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SFM extension. How does it work???


PeeJott17
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Hi guys.

I've been working on an SFM for the F104 and think, it is not too bad already. But I recognized, that the SFM has the limitation, that it only "decides" on speed and NOT on altitude. My goal is to make it take "altitude" into account as well, which I didn't get to function right now.

 

My idea was to do it like the MB339 and A4E did with their engine table_data whre there is just an "extended" afterwards and a declaration which looks like this (in red):

 

table_data =
            {
            --   M          Pmax
                {0.0,       0.0,0.0}, -- dummy table, required for 2.0+ engine module load
                {2.0,       0.0,0.0},
            }, -- end of table_data
            -- M - Mach number
            -- Pmax - Engine thrust at military power - kilo Newton
            -- Pfor - Engine thrust at AFB
            extended = -- added new abilities for engine performance setup. thrust data now can be specified as 2d table by Mach number and altitude. thrust specific fuel consumption tuning added as well
            {
                -- matching TSFC to mil thrust consumption at altitude at mach per NATOPS navy trials
                TSFC_max =  -- thrust specific fuel consumption by altitude and Mach number for RPM  100%, 2d table
                {
                    M          = {0, 0.5, 0.8, 0.9, 1.0},
                    H         = {0, 3048, 6096, 9144, 12192},
                    TSFC     = {-- M 0      0.5     0.8       0.9     1.0
                                {   0.86,  0.92,  1.012,    1.012,  1.003},--H = 0       -- SL
                                {   0.86,  0.99,  1.025,    1.025,  1.016},--H = 3048    -- 10000'
                                {   0.86,  0.96,  1.008,    1.008,  0.999},--H = 6096    -- 20000'
                                {   0.86,  0.95,  0.984,    0.984,  0.974},--H = 9144    -- 30000'
                                {   0.86,  0.94,  0.976,    0.976,  0.967},--H = 12192   -- 40000'
                    }
                },

 

I would like to do the same thing for the aerodynamics table_data.

My try (which was not successfull) looks like this:

 

extended =
    {
      Cx0 = -- Interpolierung von Cx0 bei Geschwindikeit M und Höhe H
      {-- minimum Cx0 ist xxx maximum Cx0 ist yyy
        M       = {0, 0.2, 0.4, 0.6, 0.7, 0.8, 0.9, 1, 1.05, 1.1, 1.2, 1.3, 1.5, 1.7, 1.8, 2, 2.1, 2.2, 3.9},--Machnumber as above
        H       = {0, 4572, 10668, 13716, 16764}, --Höhe = SeaLevel, 15kft, 35kft, 45kft, 55kft
        Cdmin   = {--M    0     0.2     0.4     0.6     0.7     0.8     0.9     1       1.05    1.1     1.2     1.3     1.5     1.7     1.8       2      2.1     2.2     3.9
                   {    0.015,  0.5,    0.04,   0.019, 0.018,  0.015,  0.018,  0.045,   0.048,  0.05,   0.048,  0.047,  0.046,  0.046,  0.046,   0.046,  0.046,  0.046,  0.046,}, --SeaLevel 0
                   {    0.015,  0.015,  0.1,    0.027, 0.02,   0.019,  0.02,   0.045,   0.048,  0.05,   0.048,  0.047,  0.046,  0.046,  0.046,   0.046,  0.046,  0.046,  0.046,},-- 15kft
                   {    0.015,  0.015,  0.015,  0.12,  0.08,   0.04,   0.035,  0.05,    0.055,  0.06,   0.065,  0.06,   0.05,   0.04,   0.035,   0.025,  0.02,   0.015,  0.015,},-- 35kft
                   {    0.015,  0.015,  0.015,  0.015, 0.12,   0.1,    0.07,   0.075,   0.077,  0.08,   0.075,  0.07,   0.055,  0.05,   0.049,   0.0475, 0.045,  0.035,  0.031,},-- 45kft
                   {    0.015,  0.015,  0.015,  0.015, 0.05,   0.09,   0.11,   0.14,    0.13,   0.12,   0.1,    0.09,   0.07,   0.06,   0.055,   0.05,   0.0475, 0.042,  0.035,},-- 55kft
                  },
      },
    }, -- end of Cx0

 

Which I did put right after the fully filled aerodynamics table_data.

 

Does somebody know how I could get it to work? Am I on a "right" way, or totally wrong? May be, if some ED-guys who know the deal might "nudge" me in the right direction? Any help would be greatly apreciated 🙂

 

Cheers,

 

PJ.

 

 

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sorry guys, posted the wron table.

This is the one which does (or shall do) what I posted above for the A4E-C:

 

thrust_max = -- thrust interpolation table by altitude and mach number, 2d table.  Modified for carrier takeoffs at/around 71 foot deck height
                {
                    M       =   {0, 0.1, 0.225, 0.23, 0.3, 0.5, 0.7, 0.8, 0.9, 1.1},
                    H       =   {0, 19, 20, 23, 24, 250, 4572, 7620, 10668, 13716, 16764, 19812},
                    thrust  =  {-- M    0     0.1    0.225   0.23,   0.3    0.5     0.7     0.8     0.9     1.1
                                {   41370,  39460,  38060,  38056,  37023,  36653,  36996,  37112,  36813,  34073 },--H = 0 (sea level)
                                {   41370,  39460,  38060,  38056,  37023,  36653,  36996,  37112,  36813,  34073 },--H = 19 (~62.3 feet)
                                {   41370,  39460,  38060,  38056,  37023,  36653,  36996,  37112,  36813,  34073 },--H = 20 (~66.6 feet)
                                {   41370,  39460,  38060,  38056,  37023,  36653,  36996,  37112,  36813,  34073 },--H = 23 (~75.5 feet)
                                {   41370,  39460,  38060,  38056,  37023,  36653,  36996,  37112,  36813,  34073 },--H = 24 (~78.7 feet)
                                {   41370,  39460,  38060,  38056,  37023,  36653,  36996,  37112,  36813,  34073 },--H = 250 (820 feet)
                                {   27254,  25799,  24765,  24761,  24203,  24599,  26227,  27254,  28353,  29785 },--H = 4572 (15kft)
                                {   20818,  19203,  18130,  18127,  17548,  17473,  18638,  19608,  20684,  22873 },--H = 7620 (25kft)
                                {   10876,  11076,  11128,  11130,  11556,  12193,  13024,  13674,  14434,  16098 },--H = 10668 (35kft)
                                {   6025,   6379,    6676,   6680,  6837,   7433,   8194,   8603,   9101,   10075 },--H = 13716 (45kft)
                                {   3336,   3554,    3837,   3840,  3990,   4484,   5000,   5307,   5596,   6232  },--H = 16764 (55kft)
                                {   1904,   2042,    2296,   2300,  2433,   2798,   3212,   3483,   3639,   4097  },--H = 19812 (65kft)
                               },
                },

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If it would work, that you utilize another value (such as altitude) for the SFM the next step would be, to use AoA as well, since it would come in handy for stall characteristics.

But first-things-first, how can altitude been integrated?

Are there some "global variables" which are looked for by DCS? Is there another possibility to integrate it?

 

If you could help me out, it is greatly apreciated :-)

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  • 3 months later...

Hi. Any lucky with that?

 

On 12/27/2020 at 7:09 AM, PeeJott17 said:

If it would work, that you utilize another value (such as altitude) for the SFM the next step would be, to use AoA as well, since it would come in handy for stall characteristics.

But first-things-first, how can altitude been integrated?

Are there some "global variables" which are looked for by DCS? Is there another possibility to integrate it?

 

If you could help me out, it is greatly apreciated 🙂

 

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No. Sorry. I had a help-desk request which was passed to the developers of ED...but sadly I got a message that nobody would take a look, since everybody is to busy doing other things which is a bit sad.

 

The Idea is more or less the same as the Thrust-Thing with the MB339 or A4, but there is no chance to get an answer there about that as well, since the guy who coded it for the A4 is not longer on the team, and the MB339 guys said, that since they are now a 3rd Party, they are not allowed to talk about it...

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