This question isn't specific to the B727; however, since the members here (especially Lou and Mark) have been most helpful I figured maybe one of the pilots here could assist me.

What I want to do is learn how to figure my own fuel required for a flight. In the end I will bring this lesson back to my VA and add to the knowledge base there. No one has specifically tackled this question although there are so many resources provided. Those resources figure the fuel for you. That's not what I want, I want to figure the fuel on my the old fashioned way. I tell my kids "Give a man a fish and you feed him for a day. Teach a man to fish and you feed him for life." These last few years of flight simming I have been getting fish. Now I want to feed myself.

Here is what I know but this isn't much.

1. At cruise altitude record the current fuel.
2. After one hour record current fuel.
3. This provides rough fuel use per hour.
4. Divide by 60 for fuel use per minute.
5. Multiply fpm times the time it will take to complete a flight from A to B.
6. Multiply fpm by the time it will take to fly from B to alternate C.
7. Multiply fpm by 45 for reserves
8. Multiply fpm by 30 for taxi
9. Add that all together for the total fuel you will need for a flight from A to B with alternate C.

Granted none of this takes into account weather.

Is there another way to figure fuel per hour without making a flight in the plane for one hour at cruise altitude?

If you were asked to teach this class, how to plan fuel, to a group of none-pilots how would you teach it?

Thank you for any help,
Ed

Ed, as I say I am so mad that I dumped all my old 727 fuel use charts.

FAA fuel for the trip @ M.78 = fuel to destination + 45 minutes reserve VFR (no alternate). If you need an alternate you must add fuel to the most distant alternate @ LRC (long range cruise) if you have more than one.

Let's say you want to go KLGA to KSTL, about a two hour trip. The weather is bad enough to require an alternate. You use KMCI( Kansas City, MO.) as your alternate about one hour. We used to figure 10,000 pounds per hour at the old M.86, but at slower speed of say M.78 lets figure 8,000 pounds per hour. That should cover T/O & climb. All this and we still need to look at the wind (140 pounds per minute for fuel).

Trip fuel = 16,000
Alternate = 8,000
-------------------------
                24,000

But you still need some extra fuel for the descent into KSTL and a missed approach and climb to go to KMCI. Then you need some extra fuel to maneuver around for the approach at KMCI and a little bit of comfort fuel for momma and the kids!  

Try this...

Put 30,000 pounds of fuel on the plane and a good load of people. Climb up to FL 310 or FL330. Set cruise for around M.78. After the plane settles down for a bit and is holding M.78 have a look at the FF. If the numbers come out to around 8,000 pph (2,650FF per engine) your good!
Not sure the CS FF numbers are exact, but give it a try

Nobody that I know would like to land the 727 with less than 8,000 pounds of fuel & if the weather was iffy, I'd use 10,000 as a minimum. Remember, you cannot plan to takeoff if your fuel will make you too heavy to land. In the 727-100 the max landing weight is 135,000. So your takeoff fuel minus the burn should put you under landing weight at destination.

Using the above trip, I would need to look at the EOW (empty operating weight) + payload = ZFW (zero fuel weight) + my minimum fuel at destination (8,000 pounds min - about 45 minutes at low level) should be less than max landing weight. Then you can figure trip fuel to see where the T/O weight comes out.

I'm guessing here...

EOW = 96,500
PL     = 25,000
-------------------
ZFW  = 121,500
MTO  = 152,000
Trip fuel = 24,000
T/O WT = 145.500
Only 6,500 pounds of extra fuel available for max takeoff weight. A bit tight, but doable. Are you feeling lucky?  
Since the burn is high, landing weight is not a problem. You could take extra taxi fuel as long as you do not exceed max takeoff weight.

Hope that helps a bit...

Lou

Wow!

Thanks for that great info (as usual), Lou. Unfortunately, my brain just went numb after reading it all. Must be my age.

I guess the thing to know is the fuel burn per aircraft, then all you need to do is factor in the the rest, like Maximum TakeOff Weight, Maximum fuel at destination and Maximum Landing Weight to give you the numbers for it. I don't think the Math is too hard using that guide that Lou gave us. I'll look into it for some other aircraft to see what I get.

I think the CS767 uses about 7200 pounds per hour (3600 pph x2), when cruising. If you have that, it might help with your planning a bit.

Mark

Markoz wrote on Feb 18^th, 2012 at 6:35am:


Mark,

Excuse me, but are you sure? I think there was a mistake and you're talking about the B-727. Isn't? My B-767 uses about 11,000 pph (5,500 pph x 2), when cruising @ 0.80 MACH at FL300.

Pinatubo.

Pinatubo wrote on Feb 18^th, 2012 at 2:18pm:

Well I did say "I think". I did not check before posting. Besides that, I had not flown the 767 for a while. Also, I'm usually flying the 767 at between M0.78 and M0.79 (CI of 20 for an international flight) and normally well above FL300.

In the attached image, I an flying the 767 @ FL350, CI of 40 (for a domestic flight), and the speed for the flight is M0.789. I'm getting 4,200 pph x2 so I guess my figures were off a bit, so I probably did confuse them with the 757.

Mark

I believe it is normal in all aircraft. This is why the higher you go, the less fuel the aircraft uses (saves money for the Airline company). All airliners have an optimum and maximum altitude at a given weight (seen in the VNAV Cruise page in the FMC on the 757 & 767), so I always try to fly near the optimum altitude. Lou can explain it better than I can, so I will leave it to him. I understand how it works, but I'm not very good at explaining how it works.

Mark

Does anyone know if FSX actually takes into account the planes weight when figuring fuel burn? For example if I burn off 2,000 pounds of fuel will my fuel burn over the next hour be less because the plane weighs less? I have never noticed FSX doing this.

What I'm getting at here is in planning a flight should I plan the extra fuel to carry the weight of the fuel itself? Again using the example of 2,000 pounds of fuel on a one hour flight should I load an extra 60 pounds of fuel to account for the weight of the 2,000 pounds?

EdwardS, if your A\T set to maintain speed, then as you burn fuel, aircraft become lighter, and require less power to maintain speed, so A\T will throttle back a little. A never flew plane with A\T, so i cant tell if it is correct for FSX, but it should do that i think.

Lou, could you be more specific on how engines are controlled in 727s and 707s? Those throttle levers in cabin adjusts what? and how engine know how much fuel it'll need for currrent altitude and set power?
i mean if fly DC-3, then i should manually adjust mixture. who adjust it in jets?

Thank you.