Trp Fuel
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Good Day, All, and Happy Thanksgiving to all who celebrate that.
I have a question about something that has happened in 3 recent missions, all carrying 2-330 gal. drop tanks. In the first 2 missions I carried them on stations 5 and 7, which are the centerline and inner right wing, respectively. I have seen and read that IRL the Bug can carry this loadout to improve TGP LOS. Anyway, in both missions I got a TRP FUEL warning. In the third mission I carried them on 3/7 (inner wing stations) and did NOT get the fault.
As the BMS Bug doesn’t have all the fuel controls modeled I couldn’t do all the checklist items. I did cycle the fuel probe , cycled the fuel selector switch,and did some 2G+ jinks, which did not help. Eventually, the warnings stopped on their own.
I like the 5/7 load out as it clears a weapon station for ordinance.And so, I would appreciate help with the following questions-1) Is the something in the f-18C modeling causing this?
2) How do I correct the fault in the BMS Bug cockpit? -
IIRC, there’s a trap fuel bug when you carry tanks asymmetrically. Maybe only occurs on the Hornet?
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Thx A_B, I think you’re right about the bug, considering the different circumstances of the 2 occurrences.So, is there a way to correct it in the pit. Or, should I just ignore it as a bug?
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No work around that I recall …. other than avoiding an asymmetric fuel load in the first place. I also don’t recall if it creates any lasting in-flight issue other than the caution/warning. It may go away on it’s own when the asymmetry ends??
Pretty sure devs know of this as well.
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I don’t know about the f-18 but if you get TRP fuel warning in the F-16 (usually caused by forgetting to close your fuel bay door) you go to your air source knob and switch from normal to dump and then go back to normal to re-equalise the pressure back in the tanks…. Try that in the 18 and see if it makes it go away? Sorry can’t help more…never take that much fuel with me in a Hornet.
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I had something the same, fuel message blinking in HUD. I could get it away by going into burners shortly.Not sure if it is same condition that triggers the fuel message as in your case though.Cheers Obi1
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Just a straight copy paste from the manual….
1.7.3. Fuel pressurisation
Fuel pressurisation is only partially implemented in BMS.
For fuel to transfer from the external tanks they have to be pressurized. This is done with the AIR
SOURCE knob on the AIR COND panel on the right console:
This knob controls the ECS system and thus pressurisation of the cockpit and the fuel tanks. Fuel
tanks are pressurized only in NORM and DUMP position. In NORM both the cockpit and fuel tanks are
pressurized, in DUMP only the fuel tanks are pressurized.
This is implemented and failure to pressurize the fuel tanks with the AIR SOURCE knob may trigger
TRP FUEL conditions.
When air refuelling the fuel goes from the AR receptacle to the wing tanks and to any external tanks if
carried. Normally to allow the fuel to transfer into the external tanks the pressurisation would need to
be decreased.
This would normally be done with the TANK INERTING switch located on the fuel panel in the left
console. Unfortunately that function is not implemented in BMS and as a consequence A-A and hotpit
refuelling does not require tank inerting when external tanks are carried.
That being said some depressurisation is simulated in the current code when opening the AR door.
This prevents fuel from flowing from the external wing tank to the internal wing tank when the AR door
is opened.With regards to the issue being on the Hornet… maybe the pylons havnt’ been coded for the TRP condition issue or the non standard loadout… hope some of the info above helps… if not… then its something thats been overlooked maybe…
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Just a straight copy paste from the manual….
1.7.3. Fuel pressurisation
Fuel pressurisation is only partially implemented in BMS.
For fuel to transfer from the external tanks they have to be pressurized. This is done with the AIR
SOURCE knob on the AIR COND panel on the right console:
This knob controls the ECS system and thus pressurisation of the cockpit and the fuel tanks. Fuel
tanks are pressurized only in NORM and DUMP position. In NORM both the cockpit and fuel tanks are
pressurized, in DUMP only the fuel tanks are pressurized.
This is implemented and failure to pressurize the fuel tanks with the AIR SOURCE knob may trigger
TRP FUEL conditions.
When air refuelling the fuel goes from the AR receptacle to the wing tanks and to any external tanks if
carried. Normally to allow the fuel to transfer into the external tanks the pressurisation would need to
be decreased.
This would normally be done with the TANK INERTING switch located on the fuel panel in the left
console. Unfortunately that function is not implemented in BMS and as a consequence A-A and hotpit
refuelling does not require tank inerting when external tanks are carried.
That being said some depressurisation is simulated in the current code when opening the AR door.
This prevents fuel from flowing from the external wing tank to the internal wing tank when the AR door
is opened.With regards to the issue being on the Hornet… maybe the pylons havnt’ been coded for the TRP condition issue or the non standard loadout… hope some of the info above helps… if not… then its something thats been overlooked maybe…
Thanks, U. Although I didn’t post it earlier, I believe I did cycle the fuel probe, thinking that would depressurize the tanks. Was I wrong in that assumption? I don’t remember if I tried the air source knob or not . I’m tempted to load up and give it a go.
Those are kind of my options, as I don’t believe the inerting switch is modeled in the Hornet -
Thanks, U. Although I didn’t post it earlier, I believe I did cycle the fuel probe, thinking that would depressurize the tanks. Was I wrong in that assumption? I don’t remember if I tried the air source knob or not . I’m tempted to load up and give it a go.
Those are kind of my options, as I don’t believe the inerting switch is modeled in the HornetThe air source knob to dump and back to Normal should fix the TRP warning and if it doesn’t I can only assume its a bug or oversight…. Leaving the fuel boom open would cause a TRP situation. I always run a pretty stock hornet so not ran into the issue. Hope it works for you…
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The air source knob to dump and back to Normal should fix the TRP warning and if it doesn’t I can only assume its a bug or oversight…. Leaving the fuel boom open would cause a TRP situation. I always run a pretty stock hornet so not ran into the issue. Hope it works for you…
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Single wing tank fuel load is pretty ‘stock’ in a RL Hornet … very common configuration. Try it in BMS … bet 4:1 you get a trap fuel warning.
Viper to Hornet ramp start in BMS isn’t quite 1:1, so it could have something to do with start up, although Fuel Source and Air Source are in the start up sequence. Have not ever tried (that I recall) an asymmetric fuel load from a runway or flying start. I think that would indicate whether it’s a ‘switch’ problem or not.
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Just been up testing and the air source knob does not fix the Fuel TRP issue with the asymmetrical (5&7) loadout so nothing you can do I am afraid….
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Thanks, Guys, I can confirm that cycling the probe after getting TRP FUEL is not correcting the issue.
TF seems to happen when the fuel in the drop’s fuel has burned off( Ie: not as soon as takeoff.) Dropping the tanks doesn’t solve it , either. In fact, it seems nothing I do corrects it, nothing bad happen in flight, and eventually it goes away by itself.
I’m tempted to try the Viper with the same configuration, see if it happens, and if the added fuel controls modeled in the Viper help. -
…. TF seems to happen when the fuel in the drop’s fuel has burned off( Ie: not as soon as takeoff.) …
Yes, that was my recollection as well.