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AI aircraft seem to go awefully fast...A question...

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Last night I thought it would be neat to follow a Westjet 732 on one of its flight plans. I left Winnipeg in my DF 734 - actually lining up behind it and following it down the runway on take-off roll. I had N1 at 104% in an attempt to keep up. The AI plane kept getting farther away. Once at cruise alt, I was going 500KTS ground speed and that little 732 was pulling away from me fast! :-eek The Westjet plans and a/c were produced by PAI. I do recall hearing about how fast the AI traffic is in FS2K2. Does anyone know if this is something that can be controlled, ie can we slow the AI planes down to reasonable speeds? I think it would be really cool to be able to follow another flight and have the other a/c on TCAS all the time.One other question that I would have posted on the PAI site, but couldn't get on...Do the PAI AI traffic go direct GPS from their dep to arrival airports, or do they fly a plan with VORS and intersections etc? If the latter, how can one find out the routes.Thanks a lot, Adam

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I agree that the AI planes fly faster than I can in a similar plane but I haven't found a fix yet. (To be honest, I haven't looked for a fix.) But, to your second question, the answer is, they fly a direct GPS; no air routes or waypoints. R-

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This question has been posted in PAI forum on september. The reason seems to be due to an excessive default cruise speed. For example in PAI files, speed cruise is set at 477 kts (TAS). But FS use this reference not as TAS but IAS. So it results an excessive speed. I fixed it with reducing cruise speed at 300 kts. So at FL340, AI jet speed will be around 480 kts.;)

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Does anyone know if this is something that can be controlled, ie can we slow the AI planes down to reasonable speeds?In the aircraft.cfg file for each type, there is the following Section:[Reference Speeds]flaps_up_stall_speed=full_flaps_stall_speed=cruise_speed=Edit the airspeed for cruise_speed and insert the IAS, not TAS, that you wish your aircraft to fly at. Note that this speed will be valid throughout the entire flight regime, not just at cruise altitude.For the B737-200 in your example I would enter 265, which equates to 0.72M or 422 TAS at FL310.One other question that I would have posted on the PAI site, but couldn't get on...Do the PAI AI traffic go direct GPS from their dep to arrival airports, or do they fly a plan with VORS and intersections etc? If the latter, how can one find out the routes.No one has yet identified a method for editing AI Traffic routes.Initially it was said that they fly Great Circle routes, but some observers claim that they have followed AI Traffic and noticed the aircraft performing distinct turns while in flight.As at now, routes are defined and flown by the internal FS AI Traffic engine.Stamatis

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This is an excerpt from an ICAO chart for the speed of sound at standard atmospheric conditions in knots, and the corresponding equivalent airspeed.FL, Mach1, EAS250 - 601.7, 403260 - 599.2, 396270 - 596.7, 387280 - 594.2, 380290 - 591.7, 369300 - 589.2, 362310 - 586.6, 353320 - 584.2, 345330 - 581.5, 335340 - 578.9, 328350 - 576.3, 320360 - 573.7, 312370 - 573.3, 306380 - 573.3, 298390 - 573.3, 290400 - 573.3, 285In order to properly set your AI aircraft speed, multiply the EAS number by the mach number you want it to fly and enter that speed in the cruise_speed column. For example, if you want your AI A320s to reach max cruise of .80M/460ktas at FL350, then set the cruise_speed to 256.Stamatis, I don't mean to start on you again, but if you would only do a test for yourself with some target TAS/Mach numbers versus the cruise_speed entry and checked the results with AI Tactical Viewer, you will plainly see that the number that the fs2k2 AI pilot calls its IAS is actually the EAS per your magic calculator.As for the AI routing, it does use great circle routes. It does also perform distinct turns. Those distinct turns that it performs after departure are to vector itself onto the great circle course between Airport A and Airport B. Upon arrival, it will be vectored and maneuver again to an "initial" point on either side of the final approach course from which it can perform an approximate 30 degree intercept onto final.

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Hi Kevin,Stamatis, I don't mean to start on you again, but if you would only do a test for yourself with some target TAS/Mach numbers versus the cruise_speed entry and checked the results with AI Tactical Viewer, you will plainly see that the number that the fs2k2 AI pilot calls its IAS is actually the EAS per your magic calculator.Hey, first of all you are not to blame, it was actually me starting on you :-)And I believe we agreed that AI Traffic indeed interprets the aircraft.cfg entry as EAS, not IAS. But I don't believe anyone here was interested in such a technical discussion. And since IAS is a far better known term than EAS, which would have most probably brought up questions, I used the known term :-)Where we did not agree (I think?) is that the instrument in the FS20002 panel actually displays IAS and not EAS. The fact that the displayed IAS needs a calibration (via the air file) is also realistic.But I guess we don't have to agree on everything, otherwise fora discussions would be very boring :-) Take care,Stamatis

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I had no idea you agreed with me on the EAS. Actually, I went back and took a good hard look at the airspeed indicator indications on player flown aircraft. You were correct about that aspect. They do display an actual "indicated airspeed", with compressibility factored in. I do not believe though, that either of the base or the weight line items in the airfile referencing indicated airspeed are related, as the effect was present on aircraft that did not have a factor entered into the base line and the weight is always nulled at -32768. The compressibility factor appears to be hardcoded into the indicated airspeed calculations. Any entry in the airfile only serves to impute an additional unrelated, user desired error. But if you're happy with your entries in the airfile, more power to you.But of course, this is completely unrelated to what to do with the AI aircraft. Anyways, the "265" you gave the person should have been "252" in order for the AI to achieve the .72M/420kts you stated at FL310. An entry of 265 would have caused the AI to fly at .75M/440kts at that altitude. That's the only reason I jumped in. That person would have been wondering why the resulting TAS always seemed to be 15% too high.

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Subsequently, you can goto each planes aircraft.cfg and lower the thrust.All 57000+ like values to 37000+ an 25000+ like to 15000+ lbsGives much realistic climbs.Johan[A HREF=http://www.phoenix-simulation.co.uk]Phoenix Simulation Software[/A]Unofficial PSS website:www.people.zeelandnet.nl/johdMy help may not me much usefull, or usefull much..eh?http://people.zeelandnet.nl/johd/index2/Ar...s/Leg1/klm5.jpgTrue Blue! K L M!

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Thankyou all for the help. I have gone into the .cfg files for several 737 models and changed the thrust from around 22000 lbs to thrusts ranging from 18000 - 19000 lbs depending on the specifica/c. I also changed the cruise speed settings from 411.??? to 280 - 295 kts, again depending on the a/c.I will try these settings. Thanks again, Adam

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Well my settings did nothing. I still couldn't keep up to the 732 - even with a lear jet!I will try reducing the cruise #'s even further to the ones you guys suggest. I'll try 265 and 252. If FS uses TAS, I wonder why the PAI programmers would put 411 Kts in the .cfg., though when I did lower it from 411 to 290, there really didn't seem to be any difference.I really haven't a clue what I'm doing, but I'll continue to try.Thanks again for your help guys, Adam

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The numbers you were first trying are way too high. 295 at 33000' is almost Mach .90 Look the Mach speed chart over and set a speed for @.74M .

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>................... Actually, I >went back and took a good hard look at the airspeed >indicator indications on player flown aircraft. You were >correct about that aspect. They do display an actual >"indicated airspeed", with compressibility factored in. I >do not believe though, that either of the base or the weight >line items in the airfile referencing indicated airspeed are >related, as the effect was present on aircraft that did not >have a factor entered into the base line and the weight is >always nulled at -32768. The compressibility factor appears >to be hardcoded into the indicated airspeed calculations. >Any entry in the airfile only serves to impute an additional >unrelated, user desired error. But if you're happy with >your entries in the airfile, more power to you. I investigated the airspeed 'Base' and 'Weighting' variables in AIR files. The 'Base' just sets an offset needed typically for slower GA AC such as a C172. -10 kts was fine. I found the magic value for the 'weighting' that set the IAS in the DF Archer very close to the CASIAS calibration table in the PoH. Where CAS=IAS only at 90 kts. It was close to the MS default for such AC. By changing the weighting value I could move the point IAS equaled CAS. For jets, I found that changing the default airspeed weight from -32768 to +32200 and setting the base offset to 0 gave IAS readings within a couple of knots of a table over a wide range of FL's and speeds. I especially want Mach number to be consistent with IAS readings around 250 - 285 kts, which are typical cruise values. Incidently, the IAS reading is also affected by Alpha and Beta, apparently by COS(ang) in each case. There is more than just compressability modeled. Ron

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> I investigated the airspeed 'Base' and 'Weighting' >variables in AIR files. The 'Base' just sets an offset >needed typically for slower GA AC such as a C172. -10 kts >was fine. I found the magic value for the 'weighting' that >set the IAS in the DF Archer very close to the CASIAS >calibration table in the PoH. Where CAS=IAS only at 90 kts. >It was close to the MS default for such AC. By changing >the weighting value I could move the point IAS equaled CAS. >Are you saying that by a combination of the Base and Weight, you were able to duplicate a typical instrument error profile on the airspeed indicator with the IASCAS at speeds higher than the crossover point?> For jets, I found that changing the default airspeed weight >from -32768 to +32200 and setting the base offset to 0 gave >IAS readings within a couple of knots of a table over a wide >range of FL's and speeds. I especially want Mach number to >be consistent with IAS readings around 250 - 285 kts, which >are typical cruise values. >What sort of table? Is this again an instrument error table you are talking about? One thing to remember though about the jets is that most of the more modern ones will have an ADC and the IAS that you read off your displays is actually already corrected for instrument errors and is in reality a CAS that we read in flight.So basically you are saying that the Base and Weight are to be used for building a true "IAS" profile with instrument errors. And that the speed indication we get when Base=0 and Weight=-32768 is CAS with all atomospheric/aerodynamic effects already accounted for.Thanks, I've been wondering what Weight was for.

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Hi Kevin,The compressibility factor appears to be hardcoded into the indicated airspeed calculations.Yes, this is what I had been trying to convince you about in the other forum. But their calculation in the code is wrong. Try out several IAS/TAS/Mach tests and you will see it yourself.To come closer to a more correct IAS one needs to edit the airfile entry. It will never be a perfect match throughout the whole flight envelope, but it can be a lot closer than default. A value between -7 and -9 seems to be the best fit.Stamatis

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I will look over the chart and make the appropriate adjustments. I thought to myself after I made the first adjustments...why didn't I listen to these guys and try the numbers they suggested the first time? :( The reason I initially tried #'s in the 290 area is that that's what I cruise at IAS in DF734 which roughly equates to, if I'm remembering correctly, about M.77 at FL320. The reduced thrust settings appeared to create a more reasonable climb. Still a bit fast though, so I'll probably drop them a bit lower too.The help is really appreciated!Adam

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Okay, that is fine, I have done the testing for myself. The data points from msfs that I got were closer to what the whiz wheel gave me than a -7 to -9 correction, with one data point exception where the number I got was over 12kts off what it should be. But that's ok, I agree with your point that compressibility is factored into the calculation of the displayed indicated airspeed of player aircraft but that there may be minor discrepancies between the display and what the user expects to see based on own flight computer calculations.My only argument with you was that for the purpose of AI aircraft control, which was the topic of the original thread, the cruise_speed entry needed to be an EAS number, and that you needed to run your magic calculator one more time after turning a Mach number into an IAS to convert the IAS into an EAS before you start advising other people on what number to enter in the cruise_speed line to a obtain a specfic desired resulting TAS/Mach. That was all.

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>> I investigated the airspeed 'Base' and 'Weighting' >>variables in AIR files. The 'Base' just sets an offset >>needed typically for slower GA AC such as a C172. -10 kts >>was fine. I found the magic value for the 'weighting' that >>set the IAS in the DF Archer very close to the CASIAS >>calibration table in the PoH. Where CAS=IAS only at 90 kts. >>It was close to the MS default for such AC. By changing >>the weighting value I could move the point IAS equaled CAS. >>>>Are you saying that by a combination of the Base and Weight, >you were able to duplicate a typical instrument error >profile on the airspeed indicator with the IAScrossover point and then IAS>CAS at speeds higher than the >crossover point? Yes. However, the default airspeed 'weighting' factor for SEL's such as the C182 is really OK as it is. >> For jets, I found that changing the default airspeed weight >>from -32768 to +32200 and setting the base offset to 0 gave >>IAS readings within a couple of knots of a table over a wide >>range of FL's and speeds. I especially want Mach number to >>be consistent with IAS readings around 250 - 285 kts, which >>are typical cruise values. >>>>What sort of table? I think it was in my Boeing "Performance Engineering Methods". A table that showed the effect of compressability error vs Mach Number or TAS. > Is this again an instrument error table >you are talking about? One thing to remember though about >the jets is that most of the more modern ones will have an >ADC and the IAS that you read off your displays is actually >already corrected for instrument errors and is in reality a >CAS that we read in flight. The CAS vs IAS error for the B727 is essentially zero, at least at 250 kts IAS. >So basically you are saying that the Base and Weight are to >be used for building a true "IAS" profile with instrument >errors. And that the speed indication we get when Base=0 >and Weight=-32768 is CAS with all atomospheric/aerodynamic >effects already accounted for. NO. **** Base=0 and Weight=+32200. ******=========================================== I had been setting Base to -5 kts in my jets, as Stamatis had determined gave a good IAS reading around 250 kts in cruise. However, that gave an error at approach and landing speeds. Stall speeds, Vref, etc would be off by 5 kts! Not good.>Thanks, I've been wondering what Weight was for. Use my numbers in all jets and I bet you will like them. I hope Stamatis also sees this.Ron

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Kevin,...before you start advising other people on what number to enter in the cruise_speed line to a obtain a specfic desired resulting TAS/Mach.Why this tone?This whole discussion started when in another forum you gave a list of EAS speeds and called them IAS. I simply corrected you, telling you that the speeds you call IAS are not correct. From then on you seem ######. It is not my fault if you can't tell the difference between IAS and EAS, and no, it does not take a "magic calculator" to calculate the corresponding IAS from Pressure Altitude and Mach, it only requires physics and math. No magic involved.So, please chill out, take a flight and keep enjoying flight simming.Personally, I am out of this thread.Best,Stamatis

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Please, there is no need to get upset, I did not mean to sound a "tone" there. The only reason I seemed "######" was that I was admittedly annoyed that you were insisting on a stance that was plain incorrect, such as mach having nothing to do with temperature, and the cruise_speed values that would have resulted in up to a 15% TAS/M error.I'm sorry you feel upset about it now, however I think the thread was good because 1. It proved out that the AI's IAS is actually EAS, which should be the value for the cruise_speed line and 2. I've gained knowledge of the use of the weighting entry in the airfile.I guess as long as you're out, I'm out too. Maybe I'll go watch a movie. I think "Changing Lanes" is out on video.

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