Archived from groups: alt.games.microsoft.flight-sim (More info?)
The 757 thread a few days ago sparked some interest.. had Osky 757
folder zipped onto `Aircraft Hanger' folder.. and then got a few more
via download. Now here's a case-in-point. Since then have been
Configuring, Editing, Analyzing, and converting 32-bit textures to
DXT1 and DXT3.. and now have TWO flyable 757's.. one with PW
and the other RR power.
The comment was.. cut throttles and it `drops like rock'. Well the Cdo
looks ok.. however here's some interesting info. The AIR files are
ALMOST IDENTICLE!!
AIR FILE
Compare: (<) B757-200-PW-PW2043.txt (33170 bytes)
with: (>) B757-200-RR-RB211-535E4B.txt (33179 bytes)
22c22
< Engine Type: PW2043
---
> Engine Type: RR RB211-535E4B
109c109
< Max Range: 3,900 nm (7,222 km)
---
> Max Range: 3,395 nm (6,286 km)
1288c1288
< 0.000000 52.000000 82.500000
---
> 0.000000 51.725000 82.500000
1389c1389
< FIELD 0x540 0x0 DOUBLE 1.020000 *EGT Scale Factor
---
> FIELD 0x540 0x0 DOUBLE 1.001000 *EGT Scale Factor
And here's the Engine Data (exactly the same) with polynomials fitted
over top.. followed by some brief comments.
http://home.comcast.net/~flightsim/752_1506.gif
http://home.comcast.net/~flightsim/752_1507.gif
You see now the 0.9M Thrust Factor curve dips as throttles (and CN1)
are cut.. in addition to the MSFS DEFAULT Mass Flow 1507 which is fat
in the Hi-mach region for low engine revs. The two combined will
produce a negative thrust.. which is essentially like a `reverse
thrust' while descending at hi-speed / low revs.
ALso the 0.9M Thrust Factor 1506 seems VERY aggressive.. nothing
like climbing at 4,000 fpm direct to hi-cruise while loaded!! It's a
nice rocketship sometimes!!! { grin } 757s are potent IRL..yes?
AIRCRAFT CFG
Here's another important result of Aircraft.cfg analysis.. the INLET
AREA plays a BIG role in multiplying 1507 Mass Flow table. It explains
the significant difference in the performance between PW
and RR sims. THIS NEEDS to be LOOKED AT more carefully!!
Compare: (<) 757-200 Northwest NC - PW\Aircraft.cfg (14398 bytes)
with: (>) 757-200 American - RR\Aircraft.cfg (15615 bytes)
128,133c128,133
< bypass_ratio = 6.00
< inlet_area = 33.5757 <<< important data
< rated_N2_rpm = 29920.0
< static_thrust = 43734.0
< afterburner_available =0
< reverser_available =1
---
> bypass_ratio = 4.36
> inlet_area = 51.250 <<< important data
> rated_N2_rpm = 29920.0
> static_thrust = 43500.0
> afterburner_available = 0
> reverser_available = 1
Bypass ratio hasn't been found to have an effect.. static thrust is
from MFG's data sheet. Rated N2 RPM is high but has no real effect..
more like 12,000 rpm IRL?
...can we fly it now??
)
-Gregory
The 757 thread a few days ago sparked some interest.. had Osky 757
folder zipped onto `Aircraft Hanger' folder.. and then got a few more
via download. Now here's a case-in-point. Since then have been
Configuring, Editing, Analyzing, and converting 32-bit textures to
DXT1 and DXT3.. and now have TWO flyable 757's.. one with PW
and the other RR power.
The comment was.. cut throttles and it `drops like rock'. Well the Cdo
looks ok.. however here's some interesting info. The AIR files are
ALMOST IDENTICLE!!
AIR FILE
Compare: (<) B757-200-PW-PW2043.txt (33170 bytes)
with: (>) B757-200-RR-RB211-535E4B.txt (33179 bytes)
22c22
< Engine Type: PW2043
---
> Engine Type: RR RB211-535E4B
109c109
< Max Range: 3,900 nm (7,222 km)
---
> Max Range: 3,395 nm (6,286 km)
1288c1288
< 0.000000 52.000000 82.500000
---
> 0.000000 51.725000 82.500000
1389c1389
< FIELD 0x540 0x0 DOUBLE 1.020000 *EGT Scale Factor
---
> FIELD 0x540 0x0 DOUBLE 1.001000 *EGT Scale Factor
And here's the Engine Data (exactly the same) with polynomials fitted
over top.. followed by some brief comments.
http://home.comcast.net/~flightsim/752_1506.gif
http://home.comcast.net/~flightsim/752_1507.gif
You see now the 0.9M Thrust Factor curve dips as throttles (and CN1)
are cut.. in addition to the MSFS DEFAULT Mass Flow 1507 which is fat
in the Hi-mach region for low engine revs. The two combined will
produce a negative thrust.. which is essentially like a `reverse
thrust' while descending at hi-speed / low revs.
ALso the 0.9M Thrust Factor 1506 seems VERY aggressive.. nothing
like climbing at 4,000 fpm direct to hi-cruise while loaded!! It's a
nice rocketship sometimes!!! { grin } 757s are potent IRL..yes?
AIRCRAFT CFG
Here's another important result of Aircraft.cfg analysis.. the INLET
AREA plays a BIG role in multiplying 1507 Mass Flow table. It explains
the significant difference in the performance between PW
and RR sims. THIS NEEDS to be LOOKED AT more carefully!!
Compare: (<) 757-200 Northwest NC - PW\Aircraft.cfg (14398 bytes)
with: (>) 757-200 American - RR\Aircraft.cfg (15615 bytes)
128,133c128,133
< bypass_ratio = 6.00
< inlet_area = 33.5757 <<< important data
< rated_N2_rpm = 29920.0
< static_thrust = 43734.0
< afterburner_available =0
< reverser_available =1
---
> bypass_ratio = 4.36
> inlet_area = 51.250 <<< important data
> rated_N2_rpm = 29920.0
> static_thrust = 43500.0
> afterburner_available = 0
> reverser_available = 1
Bypass ratio hasn't been found to have an effect.. static thrust is
from MFG's data sheet. Rated N2 RPM is high but has no real effect..
more like 12,000 rpm IRL?
...can we fly it now??
)-Gregory
Facebook
Twitter
Instagram