What does fuel weigh?

OK, let me give you what the good chart here at work tells me...

Oil, mineral, automotive engine: .83 - .86/ will depend on additives

Diesel automotive: .82 - .95 depending on level of refinement and additives

Petroleum, unleaded automotive : .74

And that’s why Aeroplanes order fuel to weight and not litres also why they try to get it when it’s cold.

Diesel's close to Jet A. We load it at .768kg/L

Exploder, we order fuel in pounds (set the fuel bugs on the refuel/defuel panel, calibrated in pounds).

The refueller charges us in litres.

The Load Controller enters it on the trim sheet in Kilos.

So we have to do 3-way conversions most of the time. I've never used temperature as a reason for buying fuel however. I use location (price) and weight limitations as my guide. :-) Sydney's generally cheaper than Coffs or Canberra for Jet A.

Exploder posted this followup
snip".. also why they try to get it when it’s cold. "

Would be interested to know how "they"(?) "try" and do this..please elaborate.

Cheers
Greg

Like the Flyboy said above he’s never done it, I just remembered when I studied aviation when I first left school, one of the lecture's made a mention of this, can’t remember much of any of it now but when I read this “735kg / m3 at 15 deg C” below it just jogged the memory a bit.

Like the above post said it’s measured in Weight/ pounds and that’s some how because of America apparently.

I remember doing those fuel and loading cacations for the 727.

Still got the Jefferson Flight computer or Wiz wheel somewhere, also know as the prayer wheel as you prayed to god that you used the thing right LOL. Along with a hole heap of text book’s.
.

..Further to my last post regarding comment on "why they try to get it when it’s cold"...it actually wouldnt matter. If you are purchasing fuel by weight then temparature is irrevalent...only the volume changes i.e. cold or hot you will get the same amount (number of atoms - mass) of fuel if weighed. eg order 3000 kg of fuel and you will get 3000 kg of fuel what ever temperature is. Its only when paying by volume does temperature become an issue as volume will be greater at higher temps for same amount of actual (atomic mass) of fuel.
Cheers
Greg

Bwahahaha! The old 727 (80 ton Dog Whistle). Jeez I pulled some hair out doing One engine inop and depressurised PNR's. Fortunately it grew back.

Nowadays the most complex daily calcs we do is the 3 way conversions I described above.

SG 0.8 is close enough I reckon.

i think 15 deg C is the temp at mean sea level for a 'standard atmosphere'.
so i tried to think but cannot remember them weighing buckets of fuel on a bathroom scale on the tamac when filling a jumbo up.
they must use some sort of conversion chart for temp/litres, which would be quite useful when filling up with 20,000L.
20,000L @ 15 deg C = 20,000L
20,000L @ 25 deg C = ?
last words on the cockpit recorder " i say captain, did you check the ground temp"
"no, i thought you diiiiiiiiiiiiiiiiiiiiiiiiiddddddddddddddddddddddd................"splash.

Now, your average Mars Bar, on the other hand, weighs in at around.......

Sorry Jim, couldn't resist.

Wolfie

Thanks Kev

Fill up your 20 litre plastic jerry can with water and then another with petrol. Carry both at the same time to your bathroom scales by which time you'll have noticed the considerably different weights. Ignoring the plastic you should read 20kg for the water and 14kg for the petrol. PS LPG is about 500grams per litre. Cheers.

I can read an SG chart Jim, I still can't work out bloody electronics though... But I must be doing something right, my car still moves forward and my beer is cold.

Warrie!! bathroom scales are not accurate, every time i get on them, the reading is higher!! What gives? :)

To many mars bars

Michael (Moss Vale NSW)

to bastardise a legal term, they are the "Scales of Injustice".