran a Chevy big block (468 cu.in) with ±13:1 compression. We used to go fill up at a local airstrip. I want to say it was about 108 octane, and even at that time, it was US$3.00/gallon. There would always be some kids there filling up a 5 gallon can for their "street hot rod" -- little did they know some 93 octane (@ US$0.95/gallon) would have probably been good enough.


User currently offlineA342 From Germany, joined Jul 2005, 4681 posts, RR: 3
Reply 19, posted (8 years 6 months 1 week 2 days 5 hours ago) and read 3049 times:

On www.worldaerodata.com some airports are listed which have 145 octane avgas available, and others with 130 and 115. But I´ve also seen one with 73 octane avgas. Which engine could be properly run on this fuel ?


Exceptions confirm the rule.
User currently offlineL-188 From United States of America, joined Jul 1999, 29795 posts, RR: 58
Reply 20, posted (8 years 6 months 1 week 2 days 5 hours ago) and read 3049 times:

Quoting A342 (Reply 19):
But I´ve also seen one with 73 octane avgas

No clue. What airport was it?

I know the german war machine ran mainly on 92 octane.



OBAMA-WORST PRESIDENT EVER....Even SKOORB would be better.
User currently offlineA342 From Germany, joined Jul 2005, 4681 posts, RR: 3
Reply 21, posted (8 years 6 months 1 week 2 days 4 hours ago) and read 3030 times:

Quoting L-188 (Reply 20):
Quoting A342 (Reply 19):
But I´ve also seen one with 73 octane avgas

No clue. What airport was it?

It´s TMS, Sao Tomé. Both extremes are available there, 145 as well as 73 octane avgas. Here´s the link:

http://www.worldaerodata.com/wad.cgi?id=TP57651



Exceptions confirm the rule.
User currently offlinePope From , joined Dec 1969, posts, RR:
Reply 22, posted (8 years 6 months 1 week 2 days 2 hours ago) and read 3018 times:

Quoting Buzz (Reply 13):
Alcohol is good for cars, but a lot of the aircraft hoses / seals soften in alcohol.

Alcohol based fuels also have a big problem in cold temperatures. They tend to accumulate a lot of water and icing becomes an issue.


User currently offlineMrChips From Canada, joined Mar 2005, 927 posts, RR: 0
Reply 23, posted (8 years 6 months 1 week 2 days 1 hour ago) and read 3000 times:

I think the biggest issue with alcohol in aviation fuel is the high vapour pressure of ethanol, in turn causing a huge increase in the potential for carburetor icing or vapour lock (in FI engines).

Even mogas (with a higher vapour pressure than avgas) will increase the likelihood of both of these events.



Time...to un-pimp...ze auto!
User currently offlineVC10 From United Kingdom, joined Nov 2001, 1408 posts, RR: 16
Reply 24, posted (8 years 6 months 1 week 2 days ago) and read 2989 times:

The Wright 3350 engine [ non PRT ] as used on the Constellations up to and including the 749 variant were actually initially rated using 100 octane fuel , not necessarily low lead though, so all they do is slightly alter the ignition timing [set on the engine ] to cater for the low lead of fuel now.

Full RICH mixture is used for all powers until cruise power is set so as to avoid detonation or even the risk of it.

In their day they would have a single stage, two speed supercharger, but as the aircraft these days are not pressurized there is no need for the high speed on the supercharger and so this option is now normally locked out., and the option to advance the spark is also locked out as this was needed in high speed blower.

I have to say the 3350 is notorious for spark plug fouling resulting in two procedures on the ground, one to try and keep the plugs clean and the other to clean a plug in a cylinder that has fouled up. The engine analyzer thus became the crew's friend but also sometimes the F/E nightmare as he had to try and interpret all the squibbles on the screen

still be happy little vc10


25 Buzz : Hi VC-10, Buzz here. I realize that most people won't need high blower on their big radial engines. But there's a problem to putting a bolt in the lin
26 Post contains images MissedApproach : Oh, that reminds me of a question I occasionally ask co-workers, but I've never gotten an answer. I have seen some refuelling trucks labelled MO GAS
27 Post contains images KELPkid : Can modern AD oil even be purchased by the gallon? I worked at an FBO that had some radial engine oil on hand (Aeroshell), and it was sold in 1-gallo
28 DeltaGator : IIRC not only do they run on gas/petrol but it is the old Leaded variety. When I lived in Hunstville, AL (not exactly a hillbilly town but merely an
29 Post contains images VC10 : Buzz, Those old radials often had a mind of their own, but never experienced anything like you, but we did use detergent oil all the time, and not onl
30 L-188 : The only time I have seen Radial engine oil....god I can't remember the weight. It came in a 55 gallon drum and the mechanic had to fill the DC-3 oil
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