Advanced Flight Model for other aircrafts!
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Hi there,
First of all, i’ve started this thread with the role and wishing to bring the advanced flight model in the hands of other flyable aircrafts within Falcon BMS, and also bringing this to be the first sim ever, to have all of it’s air combat aircrafts (subsonic and supersonic) adapted to this new flight model! DCS from ED doesn’t yet have an AFM for supersonic aircrafts nor for any other fighter, so BMS still rules the sky!
So, by now i already know that the one of the masters behind this brilliant advanced flight model project, is our Falcon’s beloved flight model engineer, Mav-Jp! As i’m also about to graduate the next year, becoming an aircraft engineer, and my greatest passion of all remains that to learn aerodynamics and flight mechanics…, cause i already am an active pilot! Though i already know enough aerodynamics that i’ve learned over the years, i still need to keep on learning, yet so far, i’d like to bow before Mav-Jp’s knowledge in this area!
For stating the idea of what i want to do, i’m looking forward to ask Mav-Jp for the permission of modifying a combat aircraft and sending it’s data file up here to be tested and verified and hopefully accepted as a new AFM aircraft, in fact i only want to update it’s specific aero coefficients (especially the CL, CD and Cm) that i’ve obtained using CFD (inviscid flow) on the aircraft’s wing design only (not the hole aircraft), wing that has it’s real airfoils for root and tip, also done various other tests for comparison at different Reynolds number on each airfoil (using the lift line theory, viscous flow CFD)…, the results of the inviscid tests i have then corrected/adjusted using empirical models with a mathematical program that i’ve made, while the final result is staying within an error between 0.1-4% (not more) of a realistic value!
The combat aircraft that i’m working right now on, is the MIG-23 Flogger, and i hope to finish it as soon as possible and upload it for testing where i’ll be told to!
I’m still working on tweaking a little bit the obtained CD and Cm and hopefully comming to a “common agreement” with the “.dat” file which doesn’t allow me to use more than a given number (don’t know what the limit is and where is it dictated from) for the Num Alpha and Num Mach at the aero coeffs tables (Mav-Jp knows better what i’m saying) for which i’d like to use a lower increment and have a more precise control over the steps between alpha numbers and mach numbers of the aero tables, because if that number’s value is higher than it can accept, i’ll get a “Send, Don’t send” message when trying to launch the sim, so i can’t work that easy with it!I’m willing to help in any way i can within the aerodynamical and flight dynamics aspects, so i’m looking forward to know if i may or may not work/help on this intend! Therefore i’m asking for Mav-Jp’s permission to do so!
Ok, so meanwhile i’ll leave you with a nice and old video, of how was the MIG-23 and MIG-27, built and tested to the limit!
Cheers and best regards for all the Falcon BMS’s community,
Maverick! -
BMS is an F-16 SIM … FLCS code is based on F-16 one. So whatever the a\c is… the FLCS will be F-16.
As far as I understand the team orientation, BMS is not suposed to “replace” FF and objective is not to implement all a\c. -
Couldn’t it be a more “accurate” OFM for the AI ?
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IF i learn how to i will. But possible with a small program for AFM creating is to be good
Thanks.
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Hi once again,
Yes, i understand that the AFM has been initially created for the F-16 only, due to simulating a complex/FBW FLCS mainly…, but the pitch control can be partially overriden if you modify some values in both the OFM and AFM files of the same aircraft, so you may have an AFM aircraft, with little FBW effect!
Now as another discussion, to talk a little about the F-16’s instability, that most people talk about saying that you can’t fly it at all without the FBW! At least in what the simulator shows…, i’ve already tested this on the F-16, and it’s not difficult to fly it even if the FLCS won’t limit your AoA anymore (eighter positive or negative), or the elevator not making any more adjustments to control the pitch rate or pitch accelerations, which easly end up in a pitch departure, but even so i was able to also land the aircraft as safely as normally, by not passing any limit! So yes, it is more difficult to fly an F-16 if your inputs are not filtered(no onboard computer to take care), as you may depart the aircraft if the roll rate, pitch rate and AoA level exceeds a certain value, but it’s a lie to tell that you can’t fly it at all:P, as the aircraft, even if it’s statically relaxed(slightly negative), below +20 AoA it tends to pitch down as long as the elevator is in null position!
Best regards,
Maverick! -
First there can be only one AFM and that will remain the f16.
You can use the new FM code to be used by other aircraft (like i did for the mirage 2000) but that will never be AFM. That is for semantics.
Secondly, you will never be able to nullify the FLCS from the data files as many many gains are hardcoded and you have a very limited number of parameters extenalized in the data files. As far as FLCS is concerned the NASA model originally built for AFM will certainly be more flexible for you.
Anyway before talking about flcs, we should talk about aeromodeling first.
Before starting to think about using the new FM code and hid Aero moduke it is abolutly mandatory that you work first on CL,CD and thrust tables and ensure that they are producing accurate EM performances.
When you reach that point you cans start thinking to the next step i.e. all other AFM Aero coefficients. I am a little bit surprised to read you take the Cm of the main wing only because the Aero model included in BMS does not fit with that at all, Cm depends on deltah and then therefore depends on elevator action.
Have you read the TP1538?
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Unortunatly i won’t have time to help you really as i don’t have time anymore for this
Anyway i strongly think you should follow those 3 steps:
- create hffm for your AC (CD, CL, Thrust) no need AFM files here, use OFM
- create Aero AFM data based on the NASA TP1538 modeling ( i think the best is to start from F16 data and tweak them as i did for m2k as it is impossible to calculate them from scratch or find them in the same modeling)
- tweak NASA flcs to unleash you model ( i will give you more details when you will be at that step)
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Does the mig23 have a FLCS? If not, why would he need to integrate it to the f16 NASA FLCS?
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@mAXpOWER:
Does the mig23 have a FLCS? If not, why would he need to integrate it to the f16 NASA FLCS?
Because you can not by pass FLCS with new FM code unless you use nfbw model (like a10) which i don’t advise (experimental Aero module).
I could envisage to create a way to by pass flcs with NASA Aero model though
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Hi Mav-Jp,
Thank you for reading my post, and first of all thank you for giving me the option to do what you are asking me for this concern! About the Cm…, it’s the crude Cm given to me from the 3D wing for a non-viscous flow, therefore it isn’t the final Cm as you probably talked about, which should first take into account the Deltah tables (which i believe to be the dependecy tables for the lift produced by the elevator at different alpha and beta angles, so please correct me if this is wrong) which will create a pitch momentum, that finally will be translated into one main Cm!
Nope i haven’t read the NASA’s technical paper TP1538 yet:(, but i’m doing so atm! After this i’ll try to focus on the CL, CD and Thrust tables as a primary task and test them on OFM for their performances, after which i’ll reply here with what i have achieved!Thank you very much Mav-Jp, and i’ll give you more details after i will come to that step!
Best wishes,
Maverick! -
Because you can not by pass FLCS with new FM code unless you use nfbw model (like a10) which i don’t advise (experimental Aero module).
I could envisage to create a way to by pass flcs with NASA Aero model though
Maybe experimental but useful.
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Hi molnibalage,
Yes, if i were able to make it through the A-10’s AFM and adjust it for my a/c, things would’ve been a lot easier now, but after i’ve wasted a lot of time trying to figure out the more complicated stuff from that AFM, i was forced to stick with what i had…, the F-16’s AFM for MIG-23! Although yes, the A-10’s AFM is without doubt a much better choice for 2 reasons: 1. It simulates flatspins and roll/yaw departures; 2. It uses an augment control system(not FBW) which can probably be easier to override and negate any input filters between the stick and control surfaces (anyway, even the MIG-23 still has some input filters, but are very soft anyway)
Cheers!
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Hi molnibalage,
Yes, if i were able to make it through the A-10’s AFM and adjust it for my a/c, things would’ve been a lot easier now, but after i’ve wasted a lot of time trying to figure out the more complicated stuff from that AFM, i was forced to stick with what i had…, the F-16’s AFM for MIG-23! Although yes, the A-10’s AFM is without doubt a much better choice for 2 reasons: 1. It simulates flatspins and roll/yaw departures; 2. It uses an augment control system(not FBW) which can probably be easier to override and negate any input filters between the stick and control surfaces (anyway, even the MIG-23 still has some input filters, but are very soft anyway)
Cheers!
Tsss tsss dont worry , NASA aero modeling (f16 AFM) of course can simulate spins , roll
Stall and EVERYTHING you will need. don’t worry with FLCS when the time will come I will give you the possibility to disable it completely or even use a SAS.A10 Aero module is just too much complicated to masterize and dot not bring more than NASA aero modeling. Use NASA one , period.
Anyway I doubt you finished already CD CL Thrust
Did you read TP1538 now ?
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Hello friends. I am not any kind of engineer, and do not understand too much what you are talking about (CL, CD and Cm CFD FBW) but I would like to ask, if possible:
Please can you try to tweak a little the F22 FM?
Is there a way to make thrust vectoring in Falcon 432 ?
Thanks and I hope don’t have wrote bullshits. -
Hello friends. I am not any kind of engineer, and do not understand too much what you are talking about (CL, CD and Cm CFD FBW) but I would like to ask, if possible:
Please can you try to tweak a little the F22 FM?
Is there a way to make thrust vectoring in Falcon 432 ?
Thanks and I hope don’t have wrote bullshits.You worry about FM? Come on mate finish model first
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LOL Cemil!!!
RAM22
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Hi,
First of all i want to apologize for the almost “one year late” response from me, as i was suppose to quickly send some data for the MIG-23’s aerodynamic coefficients (CL and CD vs alpha from Mach=0 to Mach=2.5), but i honestly didn’t have enough time to finish and refine them at that moment, so i ran very busy with other things!
Now i have finally managed to finish and gather all the aero data for these coefficients, not for the MIG-23ML alone, but also for the MIG-21 and F-4!
I want to send 4 files for these planes, which are: 3 OFM (one for each aircraft) and 1AFM for the MIG-23 only, where i tried, as far as i could comprehend the new AFM’s data, to replicate a more realistic motion around the 3 main axis, with a corresponding static stability of the 23.
The only problem is that i can’t seem to be able to upload them…, for some reason i get an “invalid file” error when trying to upload a .dat file or any other file.
The reason why you will see some drops in the CL vs Alpha diagrams (at least one for high sweep angles), is to simulate the partial flow separations which occur depending on the wing’s shape, within some given ranges of the AoA. So as this is a realistic behaviour of not just an airfoil, but more to a 3D wing, i’ve also included these effects within the polars and lift slope vs alpha derivatives.
About the thrust data (at least for the MIL and AB power), i can say i didn’t have much occasion to find valuable information like diagrams and charts, specifically for each engine, at least for the MIG-23’s one, yet i tried to obtain this data as well for all altitudes and speeds and now i hope it is a bit closer to to real values, for all the 3 aircrafts here. Although there is a question about how where the F-16’s (AB alone) thrust data obtained, because as far as i know, or at least for what some data agrees, is that the the static thrust for the GE F110 (sea level, Mach=0) is around 28000lbf (for F-16’s block 30, 40, 50), while for the PW 220 is around 24000lbf or for the PW 229 is 29200lbf (which equip the blocks 15, 25, 32, 42, 52). Why are all the static thrust values (for the F-16 at least) at sea level much lower than those real ones?
I’ve also read the NASA’s TP 1538, which gave me some valuable information only in some certain areas regarding the F-16 only, while the rest of the information is a known fact for an aerodynamicist or aircraft engineer.
I know it will not be perfect, but at least i can share the data i could obtain and therefore see what’s next in order to have these birds given a better flight envelope behaviour, especially for the aero data.
With honest respect,
Maverick!P.S.: Tell me what has to be done so that i can upload these files! Thank you!
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In the mean time…! After i’ve been testing the new AFM on the MIG-23ML (L comes from lightweight) to see whether or not does it’s flight envelope for manoeuverability (sustained and constant turn rates at given altitudes and weights) and accelerations replicate the real Flogger G’s characteristics, and after watching the ACMI, i was happy to see how close the now modified MIG-23ML, takes shape around the real one. I’ve also conducted some simulated dogfights using the AFM on the 23 against the newly modified MIG-21 and F-4E with their corresponding aero data, although i didn’t take any more time to try and play a little with the AFM on them also…, but from what i could see…, the outcome is very close to what is told within the 23ML’s manual! The MIG-23 has better acceleration and slightly better turn rates than the F-4 and also the MIG-21. It’s as good as it can get so far.
Here’s a useful site regarding various information about the MIG-23’s:
http://backfiretu-22m.tripod.com/id16.htmlWithin the simulator, we also have to modify the technical data, which for the moment corresponds to the less performant MIG-23M or MF (as also the 3d model of the plane, with that extended dorsal fin), and change it with the real ML’s specs, part of which can be found on the same above site.
Have a good day!
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Great news!
About the files, you will probably need to upload the files to a host, i use rapidshare, or there might be someone on the forum with a ftp who can help.
Anyway, great job!Cheers
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OK
Please send the files
As far as testing , unless you tested human vs human, dogfight means nothing as AI brain is unable to maintain speed properly
You need to draw EM charts to compare performances
As far as f16 thrust is concerned, they have been retroengineered based on accel and EM charts.
You can check, BMS f16 performance are matching the real perfectly.
I don’t trust at all anything we can find about f16 thrust because the real information is not public. Retro engineering from accel charts gives you real perfs
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Beside i will add that
Between Mach 0 and Mach 0.2 thrust values of BMS are somehow interpolated as there is no accel curve from 0
And
Noeone knows what the conditions are when they announce thrust for an engine. Most of the time this is given at high speed where the thrust is the highest
Anyway accel curves and EM are the best way to match real perfos