Engine Flameout during Rolls/Banks beyond 90 degrees

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  • #1328
    Stormilm
    Participant

      Hi Thomas,

      I am experiencing an issue with the engine flaming out during Roll’s and steep Banking (beyond 90 degrees). I’ve run through the manual to see if I’m missing something but thus far, I cannot. Can you shed any light on this?

      #1329
      Thomas
      Keymaster

        Hi Stormilm, good to see some activity in the forum again. ;)

        Flameout may occur if you fly inverted. I quote the Flight Manual:

        Flying inverted or with negative G:s is restricted to max 15 seconds to prevent fuel flow problems. The buffer fuel tanks aid in keeping the fuel flow uninterrupted, but after prolonged inverted flight you may experience flameout.

        The model regards bank angles exceeding 100 degrees as inverted flight, so this may be the cause of your problems. You should be able to fly inverted for a while before the buffer tanks are dry though. If you flameout immediately, maybe the buffers are already empty. Check the fuel levels in FSX, the buffers are Center 3.

        Cheers /Tom

        #1336
        Stormilm
        Participant

          Hi again Thomas. I can confirm from more testing that the issue I was experiencing is due to fuel depletion in the buffer tank. The flow rate and depletion seems specifically tied to the use of the afterburner and IMO, it seems a bit excessive compared to the other two internal tank flow/consumption rates. With even moderate afterburner use, the buffer tank goes dry very quickly (obviously due to it’s small capacity) which leaves still relatively high levels of fuel in the other two internal tanks to use (but rolls or inverted flight are no longer possible to remainder of the flight). I’m not sure how the Draken’s fuel system works but based on other fuel systems I’m familiar with, it seems logical that the buffer tank would be fed by whichever tanks are selected in order to maintain proper pressure & constant levels to prevent flame outs. Again, I do not know how the J35’s fuel system & tanks, just an observation. For the purpose of alleviating this particular issue, is there any way to easily make the other tanks feed to buffer tank to keep it at or near full throughout the fuel burn?

          #1337
          Thomas
          Keymaster

            The buffer tanks should of course be replenished when you level out and fuel flows normally again. I somehow forgot that part when I wrote the function… Takes some programming to solve, but I will fix it and upload a patch with an upgraded fuel system as soon as possible.

            Thanks for your input!

            /Tom

            #1341
            Stormilm
            Participant

              Thanks Tom, I will check in from time to time for the patch.

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