[2.9.17.11733] 68-494 or 68-495 fuel system?

[Stickler]

This is at the same time a question and a bug report.

According to RL Dash-1, the F-4E had the following fuel capacities:

null

Given that the following is the fuel quantity indicator of a fully fuelled jet in-game, it appears as if 68-495 and up is intended to be modelled.

Then again, the most visible feature of 68-495 was the introduction of a tank depressurization switch which is not modelled:

Thus:

1. Which fuel system is intended to be modelled?
2. Could the tank depressurization switch be added or the fuel system be retrograded to 68-494 for consistency?
3. Which fuel levels nominally show on Heatblur's fuel tape and fuel counter when cells 5, 6 and the wings are empty? 5348/5966 or 4862/5408? For the rounded Dash-1 figures see below.

[Zabuzard]

The manual is just a manual.

The real world fuel numbers are slightly different. An empty tank also isnt fully empty, it still has some fuel in it, the valves dont sit at the very very bottom of the tank.

Further, the actual amount that fits into ur tank depends on the pressurization as well. Note that the indication is in lb (weight) and not something like gallons or liters. So this depends on density and so on (which is fully modelled).

Also worth noting that this stuff is subject to aircraft condition (slider in the ME) as well.

[Stickler]

Thanks for your explanation.

Could you please provide answers to my three questions above though?

With regard to the actual amount of fuel that fits into the tanks depending on density, based on a quick test, the indication shows 12150 lbs in a fully fuelled reference aircraft at sea level both in low density conditions (OAT 50°C, QNH 28.35) and high density conditions (OAT -12.4°C, QNH 31.10 inHg).

This seems to contradict your statement and also the manual:

Edited June 30 by Stickler

[Zabuzard]

It is probably easier for you to wait with this analysis for the next update when the EFB fuel page is available. It shows individual fuel tank state: https://f4.manuals.heatblur.se/dcs/efb.html#fuel-page

And that number is then also the actual amount, factoring out inaccuracies with the sensors and the gauge.

Edited June 30 by Zabuzard

[Stickler]

First of all, I really appreciate the new EFB feature. Good job!

With regard to the original questions:

1. The fuel quantities in the cells as per the EFB strongly point to a 68-495 fuel system, albeit without the tank depressurization switch.
2. Open. Very low priority in my opinion.
3. I was not able to attain the aircraft state depicted in the manual showing the wings as well as cells 5 and 6 empty but the remaining cells essentially full. I do not have access to sufficient RL material to determine whether this indicates a problem with the manual or the fuel system modelling.

With regard to the additional question brought up, I could find no evidence that the fuel state as per the EFB or the fuel state indicated on the fuel totalizer is influenced by external temperature or air pressure in the game.