SpiraMirabilis
Possible Subversive
I dunno, I've never topped off the tanks and there is only the pound gauge, no way to tell what the actual level is. (except magna sticks which I've never used.)
Pounds per Hour vs Gallon per Hour
- Thread starter beasly
- Start date
As far as calculating pounds to gallons (for telling the fueler), I keep a handy little chart on the back of my ID badge. Makes it easy.
A rule of thumb I use for Jet-A is to take the number of lbs of fuel you need (say 1000lbs) , lop off the last 2 zeros and multiply by 8. , e.g. 1000lbs = 80 gallons.
That gives you the number of gallons of Jet-A the fueler needs to put in each wing. The aircraft I used that rule of thumb for didn't have single point fueling.
If I did decide to have the fueler fuel only one wing, I had to double the number I came up with above.
Yep. And less in hot parts of the country in the summer.
Nominal 5375 pounds usable in the Lear 40, and I've seen the indicated weight in full tanks vary by more than 100 pounds either way depending upon the temperature of the fuel. (Actually there are other factors that come into play, but the simplified version is that temperature does make a noticable difference).
///AMG
Well-Known Member
Like was said before, when I started flying aircraft that used #'s on the fuel gauge. Basically when I transitioned to turbine/jet aircraft.
It's just another unit of measurement. I think you are probably over thinking it. I will say that you tend to have rounder numbers in #'s so sometimes that makes the mental math a little easier.
Why confuse them? They are most likely reading gallons off the gauge, and all the fuel burn numbers in the books are in gal/hr so I can't see a reason to make them do an extraneous calculation just for the sake of familiarizing them with another unit of measurement.
To me that just has Gimli written all over it.......
Minuteman
Shipoaster
The thermal expansion coefficient for typical Jet-A is 0.00099/K. At -23°C (-10°F), the fuel's density will be around 0.841 g/mL (7.02 lb/gal), and at 38°C (110°F, sitting on a hot ramp), the density would be 0.786 g/mL (6.56 lb/gal). That's a almost a 7% variation between very cold and very hot.
Using SteveC's numbers, the difference between 5275 and 5475 is about 4%, so I'd say that jives.
For excessive information, at colder temperatures Jet-A's lower heating value (LHV) is less, which means you are able to extract less net energy from a mass of fuel than if it were warmer. But it's not much. For the numbers I used, the difference in LHVs between the high and low temperatures is just shy of 0.1% (so you can take on 7% more fuel mass, but it is effectively 6.9% more energy (for Jet-A)).
I'd be curious to find how much the variation in composition affects the basic density of Jet-A. I've seen "normal" numbers in the range of 0.8 to 0.815 g/mL (6.68 to 6.8 lb/gal, almost 2% difference).
ppragman
No pasa nada.
At ACE we used pph, everywhere else I've used gph. Don't really care one way or the other.
The only difficult part is ordering the fuel or (when you're an FO) knowing when to stop pumping. The trick I used was 15%. If I need 1000Lbs of JetA then I need 1000lbs/6.7Gal, or 149.23gal. (not counting changes in density, etc.). 15% of that is 150gal, pretty close I'd say. Even in the cold wx, we never calculated the change in fuel density with the cold there, we always carried beaucoup extra fuel anyway because of the way the weather works around here.
The only difficult part is ordering the fuel or (when you're an FO) knowing when to stop pumping. The trick I used was 15%. If I need 1000Lbs of JetA then I need 1000lbs/6.7Gal, or 149.23gal. (not counting changes in density, etc.). 15% of that is 150gal, pretty close I'd say. Even in the cold wx, we never calculated the change in fuel density with the cold there, we always carried beaucoup extra fuel anyway because of the way the weather works around here.
TFaudree_ERAU
Mashin' dem buttons
Yes. This is evident when you top off the mains in St Thomas in the middle of summer. It usually happens when you go inside and customs holds you up for an hour and a half for pre-clearance because they give priority to the LIAT Dash 8 that just came in from St Maarten. When you return to the airplane, you may find about 50 lbs has excused itself from the tanks and is now enjoying the hot tarmac.
This wouldn't have happened in the winter.
So yes, summer does have an impact on fuel loads.
beasly
Well-Known Member
KSCessnaDriver
Well-Known Member
Only on some of them. In fact, I"ve never seen one with the original main landing gear strut. I've had it up to gross before, and landed after a trip around the pattern, but that was in a newer DA-40.
Cptnchia
Dissatisfied Customer
Umm, aren't you just calculating the difference in TEMPERATURE here? Because, yes 6 degrees C is equal to 42.8 degrees F. What you need to be doing is calculate the difference between LIQUID measurements to get the difference in volume.
triple7
Well-Known Member
On the E145, In the well, used to be rare, but in the occasion that our fuel gauges were mel'ed or the single point refuel panel was mel'ed we would overwing refuel. The line guy inevitably would come up top and ask, how many gallons is your 5700 fuel load gona be? Yeah, you are better off doing the math yourself.
OhioStatePilot
Well-Known Member
It was a joke man!
Baronman
Well-Known Member
I remember having the fuel gauges MELed in the E145 and being down in Mexico City trying to get the fueler a fuel load.
So you know you want 10,000lbs (5,000/wing)
-First dip the tanks to figure out how much are in the tanks.
-Figure out how much you want added to each wing to get it to 5,000lbs.
-The fueler wants Liters....So...I was going pounds --> Gallons--> Liters
So you know you want 10,000lbs (5,000/wing)
-First dip the tanks to figure out how much are in the tanks.
-Figure out how much you want added to each wing to get it to 5,000lbs.
-The fueler wants Liters....So...I was going pounds --> Gallons--> Liters
beasly
Well-Known Member
Well that dashes my hopes! I was seriously considering switching to metric beer.
dang!
:banghead:
beasly
Well-Known Member
You guys are gonna love this.
I did a google for the specific gravity of beer.
http://leebrewery.com/beermath.htm
:beer:
b.
I did a google for the specific gravity of beer.
http://leebrewery.com/beermath.htm
:beer:
b.
OhioStatePilot
Well-Known Member
Great link, b. I'm sending that to the girlfriend!
MikeOH58
Well-Known Member
If you're using PPH and ever cared how many GPH you are burning in a twin, take on engines flow, drop a zero and multiply by 3.
Ex- 450/side. Drop the 0 : 45 x 3 = 135 (total GPH's) x 6.7 = 904.5 Total PPH.
The numbers aren't 100%, but they are close enough the be reliable everytime.
Ex- 450/side. Drop the 0 : 45 x 3 = 135 (total GPH's) x 6.7 = 904.5 Total PPH.
The numbers aren't 100%, but they are close enough the be reliable everytime.