A question for all of you,

Every flight i make i try to figure out how the fuel system works. I have tried the official operating manual and the sheet Lou has gives us like shown below.

http://imageshack.us/scaled/landing/819/707fuel.png

Now my problem is that everytime i'm folowing the sheet my engines stops.

Like in the first example:

I have more than  9000KG of fuel in my center tank, so here are the things i do:

• All boost pumps are on
  
• Crossfeed selectors for engine 1 and 4 open
  
• Crossfeed selectors for engine 2 and 3 closed.
  

Now if I do this, engine 2 and 3 are shutting down, the same situation only than for engine 1 and 4 if i leave 2 and 3 on and I close 1 and 4.

What am i doing wrong here?

Also if I give the aircraft her fuel and only filling the main tanks and center tanks, the other tanks gives me the warning lights for the low pressure, I understand this because there is no fuel in it. but can I turn those warning lights off or do I need to fill all the tanks for a good flight.

This information is needed because:

[1] I want to make my flight as realistic as possible
[2] In the fuel planner that I am making there is a special sheet for the fuel distribution.

Now more information about the fuel planner.

Here i a list with the thing i have added.

• Performance sheets in LBS and KG
  
• Fuel sheets in LBS and KG
  
• Flight planning forms for LBS and KG
  
• Fuel Distribution on the Fuel sheet
  
• Takeoff speeds
  
• based on VBA logic
  
• Option to print the fuel sheet with one press on the button
  
• Automatic calculation of the flight time and fuel that is left in the tanks at arrival
  

At this moment it still needs some fine tuning but for 95% of my flights it is calculating my fuel with still 45 minuts of reserve at destination.

Kindly regards,

Rick Winkelman

My flights with the use of the centre tank with 9.000+ a very rare. So far, I don't recall engine problems when using the charted setup you've posted. But I can check it again later and will post the results.
[edit]Works fine, means as charted.[/edit]

Can you confirm that your other tanks are full? The centre tank is the last one to be filled. For a quick look, click here. That's some older rw doc.
http://imageshack.us/a/img5/7440/fueltd.th.jpg
Load the sim plane from the outer to the inner tanks and you should be fine. Drain from the inner to the outer ones then.

I think those always on low pressure lights are a special of that old system setup. If my memory doesn't trick me, Lou mentioned that the FE had some caps to put on certain lights. Same for the 727.

Keep on going on the fuel planner. Your concept looks very nice and will be most welcome I think.  :)

CoolP,

The planner has been changed a lot since your last look.
Way better than first.

But maybe this is something lou can answer, (no offense ;) ) but i seems to me that if you load the plane from the center tank first the aircraft is way better steerable and you have less weight in the wings?

I could be wrong offcourse.

I hope it is good because my fuel planner is loading the fuel from the center tank first ;D

Kindly regards,

Rick Winkelman

No problem with asking for confirmation.  :) On the 707, the document shows how to load the tanks. You'd start filling the centre tank at 38.000+ lbs of fuel. Any amount below that value goes into the wings only.

Maybe it helps to look at the architecture of the plane in full when it comes to the method of keeping the wings 'heavy' as long as possible, draining the centre tank first.
Reasons are the structural load distribution and CG planning plus movement due to fuel burn. The last part is more of a logical task though and modern planes use their fuel not only for running the engines and cooling stuff, but also for trimming the plane.

A rough view, not being plane-specific. The lift generated opposes the the aircraft's weight. Since your wings are the only structural part of the airplane where that counter-acting force is generated, the rest of the plane has to be supported by them. By this, the same plane with the same overall amount of fuel but now in the fuselage (instead of the wings) causes a bigger structural load on the wings itself and the wing root. You even have to look at the fuel density as the important value is the added weight.

The weight in/on the wings therefore causes a bending moment relief. Lift goes up, weight goes down and you therefore want as much weight where lift is generated and less where having a 'dead' structure in lift terms. By that, the engines on the wings and the fuel within them can lead to a lighter wing structure.

The rear mounted engine planes for example feature more heavy and stiff wings but then allow for an aerodynamically cleaner (wing) design and the better usage of high lift devices. But there's more on the case of course.

Either way, you will find the 'load wings first' policy on many planes. If you wanted to run it the other way around ('load centre first'), the structural setup has to be different and most likely heavier in general. The 727 comes to my mind as an exception. She's running the centre tank equally and doesn't drain it first. If AUX tanks (in the fuselage) were installed, those would go first though.

Two example planes at 90t GW.

wing  fuselage  wing
  25t     40t    25t   (weight acting downwards)
    v       v       v

---o---+++---o---

  45t      0t       45t  (lift acting upwards)
    ^                ^

When you alter the fuel distribution while keeping the same GW, it may look like this.

wing  fuselage  wing
  10t     70t    10t   (weight acting downwards)
    v       v       v

---o---+++---o---

  45t      0t       45t  (lift acting upwards)
    ^                ^

Both planes are coming in at 90t but their structural loads differ a lot when it comes to the wing bending moment and the shear being caused.

Wow, it's been a long time since I flew the 707 as F/E.

The object of fuel loading and fuel burn is two fold. CG & structural.

The fuel is loaded into the wings so as to keep the balance and it is burned the same way.
As the outboard tanks are burned the CG would move forward since the wings are swept.
So the fuel burn runaround chart is using the fuel in such a way as to maintain CG while not stressing the structure.

http://img203.imageshack.us/img203/5341/panam214.jpg

As CoolP said, you need to keep fuel in the wings to counter the lifting moment.

I have never had the engines quit on a FSX flight and I really don't bother much with the F/E panel.
I suppose if I really took a long flight I might need to do a little cross feeding.
The kind of flying I have been doing in the 707 has just equal mains.

Lou

Uploaded with ImageShack.us

I use the following procedures and settings with regard to fuel management:

Refueling:

1. Load all 4 main tanks equally.
2. After 1 and 4 main tanks are full, continue to load 2 and 3 main tanks.
3. After all main tanks are full, load reserve tanks.
4. After all wing tanks are full, load the center tank.

Preflight Preparation:

Fuel System                                                TEST & SET
- Fuel Quantity Gauges                      TEST
- Boost Pumps                                       TEST
- Tank No. 2 Aft Boost Pump Switch      ON
- All Crossfeed Selectors                       OPEN
- Reserve Tank Fuel Transfer Selectors      CLOSE
- Fuel Temperature Selector                       CHECK & NO. 1 TANK
- Fuel Heat Switches                                        OFF


Before Engine Start:

Fuel System                                        SET FOR START
* “Tank to Engine” Configuration:
- One Boost Pump Switch in tanks No. 1, 2, 3  & 4      ON
- Center Tank Boost Pumps                                       OFF
- Crossfeed Selector No. 1                                       OPEN
- Crossfeed Selectors No. 2, 3 & 4                       CLOSE

Taxi-out:

Fuel System                                                            SET FOR TAKEOFF
* If Center Tank empty or less than 20,000 lbs :
->(“Tank to Engine” Configuration):
- One Boost Pump Switch in tanks No. 1, 2, 3  & 4      ON
- Center Tank Boost Pumps                                       OFF
- Crossfeed Selectors No. 1                                       OPEN
- Crossfeed Selectors No. 2, 3 & 4                       CLOSE
* If Center Tank exceeds 20,000 lbs
-> “Center Tank to Outboard, Main Tanks to Inboard Engines” Configuration:
- One Boost Pump Switch in tanks 1, 2, 3, 4 & Center      ON
- Crossfeed Selectors No. 2 & 3                                       CLOSE
- Crossfeed Selectors No. 1 & 4                                       OPEN

Cruise:
Check every 20 minutes the following set of conditions and act appropriately:

* If Center Tank exceeds 20,000 lbs and less than 12,000 lbs of total fuel consumed
->”Ctr Tank to Outbd. Eng., Main Tanks to Inbd. Eng.” Configuration:
     - Boost Pump Switches for tanks 1, 2, 3, 4 & Center    ON
     - Crossfeed Selectors No. 2 & 3                                   CLOSE
     - Crossfeed Selectors No. 1 & 4                                   OPEN
* If Center Tank less than 20,000 lbs Or 12,000 lbs of fuel consumed
-> “Ctr. Tank to All Engines” Configuration:
     - Crossfeed Selectors No. 1, 2, 3 & 4                    OPEN
     - Boost Pump Switches for tanks No. 1, 2, 3, 4 & Center      ON
* If Center Tank empty
->(1) ”Balance Main Tanks” Configuration (Inboard Tanks to all Engines)
     - Crossfeed Selectors No. 1, 2, 3 & 4                    OPEN
     - Reserve Tank Transfer Valves No. 1 & 2       AS REQUIRED
     - Boost Pump Switches for tanks No. 1, 4 and Center    OFF
     - Boost Pump Switches for tanks No. 2 & 3                    ON
     - 2nd Boost Pump Switch for Tank No. 2 or 3, whichever has less fuel      OFF for balancing
->(2) When Inboard Tanks Fuel = Outboard Tanks Fuel + Reserve Fuel: “Tank to Engine” Configuration:
     - Boost Pump Switches for tanks No. 1, 2, 3 & 4           ON
     - Center Tank Boost Pumps                                    OFF
     - Crossfeed Selectors No. 1                                    OPEN
     - Crossfeed Selectors No. 2, 3 & 4                   CLOSE


Cruise Descent:

All Main Tank Fuel Boost Pump Switches                                    ON


May you never suffer from fuel starvation. :)

Best regards

AlOl

It would be nice to see all of this in a video. I think everything would be alot clearer. Good info btw