Couple of small bugs that need ironing

[mizra108]

Ive been using IXEG 737 and over the last couple of updates to XP11, Ive noticed minor bugs happening that would really like to be taken care whenever the next update to the plane comes out.

1. Oil temperature continuously rises as you climb (FMC N1 thrust set) when reaching the the lo FL300s, they pretty much redline and stay there even throughout the cruise portion. They dont cool off until you are in the descent.

2. N1 thrust rating bug values and positions in the N1 dial dont match the actual N1 value of dial. 

3. IDG oil temp gauges in the ovhd panel are almost always stuck at 0deg in both the In and Rise positions. Sometimes, only the L one comes alive and R remains stuck. 

4. Fuel temperature seems not to be working or fuel not being heated up as fuel temperature starts at say 16C at the beginning of the flight and then decreases steadily throughout cruise and gets to the negative temps.

Anyone else experiencing these small bigs or do I have something wrong?

Edited September 14, 2019 by mizra108
Extra words not needed

[mmerelles]

to my understanding oil temperatures are pretty much default xplane code, thus not very accurate. IXEG is fully aware of this not sure if this is going to be addressed as part of an upcoming update.

 

fuel temperature is expected to be around OAT while on the ground, it will start cool down as you climb and cruize were the aircraft experiences freezing TAT temps. Min fuel operative temp is -45C while typical freezing point you must not reach for JET A1 fuel is -47C

If by any reason you approach that fuel temps, you should descend to warmer ir or increase speed for increasing TAT (kinetic heating)

note: also note fuel temp will not follow TAT temps just plain and simple, since liquid takes time to cool down (while ascending) as to heat up (as descending)

 

 

Edited September 14, 2019 by mmerelles

[Hotdawg]

The N1 thrust bugs are limit bugs. TO, R-TO, CLB, CRZ, G/A and CON. The only time you should see the N1 thrust needle at the bug is when the thrust is set to the limit for the mode your in. Most of the time the thrust will be below the bug limit except during full thrust takeoffs and full thrust climbs.

Edited September 14, 2019 by Hotdawg
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[Hotdawg]

The fuel in the tanks will get colder the longer your at cruise altitude it's really cold up there. The gage reads from the left wing tank and that is theoretically the coldest tank. The only thing that warms the fuel in the left main tank is the A system hydraulic cooler and that is the smaller system less heat than the B system that is cooled in the right main tank. There is an oil to fuel heater that heats fuel but that is in route between the fuel tank and the engine and the heated fuel gets burned by the engine. No help warming the fuel in the tanks.

If the fuel in the the left main gets to cold (below -37C for jet A. The aircraft limit is -45C or 3C below the freeze point of the fuel. The most common fuel in the USA is JetA with a freeze point of -40C) you have two options speedup (more skin friction to help heat the fuel) or descend to a lower altitude (warmer). Generally speaking this is not a problem in the 737-300 because the time at cruse is not long enough to cause the fuel temperature to drop that much. On large wide body aircraft some flight planning software will predict fuel temperature drop at cruse and help you stay out or trouble.

Edited September 14, 2019 by Hotdawg
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[mizra108]

2 hours ago, Hotdawg said:

The N1 thrust bugs are limit bugs. TO, R-TO, CLB, CRZ, G/A and CON. The only time you should see the N1 thrust needle at the bug is when the thrust is set to the limit for the mode your in. Most of the time the thrust will be below the bug limit except during full thrust takeoffs and full thrust climbs.

Thanks for the feedback. I think I was not clear in my explanation so let me try and explain it better this time:

if say, R-TO N1 limit for T/O is 86.4% as calc from the FMC for example, and I want to manually place the bugs at that value, when I dial in 86.4%, it does not coincide with 86.4% in the N1 gauge scale, but rather, it lines up with 98.1% in the scale. 

Another way of seeing this situation is that if I were to set T/O N1 at 86.4% and, say I want to line up the N1 bug dial manually with that thrust setting, the bug value in its window shows 74.7%

 

I would attach an image but for some reason it is giving me an error when uploading.

[Litjan]

Hi mizra,

we are aware of the oil-temp problem, the latest updated to X-Plane (11.40) finally makes this "accessible" to third-party designers, so I hope to adress that in a future update.

The N1 carots (orange triangle markers) are normally driven by the FMC. You can set them manually, but you have to pull out and then turn the little knobs on the instrument gauges themselves. This is just a backup method, though. The autothrottle will not adhere to the manually placed carots.

The IDG oil temperature indication is on our list to fix as well, your observation is correct.

Fuel temperature works as the other guys explained. It will drift towards the TAT (total air temperature) slowly, with the A hydraulic system only providing very limited heating.

Cheers, Jan

 

Edited September 15, 2019 by Litjan