(UTC)
  Visit Captain Sim web site  
  Welcome, Guest. Please Login or Register

  

  CAPTAIN SIM FORUM › 737 Captain › 737 Captain - General › FLIGHT DYNAMICS TWEAKS (The only thread)
‹ Previous Topic | Next Topic ›
Page Index Toggle Pages: 1 2 [3] 4  Send TopicPrint
25 FLIGHT DYNAMICS TWEAKS (The only thread) (Read 36388 times)
bud7h7
Full Member
*
Offline



Posts: 107
Location: Miami, Florida USA
Joined: Apr 3rd, 2012
Gender: Male
Re: FLIGHT DYNAMICS TWEAKS (The only thread)
Reply #30 - May 13th, 2012 at 6:12am
Print Post  
sab39v, are you using realistic thrust settings / EPR to climb with only static_thrust = 15500 ?
I don't think I can hold 2000 fpm at 2.13 EPR with that static_thrust value unless I reduce drag some more. I'll try it and see.
  
Bud Estrada i5 2500k @ 4.4 - p67 extreme4 - GTX580 - 16gb RAM - Windows 7/64 - FSX SP2
Back to top
 
IP Logged
 
CoolP
Senior Member
*
Offline



Posts: 2568
Joined: Jan 17th, 2010
Gender: Male
Re: FLIGHT DYNAMICS TWEAKS (The only thread)
Reply #31 - May 13th, 2012 at 10:30am
Print Post  
A gold medal for your efforts, guys.
  
Back to top
 
IP Logged
 
sab39v
Full Member
*
Offline



Posts: 16
Location: Brussels
Joined: Nov 22nd, 2005
Re: FLIGHT DYNAMICS TWEAKS (The only thread)
Reply #32 - May 13th, 2012 at 1:40pm
Print Post  
bud7h7 wrote on May 13th, 2012 at 6:12am:
sab39v, are you using realistic thrust settings / EPR to climb with only static_thrust = 15500 ?
I don't think I can hold 2000 fpm at 2.13 EPR with that static_thrust value unless I reduce drag some more. I'll try it and see.


Hi bud7h7,

no I'm not that deep into ciphering things . I do wanna use the correct thrust, because at the beginning it felt like this small 737 was powered with 2 CFM56-7B of the NG series  Grin

That EPR stuff is something I should look into. But first I'm trying to finish up my paints. One of them being a real "pita".
  
Regards,&&Vital&&&&
Back to top
 
IP Logged
 
Chris the Swiss
Full Member
*
Offline



Posts: 139
Joined: May 5th, 2012
Re: FLIGHT DYNAMICS TWEAKS (The only thread)
Reply #33 - May 13th, 2012 at 3:32pm
Print Post  
... but a really nice one!  Cheesy
  
Back to top
 
IP Logged
 
pbrwr
New Member
Offline



Posts: 3
Joined: May 16th, 2012
Re: FLIGHT DYNAMICS TWEAKS (The only thread)
Reply #34 - May 16th, 2012 at 8:41pm
Print Post  
As this seems to be the only fd tweak thread,

try this:

[TurbineEngineData]
fuel_flow_gain = 0.002                          //Gain on fuel flow
inlet_area = 9.6                               //Square Feet, engine nacelle inlet area
rated_N2_rpm = 29920                            //RPM, second stage compressor rated value
static_thrust = 15500
afterburner_available = 0                       //Afterburner available?
reverser_available = 1                          //Thrust reverser available?
ThrustSpecificFuelConsumption = 0.385             //Thrust specific fuel consumption (Jets)
AfterBurnThrustSpecificFuelConsumption = 0      //TSFC with afterburn/reheat engaged

An inlet area of 19.6 sq. ft.  is too much for a 737-200, 9.something seems to work much better.
  
Back to top
 
IP Logged
 
Markoz
CS Team
*
Offline



Posts: 12373
Location: Victoria, Australia
Joined: Apr 24th, 2009
Gender: Male
Re: FLIGHT DYNAMICS TWEAKS (The only thread)
Reply #35 - May 17th, 2012 at 3:09am
Print Post  
pbrwr wrote on May 16th, 2012 at 8:41pm:
As this seems to be the only fd tweak thread,

try this:

[TurbineEngineData]
fuel_flow_gain = 0.002                          //Gain on fuel flow
inlet_area = 9.6                               //Square Feet, engine nacelle inlet area
rated_N2_rpm = 29920                            //RPM, second stage compressor rated value
static_thrust = 15500
afterburner_available = 0                       //Afterburner available?
reverser_available = 1                          //Thrust reverser available?
ThrustSpecificFuelConsumption = 0.385             //Thrust specific fuel consumption (Jets)
AfterBurnThrustSpecificFuelConsumption = 0      //TSFC with afterburn/reheat engaged

An inlet area of 19.6 sq. ft.  is too much for a 737-200, 9.something seems to work much better.

Thanks. I'll give it a try.

One question though. Are the parasite_drag_scalar and induced_drag_scalar in your settings still set to parasite_drag_scalar   = 1.0 and induced_drag_scalar    = 1.0?

Mark
  
Mark Fletcher



PC: i7 10700K @3.8/5.1GHz | 64GB DDR4 3200 | 12GB RTX 4070 Super | 32" LCD Monitor | 1TB SSD & 2x2TB SSD | Win 11 Pro - FSX/FSX-SE/P3D3/P3D4/P3D5/P3D6/MSFS2020
15.6" Gaming Laptop: i7 7700HQ | 32GB DDR4 | 6GB GTX 1060 | 256GB SSD & 1TB HDD | Win 10 Pro 64bit - FSX-SE/P3D4
Back to top
 
IP Logged
 
pbrwr
New Member
Offline



Posts: 3
Joined: May 16th, 2012
Re: FLIGHT DYNAMICS TWEAKS (The only thread)
Reply #36 - May 17th, 2012 at 7:34am
Print Post  
Markoz wrote on May 17th, 2012 at 3:09am:
pbrwr wrote on May 16th, 2012 at 8:41pm:
As this seems to be the only fd tweak thread,

try this:

[TurbineEngineData]
fuel_flow_gain = 0.002                          //Gain on fuel flow
inlet_area = 9.6                               //Square Feet, engine nacelle inlet area
rated_N2_rpm = 29920                            //RPM, second stage compressor rated value
static_thrust = 15500
afterburner_available = 0                       //Afterburner available?
reverser_available = 1                          //Thrust reverser available?
ThrustSpecificFuelConsumption = 0.385             //Thrust specific fuel consumption (Jets)
AfterBurnThrustSpecificFuelConsumption = 0      //TSFC with afterburn/reheat engaged

An inlet area of 19.6 sq. ft.  is too much for a 737-200, 9.something seems to work much better.

Thanks. I'll give it a try.

One question though. Are the parasite_drag_scalar and induced_drag_scalar in your settings still set to parasite_drag_scalar   = 1.0 and induced_drag_scalar    = 1.0?

Mark


I kept the drag as it was. By reducing the inlet area you also reduce drag.
  
Back to top
 
IP Logged
 
bud7h7
Full Member
*
Offline



Posts: 107
Location: Miami, Florida USA
Joined: Apr 3rd, 2012
Gender: Male
Re: FLIGHT DYNAMICS TWEAKS (The only thread)
Reply #37 - May 17th, 2012 at 10:11am
Print Post  
That's a good idea too. I will try that as well, but I think by reducing the inlet area you reduce ram drag, mostly at higher speeds. It may be a more sudden drop in drag compared to parasite drag.

Then there's still the problem of too much drag on descent. The parasite_drag may still need to be lowered for idle thrust descent.
Also, by tweaking parasite and induced drag together you can adjust all phases of flight so none are sacrificed when others are improved.

Edit:
I tried inlet_area=10 with 15800 thrust and it works pretty well. I'll more than likely stay with editing the other two drag scalars instead, mainly because I don't want to start all over trying to get EPR/n1 just right, but also because I can fine tune climb, cruise and approach somewhat individually this way.
  
Bud Estrada i5 2500k @ 4.4 - p67 extreme4 - GTX580 - 16gb RAM - Windows 7/64 - FSX SP2
Back to top
 
IP Logged
 
Markoz
CS Team
*
Offline



Posts: 12373
Location: Victoria, Australia
Joined: Apr 24th, 2009
Gender: Male
Re: FLIGHT DYNAMICS TWEAKS (The only thread)
Reply #38 - May 17th, 2012 at 10:13am
Print Post  
pbrwr wrote on May 17th, 2012 at 7:34am:
Markoz wrote on May 17th, 2012 at 3:09am:
pbrwr wrote on May 16th, 2012 at 8:41pm:
As this seems to be the only fd tweak thread,

try this:

[TurbineEngineData]
fuel_flow_gain = 0.002                          //Gain on fuel flow
inlet_area = 9.6                               //Square Feet, engine nacelle inlet area
rated_N2_rpm = 29920                            //RPM, second stage compressor rated value
static_thrust = 15500
afterburner_available = 0                       //Afterburner available?
reverser_available = 1                          //Thrust reverser available?
ThrustSpecificFuelConsumption = 0.385             //Thrust specific fuel consumption (Jets)
AfterBurnThrustSpecificFuelConsumption = 0      //TSFC with afterburn/reheat engaged

An inlet area of 19.6 sq. ft.  is too much for a 737-200, 9.something seems to work much better.

Thanks. I'll give it a try.

One question though. Are the parasite_drag_scalar and induced_drag_scalar in your settings still set to parasite_drag_scalar   = 1.0 and induced_drag_scalar    = 1.0?

Mark


I kept the drag as it was. By reducing the inlet area you also reduce drag.

OK. I did a test with the parasite_drag_scalar=1 and induced_drag_scalar=1 (only because you had not answered at the time) and I I like it. It isn't like a rocket ship with those setting. Still powerful enough, but not too powerful. Thanks. Wink
  
Mark Fletcher



PC: i7 10700K @3.8/5.1GHz | 64GB DDR4 3200 | 12GB RTX 4070 Super | 32" LCD Monitor | 1TB SSD & 2x2TB SSD | Win 11 Pro - FSX/FSX-SE/P3D3/P3D4/P3D5/P3D6/MSFS2020
15.6" Gaming Laptop: i7 7700HQ | 32GB DDR4 | 6GB GTX 1060 | 256GB SSD & 1TB HDD | Win 10 Pro 64bit - FSX-SE/P3D4
Back to top
 
IP Logged
 
fsxpaul
Ex Member


Re: FLIGHT DYNAMICS TWEAKS (The only thread)
Reply #39 - May 22nd, 2012 at 2:33pm
Print Post  
Markoz wrote on May 17th, 2012 at 10:13am:
OK. I did a test with the parasite_drag_scalar=1 and induced_drag_scalar=1 (only because you had not answered at the time) and I I like it. It isn't like a rocket ship with those setting. Still powerful enough, but not too powerful. Thanks. Wink


I tested these settings / values with the V-One gauge and the climb and cruise performance was spot on!

inlet_area=9.6
static_thrust-15500


It exactly matched the performance I was obtaining with only static_thrust=19000 change.

I'll be using these values from now on  Smiley
  
Back to top
 
IP Logged
 
bud7h7
Full Member
*
Offline



Posts: 107
Location: Miami, Florida USA
Joined: Apr 3rd, 2012
Gender: Male
Re: FLIGHT DYNAMICS TWEAKS (The only thread)
Reply #40 - May 22nd, 2012 at 11:17pm
Print Post  
I like those values a lot. But they still leave us unable to descend at about 280kts/2500 fpm/ idle thrust. Without going into the air file, the only .cfg value that I've seen affect that area is parasite drag. Since the effects of parasite drag and ram drag (inlet_area) both begin at higher airspeed, it's difficult to reduce the inlet area that much and still be able to reduce parasite drag enough to descend properly.

I'm very close now using .6 parasite drag, .8 induced_drag, 15.5 inlet_area, and 15500 static_thrust.

With some minor tweaking to the air file I'm getting closer to achieving acceptable idle descent rates (260 KIAS/ 2800 fpm) as well as taxi thrust (about 40% n1 to break loose, then nearly idle to taxi).
  
Bud Estrada i5 2500k @ 4.4 - p67 extreme4 - GTX580 - 16gb RAM - Windows 7/64 - FSX SP2
Back to top
 
IP Logged
 
fsxpaul
Ex Member


Re: FLIGHT DYNAMICS TWEAKS (The only thread)
Reply #41 - May 22nd, 2012 at 11:41pm
Print Post  
bud7h7 wrote on May 22nd, 2012 at 11:17pm:
I like those values a lot. But they still leave us unable to descend at about 280kts/2500 fpm/ idle thrust. Without going into the air file, the only .cfg value that I've seen affect that area is parasite drag. Since the effects of parasite drag and ram drag (inlet_area) both begin at higher airspeed, it's difficult to reduce the inlet area that much and still be able to reduce parasite drag enough to descend properly.

I'm very close now using .6 parasite drag, .8 induced_drag, 15.5 inlet_area, and 15500 static_thrust.

With some minor tweaking to the air file I'm getting closer to achieving acceptable idle descent rates (260 KIAS/ 2800 fpm) as well as taxi thrust (about 40% n1 to break loose, then nearly idle to taxi).



Excellent, sounds like you're almost there! But unfortunately, at least for me, that last bit of detail is the hardest part to get through!
  
Back to top
 
IP Logged
 
bud7h7
Full Member
*
Offline



Posts: 107
Location: Miami, Florida USA
Joined: Apr 3rd, 2012
Gender: Male
Re: FLIGHT DYNAMICS TWEAKS (The only thread)
Reply #42 - May 23rd, 2012 at 1:21am
Print Post  
Here's where I'm at now:

[flight_tuning]
parasite_drag_scalar   = 0.6
induced_drag_scalar    = 0.72

[TurbineEngineData]
inlet_area = 16.3
static_thrust = 15000

For testing, I used EPRs averaged between econ and full, but leaning more toward full, also watching for realistic n1:

takeoff: 2.12 EPR (flaps 5)
elevation 800 , temp 22c

climb: 2.12 EPR (280 IAS / m 0.7)
** from 10,000 to about FL250 she holds 2800 to 3000 v/s

cruise: 1.69 - 1.72 EPR (m 0.73 @ FL300)

With additional minor air file edits, idle descent is about 255 IAS @ -2800 v/s , and thrust needed to start taxi is now only 39% n1 (103.0k lbs gross weight). More to come on that.
  
Bud Estrada i5 2500k @ 4.4 - p67 extreme4 - GTX580 - 16gb RAM - Windows 7/64 - FSX SP2
Back to top
 
IP Logged
 
toelg
Full Member
*
Offline



Posts: 40
Joined: Sep 7th, 2011
Re: FLIGHT DYNAMICS TWEAKS (The only thread)
Reply #43 - May 23rd, 2012 at 7:12am
Print Post  
Hi Bud,

thanks for Your investigation ! I'll try Your changes at the aircraft.cfg  But how can I edit the .air-file ? It would be nice, if You could upload it.  Roll Eyes

Thanks
Dietmar
  
Back to top
 
IP Logged
 
bud7h7
Full Member
*
Offline



Posts: 107
Location: Miami, Florida USA
Joined: Apr 3rd, 2012
Gender: Male
Re: FLIGHT DYNAMICS TWEAKS (The only thread)
Reply #44 - May 23rd, 2012 at 8:46am
Print Post  
Dietmar, I use the freeware app "aircraft airfile manager". I have not uploaded yet because I'm still working on the idle thrust descent rate. My goal is at least 270 KIAS at -2800 v/s, without affecting other areas of flight.
  
Bud Estrada i5 2500k @ 4.4 - p67 extreme4 - GTX580 - 16gb RAM - Windows 7/64 - FSX SP2
Back to top
 
IP Logged
 
Page Index Toggle Pages: 1 2 [3] 4 
Send TopicPrint
‹ Previous Topic | Next Topic ›
 
  « Board Index ‹ Board  ^Top   

CAPTAIN SIM FORUM » Powered by YaBB 2.6.0!
YaBB Forum Software © 2000-2024. All Rights Reserved.

Valid RSS Valid XHTML Valid CSS Powered by Perl Source Forge