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FSX XML hydraulic system engine map

D

Dave_W

Resource contributor
Messages
185
In the threads that I looked at on hydraulic systems, I didn't find anything similar to this.

This is a plane with four piston engines.

I wanted to have pumps on engines two and three only, so I changed the engine_map in an aircraft.cfg to this:
Code: 
[hydraulic_system]
normal_pressure   = 2600
electric_pumps   = 0
engine_map   = 0,1,1,0

XMLTools Logger records the following with four engines running at full throttle:
Code: 
(A:ENG HYDRAULIC PRESSURE:1, psi) 2498.6
(A:ENG HYDRAULIC PRESSURE:2, psi) 2503.5
(A:ENG HYDRAULIC PRESSURE:3, psi) 0.
(A:ENG HYDRAULIC PRESSURE:4, psi) 0.

If the engine_map is set to 1,1,1,1 then all four variables return a value.

While trying various combinations, I found that if I set it to 0,1,1,1 then variables for engines one, two and three return values. The same as I get, and would expect, from 1,1,1,0.

Have I done something incorrectly, or is there a problem with certain engine maps?

TIA
 
What happens if you shut down one of the engines running a hydraulic system?
 
Isn't this only logical behaviour?

The first engine with a hydraulic pump supplies the first hydraulic system, the second engine with a hydraulic pump supplies the second system, etc...

I think you can have as many systems as you like when you add electric pumps into the mix.
 
The "hydraulic system(s)" are not linked to any particular engine(s). As noted, if you have an engine map of 0,0,0,1 (A:ENG HYDRAULIC PRESSURE:1, psi) will be active.
 
Thanks, everyone.

There is apparently something fundamental about engine maps and hydraulic pressure variables that I am too "thick" to understand. I am back to see if I can get it this time.

I was trying to read a variable with an index, based on the engine map. I learned that it doesn't necessarily work like that.

Ultimately, it doesn't matter whether or not I can do it, but I would really like to get rid of my confusion about what is happening.

Bill Leaming said:
The "hydraulic system(s)" are not linked to any particular engine(s). As noted, if you have an engine map of 0,0,0,1 (A:ENG HYDRAULIC PRESSURE:1, psi) will be active.
Click to expand...
Bill, can you explain why the map example that you give returns a value to (A:ENG HYDRAULIC PRESSURE:1, psi) and returns zero to (A:ENG HYDRAULIC PRESSURE:4, psi)??

I think that is what has me confused and that I don't really understand what A:ENG HYDRAULIC PRESSURE:index means. Maybe I don't understand engine maps either. Even with the SDK description. :scratchch

Naruto-kun said:
What happens if you shut down one of the engines running a hydraulic system?
Click to expand...
I don't think this is relevant to my confusion, but you made me curious. It changes the value of the next lower variable, but doesn't change the variable of the engine shut down. For example, I shut down engine 3. Engine 2 pressure goes to a bit under 49 psi. Reload the plane, start the engines, shut down number 2. Engine 1 goes to around 42 psi. Supposedly, I don't have a pump on engine 1, but if I shut it down, the value stays around 2500 psi. I suppose that is because I have a pump mapped to number 3?

Bjoern, I might not understand your reply correctly, but I thought that is what I was doing with the map in
the OP.

Roy, I have read that thread a few times in the last couple of months. The OP was trying to do something
much more sophisticated than I am. With all of the things that are explained in it, I may have overlooked something that would have helped me.
 
Try looking at it this way:

Here is your engine map in the cfg:
Code: 
engine_map   = 0,1,1,0

Here is how it will work in the sim var:

Code: 
index 1 = engine 2
index 2 = engine 3

Lets say you have a engine map like this:
Code: 
engine_map = 1, 0, 1, 1

If we follow the above logic, we will get this:
Code: 
index 1 = engine 1
index 2 = engine 3
index 3 = engine 4

So basically, to figure out which index to use for which engine, remove the zeros from your engine map, and move everything to the left to fill in the gaps.
 
Heretic said:
And all of this I've already stated in post #3...
Click to expand...
Yes you did! The SDK isn't terribly clear in describing the indexed variables apply to "Hydraulic Systems", and that engine (or electrical) pump indexes are not the same as those for those hydraulic systems
 
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