Pounds per Hour vs Gallon per Hour

beasly

beasly

Well-Known Member
You pros deal in Lbs/hr while we CFI types deal in gph.

Here are a couple of questions....


  1. when did you make the jump from gph to lbs/hr?
  2. is it intuitive? i.e. you need to get from x to y, so I need z lbs
  3. I think I am going to start teaching fuel to my primary students in terms of lbs with gph as a secondary approach. agree? disagree?

Your thoughts?

Cordially,

b.
 
beasly said:
  1. when did you make the jump from gph to lbs/hr?
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  1. When the fuel quantity and fuel flow indicators indicated pounds and not gallons.
    [*]is it intuitive? i.e. you need to get from x to y, so I need z lbs
    Click to expand...
    About as intuitive as flight planning using GPH. "I burn x pph/gph and I'm doing y knots. I need to go z miles so I need a pounds/gallons. Pretty simple math either way. The hard part for me was and still is hopping out and not telling the line guy "give me 1200 pounds per side without please". If I've done that to anyone out there, sorry...I keep second guessing myself when I use the "rule of thumb" method.
    [*]I think I am going to start teaching fuel to my primary students in terms of lbs with gph as a secondary approach.
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    Eh. I might cover the different ways we talk about fuel (gallons, pounds, liters, etc.) but I don't know I'd make it a primary method. Maybe. It would depend on the student and the plane. If the fuel flow indicator says "GPH" on it I won't have them do the mental math in the plane to tell me how many pounds they need to get to ABC airport or VOR. On the way, I may ask them to compute a landing weight but not mentally.
-mini
 
minitour said:
The hard part for me was and still is hopping out and not telling the line guy "give me 1200 pounds per side without please"
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Get a Hawker. When its 12*F outside and snowing a blizzard, you can stand inside the cabin, enjoy the heat and yell out "you start pumping, I'll shut it off with the valves when I got enough."
 
I would teach your student in whichever metric the book and airplane use. I use pounds of fuel in the 402, but the book is all in pounds and the fuel gauge says pounds. If I go fly a 172, I'll set the cruise fuel flow to whichever GPH is calculated from that book.

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. :)
 
When I used to work the line, we had a girl working on her multi. One day she called out and requested we put x lbs in the airplane for their flight. It wasn't a really big deal, but after working there 2.5 years that was the first time I've ever had someone ask for lbs instead of gallons in a piston twin.

Do you really want the lineguy to do the math for you?

(Insert NTSB report here)
 
TFaudree_ERAU said:
Get a Hawker. When its 12*F outside and snowing a blizzard, you can stand inside the cabin, enjoy the heat and yell out "you start pumping, I'll shut it off with the valves when I got enough."
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I used to love the van's with single point. I'd hang out doing my paperwork and say the same thing. "It's set...you just pump, I'll tell you when it's done."

dasleben said:
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. :)
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Drop a zero and add half? Something like that.

1000 pounds
Drop a 0
100
Add half
50
100+50=150 Gallons for 1000 pounds.

1000/6.75=148.14814814814814814814815

Close enough I guess, but I always second guess it.

Over wing sucks.

-mini
 
Single-point that doesn't have an automatic shutoff? Cavemen, all of you. :D

But yeah, see, all that math...ehhh. I just say "Hey, I need 500 pounds," flip my ID over, read where it says "500 pounds - 83 gallons - 42/side." It's easy, but then again, my fuel loads don't change much.
 
dasleben said:
Single-point that doesn't have an automatic shutoff? Cavemen, all of you. :D
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It does, but sometimes it would shut off early...then you'd find yourself on downwind with a fuel level low annunciator on instead of on final. I had to supervise fueling anyway (company policy), so I might as well hit the switches when I had enough go juice to make me happy. :dunno:

But yeah, see, all that math...ehhh. I just say "Hey, I need 500 pounds," flip my ID over, read where it says "500 pounds - 83 gallons - 42/side." It's easy, but then again, my fuel loads don't change much.
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You fancy airline pilots.;)

-mini
 
Uhhh, I'm not sure if you were pullin the numbers out, but 500 lbs isn't 83 gallons! Rule of thumb produces 75 gallons while 6.71 lbs/gal produces 74.5 something gallons. Just tryin to keep ya honest!

I'll say this though, any line guy worth their job will know how to perform the calculations, particularly if they fuel airlines. An airline fuel service record, at least for Delta, requires conversion between gallons and lbs based on the current actual fuel density and the lbs must equal gallons pumped within specific limitations.

Strangest one I've dealt with so far are the Atlas 747's that measure fuel load in Kg!
 
OhioStatePilot said:
Uhhh, I'm not sure if you were pullin the numbers out, but 500 lbs isn't 83 gallons! Rule of thumb produces 75 gallons while 6.71 lbs/gal produces 74.5 something gallons. Just tryin to keep ya honest!

I'll say this though, any line guy worth their job will know how to perform the calculations, particularly if they fuel airlines. An airline fuel service record, at least for Delta, requires conversion between gallons and lbs based on the current actual fuel density and the lbs must equal gallons pumped within specific limitations.

Strangest one I've dealt with so far are the Atlas 747's that measure fuel load in Kg!
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It's 83 gallons if ya fly something that doesn't take Jet-A. ;) I fly a Cessna 402 for a living. 100LL is ~6 pounds per gallon.
 
OhioStatePilot said:
Strangest one I've dealt with so far are the Atlas 747's that measure fuel load in Kg!
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Kg's are cool. Should be part of the mix. Makes physics, engineering, thermo, materials easier. Again--part of the mix--not the standard. I like the chaos we have in the U.S.of A--keeps us on our toes.

b.
 
What's the smallest airplane you can think of where the max landing weight is less than the max takeoff weight?

Just as a guess, I bet the transition from using volume to mass is somewhere around there. (Although the King Air blows that theory and I haven't been able to find what indication the Douglas and Lockheed recip. transports prefer.)
 
Minuteman said:
What's the smallest airplane you can think of where the max landing weight is less than the max takeoff weight?

Just as a guess, I bet the transition from using volume to mass is somewhere around there. (Although the King Air blows that theory and I haven't been able to find what indication the Douglas and Lockheed recip. transports prefer.)
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Probably the smallest thing with a max landing weight, is something along the lines of a Seneca I.

But, back to the GPH versus PPH. Play with it in a G1000 aircraft, if you want a student to see both. It'll change, if you go into the Aux menu's
 
beasly said:
Kg's are cool. Should be part of the mix. Makes physics, engineering, thermo, materials easier. Again--part of the mix--not the standard. I like the chaos we have in the U.S.of A--keeps us on our toes.

b.
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Someone once explained to me how a metric 6 pack was 42 beers imperial...

Bf = Beers Farenheit, Bc = Beers Celsius

Bf = ((9/5)*Bc)+32
Bf = ((9/5)*6)+32
Bf = 10.8+32
Bf = 42.8 beers

It works, I love the metric system! :beer:
 
It sounds like the question is answered so I will get :offtopic:

For you guys that fly with much bigger fuel tanks than I do; can you get a noticeably larger number of lbs in your tanks up north in the middle of winter?

Just curious :dunno:
 
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