Fuel slider in Planner/Editor/Rearm Menu should change TOTAL fuel

[Nealius]

The way DCS handles the fuel slider has some issues regardless of how it's changed or what module is being used.

First issue is in the Mission Planner or Editor, where the fuel slider does not properly reduce the fuel amount. Taking the Hornet as an example:

Full internal fuel = 10,803lbs

Full internal fuel + Three 330gal tanks = 17,536lbs

Set slider 30% fuel, expected fuel load is 5,261lbs (rounded up). Actual result is somehow 9,974lbs (56.8% fuel). 

Second issue is once you step in the jet, and this is not unique to the Hornet. I see it in all modules:

Taking the above 9,974lbs, and knowing that full internal fuel is 10,803lbs, expected result is that internal tanks are at 9,974lbs and external tanks are empty. Actual result is 3,200lbs internal fuel total 9,650lbs fuel according to IFEI.

I assume the missing 324lbs are unusable fuel so that's a non-issue. The issue is the uneven distribution of fuel. 

3,200lbs happens to be 30% of internal fuel. The remaining 6,450lbs in the external tanks is, well, 100% (minus unusable fuel, I assume) of the three external tanks.

In the course of this investigation the two issues above are actually the same singular issue: Why is the fuel slider taking fuel from internal tanks and not external tanks? This serves no purpose at all. The slider should be adjusting total fuel including external tanks. This is mainly an issue for naval aviation assets like the Hornet, Harrier, FlankerD, and Tomcat, where max trap weights are a thing that need to be accounted for. Particularly when doing pattern work. No one wants to be orbiting the carrier for 30 minutes dumping fuel just so they can do some bolter-and-go's. Removing the tanks doesn't give the same handling characterisitics one would find when returning from a mission so I would consider that to have negative practice value. 

[AndyJWest]

As I understand it, a real-world Hornet can only be catapulted with external tanks if they are either entirely full, or completely empty. I'd guess that is the reason they are done that way.

[Exorcet]

Working as intended. The fuel slider is for internal fuel. External tanks, including their fuel, are stores.

[Nealius]

48 minutes ago, AndyJWest said:

As I understand it, a real-world Hornet can only be catapulted with external tanks if they are either entirely full, or completely empty. I'd guess that is the reason they are done that way.

Then why applied to all aircraft? What about airstarts or shore starts where catapult launch is irrelevant?

33 minutes ago, Exorcet said:

Working as intended. The fuel slider is for internal fuel. External tanks, including their fuel, are stores.

And the intention is quite useless. It should be total fuel, not internal fuel that is changed. DCS is the only sim that does this. "Working as intended" is for bug reports, not wishlists, as well. Wishlists are for changes to "intended" functions that are lacking in functionality, or additions of nonexisting functionality. I guess this is technically both. 

Edited October 28, 2021 by Nealius

[Exorcet]

I'm not against adjusting the fuel tanks, but you mentioned the fuel slider not working properly and what your expected result was. That is why I answered as I did. The current system treats external tanks as ordinance, and given that it makes sense as is. When loading the aircraft I'm not sure if external tanks are ever partially filled. The devs didn't originally consider trying to simulate air starts representing a long flight.

[Nealius]

35 minutes ago, Exorcet said:

When loading the aircraft I'm not sure if external tanks are ever partially filled.

I'm guessing in most cases they would be loaded empty for a carrier launch, then topped off at a tanker. It may be applicable for shore based aircraft as well if they're hot and heavy I guess. But currently the only two modules that offer empty tanks (IIRC) are the Harrier and Tomcat....

Edited October 28, 2021 by Nealius