Food, or Should I Say "Fuel" for Thought

[Guest Heather 636]

As some of you know, I have been working on a Grumman Duck project, a WWII era aircraft.As far as I know, so far, this aircraft had a 200 U.S. Gallon fuel tank.Now, that's where things get interesting (as well as for sim flying other WWII era aircraft).I had just finished reading a note in the Stearman Kadet cfg file that the leaded gasoline used during WWII was 7% denser than the U.S. aviation fuel used today.That would mean that if you are going to fly WWII birds today, for example, my Duck, it should hold only 186 gallons of fuel?? I disagree.My reasoning for disagreement is because many years ago, I got involved in scuba diving for a very short period. I still distinctly recall being taught during those lessons that a liquid, versus air, CANNOT be compressed (i.e.; one gallon of gasoline would occupy the same volume of space that water would, despite the weight difference.Based upon this, I can see 200 gallons of WWII gasoline weighing 14 lbs. more, but occupying no more, or less, space than modern day gas.Am I right or wrong on this?Regards,Heather

[Guest Lizardo]

Denser: weighs slightly more; same volume. We rule-of-thumb at 7lbs/gallon. (hint: weighs more because more lead). "Back when" it was 145 octane and purple, by the way can tell octanes by the color of them..80 octane mo-gas is red; then they went to 115/145. (max/min have to adjust flight according to what you got).

[Tom Allensworth 1,532]

As Lizardo points out, density does not equate to volume. You would still have 200 gallons of fuel, but your weight would definitely go up.

[Guest DNelson]

Heather,Sounds right to me. Volume (gallons) and density (pounds per gallon) are more or less independent of each other for incompressible liquids. You could put 200 gallons of most any liquid in the tank and it would still be 200 gallons. The density of the liquid determins how much total weight there is.200 gal avgas ==> 1200 lb200 gal Jet A ==> 1340 lb200 gal water ==> 1660 lb200 gal liquid mercury ==> 22,500 lbDan(chemical engineer in a former life)

[Guest Heather 636]

Thank you for your input.I was sure hoping that I wasn't going to have to learn my basic science all over again.Here is where I saw this:[fuel];43 US gallons of modern unleaded AVGAS is about 258lbs;the leaded fuel used during WW2 was 7% denser;to load WW2 fuel change 43 below to 46LeftMain=0.000000,0.000000,0.000000,43.000000,0.000000fuel_type=1.000000number_of_tank_selectors=1Now, another thought occured to me as to why the author, who is no idiot, may have done this.I don't know how FS2002 does the math with quantity of fuel, lbs or volume.The above fuel load may have nothing to do with how many gallons are really carried but acts as an integer for the weight?Therefore, I would be right in my disagreeing that a denser liquid would occupy more space, but in the interests of how FS2002 handles it's math, his figuring could very well be correct. I don't know. You tell me?Regards,Heather