Dr_Arrow

OK, I solved it. After a lot of investigation I've found that Su-39 is nice and shiny. So I found out that by copying the *.json file of Su-39 to Su-25T, the T-Frog will also get some shiny/metallic effects - much better than the previous version and in line with other aircraft models. See screenshot:

I do not know if this gets noticed, but our Su-25T does not have any reflective surface on its skins - while the Su-25A has. Would it be possible to update somehow at least the default skin with a specular map to get a bit of shining effect, is there someone who could do it?. Without it, the aircraft looks flat compared to other FC3 aircraft. Thanks a lot for any help!

The altimeter is bugged, the small scale is not correctly calibrated in the sim. There is no such methodical error on the real Mig-21bis, which would cause the altitude be different by 1000 meters. I use the fix devised by Frederf here: https://forums.eagle.ru/showthread.php?t=212575&highlight=Altimeter

As of October 2018, it is still an issue, I've done several bombing tests, but could not find a pattern either when it happens and when not :(

Me neither.

I am using Warthog with the recommended curves (around 20) and have no problems in keeping the plane steady, even fly hands of if properly trimmed.

This would be great, can we somehow mod it?

With the new landing lights, it is now even worse. All AI wingmen fly with landing lights on, which really destroys immersion in night missions. Isn't there really any workaround for this?

I would rather like to see older Mig-21 versions like MF, PFM or F-13, which would fit in far more scenarios.

Unfortunately not, it is the same problem - AI is running at 99% throttle all the time and has even big problems to climb to 5000 meters. Seems like engine power at altitude is insufficient. L-39ZA works well.

This might be a broader problem with the AI. Although a completely different beast, L-39C has a similar problem, it simply cannot fly at higher altitudes, at 8000 meters it will fall out of the sky, while L-39ZA has no such problems (same engine, nearly same airframe, even heavier): https://forums.eagle.ru/showthread.php?t=218357

Well, stating that the project is not dead, does not sound very hopeful to me.

L-39C AI is not able to maintain level at 8000 meters and will stall the aircraft. It seems like the engine is not producing enough power, it is running at 99% but the speed decreases to 216 km/h IAS as seen in the screenshot. The same mission, same parameters, weather, AI, starting position just changed aircraft to L-39ZA and there is no problem: L-39C is starting to struggle above 3000 meters making the aircraft useless in nearly any sensible AI role, moreover if it gets to FC4. I hope it gets noticed here, as the L-39 BUG forum seems to be abandoned by devs, sorry for reporting it again. L-39c_cruise_8000_600.trk

At 8000 meters AI is not capable of flying at all and will stall and fall out of the sky. Does this really bother no-one? At 8000 the aircraft is falling out of the sky, it seems like engine power is not well defined or L-39C AI is using some bad flight model. AI L-39C is unusable this way in campaigns or anywhere above 2000 meters.

Still not fixed (or noticed) in the latest update - DCS 2.5.2.20601 Update 9 OB. I am also attaching a track showing flight of AI L-39C set to maintain 600 G/S at 5000m but barely managing 416 G/S with its throttle set to 99%, there must by something of in its AI flight model. AI L39-ZA is working fine, human L-39s are both working fine. L-39c_cruise_bug.trk

Although most simmers do not care about things like landing weight, for the real Su-25 it is specified as follows: It is absolutely forbidden to land the aircraft with total weight exceeding 13 300 kg, such landing is allowable only in emergency and all weapons that are jettison-able have to be jettisoned. The manual moreover states that landings with total weight more than 12 200 kg are allowable only in rare cases and can form only 3% of all landings, if this number is exceeded the aircraft has to undergo a major technical overhaul. Of course it is possible to land Su-25 even at 19500 kg, but you are putting the gear assembly tires and airframe over their projected stress levels. When landing with weight below 12200 kg, you can touch the runway safely at 230 - 240 km/h without problems and land on real wheels, aerobrake and than release chute without ever touching brakes, just like RL. DCS has a very good FM for Su-25 very close to published numbers. People often moan about flight models, minor cockpit details or small systems errors, but operate their aircraft in a way, which would be unimaginable in RL.

I have already posted that L-39C AIs are too slow: https://forums.eagle.ru/showthread.php?t=209586 This is some serious AI flight model bug which prevents use of L-39c in any realistic manner in missions as wingman or other tasks (recon, aerobatics, training, etc.). If you set AI L-39C to fly for example at 5000 meters at 600 G/S, its speed will continuously drop up to 323 km/h IAS, which translates to 417 G/S at standard ISA atmosphere. The AI has its throttle at 99% and is flying at 5.7 degrees of AoA and cannot attain any higher speed than 323 km/h. See the attached picture: Why is it a bug?? Because the L-39c in clean config should not have any problem to maintain cruise at 5000m at 464 km/h IAS = 600 km/h GS at standard ISA and if you change the aircraft to L-39ZA, which is heavier and has the same engine and nearly the same airframe it has no problem to maintain the set ground speed, it uses 90% RPM and flies at 2.9 AoA: This regards only AI flight model, which is correct for the ZA but not working for the L-39C, which seriously limits the use of this aircraft in AI scenarios.

Great, thanks a lot for your hard work. Let's hope it gets implemented soon.

Any advancement on this front? :pilotfly:

I suppose that for normal start-up, you would use only the DC socket. For maintenance, radar checks, etc. - both sockets would be used.

Nothing to apologize for, I am glad it is clear. Anyway AI should be able to keep up with this power setting without problems.

According to the manual cruise setting for the engine AI-25TL is 99.6% HPC (High pressure compressor) revs - Needle 1, see page 91. At 85% HPC revs at 4000 you will be going at 350 km/h or less, hardly a cruise speed. AI had the same power setting as me, but was doing only 400 km/h. Although this might translate to 85% of Low pressure compressor revs - but engine settings for AI-25TL are given for HPC as the LPC is not controlled and its revolutions vary.

Thanks for answer and thank you for all your hard work and fixes you've made. The current cockpit looks great :thumbup:

Recently, I've found that AI wingmen are not able to keep formation with me when flying L-39C. Yesterday I was cruising at 4000 m at 500 km/h IAS with engine set to cruise mode 99.6%. AI wingman was able to do only 400 km/h IAS and was trailing many kilometers behind. I think there might be something off with L-39C AI flight model or control logic.

Night lights in the cockpit are much improved in 2.5.2, however now the gear lights shine again through fuselage into the cockpit and light it up badly.