aviation fuel

[Tom P.]

Re: aviation fuel

Tom
Are you going to run big or small block chevies in that old bird? LOL, just kidding, nice project, and I thought restoring a Corvette was expensive and time consuming.
Terry

Terry,
That's a WWII A-26 (built by Douglass) that we're doing a full "frame off" restoration on.
The engines are Pratt & Whitney R2800s/2000hp each (that's 2,800 cubic inches!!), which are being more than totally overhauled (one engine is already done). Virtually everything on each engine is being rebuilt, and all 18 cylinders on each engine is being replaced with brand new (surplus) cylinders (commonly referred to as jugs). So, for all practical purposes we are going to have essentially brand new engines. They will be equivalent to a rebuilt 427 which only retains the original pan, intake, carb and dist.We've been working on it for 12yrs and hope to have it airworthy in 2 more years.

This is our "restored" A-26 in front of our hanger (actually, it's a photoshopped image as correct as we can project).

[John R.]

Re: aviation fuel

Trick question, but I'll take a shot at it: ( Thermodynamics, physics, and pchem were many years ago, so take this with a grain of salt... ) Since in deep space, pressure is essentially zero, (and space itself has no temperature) water will boil immediately at any temperature at which it has enough energy and some vapor pressure. If liquid water were expelled into deep space by a rocket ship, part of it would have enough energy to boil instantly at whatever temperature the water was when ejected. The remainder would have its heat sucked out and cool to near absolute zero, freeze, then sublimate into vapor as more energy was absorbed. Maybe...

Mike

Your overview is actually fairly close. When the shuttle does a water dump, some of it instantly sublimates, which in turn cools the remaining water and it freezes, some of the sublimated water can also de-sublimate and return to solid form (ice). If the ice remains in a shadow it will stay frozen for the most part, however once it is in the sun it will all sublimate over time.

http://spacefellowship.com/2009/09/18/space-shuttle-flushes-the-toilet-for-all-the-world-to-see/

http://www.newton.dep.anl.gov/askasci/gen01/gen01060.htm

http://www.straightdope.com/columns/read/118/would-a-glass-of-water-in-space-freeze-or-boil

This is why comets (which are believed to be mostly ice) can exist in deep space, as they approach the sun their surface starts to sublimate, thus giving the long comet tail everyone associates with them.

We actually had a problem years ago where a water dump went wrong on the Space Shuttle and it froze all over the side of it which could be dangerous if it broke off during the early phases of re-entry.

Sorry, I say we, I work at Johnson Space Center on the Space Shuttle and International Space Station programs... lots of fun working my dream job....

John << gets off his soapbox now

[John D.]

Re: aviation fuel

Thanks all for the education. Much appreciated. JD

[George J.]

Re: aviation fuel

My '65 fuelie runs fine on Sunoco 94 octane pump gas. I have noticed that I need to be more careful this year with the hot starts. If I don't get it right the first time, I may flood the engine and then have to wait a while to start it. I should mention that this fuel has 10% ethanol as well.

George

[Paul Y.]

Re: aviation fuel

On hot starts, my fuely acts like the check valve in the spider is reluctant to open. I had a similar action back in the 80's when fuel was totally different(if it was). I just keep on tapping the accellarator until it acts like it gets fuel and away I go. Not a big inconvenience and I assume that it is because the fuel has boiled away.

[Jim L.]

Re: aviation fuel

I just keep on tapping the accellarator until it acts like it gets fuel and away I go.

Paradoxically, if you will start driving as soon as the engine can be kept running, it will instantly smooth out and run well.

The reason it's running rough is well known: fuel percolation in the spider and copper fuel lines.

The fuel percolates because its vapor pressure is greater than the pressure being applied to it by the FI unit. If you put the engine under load, as happens when you drive, the fuel pressure immediately rises to a level higher than the fuel's vapor pressure and boiling instantly stops.

Jim

[Ian G.]

Re: aviation fuel

Hey guys, does racing fuel have similar longevity (won't go bad) in the tank as aviation fuel?

[Paul Y.]

Re: aviation fuel

Paradoxically, if you will start driving as soon as the engine can be kept running, it will instantly smooth out and run well.

The reason it's running rough is well known: fuel percolation in the spider and copper fuel lines.

The fuel percolates because its vapor pressure is greater than the pressure being applied to it by the FI unit. If you put the engine under load, as happens when you drive, the fuel pressure immediately rises to a level higher than the fuel's vapor pressure and boiling instantly stops.

Jim

That's exactly what I do. Thanks Jim

[Kurt G.]

Re: aviation fuel

One thing I didn't see mentioned in the posts so far, and if I missed it, I apologize. Avgas may have the octane you are looking for, and even the 100LL has lead in it. However, avgas is a more highly refined product, coming off the cracking tower a little higher up in the heat column, and as a result is a much drier fuel, meaning it doesn't have as much residual oil in it. As a result, avgas will burn about 10 to 15 percent hotter than the stuff we get at the local gas pump. The end result is higher internal engine temps, including the pistons, and more wear on the engine components. Back in the 70's I flew for an independent oil company that refined kerosene, diesel, and gasoline, including avgas. The local, resident petrochemical engineer advised me not to put much avgas in my engines, as it would burn them up over time. He suggested a mix of about 2 gallons avgas (at that time you could still get 95/110 octane avgas, the green stuff) to 5 gallons of regular car gas, which was unleaded. Worked great and didn't burn up any parts. If you use the same ratio of 100LL today you'll still have enough lead to lub the top of the older engines the way the old premium gas used to.

[John D.]

Re: aviation fuel

On the 64-65 '7380 unit make sure you hold the pedal to the floor when attempting to start it when warm or hot. Reason for this is you do not want the Skinner valve-starting solenoid to be working. If it is you will have a flooding condition.

On the 63-early64 if you are tapping the accelerator pedal -goosing the pedal when starting the car when it is hot you are not accomplishing much except for goofing things up.
At this point the accelerator pedal is an "air" pedal. The accelerator rod is not connected to anything but the air meter linkage. On a 63 the best way to start it when hot is to hold the pedal to the floor and turn the key to start position and crank it till it starts.
Read your owners manual. It says hold the pedal 2/3 the way down to the floor. JD

[Valeria H.]

Re: aviation fuel

I have a contact to aviation gas (not easy to obtain) and am going to try out the 50 - 50 mix with Shell high octane and see how she runs. If this thread is still running I'll let you know if I see a difference.
Valeria

[Bruce B.]

Re: aviation fuel

Hey guys, does racing fuel have similar longevity (won't go bad) in the tank as aviation fuel?

Ian,
The 100LL is extreamly stable and will not go bad when stored. It will not form varnish or any other cruddy stuff for many years.

[Paul Y.]

Re: aviation fuel

On the 64-65 '7380 unit make sure you hold the pedal to the floor when attempting to start it when warm or hot. Reason for this is you do not want the Skinner valve-starting solenoid to be working. If it is you will have a flooding condition.

On the 63-early64 if you are tapping the accelerator pedal -goosing the pedal when starting the car when it is hot you are not accomplishing much except for goofing things up.
At this point the accelerator pedal is an "air" pedal. The accelerator rod is not connected to anything but the air meter linkage. On a 63 the best way to start it when hot is to hold the pedal to the floor and turn the key to start position and crank it till it starts.
Read your owners manual. It says hold the pedal 2/3 the way down to the floor. JD

John, I only tap on the acc. pedal after it starts to get it to get RPM. I always hold the throttle down until it starts on hot starts. Thanks for the help. I've got 5 thousand miles on it since April 24,09. Paul

[Valeria H.]

Re: aviation fuel

Just obtained some 100LL for my 1960 which I am due to receive back from my mechanic tomorrow. I can not wait to try her on this gasoline. I'm hearing purring noises in the distance.
After a thread of my own on gasoline perferences for the C1 cars and research on my own I learned that even Shell Premium has 5% ethanol content.
I'm sticking with the avgas for the life of my car.
Valeria

[Ian G.]

Re: aviation fuel

That's good news That's definitely what I plan to run to avoid the fuel-percolation problems in my FI everyone complains of. At least till the price of gas gets too high, then I'll prolly try to insulate the spider lines..