[AS INTENDED] Fuel System irregularities

Hi,

From an AA intercept payload, I decided to ask the ground crew for an extra fuel tank. Then I left the parking without waiting for the ground crew to finish (I know it's bad).

This resulted in a configuration where I had extra fuel (4000+ kg on the right gauge), but no RP on the PCA, and a warning when FBW is on Charge (and no warning on AA). I could not check if the tank was present on external view as the server did not allow it.

Is it a bug or a feature? It's a potential bug & cheat if the resulting flight dynamics do not account for the tank, but you have the fuel. I could not do enough tests to assess it.

The fuel in excess of the internal load is not sensed in any way. There's just a knob the human turns to a known value which the airplane trusts is correct (and really DCS should let you turn that knob to your heart's content). Just because the totalizer says there is X fuel doesn't mean there is X fuel present.

Physically if you turned the knob to indicate so much fuel the airplane would believe you and indicate as such. If the charges mode would warn you that depends on the logic of that system, does it depend on fuel totalizer or PCA fuel tank presence or some intricate mixture of both.

You should recreate that situation and try to burn it. If the fuel is actually present in the sim then the internal amount should remain full despite consumption until the totalizer is reduced equal to internal. If the fuel is not present then you'd find the internal fuel number decreasing immediately. The best situation for a real simulation is that this is a bug where the fuel gauge is set in error but physically there is no phantom fuel.

Also it would be good to know if the RP tank was present or not. There are really three things going on: PCA data updated for stores presence, fuel totalizer cranked for expected total fuel, actual tank strapped to airplane.

Galinette, if you can confirm this still present in the latest update from 23/09/2020. If so, please attach a new .trk file i would need you to follow the same steps to be able to see if this is a bug we can fix or if its an ED fix thanks.

Here is the trk!

How to reproduce : ensure wheel chocks are removed. Ask ground crew to add an external fuel tank. As soon as the fuel gauge is updated (about 4000kgs), start taxiing. The ground crew complains you are stupid. The fuel tank is there but no RP on PCA.

It may be not a bug and that's fine, if only the PCA is not updated for the tank. And anyway not a big issue as other bugs.

rp-bug.trk

Whenever the Mirage refuels with the tanker with only internal tank, the tanker will not notify when finishes refueling. You could continue to have the probe connected to the basket.

This was confirmed by another user:

https://forums.eagle.ru/showthread.php?p=4508013&posted=1#post4508013

Works fine when no dropped tanks.

Just tested it on latest OB:

- Air Start, slick configuration, i get the notification

- Air Start, 1xRPL 522 or 2xRPL541 configuration, jettison tanks, i don't get the notification

i can provide tracks if some other guys can confirm the same behaviour.

AAR notank.trk

AAR cenraltankjettison.trk

Works fine when no dropped tanks.

Just tested it on latest OB:

- Air Start, slick configuration, i get the notification

- Air Start, 1xRPL 522 or 2xRPL541 configuration, jettison tanks, i don't get the notification

 

i can provide tracks if some other guys can confirm the same behaviour.

After doing a few AARs today, I can confirm point #1 and #2.

After doing a few AARs today, I can confirm point #1 and #2.

Thx, i've add tracks to my previous post

Might be an issue with |DCS not recognizing something. Has this occurred in any other A/C? Regardless I will add this to the internal tracker.

Ok so I've merged the Fuel amount bug on the ground and the refueling bug after dropped tanks bugs together as it appears that they are inter connected. So to preface, how the fuel amount works right now is automatic. In the real jet, on the fuel panel, the left fuel display shows internal fuel, the right display shows internal PLUS external. The aircraft does not know the quantity but only knows when the external tanks are empty, it predicts the amount of fuel left by using the fuel flow to the engine. ( similar to the MiG-21 where the fuel usage is predicted and not actual.

Normally, in the real jet, you would have to manually set the added external fuel load to the jet onto the fuel display. For ease of use we have implemented an automatic feature which takes that out of the equation for the end user. HOWEVER, for instance if you move on rearming, the rearming window has told the mirage that it will take X amount of external fuel before the tanks have been loaded ( as per the automatic feature). When it comes to refueling ( ideally you would never ever dump your fuel tanks IRL but this is a DCS ism habit players should break.) the Tanker sees what the maximum fuel load should be according to the automatic feature and attempts to give you that amount of fuel even if you have jettisoned your tanks. 

So there's a two for one and why those issues are occurring. There is not an easy fix for this as the entire fuel logic would have to be re-written and at that point it would most likely not be worth the dev cost to do so. If we were to do it, we could potentially change it to a manual system in which case if you were to re-fuel with tanks, you would have to manually calculate the amount of fuel you are adding and input it manually.

For the time being, I will mark this AS INTENDED as any future implementation of the manual setting would be subject to whether the input outweighs the output. Perhaps when and if we do another M2K model we will take this into account and carry it over to the 2K C.