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This report details inconsistencies in the DCS F/A-18C Hornet's flight model behavior at high Angles of Attack (AOA), especially the stability and controllability derivatives, comparing public wind tunnel data by NASA, and other papers. Issues: 1. Minimal Adverse Yaw: At high AOA (around 40-50 degrees), the aircraft exhibits minimal adverse yaw during aileron deflection rolling maneuvers with MSRM activated. This is unrealistic, as real Hornets experience significant adverse yaw at these AOA due to asymmetric induced-drag generated by both the aileron and the differiential stabs. 2. Excessive Roll Control Authority: At high AOA, the ailerons & differiential stabs appear to retain an unrealistic amount of roll control authority. Real F/A-18C Hornets experience a reduction by more than a half in roll control effectiveness at high AOA compared to those at 0 AOA, according the Cl-δA chart from NASA. Note that this also doesn't include the contribution by the differiential stabs. 3. Excessive Yaw Stability: Check post below. 4. Lack of departure quality: There's a lack of nose-slice and sideslip excursions that can result in a falling leaf OCF. Supporting Evidence: The report "AERODYNAMIC PARAMETERS OF HIGH-ANGLE-OF-ATTACK RESEARCH VEHICLE (HARV) ESTIMATED FROM FLIGHT DATA" (NASA TM 202692 with a link https://ntrs.nasa.gov/api/citations/19900019262/downloads/19900019262.pdf) provides real-world aerodynamic coefficient data relevant to the F/A-18C. Specifically, the following parameters are crucial: Cl-δA: This coefficient represents the rolling moment generated by the aileron deflection. A decrease in this value at high AOA signifies reduced roll control effectiveness. Checked by ED. Cl due to differential stabs: Not included in the NASA document. But worth checking. Cn-δA: This coefficient represents the yawing moment generated by the aileron deflection. A positive value at high AOA signifies adverse yaw. Checked by ED. Cn due to differential stabs: Not included in the NASA document, so the total amount of adverse yaw moement should be higher than a single Cn-δA. Cn-β: Check post below. The data from this report can be used to compare with the current flight model's behavior and identify discrepancies. Testing Information: MSRM (manual spin recovery mode) is used for separate control surface manipulation. Turn on the MSRM switch to the rightside of the right DDI before testing. Thank you for your time and consideration. Video link: https://packaged-media.redd.it/uk23tvykr6uc1/pb/m2-res_480p.mp4?m=DASHPlaylist.mpd&v=1&e=1713337200&s=f9d5e02a332e95290ab60fe357a05fb884d866ab#t=0 F18 no adverse yaw at high AOA.trk

The Flight Model of the BGM-109 Tomahawk is broken. While I was operating my mission on the current version(DCS 2.9.3.51704) of the DCS world, I found that the BGM-109 Tomahawk missile was flying at a weird altitude (launched > start level flight at around 3000ft > climbing > hit 8000ft then dive with a shaky maneuver to hit the target) and trajectory compares how it used to. It used to fly at an altitude of ASL 164ft and then pop up 7NM before hitting the target. (please check the 4.9 Mb attached Tacview file / Game version : DCS 2.7.15.26783 ) I attached the test mission on the latest version of DCS World to this post. (1.5Mb Tacview file, 117Kb track file, 9Kb mission file) Please check this problem and I hope this bug is being fixed soon. Tacview-20220709-212501-DCS-Operation Be the Maverick v.06 by 8KIDD8.zip.acmi bgm109 fm test 001 .trk Tacview-20240409-064053-DCS-BGM109 test 001.zip.acmi BGM109 test 001.miz

Up at 45000, full burner, I encountered some interesting autopilot behavior: 1) Coupled mode is fine until it hits the selected heading, where it oscillates, making corrections in roll back-and-forth for more than a minute before gradually settling into the heading. 2) This behavior does not exist for Heading Select, where the autopilot behaves predictably, steering to its heading accurately without oscillating in roll 3) Engaging BALT at 3 degrees nose down causes such a severe vertical oscillation, centered on the horizon, that the aircraft nearly departs. I have not tested to see the effects if left on, but I will. Structural failure seems likely. It's that violent. 1 and 3 are so extreme that, if the real aircraft were to behave in such a manner, there'd be an ops bulletin in the latter case (like, "don't engage BALT at high altitude within normal parameters") and likely a software update in the former. Ship was at half fuel, 6 AMRAAMS, 2 Sidewinders. Anyone else tried these things with the new FM? Thoughts? I'll repeat this tomorrow and attach some vids if necessary

After over a year of refinement, trial and error and learning from other flight model projects, I present to you the successor to my previous FM project. Basic External Flight Model (EFM) template! This is an enhanced version of the EFM template provided by Eagle Dynamics, with emphasis on simplicity and editability while also feeling smooth and believable. This FM template was designed to work "out of the box", designed like a two-engine subsonic trainer/fighter. What is included: Lift, drag, side, and thrust forces. Axis and discrete (keyboard) pitch, roll, and yaw controls with trim. Landing gear, flaps, slats, and air brakes. Engine startup/shutdown. Basic fuel draining system. Basic damage mechanics. Semi-realistic stalling, Dutch-rolling, and other oscillations. Infinite fuel and easy flight options. Example parameter to interface with the Lua environment. Lots of comments explaining how things work. The template itself and a pre-built .dll file can be found on GitHub! https://github.com/IGServal/DCS-Basic-EFM-Template Requirements: Microsoft Visual Studio (2019 was used to create this, but other versions might work as well). Basic understanding of C++, Lua, and flight physics. Feedback, bug reports, and suggestions are always appreciated!

After several months of trial and error and learning from other flight model projects, I present to you: Serval's custom Flight Model mod! Credit goes to CptSmiley for creating the prototype F-16 FM that I edited to make this. You can find that here: What is this mod? Every player-controlled aircraft in DCS needs a flight model (FM) along with it. For a while, modders used the FMs from Flaming Cliffs 3 (FC3) aircraft for their mods. At some point last year, an update came along that made those files encrypted, leaving modders with the terrible default FM. The idea behind this mod was to create a flight model that imitates the Su-27/33 "game" flight mode behaviour used along with FC3 style cockpits for unofficial, community-made mods; as a replacement for the awkward and jittery default flight model (I seem to be one of a few people to notice how awful it is. see this post of mine for a demonstration of it: https://forums.eagle.ru/topic/264462-default-flight-model-is-awful-with-video-demonstration/?tab=comments#comment-4591944 ) I am not a programmer or aerodynamics expert; so I apologize if anything looks weird. Now, before I share the files, please read the following warning: DO NOT USE THIS MOD TO FLY OFFICIAL AIRCRAFT. BUY THE MODULES AND SUPPORT THE DEVELOPERS! The files can be found here: CustomFM mod v7.zip Here's the source code. It may take some time for me to update this after the main mod. Now you can fly smoothly without awkward jittering at high angles of attack! Have fun! Be sure to check the follow the instructions in the .README file and give feedback if you have any! Here's a few things that are still in the works: - Cockpit controls; as of now the stick, throttle, and rudder pedals don't move at all despite input. - Engine startup behaviour. - Autopilot. If you wish to integrate this into a mod and redistribute it, go ahead but please give credit to me and Cpt.Smiley. If you wish to modify the source code and re-release it under your name, you may do so; but again, please give credit. Version 2 changes: + Improved engine on/off logic. + Idle RPM is now 50% instead of 25%, afterburners now ignite at ~92% instead of ~85%. + Control surfaces now move smoothly. + Flaps (for aircraft that have them). + Digital or "keyboard" pitch and roll controls are faster. + Improved FBW stability and anti-stall logic, death spirals are now a lot less likely to happen. + Behaviour on the ground is now a bit more realistic, it now takes a bit longer to achieve takeoff speed (~300 Km/h). Version 3 changes: + Improved ground handling. + Smoother FBW stability. + Tail hook functionality (for planes that have one). + More realistic flap and air brake aerodynamics. Version 4 changes: + Reworked stability system, much improved dogfighting performance. + Improved afterburner thrust. + Corrected wheel positions and springs. + Cleaned up the source code, including more comments. Version 5 changes: + Autopilot! Sadly, no route-following mode (yet). + Damage modeling. Wings, tail, and engines have their own effects on flight behaviour when damaged. + Using wheel brakes no longer leaves skid marks. Version 6 changes: + Smooth engine startup and shutdown (at last!) + Slightly tweaked autopilot. + Stability system now behaves a bit more like the Mirage-2000 and MiG-29. + Controls are a bit more responsive, especially downwards pitch. + Pitch trim is slightly faster. + Flaps generate a bit more lift. + Fixed a bug where altitude and roll hold autopilot doesn't reset when restarting a mission. + Damage modeling has been tweaked and made (somewhat) more advanced. Version 7 changes: + Much stall recovery and post-stall behaviour, unrecoverable spins are pretty much impossible now. + Better analog roll control. + Slightly tweaked damage stuff. (ps: this is the first mod I have ever published!)

Subject. I do not have any real data, but these oscillations look and feel weird when doing a basic crank maneuver. Oscillations are less violent when you are slower. Added: on 0.9M it feels nice and smooth. I think the current FCS implementation can't keep up on 1.4+. Have added second track with full stick deflection. F-18-oscillations.trk F-18-oscillations2.trk

Hello Could someone give me an idea of what the flight models in DCS "look like" and how they are integrated with the DCS engine. What are the inputs and outputs? What data from DCS are accessible for mods and what data is not? Are the FMs a set of equations with different inputs and outputs? Are the FMs a set of tabulated values for each possible flight case? Are they something else? I'd very much appreciate if examples could be provided either as screenshots, formulas or code. All answers are very much appreciated!

DCS Mi-24P QuickStart RU.pdf DCS_Mi-24P_Weap_Summ_Logic_ver5.pdf

Hey, something must be a bit faulty with single engine performance. In helicopters, if troque is the limit, you can take double engine performance and multiply it times two to get your single engine power. So i compared some numbers while taking one engine to idle in flight (tried with engine 1 and engine 2): double engine power = 2 x 30 % TRQ single engine power = 1 x 80 % TRQ (should be 1 x 60 % TRQ) double engine power = 2 x 40 % TRQ single engine power = 1 x 112 % TRQ (should be 1 x 80% TRQ) Find the attached trackfile to see what i mean. SINGLE ENGINE PERFORMANCE BUG.trk

All charts are sourced from SFI AJ 37 del 3, 1979 print. Test flights were flown in ISA, using weights as close as possible to those described for each loadout (remembering that the AJS is somewhat heavier than the AJ), either start weight or flight weight depending on what the chart in question described. LEVEL ACCELERATION Tests were run at 0km, 6km, and 11km in ISA conditions only. Each test included two runs (one by myself, one by Airhunter) with clean config/rent FPL. In addition, I ran a second set of 0km tests with a group 3 loadout (4x ARAK + XT), and 6km tests with a group 4 loadout (4x SB + XT). Two tests were run at 11km with the loadout stipulated in the manual, one by myself and one by Airhunter. Airhunter provided me with tacview files and graphs which I then charted against the manual (obviously only for the clean config 0km and 6km tests, and the 11km test). On my own end I forgot to save tacviews, but did save trackfiles, which are attached as well. The results show what I'd found myself: At sea level, mil thrust is maybe a touch slow to accelerate to M 0.9 but is still relatively close, and zone 3 is tuned almost on the dot. Zone 1 and 2 show discrepancies, particularly zone 1, although they aren't very large at this altitude. Excuse the rather unscientific graphs, but unfortunately just overlaying the ones from tacview wasn't really workable and I'm working with what I've got here: At 6km alt, mil thrust gradually diverges from the chart, ending up a little slower than expected. Zone 1 and 2 show large discrepancies. Zone 1 follows zone 2's curve, zone 2 follows zone 3's curve, and zone 3 is doing something else entirely. At 11km alt, only zone 3 was tested. The results were very far off the expectation: according to the chart, level acceleration from M 0.9 to M 1.6 should take about 5 minutes and 45 seconds. In the sim, this was achieved in just one minute (!), while acceleration from M 0.9 to M ~1.63 (as far as the line is drawn) should take about 7 minutes and 15 seconds, while in DCS it took 1 minute and 15 seconds. This is a very large discrepancy even compared to the aircraft's own charts, but also compared to acceleration profiles of other aircraft known to have phenomenal performance in this area (F-104, MiG-23, MiG-29). Something is clearly causing an issue here but I don't know what. Big thanks to Æck for spotting this one during a MP session and bringing it to light - I wouldn't have thought to test it otherwise. Finally for now, THRUST/DRAG EQUILIBRIUM SPEEDS AT SEA LEVEL This has been something I've been meaning to report for a while, but invariably by the time I got trackfiles, DCS would update and break them. As a result I'll just post the results of my testing now and drum up the trackfiles when I get time. Please note that this is separate to, but was compounded by, the now-fixed drag issues with Sidewinder launch rails. Each test was run using the circled loadout group from the AJ 37 loadout tables - so rent FPL was clean, group 1 was KA-24-XT-24-KB, group 2 was KA-24-XT-blank-04, group 3 was RA-RA-XT-RA-RA, group 4 was SB-SB-XT-SB-SB. All loadouts except group 4 (bombs) reach thrust/drag equilibrium above the intercept of MAX ZON 3 lines and thrust/drag lines, some significantly so. Group 4 is slightly slower than expected, the clean airframe flies beyond even SAAB's estimate for a world speed record using a stripped and polished modified aircraft, groups 1 and 2 are beyond the aircraft's Vne and fall off the chart, and group 3 (which should be the slowest according to the chart - just barely subsonic, likely due to the rocket pods generating enormous amounts of transonic drag compared to anything else tested) is sitting slightly above the aircraft's Vne. It seems drag values need looking at. I don't have trackfiles handy for these tests (the ones I did have are now several DCS patches old), but I do have tacviews for them. I can get tracks again if necessary. I haven't checked climb performance yet, but hopefully there won't be anything to add for that. OWN TRACKFILES.zip Tacviews from Airhunter.zip drag tests.zip

I'm experimenting with the creation of a custom flight model. I got the FM template, but I can't find any tutorials or guides on how to implement all the functions into DCS. By "functions" I mostly mean engine control (throttle), landing gear, flaps, etc. However, pitch, roll, and yaw with trimming work just fine out of the box.

I've seen a couple mods with smooth flight behaviour thanks to custom flight model binaries. The best example I can see is Freebirddz' Su-30 mod ( https://forums.eagle.ru/topic/247098-dcs-su-30mmk-mod/ ) The default flight model for custom aircraft feels too static and awkward, so I am impressed by mods with these flight models. I'm wondering if there's a template (preferably a .sln file) somewhere I can use to make my own.

I honestly can't believe this is such a hard thing to fix. It's been known since ages, and still we have the wrong airspeed values being displayed on the HUD in all modules. At high speed and altitude there's a difference of as much as 200+ knots between what's displayed on the HUD and the actual CAS that ***should*** be shown instead. I like the new clouds and all that, but can we at least get our basic flight instruments to work correctly??