A rather embarassing power off emergency landing on a country road outside of Toledo, Ohio proved to me that I don't fully understand the JetpropX's fuel system.I thought after the fuel was exhausted in each wing (total 140 gallons) that the 11 gallons in the header tank would be used up before the engine died. Sort of a very small reserve tank, if you will.In actuality, the engine died when the fuel in the wing tanks was exhausted and the level in the header tank never changed from 11 gallons.In reading the manuals at www.jetag.ch, I learned that fuel goes from the wing tanks to collector tanks in each wheel well. Then the fuel from the collector tanks is pumped into the header tank, which supplies the fuel to the engine.Wouldn't the engine stay running for a short time from fuel supplied from the header tank? Also, shouldn't the header tank fuel level drop after the wing tanks are exhausted?p.s Sorry about the "heaher" tank in the title. I can't seem to edit the title.

Edited February 18, 201214 yr by Lifeguard911

I could be totally wrong, but from reading the aircraft.cfg and the FSX fuel dialogue, I'd say the only tanks FSX sees are those two.

[fuel]LeftMain = -1, -4, -1, 70, 1		 //Longitudinal (feet), Lateral (feet), Vertical (feet), Usable(gallons), Unusable (gallons)RightMain = -1, 4, -1, 70, 1		 //Longitudinal (feet), Lateral (feet), Vertical (feet), Usable(gallons), Unusable (gallons)fuel_type = 2								 //Fuel type: 1 = Avgas, 2 = JetAnumber_of_tank_selectors = 1					electric_pump=1

Means that the 11 gallons in the header tank are there, but only on the gauge in the VC. The tank itself isn't modelled.If you would like to use those 11 gallons, maybe add 5.5 to every wing tank in the config (shouldn't harm the CG too much), so you can refuel some more. But the weight situation the JetProp already is touchy, same on the rw plane if I'm right. However, if the current weights don't include the fuel weight of the header tank, you'd get even closer to the real thing with that modification.So that's 75.5 instead of those 70.

I wonder if the HT is added as a third fuel tank, would the HT gauge be effected and would it show a change in HT fuel levels? I tend to think the HT gauge is for display only in the PA46T and would not function if another tank was installed. An additional 11 gallons wouldn't get you very far anyway, about 15-20 minutes of flight time.Next time I will know that when my wing tanks go empty, I had better be parked at my destination!

Edited February 19, 201214 yr by Lifeguard911

I tend to think the HT gauge is for display only in the PA46T and would not function if another tank was installed.

I share that thought. Perhaps the gauge code guys could look into it. But the system itself would also have to prioritize certain things. So it's not only about reading a third tank.The rw system isL wing tank > L collector tank (with electrical pump) > header tank < R collector tank (with electrical pump) < R wing tankNow the only tank allowing direct engine feeding is the header tank. Runs on 2 electric pumps. No gravity feed possible. The pump switches in front of the pilot should be the ones for the header tank to feed the engine driven pump. I think the wrong lights come up though.One of them must be on all the time (loud!). They pump the fuel to the engine driven pump and also cause a low pressure in the header tank, which then 'grabs' fuel from the collector tanks in the wings.The pumps sitting in the wings, for the pure collector tank to header tank action are operated automatically or on manual. Their switches are on the overhead. Auto causes them to activate if the sensors detect that the header tank isn't kept full all the time. As said, if this one tank is empty, the powered flight may be over, if I understood it correctly.Regarding the wrong lights statement, it sort if is correct when you enable the header tank pump 1 or 2, which then empties the header tank, which then leads the system to detect that the header tank isn't full and therefore triggers the wing mounted pumps in the collector tanks to activate. However, the wing stuff would enable at some 9.0 gallons if in auto. So not at 11.0. Therefore, the lights come up too soon.

I've edited the sound file of the fuel pumps to be a bit less noisy. I don't think Carenado did wrong there though. The videos 'show' that those pumps are very loud. The tank they are working in is right next to your ears, behind the copilot's seat. However, we sim pilots don't have nice headset to cancel the noise, so I've reduced a few db.The file is at SimObjectsAirplanesCarenado P46T Malibu JetProp DLsound, jetfuelpump.wav.

Playing around with the boost pumps switches, I've noticed that they have no effect on whether or not the engine runs. You can leave them off and it still will run. They have no visible effect on the fuel level displayed for the HT, even after the wing tanks are dry.As to the noise they make, it is not realistic to leave them off to avoid the noise. Lowering the cockpit sound level in sound options to make them quieter, but it lowers all of the cockpit sound levels, not just the pumps. How did you edit the jetfuelpump.wav to make just that wav quieter?

Edited February 19, 201214 yr by Lifeguard911

I've used Audiocity (freeware editor), loaded the wav, set it to general -6db and saved it. Works fine.Right you are, doesn't make a difference in the sim if the pumps are running or not. As we saw, the simplified fuel system rendition may be the cause there. However, with the quieter sounds, I have them on 'lust like in real life' and explain the quieter pump action with the imaginary headset of mine.I wouldn't want to lower the engine sounds, just like you. That's a part of the immersion of that bird and I think the real one isn't a charming low noise cruiser. Though certainly more enjoyable than the piston version.Another edit, maybe to avoid touching the wav. In the sound.cfg, there is[FUEL_PUMP]filename=jetfuelpumpflags=0viewpoint=1Perhaps one can addminimum_volume=0maximum_volume=10000and then tweak the numbers, to let the FSX sound system itself tone down the fuel pump. 10000 should be max, so maybe try 5000 or so. Or even 2500. Trial and error.

Edited February 19, 201214 yr by CoolP

Thanks for cfg tips. I will give them a try tomorrow and let you know how it went.

CooIP,I played with various sound settings in the sound.cfg Like you suggested. The settings below work pretty well. The pump is not overly loud now that you hear it while the engine is running, but is easily heard with the engine shut off. Thanks again for the tip.minimum_volume=3000maximum_volume=9000Bill

I have to thank you. Nice tweak values and testing. :(

I have tried it too.... Much better.....Thanks alot.

What? I can't hear hear you. I ran the original value for too long.

On a side note about the header tank... anyone try the "emergency fuel" switch on the overhead to see if the header tank draws down then? I haven't tried it yet, and was curious.

anyone try the "emergency fuel" switch on the overhead to see if the header tank draws down then?

The emergency pump is located between the wing tanks and the header one, to allow filling it when the normal collector tank pumps fail. So that's the redundant element on the way from the wings to the header tank.The header tank receives redundancy through the two electrical pumps and, maybe, from the 'last resort', the suction from the engine driven pump. If those things fail, the engine goes offline, even with plenty of fuel in the tanks.But the main problem on the header tank topic is that FSX doesn't know about any third tank. It only sees the wing tanks and there's no Carenado module running to allow any cheating on that.Now we could add some third tank, but we would also have to tweak the gauges to read the contents and to allow the rather complicated way of the fuel, from the wings, to the collector, to the header, to the engine.Despite the altered CG due to the third tank placement, this isn't easy work to do in my eyes. :( However, if one would add that detail, I would call myself a fan of his. :(

Interesting. At any rate.. The RW plane using a "header" tank seems like an unnecessary complication.