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Posted

Hi, I was tuning a sfm piston engine and I'm not sure what some of these specs are. Could someone please decipher them?

Any help would be greatly appreciated.

 

 

k_adiab_1                    = 0.037923,
k_adiab_2            = 0.0562,
MAX_Manifold_P_1        = 180000,        
MAX_Manifold_P_2        = 180000,        
MAX_Manifold_P_3        = 180000,        
k_after_cool            = 0.0,
Displ                = 35,
k_Eps                = 6.5,
Stroke                = 0.165,
V_pist_0            = 13,
Nu_0                = 1.2,
Nu_1                = 0.9,
Nu_2                = 0.001,
N_indic_0            = 1052480,
N_fr_0                = 0.04,
N_fr_1                = 0.001,
Init_Mom            = 220,
D_prop                = 3.5,
MOI_prop            = 45,
k_gearbox            = 2.4,
P_oil                = 495438,
k_boost                = 3,
k_cfug                = 0.003,
k_oil                = 0.00004,
k_piston            = 3000,
k_reg                = 0.003,
k_vel                = 0.017,

  • 3 years later...
Posted

Hey, did you ever find info on this else where? I have added comments to the parts I know but the others are still a mystery

 

 

 

k_adiab_1                    = 0.037923,
k_adiab_2            = 0.0562,
MAX_Manifold_P_1        = 180000,    -- from study of aircraft files these manifold pressures should be increasing in value and not the same. not sure what they represent though
MAX_Manifold_P_2        = 180000,        
MAX_Manifold_P_3        = 180000,        
k_after_cool            = 0.0,
Displ                = 35,   --displacement in litres
k_Eps                = 6.5,
Stroke                = 0.165, --stroke in meters
V_pist_0            = 13,  -- number of pistons
Nu_0                = 1.2,
Nu_1                = 0.9,
Nu_2                = 0.001,
N_indic_0            = 1052480,
N_fr_0                = 0.04,
N_fr_1                = 0.001,
Init_Mom            = 220,
D_prop                = 3.5,  --diameter of prop in meters
MOI_prop            = 45, -- moment of inertia of prop (not sure of units, probably kg * m^2)
k_gearbox            = 2.088, -- prop to engine ratio (gearbox ratio) eg (P51D - Prop reduction ratio=0.477, 1/0.477 = 2.088)

----------
-- all of below have the exact same figures for both the p51d and l16 so not sure if they do much
---------
P_oil                = 495438,
k_boost                = 3,
k_cfug                = 0.003,
k_oil                = 0.00004,
k_piston            = 3000,
k_reg                = 0.003,
k_vel                = 0.017,

Posted

Pretty sure that V_piston_0 is not the number of pistons. Not sure what it is but fairly sure it is not that. Not many 13 cylinder engines out there in the WW2 piston engine space

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