correct as is Fuel warining bug

[Geraki]

Version 2.7 

Steps 

1. takeoff (with 2x370 gal tanks) optional 

2. list-2 -> fuel Bingo set , when change e.g into 7200 i get fuel warning indication in HUD.

[=Panther=]

Correct as implemented in DCS. Only the value of the fuselage is considered and the wings are not part of the fuselage. So a value of BINGO at 7200 is setting off the warning because the internal fuselage is only 6000 +/-. 

[Dee-Jay]

Hi!

 

With the FUEL QTY SEL switch in NORM, the bingo computation is based on the lesser of fuselage fuel weight or total fuel weight. That is, with the FUEL QTY SEL switch in NORM, bingo fuel warning will be triggered when either fuselage fuel or total fuel decreases below the bingo fuel value.

 

Additionally, I've seen nowhere in -1 that EXT WING and/or EXT CTR fuel QTY are not sensed (But it doesn't means that it is necessarily  the case. It could also be the totalizer minus FF  x time like on M2000 or Jaguar IIRC. However, in that case, pilot and/or ground crew should be able to manually initialize the totalizer taking in account the EXT tank fuel level ... and nothing can be found about it neither).

 

Regards.

[Dee-Jay]

Not "correct as is"

 

Geraki is right: "BINGO WARNING" is wrong.

 

Here is the Track file : https://www.dropbox.com/s/s182x93e821njq4/F-16 BINGO.rar?dl=0

[Dee-Jay]

On 4/30/2021 at 12:05 PM, =Panther= said:

Only the value of the fuselage is considered and the wings are not part of the fuselage ... // ... the internal fuselage is only 6000 +/-. 

 

Incorrect. Wings are part of the internal QTY. (Total Internal = FWD & AFT Fuselage + Rsrv + Left & Right Wings)

 

- Total max internal is about : 6800lbs +/-300lbs (Internal Fuselage + Rsvr + Internal Wings considering JP-4)

- Total max external is about : 6400lbs +/-300lbs (Ext Center-line + 370Gal Ext Wing Tanks considering JP-4)

- Total max external is about : 9300lbs +/-300lbs (Ext Center-line + 600Gal Ext Wing Tanks considering JP-4)

[SpaceMonkey037]

9 hours ago, Dee-Jay said:

 

Incorrect. Wings are part of the internal QTY. (Total Internal = FWD & AFT Fuselage + Rsrv + Left & Right Wings)

 

- Total max internal is about : 6800lbs +/-300lbs (Internal Fuselage + Rsvr + Internal Wings considering JP-4)

- Total max external is about : 6400lbs +/-300lbs (Ext Center-line + 370Gal Ext Wing Tanks considering JP-4)

- Total max external is about : 9300lbs +/-300lbs (Ext Center-line + 600Gal Ext Wing Tanks considering JP-4)

In our F-16 we have JP-8 fuel, so total iternal is about 7160. However, I am very positive that you are correct in saying that wings are part of the equation.

[=Panther=]

14 hours ago, Dee-Jay said:

 

Incorrect. Wings are part of the internal QTY. (Total Internal = FWD & AFT Fuselage + Rsrv + Left & Right Wings)

 

- Total max internal is about : 6800lbs +/-300lbs (Internal Fuselage + Rsvr + Internal Wings considering JP-4)

- Total max external is about : 6400lbs +/-300lbs (Ext Center-line + 370Gal Ext Wing Tanks considering JP-4)

- Total max external is about : 9300lbs +/-300lbs (Ext Center-line + 600Gal Ext Wing Tanks considering JP-4)

Wrong interpretation of the diagram. What you write  is for total internal fuel but not to be confused with fuselage fuel.  
 

The bingo value takes the lesser of fuselage fuel value or total fuel weight. Under normal operating conditions the fuselage will always be the lesser value over total fuel. We do not have fuel system malfunctions that I have seen in DCS yet.

 

A viper fuselage: 6060

Slick Viper total fuel weight: 7160

A viper configured with centerline, fuselage still the same: 6060

Total fuel with centerline: 9050

 

A viper configured with 2 externals, again fuselage still the same: 6060

Total fuel with the bags: 12000

 

Viper with 3 bags, fuselage: 6060

Total fuel: 13890

 

The F-16 fuselage fuel storage consist of the following:

 

F-1 Fuselage

F-2 Fuselage

FWD Reservoir

 

A-1 Fuselage

AFT Fuselage

 

The internal wings are not part of the Fuselage fuel. 
 

In order for Bingo to compute, the FUEL QTY Select switch must be in NORM. Then only the above fuselage storage breakdown is read while in NORM. With the FUEL QTY Select out of NORM, an artificial fuselage value of 6667 is used. 

 

If the problem is one wants to know when their external tanks are empty, what do we get in DCS with the FUEL QTY Select out of NORM? Does the bingo go off at 6667 or does it wait for a value imputed by the user? 
 

PS written from knowledge, trying to avoid any verbatim data from -1, 28GS-00-1 to avoid any forum rules violation. Source: system matter expert of the Fuel System on the F-16. Additionally wrote on mobile and formatting is terrible, plus text changed color on me. 

Edited May 3, 2021 by =Panther=

[SpaceMonkey037]

2 hours ago, =Panther= said:

In order for Bingo to compute, the FUEL QTY Select switch must be in NORM. Then only the above fuselage storage breakdown is read while in NORM. With the FUEL QTY Select out of NORM, an artificial Bingo value of 6667 is used. 

 

If the problem is one wants to know when their external tanks are empty, what do we get in DCS with the FUEL QTY Select out of NORM? Does the bingo go off at 6667 or does it wait for a value imputed by the user? 

I am a bit confused about why the artifical bingo is set to 6667 when out of norm. If I have manually inputted bingo of 3000, and a total fuel of 5000. When switching FUEL QtY select out of norm, will the bingo go off because total fuel is less than 6667? (I am referring to the real aircraft, not how it currenlty works in dcs.)

[=Panther=]

1 hour ago, SpaceMonkey037 said:

I am a bit confused about why the artifical bingo is set to 6667 when out of norm. If I have manually inputted bingo of 3000, and a total fuel of 5000. When switching FUEL QtY select out of norm, will the bingo go off because total fuel is less than 6667? (I am referring to the real aircraft, not how it currenlty works in dcs.)

Sorry for confusion, you confused me a little and then I realized my mistake was I wrote bingo value instead of fuselage value of 6667 (corrected). So with Fuel QTY Select out of NORM, the fuselage value is artificially set at 6667. 

[SpaceMonkey037]

1 hour ago, =Panther= said:

Sorry for confusion, you confused me a little and then I realized my mistake was I wrote bingo value instead of fuselage value of 6667 (corrected). So with Fuel QTY Select out of NORM, the fuselage value is artificially set at 6667. 

So, for all purposes this is really just a way to disable fuselage fuel when out of NORM so that you don't get a bingo warning whenever you go out of NORM. Got it thanks.

[Dee-Jay]

@=Panther=

 

Yep you're right, for some reasons, I've confused the "fuselage" and "internal" in your post (despite the fact that I've quoted it!) while I wasn't confused in my reply. Sorry about that.

So we are on the same line. However ...

 

With the FUEL QTY SEL switch in NORM, the bingo computation is based on the lesser of fuselage fuel weight or total fuel weight. That is, with the FUEL QTY SEL switch in NORM, bingo fuel warning will be triggered when either fuselage fuel or total fuel decreases below the bingo fuel value.

 

For you, what is "total fuel "?

 Is it Internal (Fuselage + Rsvr + Wing) or is it Internal (Fuselage + Rsvr + Wing) + Externals ... ?

 

In other words ...

 

Does the bingo warning triggering with a value set above 6000lbs?

 

I.e. Considering the following initial configuration:

 

Quote

 

Viper with 3 bags, fuselage: 6060

Total fuel: 13890

 

 

- Knob on NORM position.

- Actual total fuel remaining = 8000lbs.

- BINGO set at 9000lbs.

 

... Is the alarm triggers in that situation?

 

 

 

[SpaceMonkey037]

15 hours ago, Dee-Jay said:

 

With the FUEL QTY SEL switch in NORM, the bingo computation is based on the lesser of fuselage fuel weight or total fuel weight. That is, with the FUEL QTY SEL switch in NORM, bingo fuel warning will be triggered when either fuselage fuel or total fuel decreases below the bingo fuel value.

 

For you, what is "total fuel "?

 Is it Internal (Fuselage + Rsvr + Wing) or is it Internal (Fuselage + Rsvr + Wing) + Externals ... ?

 

In other words ...

 

Does the bingo warning triggering with a value set above 6000lbs?

 

I.e. Considering the following initial configuration:

 

 

- Knob on NORM position.

- Actual total fuel remaining = 8000lbs.

- BINGO set at 9000lbs.

 

... Is the alarm triggers in that situation?

 

 

 

I don't think you can set bingos that high. Don't know the exact limit but if you put a bingo over 6000 it will trigger in FUEL QTY select switch NORM because it uses fuselage fuel or total fuel, whichever is the lowst. This means that once fuselage fuel decreases below your bingo it will trigger, or when total fuel decreases below the bingo, whichever happens first. However, if you go out of NORM the bingo will not trigger untill total fuel has decreased below the set number, or if the bingo number is over 6667 (which i don't think is possible). Total fuel in this case is ALL fuel, every fuel tank combined. I know this is the case because if you have trapped fuel (external tanks) with the FUEL QTY select switch out of NORM you will, depening on bingo number, get a delayed bingo warning or no warning at all. 

[=Panther=]

It will always use the lesser between the fuselage and total fuel. So the 9000 value would alert because 6060 is in fuselage and below bingo value. 

 

Additional info with the Fuel QTY Select Switch and it’s importance to the system. 
 

The switch in NORM has a guarded feature that protects against trapped fuel. You could in theory have 7940lbs of total fuel. You set a 2000 Bingo value before flight. Mid flight you receive a BINGO BINGO. 

 

On the top layer it looks like you have plenty of fuel, but since the jet uses the lesser of two values you would get a bingo alert because only 2000 is in the fuselage, the remaining 5940 is trapped. If it had waited until total fuel was 2000 to send BINGO, you would have flamed out at 5940 total fuel remaining. 
 

Second layer of protection is the jet also sends a Fuel warning if weight is off wheels, the fuel quantity select switch is out of Norm greater than 5 minutes or 500lbs, whichever occurs first.
 

The reason the Fuel QTY Switch is to remain in NORM for flight is the Automatic Forward Transfer only functions when in NORM. This system is designed to automatically maintain CG by automatically transferring fuel from AFT to FWD. Fuel can only be moved from AFT to FWD, it can not correct a FWD imbalance. 

Edited May 4, 2021 by =Panther=

[SpaceMonkey037]

1 hour ago, =Panther= said:

The reason the Fuel QTY Switch is to remain in NORM for flight is the Automatic Forward Transfer only functions when in NORM. This system is designed to automatically maintain CG by automatically transferring fuel from AFT to FWD. Fuel can only be moved from AFT to FWD, it can not correct a FWD imbalance. 

 

I've been trying to figure this out but I've not been sucessful yet, from where does the automatic forward transfer take fuel from? Is it from the reservoirs or is it from the fuel flow proportioner? And if you know, what type of pipe is it? is it a fuel transfer pipe or a boost pump pressure pipe etc.?

EDIT: Upon some further reaserach, could it be that the cross feed valve opens and the electric pumps in the FWD fuel system are de-energized, so that the fuel flows through a pump drive pressure pipe into the FWD fuel tanks?

RE-EDIT: Upon even more reasearch, it looks like the automatic forward transfer system has a transfer bleed pipe going from the boost pump pressure pipe aft of the FFP and through a solenoid valve, and reconnects with the fuel system at the cross feed valve. I don't understand how this would help at all, it clearly shows that it connects directly to the crossfeed valve, and not on the FWD fuel system side of the valve. Is this a badly made picture or is there something more to the system that I'm missing?

Edited May 4, 2021 by SpaceMonkey037

[=Panther=]

It is a sense line, it takes from the aft fuselage and sends it to the fwd fuselage via a trim distribution valve. 
 

I don’t know what image you’re looking at but it isn’t linked to crossfeed nor boost pumps at all. 

[Dee-Jay]

So we are all on the same line.

And I do confirm that in some conditions, the Bingo warning does not occurs while you have less fuel than the selected Bingo value.

 

But it could be a matter of Warn Reset. To be confirmed, it may only happens if/when Warn Reset has been activated once and Bingo value has not been also reset to a lower value than the actual one. It seem to be "sucked" on a non detection state. (Sorry, hard to explain).

 

Will try to find a solid repro case if/when time permit.

Edited May 5, 2021 by Dee-Jay

[Dee-Jay]

Repro case (actually, VERY easy):

 

- Caucasus

- Instant Action

- TakeOff

- FOB 12000lbs Set BINGO 11000lbs

- Takeoff, keep AB on.

- When actual total remaining fuel goes below BINGO => no WARN

(note that during my test, BINGO became effective below 5000-4500lbs ... )

 

Track : https://www.dropbox.com/s/6kk0ghif9qfkl0p/F-16 BINGO.rar?dl=0

 

Video :