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Modified Concorde.air and Fuelburn.ini-files for more accurate Fuel Flow (v1.23) [UPDATE 27-04-2017]


Konstantin

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Konstantin

Hello,

As some of you know, I have been working on improving the accuracy of subsonic fuel consumption in Concorde-X. Having done some measurements, I have noticed that while the supersonic fuel consumption is very accurate, the subsonic fuel consumption at M0.95 deviates by more than 1000 kg/hr/e from the real-world counterpart at most altitudes, which is quite a lot. I have therefore taken some time to address this issue by modifying the Concorde.air-file and the very important fuelburn.ini-file.

Here is an overview of the changes and improvements made to the files (you can download them below):

 

Concorde.air:

- The wave drag at M0.95 has been slightly reduced to achieve a (needed) lower fuel consumption at that mach number at all altitudes. No changes have been made whatsoever to the supersonic drag (and all other mach numbers).

- The thrust gain from afterburners should be around 20% at lower speeds and progressively decreasing at higher altitudes and mach numbers. In the original air-file, the thrust gain from afterburners jumps up to 40% between Mach 0.0 to Mach 0.2, and then back to less than 10% at Mach 0.32. This has led to excessive afterburner fuel consumption during takeoff acceleration (reaching peak values of over 27000 kg/hr/e, as you can see in Ramon Cutanda's tutorial videos). Having watched a few takeoff videos made in the real-world Concorde cockpit, I have always seen the fuel flow needle rather stable at 22000-23000 kg/hr/e during the takeoff run. So I unless I'm missing something, I can't imagine that the pattern was realistic. I have equalized the thrust gain from afterburners to 20% during takeoff, so now the afterburner fuel flow during takeoff no longer reaches excessive values

 

Fuelburn.ini:

- The most important part of the modification of the fuelburn.ini-file is to match the subsonic fuel consumption better with real-world values. The real-world values can be extracted from this chart that seems to have been officially used by Air France. My goal is obviously to get the figures in Concorde-X as close as possible to the values in the chart. (Note: the table with the measured values that was listed previously is no longer valid, since the fuelburn.ini-file has been updated. Check the updated information below).

- I have smoothed out some jumps of the fuel flow coefficient at low speeds and altitudes, preventing an excessive fuel consumption during approaches (many times, I had over 8000 kg/hr/e during final approach, while in Concorde videos from the cockpit (including the ones with Captain David Rowland in the well-known and comprehensive ITVV DVD), I have rarely seen the needle exceeding 5000 kg/hr/e).

- [UPDATE 15-04-2017]:  According to the French chart that lists the specific distance for different weights and altitudes at subsonic speeds, the specific distance should increase by 0.02 NM/1000 kg for each degree Celsius ambient temperature below ISA, and decrease by 0.02 NM/1000 for each degree Celsius above ISA. This was very poorly (if at all) reflected by the original AND my previously modified fuelburn.ini-file. (I only tested the fuel flow under ISA 0, assuming that the figures for ISA+XX and ISA-XX would be fine. I was wrong!)  I have spent a good chunk of time adjusting the fuel flow for different temperatures, and I think that the results are quite good considering the limitations of the table structure. An updated table with the measured fuel flows and real-world target fuel flows for different altitudes, weights and temperatures can be found below. This table can help you see the improvements over the original fuelburn.ini-file, and you can find out what figures to expect on your flight.

- [UPDATE 15-04-2017]:  There is a problem with the supersonic fuel consumption under some circumstances. Since the release of v1.3, Concorde-X reads the fuel flow at altitudes above FL430 (where Concorde flies supersonically) no longer from the fuel flow coefficients as with subsonic speeds, but from direct fuel flow values for given altitudes, temperatures and weights that correspond to the real-world figures (if you open the fuelburn.ini-file and scroll down, you can see those values). While this is a good idea and sounds like it provides the best possible accuracy, there are unintended consequences in some situations. For example, unlike with simple fuel flow coefficients that can be altered for 30% N1, 50% N1 and 100% N1, there is no smooth and proportionate interaction between the listed fuel flow figures and the thrust lever setting (or the N1 number): The values in the table actually take effect at a thrust setting of 100%. I have seen quite often that decreasing thrust leads to an increase (!) in fuel flow at some altitudes and weights (e.g. FL540 and 120T), because when the throttle setting is reduced, the airplane apparently starts to use the simple coefficients instead of the directly listed figures to calculate the FF, and it seems like there is a mismatch between the two. I have modified the simple coefficients for high altitudes and mach numbers in a way that avoids an increase if fuel flow when you pull back on the throttle lever under the above described circumstances.

- [UPDATE 15-04-2017]:  Another problem with the direct values is that the weight directly affects the fuel flow, while it should only be affected indirectly. What I mean is that, for example, if your weight is 160 T and you have your throttle all the way forward climbing through FL450 using Max Climb mode, the fuel flow will be 6412 kg/h/e (assuming ISA 0). However, if you change the weight to 120 T (e.g. by jettisoning fuel), your fuel flow at the same altitude will change directly to 5648 kg/h/e, although you have not changed the throttle setting. In the real-world, the rate of fuel burned by the engines should not directly depend on aircraft weight (the engines don't care how heavy the airplane is, their fuel thirst primarily hinges on the thrust setting, pressure altitude, ambient temperature and velocity). The established fuel flow at Mach 2 and constant altitude for each weight should be taken care of by aerodynamics (lighter weight -> lower thrust setting -> lower fuel flow, and vice versa). The direct values entered in the table seem to refer to the cruise fuel flow (where the rate of climb is very low), and they don't allow you to achieve the correct climb fuel flow at full throttle that is obviously higher than the constant-altitude cruise fuel flow (due to the issue described in the point above). In the original state, you can achieve perfectly correct amounts of fuel consumed ONLY if you take off at near MTOW and transition to the supersonic regime quickly. However, if you take off with lower weights, your total fuel consumed will be too low because of the described problem. (To avoid the problems listed in this point and the point above, I would actually suggest to the developers of Concorde-X to remove the direct FF values in the lower part of the fuelburn.ini-file and resort back to the simple FF coefficients in the future, but have the values adjusted correctly and tested - I would be willing to do that). What I did in the update is to achieve the correct, identical fuel flow figures during supersonic climb at full throttle irrespective of the aircraft weight (except when the ambient temperature is unusually cold, and the airplane climbs faster than expected). The only disadvantage of this undertaking is that you won't get most accurate fuel flows if you intend to fly M2.00 at lower altitudes than the airplane is capable of (i.e. not having the throttle levers at max.). However, if you use "MAX CLIMB" and/or "MAX CRUISE" mode in combination with full throttle, the autopilot will let Concorde climb continuously, and for this purpose, the adjustment is perfectly suitable.

- [UPDATE 15-04-2017]:  On many of my previous flights, I ran into instances where during the deceleration from a supersonic flight at the deceleration point, the fuel flow at a throttle setting of TLA 18° (and then >18°) was hardly lower than during M2.00 cruise (for example, coming from a fuel flow of just 4500 kg/h/e at FL580, I had 4000 kg/h/e after I pulled back the throttle lever to slow down, but the descent rate was -4000 ft/min). With the update, I have reduced the fuel flow coefficients for low N1 values, which gives you lower idle fuel consumption during deceleration from supersonic flights.

- [UPDATE 15-04-2017]:  I made some additional small adjustments to have more consistent fuel flows at lower altitudes over a wide range of speeds.

- [SECOND UPDATE 15-04-2017]:  Established file version for better reference, added file version number in the fuelburn.ini-file, corrected one little inconsistency for FL370 between ISA+30 and ISA-30.

- [UPDATE 18-04-2017]:  Corrected the erroneous ground idle fuel flow error from the previous modifications (was 1400 kg/h/e, now is 1100 kg/h/e, as it should be).

- [UPDATE 27-04-2017]:  Tightened the deviations between the Concorde-X subsonic fuel burn figures and the real numbers at FL350 for all weights. Updated the Excel-table reflecting the new figures, and the table also indicates the deviations in absolute values and percentage changes.

- [UPDATE 27-04-2017]:  Reduced the fuel flow at high KIAS (350+ kts) between FL100 and FL200. (It was too high in the previous state, e.g. if you flew 395 KIAS at FL200 at light weight, you consumed almost twice as much as if you flew 395 KIAS at FL250. Now you consume a little less than that).

 

[Update 2017-04-13: Important Information for FSX SP2 users]

If you use FSX SP2, you will NOT be able to take full advantage of the improved fuel flow figures during subsonic flights! The reason is that FSX Acceleration introduced table 154a in the .air-file of supersonic airplanes, which allows adjustments of the wave drag vs. Mach number at variable Mach intervals, while the old table 430 only allows to do so at fixed Mach intervals of M0.2. FSX SP2 and previous releases/simulators (including FS2004, FS2002 and FS2000) are totally unfamiliar with the new table and only rely on the old one. Because the main part of my modification of the Concorde.air-file was done on table 154a, you will not reap full benefit if you DON'T use Concorde-X with either of the following simulators: 

FSX Acceleration
FSX Gold Edition (which is basically FSX + FSX Acceleration)
FSX Steam Edition
Prepar3D (any version)

It is not possible to have table 430 modified in a way that reflects the improvements by table 154a due to the less precise nature of table 430. The consequence is that when you use a simulator not listed above, the wave drag at M0.95 is still too high (and with it the fuel flow), while the sound barrier at M1.00 is too weak (meaning that you break too quick through it).

You can check the following source for more information:
http://www.fsdeveloper.com/forum/threads/fsx-acceleration-air-file.10602/

In this regard, if you use FSX SP2, I highly recommend upgrading your simulator to one of the above versions.

 

[General information]:

Note that if you downloaded the fuelburn.ini-file before the updated information on 27-04-2017, please redownload that file. Note that no changes were made to the Concorde.air-file with the update. I hope you will like these files and be able to achieve a more accurate fuel consumption during subsonic- and supersonic flights. I may update the files in future if needed - I will certainly notify you about it. Have fun flying!  (Oh, and don't forget to make a backup of the original files!). If you wonder where to copy the files, here are the directions:

Concorde.air:   [FSX or P3D root folder]\SimObjects\Airplanes\FSLabs_BAe-Concorde

FuelBurn.ini:    [FSX or P3D root folder]\FSLabs\Concorde\Fuel

 

Here are the files (latest version of the fuelburn.ini-file is v1.23):

Concorde.air

FuelBurn.ini

Concorde Fuel Burn Table 27-04-17.jpg

  • Like 12
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Ray Proudfoot

Thanks afterburner. Appreciate the effort you put in to make Concorde even better! :)

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Fraser Gale

Let's hope the graph is correct haha! 

The CCM has tables for flight levels where it states N2, fuel burn and true airspeed against weight so when I have time to do more flying I will cross check the new fuel burn.

 

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Ray Proudfoot

I've just completed my subsonic test flight from EGLL to EIDW. 100pax, FL340, Mach 0.95, TOW=115T. Previous afterburner fuel data in brackets...

EGLL 24390 (24531)

CPT 21047 (21325)

MEDOG 17546 (15445)

ABLIN  15950 (14055)

EIDW 14222 (12567)

CPS-X calculated 14338 on landing so the new fuel burn figures are extremely accurate for this flight at least. Well done afterburner. :)

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Konstantin

Wow, I am happy to hear that the figures on your test flight were so close to the value calculated by CPS-X (which, as you stated, is based on real-world Concorde data). Looks like this is indeed a great tool, which I should definitely give a try on my next flight ;)

I would say that striving for accurate fuel burn figures in each flight regime makes a positive contribution to having realistic amounts of fuel left after landing. When I modified the values in the FuelBurn.ini-file, I made sure to avoid radical changes and adjust the values gently but decisively, trying to change as few figures as possible, but as many as necessary in a sensible way. Taking on a radical approach can easily screw up other parameters, so it is not a good idea in my opinion. Let me know if you notice any other important discrepancies between the real-world figures and Concorde-X with the original or the modified files that you wish to have a look at.

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Ray Proudfoot

afterburner,

I tried another subsonic flight this afternoon. EDDM-LEPA (Munich - Palma de Mallorca). Fuel consumption was far greater than CPS-X calculated. But looking at the EFB flight log there was a short period when fuel consumption went through the roof. I'm not sure why.

I'm going to fly it again and see how it goes. Probably later in the week. I'll keep you posted. I must remember next time to change the engine control to Flyover instead of Normal. Easily forgotten when you have a million things to do.

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Konstantin

Could you make the EFB flight log available?  I want to look at it and figure out when and how the fuel consumption went through the roof. I don't want to have any obvious outliers in the files, so I will correct them if something is not right with the numbers.

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Ray Proudfoot
2 minutes ago, afterburner said:

Could you make the EFB flight log available?  I want to look at it and figure out when and how the fuel consumption went through the roof. I don't want to have any obvious outliers in the files, so I will correct them if something is not right with the numbers.

Here you are. Hope it helps but I'm not sure there's enough info to assist.

https://dl.dropboxusercontent.com/s/keavkvox3r9wabz/EDDM_LEPA_20170410_1559.pdf?dl=0

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Konstantin

I looked at the log, and it is quite puzzling to me why the fuel flow went through the roof when you were climbing from 11000 ft to 19000 ft. I just did a short test with takeoff and climbing to 20000 ft, and I didn't see any abnormalities. Maybe it could have something to do with the fact that I used the virtual flight engineer on my test flights, while you were flying without?  Also, the math somehow doesn't add up. Consuming 3 tons of fuel in 3 minutes is a lot, but it equates to a fuel consumption of 60 tons/hour and not 112.2 as stated in the log. By the way, what remaining fuel amount did CPS-X predict?

[Addendum: Also, according to the log, you had 23071 kg in your tanks after 15 minutes of flying, and then 10534 kg one hour later (at 1:15 after takeoff). During that one hour, you have consumed (23071 kg - 10534 kg =) 12537 kg, which is actually consistent with the values in my table (=3134 kg/hr/e), but the log lists higher figures for some reason. I wonder what algorithm the log software uses to calculate the consumed fuel...]

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Ray Proudfoot

That's why I was reluctant to provide details until I had tried the flight a second time. CPS-X predicted 14.2T on landing. Clearly something went very wrong but it's far too early to point any fingers until I've flown the route at least one more time.

The fuel flow at that waypoint is just a snapshot and I've never seen a rate so high. EFB seems to grab the correct data from FSX. It accesses the default FSX values rather than anything from within Concorde. It uses SimConnect I believe.

Anyway, let me fly it again on Wednesday and see how it goes. if you want the route here it is:-

ALG DCT UMTEX UQ227 ULMES DCT KOGAS UQ209 BALSI UQ211 VATIR UN852 PIVUS DCT VERSO UL129 LUNIK

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Konstantin

Ok, let me know how the flight on Wednesday will be.

One more aspect to ponder: When you flew the short route EGLL - EIDW, you took off with 24390 kg according to your data, and the flight must have taken 0:36 hrs (I am taking this figure from your log in a different thread). The EDDM - LEPA flight takes exactly one hour longer, but you have only taken ca. 8300 kg more fuel compared to the EGLL - EIDW flight. However, if you intend to spend one additional hour in the air and land with the same remaining fuel as before, you need at least 13000 kg of additional fuel, but only 8300 kg more was taken on your trip. So here, I doubt that taking off with 32600 kg fuel is enough to cover a distance of 711 NM in 1:36 hrs and land with 14200 kg... (that would require an average fuel consumption of 11500 kg/hour including takeoff, reheat, climb, etc. - but this is lower than the consumption during cruise @110 tons @M0.95 @FL350.)

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Ray Proudfoot

Yes, I agree that something doesn't add up when you break it down like that. But CPS-X has not failed me during extensive testing so it would be very strange if it did now.

At least with EFB we have a record of fuel used so it should be a relatively simple job to see what's gone wrong after my next flight.

Taxiing was further at EDDM and the pushback was quite slow but it doesn't explain why I had so little fuel on landing. 

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Konstantin

To get back to your EDDM - LEPA flight, out of interest, I have performed a manual calculation of the expected approximate amounts of fuel needed in each flight segment based on the flight time in your log. You will find the breakdown of the math in the image below. I have used commonly known fuel burn figures for each segment. 

As you can see, the amount of fuel required between takeoff in EDDM and reaching the waypoint VERSO is 22051 kg as per the calculation. According to your flight log, it took you [32613 kg - 10534 kg] = 22079 kg to get there, which is very close to the manually calculated expected value. (I have not performed the calculations for the descent and landing, since the fuel flow is low and variations are small). I would say that even if I subtract 1000 kg from my calculation to have a generous margin of error, the amount of fuel you have consumed on your flight is within expectations and not far off from what the real-world Concorde should have consumed. In this regard, I can't see how the fuel amount computed by CPS-X is correct...

EDDM - LEPA.JPG

 

[EDIT: Looks like the expected fuel flow numbers used in the above calculation are a little overestimated after all. I did not fully take into account that you took off with a light weight and that the time between slamming the throttles forward and the noise abatement procedure is rather 1 minute instead of 1:15. Here is a recalculation based on fuel flows for a lighter takeoff weight (125 T)]:

Takeoff with reheat                              -> 23000 kg/h/e -> 1:00 m -> 1533 kg -> 1533 kg
Noise abatement climb to FL110         ->   8000 kg/h/e -> 3:00 m -> 1600 kg -> 3133 kg
Acceleration to VMO, climb to FL190  ->   8000 kg/h/e -> 4:00 m -> 2133 kg -> 5266 kg
Climb to FL271 (to ALG)                     ->   8000 kg/h/e -> 2:00 m -> 1067 kg -> 6333 kg
Climb to FL340 (to UMTEX)                ->   7000 kg/h/e -> 3:00 m -> 1400 kg -> 7733 kg
Climb to FL350 (to AKABI)                  ->   4000 kg/h/e -> 2:00 m ->   533 kg -> 8266 kg

Cruise AKABI - VERSO                       ->   3100 kg/h/e -> 1:00 h -> 12400 kg -> 20666 kg

The calculated value is 1400 kg less that what you consumed, but that is still not worlds away from it.

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Ray Proudfoot

Hi afterburner,

Thanks for that info above. Fuel consumption seems fine then. I'm flying the route again now. Should land in an hour or so. Only change this time was changing engine to flyover instead of normal.

CPS-X calculated 33881Kg fuel. That doesn't include 400Kg of ballast fuel in Tank 11 which of course can't be used. Does that sound a reasonable amount? CPS-X has always been all right with fuel calculations.

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Ray Proudfoot

I've landed at LEPA. Fuel remaining was 9976Kg. CPS-X estimated 14200Kg. Less fuel used than yesterday but still too much according to CPS-X. I'll have a chat with Pierre.

Log attached so you can compare and calculate fuel burn. Oh, my FL today was 340 compared to 350 the other day. Not sure if that makes much difference.

I maintained 250kts to FL100 and thereafter increased thrust to maintain 395kts reducing as required to maintain Mach 0.95. Flyover mode enabled on Engine Schedule.

https://dl.dropboxusercontent.com/s/7i4szs2bsjfs6bn/EDDM_LEPA_20170412_1352.pdf?dl=0

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Konstantin

To me, it looks like the amounts of fuel consumed are well within the expected region (from taking off to reaching VERSO, you have consumed 20200 kg - very close to what I calculated above). The spike in fuel flow @AMEXO must really be a glitch by EFB, otherwise you would have much less fuel left after passing that waypoint.

I would be interested in the formula that CPS-X uses to compute the required trip fuel.

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Ray Proudfoot
1 minute ago, afterburner said:

To me, it looks like the amounts of fuel consumed are well within the expected region (from taking off to reaching VERSO, you have consumed 20200 kg - very close to what I calculated above). The spike in fuel flow @AMEXO must really be a glitch by EFB, otherwise you would have much less fuel left after passing that waypoint.

I would be interested in the formula that CPS-X uses to compute the required trip fuel.

Thanks ab. Pierre is away this week but when he returns next week I'll ask him about CPS-X fuel calculations. It appears to be accurate with shorter subsonic flights (EGLL_EIDW, 35mins) but not on a longer one (EDDM-LEPA, 1h 30m).

I know it's modelled on r/w data so should be spot on really. I agree about EFB's probable glitch. Same place as last time but AT1/2 were engaged.

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Ray Proudfoot
2 minutes ago, AdrianSmith said:

Does CPS take account of forecast winds and do they correlate to actual winds on the route?

Yes of course. It uses either NOAA data (default) or AS16 if you own that. CPS-X doesn't store any data when you process a flight plan so it's not possible to compare. It just presents an average wind speed and whether it's a tail or head wind. Average deviation of ISA is also shown for supersonic flights but not for subsonic.

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Konstantin

The information in the first post has been updated.

Ray, please read through it, as it contains important information for FSX SP2 users!

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Ray Proudfoot

Thanks afterburner. It seems that unless I move to Steam or P3D I'll have to live with inaccurate fuel burn. Now some better news. As a beta tester I have asked for a licence for P3D and assuming it's granted I intend to switch to P3D v3 quite soon. I fully accept that Concorde will never be as accurate in FSX:SP2 as P3D and that's despite the best efforts of your good self and the FS Labs team.

My decision has come about after upgrading my 780 GTX 3Gb card to a 1080 GTX 8Gb and seeing no improvement in fps in FSX. Time to update to a modern simulator that can take advantage of all the things now available to us.

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Konstantin

Well, this is good news then. Most modern GPUs are an overkill for FSX anyway (whether it's just FSX SP2 or Steam Edition), simply because FSX is heavily CPU bound. Even DX10 doesn't help a lot on that front. I think the decision to move to P3D v3 is a wise one, because you will able to enjoy better visuals and achieve a smoother performance at the same time, while saving on VAS. Let us know when you will make the transition.

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Ray Proudfoot

Within an hour of making the request Lefteris had issued me with a coupon for P3D. :) Concorde now downloaded. I shall purchase P3D tomorrow and then start the transition. It might take a while to get all my scenery downloaded and installed but that can be done in slower time. P3D and then Concorde first.

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Konstantin

OK guys, I have made an update to the fuelburn.ini-file. This was a massive undertaking, and it took me almost a whole day to do the modifications and testing (it took longer than the first modification)!  This time, I have not only improved the accuracy of temperature changes on the subsonic fuel flow, but I have also addressed some issues with supersonic fuel flow that are explained on the first page. Be sure to redownload the new file.

I know it sounds crazy, but I just want to have the fuel burn figures as close and balanced as possible to the real thing once and for all. I don't regret having invested the time, for it is a tribute to an aviation icon! :)

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Pierre Chassang

Excellent job Afterburner,

Your work will allow me to check (with the help of Ray) the CPS-X sunsonic fuel predictions with a better accuracy.
I'm actually working on modification of the wind integration into this calculation.

With your permission I'll add you files into our download web page.
Let me know.

Congratulations.

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AdrianSmith

Any chance that a short thread with just the latest .air and .ini files can be made into a sticky, in case there are further updates and to make them easier to find?

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Konstantin
12 minutes ago, Pierre Chassang said:

Excellent job Afterburner,

Your work will allow me to check (with the help of Ray) the CPS-X sunsonic fuel predictions with a better accuracy.
I'm actually working on modification of the wind integration into this calculation.

With your permission I'll add you files into our download web page.
Let me know.

Congratulations.

Thank you, Pierre!  

Yes, you are welcome to add the files to your download web page. I'm looking forward to the new CPS-X. 

And I agree that making the thread sticky would be a great idea, otherwise it may "sink" at some point.

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Pierre Chassang
54 minutes ago, afterburner said:

And I agree that making the thread sticky would be a great idea, otherwise it may "sink" at some point.

Of course...;-)

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Konstantin

Hi Pierre, thank you for uploading the files on your website. Make sure to update the fuelburn.ini-file when there is a new version available (as today with v1.22). I will work hard to lessen the frequency of updates (since it can be time-consuming for you to update as well), but the latest one is important, since it rectifies the slightly messed-up idle fuel consumption on the ground from the previous modification. I appreciate the cooperation!

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Steve Prowse

 

@afterburner

Many thanks for all your input to our community Afterburner, (any danger you might consider using your real name as required by FSL forums).  After reading your paragraph  on FSX SP2:

 

"  [Update 2017-04-13: Important Information for FSX SP2 users]

If you use FSX SP2, you will NOT be able to take full advantage of the improved fuel flow figures during subsonic flights! The reason is that FSX Acceleration introduced table 154a in the .air-file of supersonic airplanes, which allows adjustments of the wave drag vs. Mach number at variable Mach intervals, while the old table 430 only allows to do so at fixed Mach intervals of M0.2. FSX SP2 and previous releases/simulators (including FS2004, FS2002 and FS2000) are totally unfamiliar with the new table and only rely on the old one. Because the main part of my modification of the Concorde.air-file was done on table 154a, you will not reap full benefit if you DON'T use Concorde-X with either of the following simulators: 

FSX Acceleration
FSX Gold Edition (which is basically FSX + FSX Acceleration)
FSX Steam Edition
Prepar3D (any version)

It is not possible to have table 430 modified in a way that reflects the improvements by table 154a due to the less precise nature of table 430. The consequence is that when you use a simulator not listed above, the wave drag at M0.95 is still too high (and with it the fuel flow), while the sound barrier at M1.00 is too weak (meaning that you break too quick through it).

You can check the following source for more information:
http://www.fsdeveloper.com/forum/threads/fsx-acceleration-air-file.10602/

In this regard, if you use FSX SP2, I highly recommend upgrading your simulator to one of the above versions".

 

My question is; is there any benefit for those of us using FSX in using your updated files, or should we just use the default .ini and .air?

Cheers

Steve

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Konstantin

Hi Steve, good question!  If you use the updated files with FSX SP2, you will achieve better subsonic fuel flow than with the default files, but not as good as if you used any of the above listed simulators (meaning that your fuel flow figures will be higher than those stated in my table). However, when it comes to supersonic flights, the afterburner fuel flow and the impact of temperature deviations from ISA +0 on the fuel burn, the improvements outlined on the first page also apply to FSX SP2. I hope that answers your question.

(BTW, my name is Konstantin if you want to address me with my actual name) :)

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Kyprianos Biris
On 15/4/2017 at 10:15 AM, AdrianSmith said:

Any chance that a short thread with just the latest .air and .ini files can be made into a sticky

As I see it has just become sticky ;)

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Konstantin

Okay Gentlemen, here is another update to the fuelburn.ini-file (v1.23). It's nothing dramatic, but it makes further improvements to the accuracy, which I will elaborate in the following.

With the previous modifications, I was a little bothered by the high deviations at FL350. If the airplane was very heavy, the subsonic fuel burn was 11% less than it should be, and when the weight was most efficient for the altitude, the consumption was almost 15% more than in the real world (at ISA+0). With the update, I have tightened the deviations a little bit, so that the spread between the two figures is less (9% less at 170 t vs. 10.9% more at 110 t). While it is theoretically possible to tighten this spread even more, it would magnify the side effects, such as too high fuel flow at high N1 values and too steep of a reduction when the throttle levers are pulled back to reduce N1. This is due to the limited increments (or "resolution" so to speak) in the table between the coefficients for different N1 values. The present state already is a trade-off that requires sacrifices on both ends, so that the side effects would outweigh the gains if I were to attempt to tighten the deviations further. On a positive note, the values are still much closer to the real-world figures than with the original files despite the deviations. By the way, I have updated the Excel-table that reflects the new figures.

Another aspect that is improved with the modified file is the fuel flow at high KIAS speeds and low altitudes (FL100 - FL200). In the previous state, if you flew at 395 KIAS at these altitudes while the aircraft weight was light, you consumed almost twice as much fuel as at FL250. Now the consumption is not as high at FL200, even though it is still considerably more than at FL250 (at least at light weights. When the aircraft is heavy, the story is a little different). If you fly at lower KIAS (310 kts), the difference is much less. Again, if I try to lessen the fuel flow at low altitudes and 395 KIAS, then the figure becomes unrealistically low at 310 KIAS, and vice versa. So you see how this is a balancing act around the trade-offs.

Personally, I expect this update to be final, because with the current structure of the .ini-file, I can't see much potential for further improvements. So go ahead, download the new fuelburn.ini-file, and enjoy squeezing out a few more miles from the Concorde!  (Note that no changes were made to the .air-file, which has been unaltered since the first post).

PS: Pierre, if you would be so kind to update the file on your website one more time...  :)

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Konstantin

You can find the links in the first post at the bottom above the table.

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  • 2 years later...
Ray Proudfoot

Hi @Konstantin, I've just completed my longest flight with my now fully functioning Concorde. A flight from GCTS to KMCO. 3452nm in 3h 32m. But what impressed me was the fuel burn using your modified files.

Calculated fuel remaining by CPS-X was 11.278T. Actual was 11.3T which is incredibly accurate. Your calculations are spot on. Together with Pierre's CPS-X they make flying Concorde a real pleasure. :)

Oh, and with two third party airports and UT Live Ai I even managed to have 263Mb of VAS remaining when I parked. :D

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Konstantin

Hi @Ray Proudfoot,

It has been three years ago that I modified and uploaded the fuelburn files, but I am very happy to learn that people download and use it to this day and that the results are quite accurate. The efforts that were put into the modification paid off!  I am also glad to see that you are enjoying your flights CTD-free after having nearly given up on Concorde a few weeks ago...

Until we get a 64-bit Concorde, regardless which platform it will be made for, this is the best you can currently get. Again, thank you very much for providing a positive feedback!  I am always open for it.

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