I've completed a modified flight model for the Captain Sim 727-200.  This will give you realistic EPR values, realistic descent, accurate fuel consumption and allows you to set power for take-off, climb and cruise using real world power tables.  I have tried as well to get pitch attitudes exactly right for all modes of flight.  JT8D-9 engines are modeled. The link to download is as follows:

http://www.mediafire.com/file/5xjxa2bf87ie6tl/727%20200%20flight%20model%20mod%201.0.zip

One thing I forgot to put in the readme: on final approach, use fuel flow to set power.  Fuel flow with 30' flaps should be about 3300 lbs per hour on each engine at typical landing weights.

Thanks, and I'll give this a try ASAP.

Michael,

Thank you very much. Tonight I downloaded and made a test flight. EPR on TARGET.
Tomorrow I will make a another test flight and will inform.
GREAT JOB  :) :) :)
Sanal

Michael

I have downloaded your B727-200 mod package, but I have a question. I compared the data in the current aircraft.cfg file and the one you propose. I notice that you have reduced the weights (max, empty and max_zf to nearly the same values as the -100. Is that necessary? Does that represent the real -200?

In the first place, what drew me to your post in the forum were the problems I am having with controlling this aircraft, which is new to me. I was trying to do a flight from Toronto (CYYZ) to Montreal (CYUL), about a 1-hour flight. My payload was as follows:

•      155 passengers at 180 lbs = 27,900 lbs
•      4 3,000 lbs containers (2 front, 2 aft) = 12,000 lbs.
•      Crew = 510 lbs
•      Total payload = 40,410 lbs

I loaded 18,500 lbs of fuel, spread equally amongst the 3 tanks.

The problems I encountered are:

•      Climbing beyond 25,000 ft. was very difficult. I managed to reach only 31,000ft in about 18 minutes from takeoff.
•      Once in the cruise portion, I tried to maintain a constant speed of M0.8, but the speed kept changing up and down, so I constantly had to adjust the throttle. I was on real weather, but the winds were pretty constant. I never have such variations in other planes (C-130X, B-52).
•      When descending, I found it hard to slow the airplane and had to use the speed brakes to reduce the speed once I got below 10,000 ft. (Incidentally, the speed brake lever does not work. I had to use a keystroke. Is that a known bug?)
•      In the turn from the base leg onto final, it slowed down very rapidly from 150 Kts and I lost it; it stalled and crashed. My flaps were at 15° when I was at 150 Kts.

Is this the normal behaviour for this plane? Or am I doing something wrong? Or is it something that your mod would fix?

Hi GDex.

I'm not trying to detract from what Michael has done, but all I did to improve the performance of the 727-200 was to increase its static_thrust. Here is what I change it to:

[TurbineEngineData]
fuel_flow_gain= 0.003
inlet_area= 18.000
rated_N2_rpm= 29920.000
static_thrust=17400     //15500
afterburner_available= 0
reverser_available= 1
ThrustSpecificFuelConsumption = 1
AfterBurnThrustSpecificFuelConsumption = 0

I increased it from 15500, which is the same as static_thrust as the 727-200.

The reason I chose 17400 comes from find this: Eight models comprise the JT8D standard engine family, covering the thrust range from 12,250 to 17,400 pounds-force (62 to 77kN) and power 727, 737-100/200, and DC-9 aircraft. on wikipedia. I couldn't find specific thrust for specific engines. I simply did not want to waste a lot of time searching it out. I wanted to fly it. Making that simple change has improved the climbing ability of the 727-200 immensely. Mine climbs to FL350 quite easily now.

Mark

GDex wrote on Feb 11^th, 2011 at 3:50am:

Michael I have downloaded your B727-200 mod package, but I have a question. I compared the data in the current aircraft.cfg file and the one you propose. I notice that you have reduced the weights (max, empty and max_zf to nearly the same values as the -100. Is that necessary? Does that represent the real -200? In the first place, what drew me to your post in the forum were the problems I am having with controlling this aircraft, which is new to me. I was trying to do a flight from Toronto (CYYZ) to Montreal (CYUL), about a 1-hour flight. My payload was as follows: •      155 passengers at 180 lbs = 27,900 lbs •      4 3,000 lbs containers (2 front, 2 aft) = 12,000 lbs. •      Crew = 510 lbs •      Total payload = 40,410 lbs I loaded 18,500 lbs of fuel, spread equally amongst the 3 tanks. The problems I encountered are: •      Climbing beyond 25,000 ft. was very difficult. I managed to reach only 31,000ft in about 18 minutes from takeoff. •      Once in the cruise portion, I tried to maintain a constant speed of M0.8, but the speed kept changing up and down, so I constantly had to adjust the throttle. I was on real weather, but the winds were pretty constant. I never have such variations in other planes (C-130X, B-52). •      When descending, I found it hard to slow the airplane and had to use the speed brakes to reduce the speed once I got below 10,000 ft. (Incidentally, the speed brake lever does not work. I had to use a keystroke. Is that a known bug?) •      In the turn from the base leg onto final, it slowed down very rapidly from 150 Kts and I lost it; it stalled and crashed. My flaps were at 15° when I was at 150 Kts. Is this the normal behaviour for this plane? Or am I doing something wrong? Or is it something that your mod would fix?

All of the information I used comes from Boeing and airline manuals for the real aircraft, and some material taken from the engine manuals as well.  As for the weights, they are accurate.  The 727 200 Advanced had a significantly higher maximum weight, but that is not the aircraft I modeled. See page 5 of the following document from Boeing as to weights:

http://www.boeing.com/commercial/airports/acaps/727sec2.pdf

Your total weight was 194,000 lbs which was more than 20,000 lbs in excess of the maximum takeoff weight.  In the readme I noted that it quite easy to overload the basic 200 model and that you should check to see that you haven't done so in the FSX fuel and payload dialog.

I don't have detailed climb performance charts for the 200 with JT8D-9 engines, but I do for the 100 and for a 727-100 starting at 170,000 lbs with JT8D-7s, the climb to FL310 is 21 minutes at standard temperatures, so I am not sure why you perceive your results to be a problem.   If anything the climb performance may be too good based on your figure, although I wonder if you used more than maximum climb power since you perceived the performance as deficient?

My figures are from a Boeing performance manual.  Climb above 25,000 feet is only going to be around 1000' feet per minute.  That is the performance of the real aircraft.

As for the cruise behaviour, there is nothing in the flight model that could cause varying speed with a constant power setting.  And I have yet to experience "pretty constant" winds aloft with any of the weather programs I have tried.  Try again with "clear" weather, which has no wind at all, to see if in fact you really have a problem with this.

I can't use the mouse to operate the speed brake lever either -- I have to either use a key or a joystick slider, but I haven't done anything to cause that problem.

I don't find that I need speedbrakes to slow down. I start descending at 2,500 fpm at 290 knots at 55% N1 (which is the desired behaviour). I set the autopilot for that rate of descent and reduce it to about 2000 fpm at 20,000 feet and 1,500 fpm at 15,000 and then 1000 fpm under 10,000.  You will not need speed brakes if you do that.

With flaps 15 in level flight you need a fair amount of power.  I have two unreliable airspeed charts for the 727-200.  The one says you need an N1 of 74 and 7' of pitch at 150 kias at a typical weight.  The other chart is more detailed and shows for a weight of 160,00 lbs:  EPR of 1.43/N1 of 74 and 7' pitch at 160 kias.  I have tweaked my flight model to approximate these figures.  And of course if you are turning with a lot of bank angle you are going to have to increase your power from those figures in the turn.

So I think that yes, you are doing something wrong.

Michael

Thanks for your prompt response. I will try your suggestions. However I have 2 points to note:

My Ramp Weight was not 194.000 lbs, but 159,610 lbs arrived at as follows:

•      Basic Operating Empty Weight:        100,700 (CS number)
•      Payload Weight:                      40,410 (passengers, cargo, crew)
•      Fuel Weight:                    18,500
•      Total Ramp Weight:              159,610

I figure 1,000 lbs burned in taxi, so my takeoff weight would be 158,610 lbs approx. This is well below the Gross Takeoff Weight  published by CS (209,500) and even below the Maximum Ramp Weight published by Boeing (173,000). I would not expect to take off if I was 20Klbs overweight!

As or the speed brake lever not being active, I noticed that from day 1 on the CS product; not caused by your modified files.

Coming back to the weights issue, why in the world is CS using numbers that vary so much from the real aircraft?  I never had such problems with their C-130X. Why do they rely on external people such as yourself to solve their problems?

Michael

Looking again at the Boeing chart you supplied, I see the CS numbers match the highest numbers provided in it (rightmost column). So I withdraw my comment in the last paragraph about their choice of weights.

Sorry, I was in a hurry when I replied to your post and I mistakenly added your payload and fuel to the maximum zero fuel weight instead of the empty weight. By the way, the empty weight should be 97,650 lbs, not the number you mentioned.

The climb charts for a 727-100 at 160,000 lbs take-off weight show 19 minutes, so it looks like your climb, and the flight model was pretty accurate.

I don't think Captain Sim relies on anyone to tweak their flight models and I can't speak to how they develop them or what their goals are in that respect.  I do note, however, that they designed a sort of generic flight model to represent several different aircraft variants, so there is no way they can have real world numbers with that approach to the product.

Anyhow, I built my own flight model in an attempt to model one varient of the 727-200 that interests me and for which I have the necessary data.

Mark, Michael

As I indicated earlier, it seems that CS chose to model the Advanced version of the -200. So since I wanted to use the heavier version and the CS ACE, I decided to keep the original CS files, but modified the aircraft.cfg file as suggested by Mark. However Michael’s comments on engine settings, speeds and FPMs were still very useful, and I performed the flight successfully. Now, the aircraft climbed as it was supposed to.  It took me just under 20 minutes to reach FL310 from the time I started the takeoff roll.

As Michael suggested, I did the flight in clear weather. There was not as much variation in speed (in cruise) as when I was in real weather, but it still varied more than it does in other aircraft. This may have to do with a lack of precise control in my joystick throttle paddle, and the fact that those old jet engines were slow to react to any change in throttle input.

Mark, I do have a question on EPR and N1 values. Prior to making the change you suggested, the EPR could go as high as 2.3. Now I notice that with the new value, the maximum EPR I can reach, with throttles to the wall and N1 at 100%, is 1.98. Is that normal? I also noticed that after a few minutes, the EPR went down to 1.82, while N1 was still at 100%, and the throttle still all the way forward. Why the change? Is it Pt2 that goes up or Pt7 that goes down?

I also have a question on the EPR gauge. The manual explains that the Engine Pressure Ratio Setting Knob (13-15) sets “the reference index and the digital indicator to the preselected EPR value when the knob is pulled out to the manual position”. It also explains what it does if the button is pushed into the automatic mode. First of all, when I push on it, it always stays in manual mode; possibly the automatic function was not modelled? More importantly, when setting it manually to some value, I see the bug moves up to that value and the value is also shown digitally. Is that only to act as a reminder of some value we want to reach, or does it actually limit the EPR to the value selected?

Now all I need to do is to practice, practice, practice, particularly the takeoff and initial climb, so that my vertical path will somehow resemble the prescribed speed and climb rate numbers! In particular, I have trouble when switching from manual  control to the autopilot: as soon as I activate the AP, the aircraft pitches down into a descent! Not a good deal!

Thanks to both of you for all the help.

"I have trouble when switching from manual  control to the autopilot: as soon as I activate the AP, the aircraft pitches down into a descent! Not a good deal!"

I have the same problem, as you described. :(

There is no auto-function for the EPR bugs modelled.  The EPR bug is just to remind you of what power is needed for whatever phase of flight you are in.  You should use it for takeoff, climb and cruise and also for go around power on your approach. In climb, the EPR needed will change quite a bit as you climb, but you will not have to move the throttles much as the EPR will rise on its own to some degree with a constant throttle setting as you climb.  The bug does not in any way set power -- you do that manually with the throttles.

The EPR gauge is my mod is modelled to show EPR as a function of corrected N1.  What you see on the gauge is just N1, so on the gauges you see, the relationship between N1 and EPR will vary with ram air temperature and thus with outside air temperature, altitude and Mach, all of which will change a lot over the course of a flight.  The end result is accurate. The Captain Sim epr gauge does not give meaningful values for any engine variant if that is what you are using.

My flight model will only perform properly with the air file and and all aircraft.cfg changes and to be able to fly realistically you also need to install the EPR gauge use the thrust charts. If you pick and choose bits of it will not function as intended or accurately.

If you want to model an advanced version I suppose you can change the thrust and weights, but you then need thrust setting charts for JT8D-17s or whatever it is your modelling and my EPR gauge and turbine tables in the air file may very well not give the desired results because they were made to model a different engine variant.

By the way Asanal has sent me an email indicating that he has discovered his trim problems are connected to his yoke trim calibration and possibly third party software he is using to load the aircraft. It's nothing to do my flight model modification.

When you turn off the autopilot, the aircraft should stay in trim.  As I stated in another thread, none of my modifications do anything to affect trim or the autopilot operation.  And you can use the MAC gauge included in the package to ensure you your weight distribution is within reason.

Hmmm. I find it interesting to see that somehow I forgot to replace the original cs727200.air with the modified one provided. I'll have to put that in there and redo my tests. I just can't believe that I somehow skipped that. :(

Aside from that, using the original air file the 727-200 performed very well, provided it was not overweight.

I shall try again with the correct air file and let you know how I do.

Mark,

When installed Michael  727-200 EPR Mod, It did not function as 727-100.
I went through MOD  installation  item by item and I found like you I did-not insert new air file. After Air File replaced. EPR function was PERFECT.
Sanal

Thanks for your efforts here, Michael2. These modifications really add something to the good old 727. Good work!

I'm hoping that the thanks and praises towards your work here motivate you to continue since such testing takes a lot of time.

Thanks for your encouragement CoolP.  I'm doing the same for the 707 but it'll be a while since my wife and I just had a baby.  Not a lot of time for this right now.

Michael2 wrote on Feb 16^th, 2011 at 1:24am:

my wife and I just had a baby.

Congratulations to you and your wife Michael on the birth of your child. :)

Congratulations! All best wishes to you and your new family member!

Michael2 wrote on Feb 16^th, 2011 at 1:24am:

Thanks for your encouragement CoolP.  I'm doing the same for the 707 but it'll be a while since my wife and I just had a baby.  Not a lot of time for this right now.

Michael, think about it. Isn't a safe flight the best insurance for a new born human being?  :P

Just kidding of course. Take your time and congratulations to your latest and obviously greatest development. :)
I just wanted you to know that your work here is and will be very appreciated.

Congratulations Michael!!!!!!!


I haven't try this new model (got only 727-100 :() but if it works like the previous one (for sure it does), then it is an amazing!!!!! CS should include it in their future patches.

Thanks everyone for your kind words.

I just installed your fine mods for both the -100 and the -200.

Nice work!  Thanks so much for putting so much time and care into this.   Bravo!

Question-- is the TAT gauge reading in centigrade or fahrenheit?

Centigrade.

Question about modding this.  I downloaded both the -100 and -200 and read the readme file.  There is an "installer" app and the proposed mods to the .cfg file.  When I click on the installer I get an error that it is corrupted.

So, is all I have to do modify the various files by hand?  There's nothing else?  I've never modded an aircraft before, so I'm a little nervous, although it looks to be easy, but tedious work.

Best.

Doug

Can you name that installer file, Doug?
I didn't have such a thing and just followed the readme file.

Crap.  I just downloaded it again (I'm at the office and it looks fine).  I don't know what happened.

I think I can handle the cut and paste job unless someone wants to tell me that its harder than it looks.  

If you backup the original files before editing, there's no risk, but the outcome is really nice to fly.  :)

Just back up both aircraft folders before you start.   Make sure you put the gauges where they are supposed to go.   Modifying the Aircraft.cfg file, just have the readme file with the changes open side by side with the Aircraft.cfg file, and go one line at a time, and take your time.

There's no installer, sorry.  You have to do it by hand.

For some reason, certain ZIP/RAR type utilities seem to think that the replacement .AIR file is an installer, which it isn't.  You just copy this file that appears to be an installer into the aircraft folder, and let it overwrite the existing file.   I was confused by this same issue at first.

I have really been having fun learning more about prototypical operation of this bird thanks to these mods.  It's neat when everything happens more or less like it would in real life.

Thanks very much for the mods and making them available. Could I please have the link for the 100 version?

Much appreciated!

Cheers
Butch

The flight model mod for the 727-100 is here:

http://www.mediafire.com/file/mgim4k44wzz/...20mod%201.1.zip

Michael -

Thank you for the great mods, I have installed them both and they make flying the cs727 great.

2 problems (the but).
1. On the 727-100, the mac shows up as a (-) minus, number.  Did I do something wrong?

2. On the 727-200, the AP does not come up as it does on the 100.  It did before the mod.

Art Stuart

A minus number for the MAC% would indicate a very nose heavy aircraft, so either you made an error in modifying the aircraft.cfg so as to move the centre of gravity somewhere it shouldn't be or you are doing something wrong in loading the aircraft.  You should only use the Captain Sim Ace utility to load it.  Or yoo may have forgot to install the replacement air file which I seem to recall moves the centre of lift.

I'm not sure what you mean by the "AP doesn't come up." If you mean there's no popup when pressing shift-4, I guess you did something wrong in modifying the panel.cfg file when you enabled the MAC/TAT gauge.  

I got the same- a negative CG, both in the 100 and 200. I checked and rechecked the modding steps but couldn't find any error I could have done. The aircraft was loaded with ACE, in the 200 for example 104 pax and 3 cargo containers in each compartment.

Matze, can you post a screenshot of your "fuel and payload" FSX screen?
So I can set my plane to the same numbers and show you my MAC, staying in positive ranges.

Or I'll give you an example of mine, together with the MAC reading. I'm with Michael2 on this, there seems to be something wrong in your aircraft.cfg.
Here's my example of a loaded 727-100 Passenger version. 82 Passengers, 8 Containers (4 front, 4 aft) at 1102 lbs each.
20.000 lbs of fuel, 8.000 in the center tank and 6.000 in the wings.

http://img26.imageshack.us/img26/7536/payload7211.jpg

http://img864.imageshack.us/img864/9712/mac.jpg

Make sure that the aircraft config line "empty_weight_CG_position     = -8.5, 0, 0 "  was edited correctly.  Note the Minus sign in front of the 8.5 there.  

I edited my -100/F and -200/F files today, and accidentally left out the minus sign for that line.  That gave me the negative MAC reading that the OP seems to be getting.

Could somebody make a mod to make the 727 sound louder? For the noisiest jetliner, the CS model sure is quiet... It's one of my very few complaints.

Thanks for the mod! One problem though, after installing the TAT and MAC guages the autoplilot doesn't show up when I hit Shift + 4? Only the TAT and MAC guages appear. In the -100 everything shows up fine. Can anyone help?

Best regards
Tor

Is the 727-200 mod suitable for Freighter expansion pack??

liser wrote on Jul 7^th, 2011 at 7:41pm:

Is the 727-200 mod suitable for Freighter expansion pack??

I installed the mod for my 200-F and it works fine for me.  

Thank you! I'll give it a test.

Quote:

One problem though, after installing the TAT and MAC guages the autoplilot doesn't show up when I hit Shift + 4? Only the TAT and MAC guages appear. In the -100 everything shows up fine. Can anyone help? Best regards Tor

I had the same prob.  Worked great in the -100, but I only got the TAT and MAC in the -200.  My solution was to make all the suggested changes to [Window03] in the panel config file, but substitute this for the 6th line -- the one that references the gauge.

gauge00=..\..\CS_B727-100\panel\Captain_Sim.p721.P12!P12_001_ap, 0,0, 427,106

Since the -200 is essentially an add-on to the base -100, that appears to be where the gauge lives...in the -100.

Also, a very nifty work-around the sound problem was to be found in the "Sounds" thread of this forum.  On page 6 a post by CoolP suggests substituting the 707 sound gauge for the 727 sound gauge.  of course, you have to own the 707 to get the gauge, but by gosh, it works.  Sounds first time, every time, no double loading...just a couple of transient error messages that go away quickly and leave no aftertaste.  Check out the thread for details.

These two fixes have worked for me.  Your mileage may vary.

Gents,

Taking into account the company's data that simulate (Rio Linhas Aéreas), which used the 727-200F JT8D-17R engine with S3.

I changed the thrust of 14k to 17.4k, the MTOW for 201.300lbs (Because of the Hush Kit Stage 3) and the RPM of the N2 to the real value of 12.250RPM.

Only I could not change the sensitivity of the trim, does anyone have a tip on how to change? Why be trimmed by VC sucks!

[]s

If you have a registered copy of FSUIPC you can get complete control of the trim sensitivity.  I would give you my settings, but I had to delete them (temporarily) for another addon.

This has been just what I've been looking for.  I can't thank you all enough.  I had almost completely given up on Captain sim's 727 until now.  The epr cauges work as they should.  Now if any one can tell me how I can get the stab trim to move slower, MUCH slower, I may just be able to make this a flyable airplane.  I have FSUIPC but can't figure out how to get it to take control of the stab trim.  Thank you very much for what you've done & thanks in advance for any help with the stab trim feature.   Warm regards, Steve

Are you sure the mod is better than the original FM?

http://img43.imageshack.us/img43/5567/m20027.jpg

Hi Tanya, y know my query is on the wrong place but do not you know if a necessary update is coming? sorry but y love Captain sim 727 and y think an update is deserved.

David Paul wrote on Mar 12^th, 2011 at 8:44pm:

Make sure that the aircraft config line "empty_weight_CG_position     = -8.5, 0, 0 "  was edited correctly.  Note the Minus sign in front of the 8.5 there.   I edited my -100/F and -200/F files today, and accidentally left out the minus sign for that line.  That gave me the negative MAC reading that the OP seems to be getting.

In the readme.txt it says:

"empty_weight_CG_position     = -6, 0, 0"

I'm having problems with pitching up at takeoff. I set the trim as per the Trim Chart but have to fight to keep the nose under 20 degrees. Maybe this is my problem?

[quote author=AVIATor-Olav link=1296889437/30#39 date=1304680127]Thanks for the mod! One problem though, after installing the TAT and MAC guages the autoplilot doesn't show up when I hit Shift + 4? Only the TAT and MAC guages appear. In the -100 everything shows up fine. Can anyone help?

I had the same problem. The readme.txt says to add

"gauge00=Captain_Sim.p721.P12!P12_001_ap, 0,0, 427,106"

to the panel.cfg. My AP didn't work so I changed it to

"gauge00=..\..\CS_B727-100\panel\Captain_Sim.p721.P12!P12_001_ap, 0,0, 427,106"

and it works fine. I have no idea whether this might cause other problems so proceed with CAUTION, and maybe someone else can shed some light on this.

Great mod and thanks much for the work that went into it. This is one of my favorite aircraft and this is going to make it all that much better...

Thanks,
Bill

I downloaded this mod, but I can't get to the performance charts. The link in the download isn't working for me. Is it still working for anyone else?

Hi! I can email em to you. But thats odd, some perf tables included in zip file with mod, + you can get some more from boeing.com

send me your email via P.M.