Am I Missing Something Related to Piston Engines?

Game Discussion General Discussion
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1

I’ve found data on Merlin engines and purchased the handbooks for the UK 6.0 Hornet F.I and F.III, but was told that the engines being unable to feed fuel is intentional by the Game Devs due to a small “header fuel tank”. In the manuals, there was a snippet that said that oil pressure was at risk during Negative-G, but nothing about fuel feeding issues.

Background: the 6.0 Hornet F.I, Hornet F.III, and 4.7 Welkin F Mk.I all have a weird “Fuel Starvation” issue that immediately cuts the engines after surpassing -1.0G in WEP, or a few seconds at 100% throttle.

I have re-created the report for the Hornets with additional information containing fuel diagrams and fuel tank behavior in relation to the fuel pumps for the fuel injection system they possess. It is also worth noting that the Hornet F.I fuel system is modelled entirely wrong, almost like the pilot’s notes were not referenced during its creation. I find this incredibly strange for a number of reasons.

Another novel behavior by these aircraft is that (when using the extended info menu) I can see that for the first few seconds in WEP, they use extra fuel. For the Hornet F.III it is 24.62 kg/min and drops to 17.87 kg/min after a few seconds. After the consumption drops is when Negative-G maneuvers are no longer safe to perform. I can not even begin to explain this behavior, as it is only present on the Hornet F.I, F.III, and Welkin F.I. It is NOT related to 150 octane fuel or the Merlin engine series; I cannot reproduce this behavior on ANY other airframe in-game.

There are no other aircraft with the issue in-game to my knowledge and I feel like it is a bug rather than correct airframe behavior. It is NOT the same issue as early Spitfires, as that is carburetor flooding that makes the engine fail. I cannot find a reasonable explanation for this to be modelled in-game they way it is; would there be a technical aspect of engines and fuel feeding I do not know perhaps? Anyone with additional info would be a welcome voice on this issue to help me understand this better!

2

Was this in the engine manual or the airframe manual?

3

Provisional Pilot’s Notes for the Hornet F.I; AP 2864A, Provisional Pilot’s Notes for the Hornet F.III; AP 2864C, Provisional Pilot’s Notes for the Sea Hornet F.XX; AP 4037A, and the Rolls-Royce Two-stage, Two-speed Engine Maintenance Manual, Publication No. T.S.D. 94.

4

But which one did you get the note about the oil pressure from

5

Per the Provisional Pilot’s Notes for the Hornet F.III; AP 2864C; on page 27, Part II, section 45: Aerobatics; “(ii) No attempt must be made to maintain inverted flight as oil pressure very quickly drops to zero.”. The same statement verbatim can also be found in the Provisional Pilot’s Notes for the Sea Hornet F.XX; AP 4037A; page 40, Part II, section 57: Aerobatics.

6

Ok so its sounds more like tips for pilots rather than a comprehensive systems manual. Theres no reason to mention how the fuel system behaves in negative g if the drop in oil pressure would kill the engine first. All the pilot needs to know is “don’t do negative g maneuvers”

7

Yes, it’s the pilot’s notes. Each RAF aircraft has one put together. I think the Merlin 130/131 did not have a proper way to combat oil flow in negative-g, but it was not problematic enough to warrant a full solution other than “dont stay upside-down for too long”.

This still doesn’t explain Gaijin’s reasoning for the engines not feeding fuel despite measures for that being in place.

8

Because its a simple system they applied to all aircraft. The engine would die either way due to the oil pressure but in game it says fuel starvation. For all practical purposes, it acts as it should

9

I don’t think so. The very unusual way the fuel is handled tells me there is a problem. I’m starting to think that the fuel consumption is outpacing the fuel accumulator.

10

This game is not as complex as it seems, especially when it comes to systems like that