Knowledege base on engine data needs update?

[+nele]

Uh, maybe I am discovering a "hot water", but I think QB needs a little update. I am just finishing a major tweak of data.ini for old flogger series and I have the engine chart. I think I decyphred DryMachTableNumData and WetMachTableNumData entries as Trust-to Mach dependency of engine(s). Like,

 

DryMachTableNumData=4

DryMachTableDeltaX=0.4

DryMachTableStartX=0.0

DryMachTableData=1.000,0.980,1.172,0.000

 

can be decyphred like "dry thrust is equal static at M0, is of value 0.98 at M4 and 1.172 at M0.8, is none at M0 (as AB kicks in)".

 

This in combination with AltitudeTableNumData gives engine thrust/Mach/Altitude "curve"

 

Ditto for WetMach. If I am correct, this is very important! I changed this for a test (punched in real, chart engine values) and it works fine up to cca. 33,000ft where it gets too much drop in thrust.

 

If I am right, would some give me a "correction factor" to fix this? I have currently roughly replaced (test) "1" with "2" for values over M1.2 for "Flogger" series (and it is lower that is in current use, cca. 70 over 90-100% increase in Lightning F.6).

 

Could somebody help a perfectionist, so I could release those floggers as best as I can on schedule ;)

 

Nele

 

P.S. If I am right, say thanks to Tumansky and MiG bueraus for very nice engine chart in the manual :)))

[+Fubar512]

Nele,

 

Did you factor in the engine altitude tables? Most of the models out there (both default and third-party) are using tables with values plotted every 3048 meters. That's every 10,000 feet!

 

Here's an example. This is from Thirdwire's F-4B

 

AltitudeTableNumData=8

AltitudeTableDeltaX=3048.0

AltitudeTableStartX=0.0

AltitudeTableData=1.000,0.690,0.463,0.300,0.182,0.123,0.054,0.000

 

 

This is from Streakeagle's F-4B

 

AltitudeTableNumData=91

AltitudeTableDeltaX=304.8

AltitudeTableStartX=0.0

AltitudeTableData=1,0.971106394,0.942855852,0.915238387,0.888244103,0.861863187,0.836085916,0.81090265,0.786303837,0.762280013,0.738821797,0.715919894,0.693565098,0.671748283,0.650460414,0.629692538,0

.609435786,0.589681377,0.570420613,0.55164488,0.533345649,0.515514475,0.498142997,0.481222939,0.464746105,0.448704388,0.433089758,0.417894274,0.403110075,0.388729381,0.374744499,0.361147815,0.34793179

9

,0.335089002,0.322612056,0.310493678,0.298726662,0.285193242,0.27240596,0.26022405,0.248620308,0.237562406,0.226989891,0.216908987,0.207331873,0.198193216,0.18941235,0.181041534,0.173024394,0.16538841

7

,0.157978038,0.150909904,0.143808453,0.137043248,0.131316926,0.125837043,0.120517912,0.115176317,0.110071472,0.105192884,0.100530525,0.096074811,0.091816584,0.087747089,0.083857963,0.08014121,0.076589

1

91,0.073194605,0.069950474,0.066850129,0.063887197,0.061055589,0.058349483,0.055763318,0.053291776,0.050929778,0.048672468,0.046515207,0.04445356,0.042483289,0.040600345,0.038800856,0.037081125,0.0354

3

7615,0.033866949,0.032365898,0.030931377,0.029560436,0.028250259,0.026998151,0.025801539

[+nele]

Yap, ditto :) There is a great R-35 engine chart, both altitude-thrust and Mach-thrust related. I have entered it for the Flogger(s) for 0-24 km altitudes in one km increments. It seems that it behaves just a little below norm, but Mach table (in my 1st post) is off by cca. 200% (rather that initially estimated 100%).

 

This is from the sheet:

WetMachTableNumData=7 (no.of entries)

WetMachTableDeltaX=0.4 (M0.4 increments)

WetMachTableStartX=0.0 (staring from M0)

WetMachTableData=1.000,0.960,1.250,1.500,1.330,1.160,1.083 (thrust multiplier at M0, M0.4, M0.8, M1.2, M1.6, M2.0, M2.4). This gives 18-19000kgf thrust in real engine at ceiling (M.1.6).

 

The last number for "stock" Phantoms is over 3! When "default" table is put, Floggers can do something over 10,000m. Else engines "die" in the air too poor but too thick. Maybe TK made Nytrogen atmosphere? ;)

 

As in the Thirdwire-StreakEagle's mod for J79, "altitudetablenumdata" of R-35 in manual is a little "thinner" above 9-10,000m. I suppose StreakEagle took his from a manual, too (only he did cut it a bit fine, 91 300m-steps to cca 21,000m and I did it in 1000msteps to 24km)!

 

In overall, I think that wetmachtable is the one that needs "corrective factor" starting from cca. M1. For values above M1 I entered "default" correction, and it behaves more-less ok, but it would good to know the real "offset behaviour".