Engine core ice shedding procedure (when in freezing fog)

[Hardy Heinlin]

Good evening,

if you like to know how much ice is accumulated in the simulation, or how much ice is shedded, here's a little demo.

Load an on-ground situation and create freezing fog by setting the surface temperature to 0°C or less, and the visibility to 300 meters or less:




On Instructor > Analysis > Miscellaneous find the item "Ice wL;wR;e1;e2;e3;e4". This indicates the ice weight in kilograms on each component, from left to right: Wing left, wing right, then engine 1, 2, 3, 4. The maximum value displayed is 99. (By the way, ice accumulation and melting can be accelerated with the Time acceleration slider on Instructor > Situation > Time.)




Just to demonstrate the difference between the four engines, set engine #4 to 60% N1 and watch the ice weight on the Analysis page. It will decrease as the ice will be shedded in short random steps within circa 10 seconds. A small fraction below 10 kg may remain; note that the indication includes both nacelle ice and internal ice. So the rest may be nacelle ice. -- An engine may fail during takeoff at random when the related value is above circa 35 kg.




Normally, you set all four engines to 60% N1 at the same time (for 10 seconds). This is to be repeated every 30 to 60 minutes; there are special situation dependent time schedules to determine the exact procedure.




To get instantly rid of the ice, click the De-ice button on Instructor > Situation > Service. This simulates the airport's de-icing service: The service personnel will spray anti-ice fluids onto the aircraft cell and will lay hoses into the engine intakes to de-ice the engine core by hot air (anti-ice fluids must not get into the core). -- Note that the anti-ice fluid holdover time will just affect the fluid on the aircraft skin, not the engine cores.




Regards,

|-|ardy

[cagarini]

Very interesting info Hardy.

I wonder if ice accretion is simulated over other aircraft surfaces.

For instance, when we read the wL and wR values, do these include both main wings & stabilators ?

Is fuselage taken into consideration too ?

Also, in the presented examples I can see a ( symmetric ) value of 4 kg for each ( main ? ) wing while the engines totals read above 40kg. Why would the total ice accumulation on engines be 10x superior to the wing accumulation ?

[Hardy Heinlin]

The main purpose of the icing simulation is to demonstrate effects in these sections:

• Ice detector system logic
• Anti-ice system logic
• Aerodynamic lift reduction (thicker laminar profile)
• Weight increase (very small)
• Random engine failures

For example, the ice detectors are mounted on the fuselage, yet they work in the simulator and detect ice. So when you read the "kilogram" indications you shouldn't strictly assign them to wing and engine areas only. The numbers just indicate some rough references. You may use your imagination to get an overall situation of the icing on the entire aircraft; feel free to distribute fractions of these values to other areas as well (in your mind) :-)

Re wing icing rate: That was higher in older PSX versions; I reduced the rate some years ago after a discussion with Peter. I've learned that wing icing isn't such a big problem on the 747. As you know, wing anti-ice only works when the leading edge flaps are retracted. Flying with flaps out may take several minutes, but even in icing conditions this isn't a big problem. (I didn't reduce the other icing rates.)


Regards,

|-|ardy

[Blake H]

Very Very cool.



Thank-you Hardy

[United744]

Thank you Hardy!!