FishBike Posted October 21, 2014 Share Posted October 21, 2014 I'm not sure if this is a bug, but I'm noticing a sudden loss of engine thrust whenever I fly about 15,000m altitude. For example I will fly up to 10,000m and then begin acceleration up to Mach 2.0. I can climb at that speed until reaching 15,000m and then suddenly my airspeed will decrease as if I had pulled the throttle back to idle. Descending below 15,000m, everything goes back to normal. Link to comment Share on other sites More sharing options...
TurboHog Posted October 21, 2014 Share Posted October 21, 2014 High altitude performance is still being tweaked. There is a big thread about it here: http://forums.eagle.ru/showthread.php?t=130722 Last patch actually improved some of the problems reported already... 'Frett' Link to comment Share on other sites More sharing options...
Britchot Posted October 21, 2014 Share Posted October 21, 2014 I'm not sure what I've been doing wrong but I'm having issues getting the MiG over Mach 1.1 when I'm clean. [sIGPIC][/sIGPIC] CPU - Intel 8088 @ 4.77 MHz; Memory - 128KB; 360KB double-sided 5 1/4" full-height floppy disk drive; 10MB Seagate ST-412 hard drive JG-1 MiG-21bis Checklist Link to comment Share on other sites More sharing options...
Fishbreath Posted October 26, 2014 Share Posted October 26, 2014 I've been up to Mach 2.05 at 11,000 meters. You have to be at high altitude to see Mach 2, and subsonic and low supersonic acceleration is poor at altitude. If you're able, go supersonic at 7,000 meters or so, and try to stay supersonic until you've reached about 10,000 meters. You should be able to hit top speed pretty easily there. If you can't do a supersonic climb from lower altitude, make sure you're starting no lower than the recommended climb speed (870kmh true airspeed). The faster you're going, the faster you'll accelerate past the difficult transonic and low supersonic regimes. Black Shark, Harrier, and Hornet pilot Many Words - Serial Fiction | Ka-50 Employment Guide | Ka-50 Avionics Cheat Sheet | Multiplayer Shooting Range Mission Link to comment Share on other sites More sharing options...
Vinny002 Posted November 11, 2014 Share Posted November 11, 2014 Hi, guys! I'm having the same issue too with the speed decreasing at around 15,000 meters even at full afterburner. Does anyone else have this problem? Thanks! Cheers, Vincent Link to comment Share on other sites More sharing options...
Kaiza Posted November 11, 2014 Share Posted November 11, 2014 (edited) Sounds like the tropopause may be modeled in dcs world. Did you take note of your OAT? Temperature does not increase with altitude above the tropopause which impacts performance. Edited November 11, 2014 by Kaiza [url=http://www.aef-hq.com.au/aef4/forumdisplay.php?262-Digital-Combat-Simulator][SIGPIC]http://img856.imageshack.us/img856/2500/a10161sqnsignitureedite.png[/SIGPIC][/url] Link to comment Share on other sites More sharing options...
Vinny002 Posted November 12, 2014 Share Posted November 12, 2014 Hi, Kaiza! Is that right. No, I didn't take note of my OAT. I read in this forum about the cruise performace, the Mig-21bis is said it flew straight and level at an altitide of 62,404 feet or about 19,000 meters or 19 kilometers. Thanks! Cheers, Vincent Link to comment Share on other sites More sharing options...
iFoxRomeo Posted November 12, 2014 Share Posted November 12, 2014 Hi, guys! I'm having the same issue too with the speed decreasing at around 15,000 meters even at full afterburner. Does anyone else have this problem? Thanks! Cheers, Vincent Which speed? IAS or TAS or MACH. And what are your speeds at 15km? Sounds like the tropopause may be modeled in dcs world. Did you take note of your OAT? Temperature does not increase with altitude above the tropopause which impacts performance. You surely mean "Temperature does not decrease with altitude above the tropopause..." As it decreases with increasing altitude up to the tropopause. Hi, Kaiza! Is that right. No, I didn't take note of my OAT. I read in this forum about the cruise performace, the Mig-21bis is said it flew straight and level at an altitide of 62,404 feet or about 19,000 meters or 19 kilometers. Thanks! Cheers, Vincent Vincent, please state the source for "...the Mig-21bis is said it flew straight and level at an altitide of...19 kilometers." The flight manual of the "Bis" version mentions 17,5km with two missiles and 700l fuel as ceiling altitude at fulll reheat. It can reach higher altitudes with zooming, but this is not "straight and level". Fox Spoiler PC Specs: Ryzen 9 5900X, 3080ti, 64GB RAM, Oculus Quest 3 Link to comment Share on other sites More sharing options...
Vinny002 Posted November 12, 2014 Share Posted November 12, 2014 Hi, iFoxRomeo! I saw Tango's post saying the Mi-21bis held sustained level flight at 62,400 feet or about 19,000 meters or 19 kilometers in the the cruise not realistic thread. Thanks! Cheers, Vincent Link to comment Share on other sites More sharing options...
iFoxRomeo Posted November 12, 2014 Share Posted November 12, 2014 19km service ceiling does not apply to the MiG-21Bis. Fox Spoiler PC Specs: Ryzen 9 5900X, 3080ti, 64GB RAM, Oculus Quest 3 Link to comment Share on other sites More sharing options...
Vinny002 Posted November 13, 2014 Share Posted November 13, 2014 Hi, iFoxRomeo! Very interesting how Tango got the Mig-21bis in sustained level flight at 62,400 feet or 19 kilometers!! Thanks! Cheers, Vincent Link to comment Share on other sites More sharing options...
iFoxRomeo Posted November 13, 2014 Share Posted November 13, 2014 Hi, iFoxRomeo! Very interesting how Tango got the Mig-21bis in sustained level flight at 62,400 feet or 19 kilometers!! Thanks! Cheers, Vincent If you are referring to his post you should look at the whole picture. A descend rate of -20m/s is far away from sustained level flight. He zoomed to this altitude. Fox Spoiler PC Specs: Ryzen 9 5900X, 3080ti, 64GB RAM, Oculus Quest 3 Link to comment Share on other sites More sharing options...
Vinny002 Posted November 13, 2014 Share Posted November 13, 2014 Hi, iFoxRomeo! That makes sense! Thanks! Cheers, Vincent Link to comment Share on other sites More sharing options...
Art-J Posted November 13, 2014 Share Posted November 13, 2014 With very steep zooming from max speed you can get almost to 22 km now... but your plane turns into a rock shortly afterwards :D. i7 9700K @ stock speed, single GTX1070, 32 gigs of RAM, TH Warthog, MFG Crosswind, Win10. Link to comment Share on other sites More sharing options...
Vinny002 Posted November 13, 2014 Share Posted November 13, 2014 Hi, Art-j! I think the flight model in the Mig-21bis is more accurate now since the update to 1.2.11! Thanks! Cheers, Vincent Link to comment Share on other sites More sharing options...
iFoxRomeo Posted November 13, 2014 Share Posted November 13, 2014 With very steep zooming from max speed you can get almost to 22 km now... but your plane turns into a rock shortly afterwards :D. I managed 22.2km with zooming. But after passing 22km the engine had a flame out. Here an excerpt from the flightrecorder Time________H (m)_______ IAS (km/h)_ RPM 1594.000000 21947.527075 507.137423 100.020000 1595.000000 21989.197958 505.715399 100.032000 1596.000000 22028.176426 501.279203 97.788000 1597.000000 22063.145394 496.736105 94.800000 1598.000000 22094.473469 492.955246 91.794000 1599.000000 22121.978599 489.607003 88.788000 1600.000000 22145.546965 486.478861 85.800000 1601.000000 22165.372018 483.514839 82.794000 1602.000000 22181.085186 480.898518 79.788000 1603.000000 22192.397518 478.550396 76.800000 1604.000000 22199.202117 476.418509 73.794000 1605.000000 22201.253640 474.616329 70.788000 1606.000000 22198.481273 473.043562 67.800000 1607.000000 22190.785310 471.761642 64.794000 I could restart the engine, but only after dropping below ~5000m Fox Spoiler PC Specs: Ryzen 9 5900X, 3080ti, 64GB RAM, Oculus Quest 3 Link to comment Share on other sites More sharing options...
Frischi234 Posted November 13, 2014 Share Posted November 13, 2014 (edited) short time later flameout Edited November 13, 2014 by Frischi234 Link to comment Share on other sites More sharing options...
Art-J Posted November 13, 2014 Share Posted November 13, 2014 Sounds cool. Question to both of You, what was initial Mach number and altitude before the zoom? And what climb angle did You choose? I'm still trying to figure out the optimal value. Can't wait for similar strato- fun when EDGE comes, with dark sky, visible earth curvature and stuff... iFox, You can re-light the engine a bit higher, as long as you comply with limitations written in manual (IIRC max 10km and Ma=0.9). I was forced to test it quite a few times :D. i7 9700K @ stock speed, single GTX1070, 32 gigs of RAM, TH Warthog, MFG Crosswind, Win10. Link to comment Share on other sites More sharing options...
iFoxRomeo Posted November 13, 2014 Share Posted November 13, 2014 (edited) Yeah, was obviously too fast for relighting. Interestingly it was exactly 22km on the altimeter, when the flameout occurred. I climbed to 12.5km with full mil thrust@ ~870km/h TAS, then accelerated with full reheat Mach 1.8+ and then continued to climb with the nose up to 15°. @Frischi: 22,5km, not bad. Short video just prior the flame out. Fox Edited November 13, 2014 by iFoxRomeo too high nose up Spoiler PC Specs: Ryzen 9 5900X, 3080ti, 64GB RAM, Oculus Quest 3 Link to comment Share on other sites More sharing options...
Art-J Posted November 13, 2014 Share Posted November 13, 2014 (edited) On one of our aviation discussion forums I've gone through a thread with young MiG-21 enthusiasts, but also veteran pilots and mechanics discussing their favourite ride they operated decades ago. One of the pilots described how a sortie for dynamic climb to max altitude looked like, sadly, not specifying which version of 21 it applied to (the guy flew mostly on PFMs, don't know about his experience with later versions). Combat excersise No. 112: Take off, climbing with TAS=850km/h to 4000m (max thrust without AB), 45 deg. turn for intended course, climbing to 11000m (thrust as previously), accelerating to Mach 1.3 (full AB from now), accelerating to Mach 1.7 with U=10m/s, climbing to 15000m with U=10-25m/s, accelerating to Mach 1.85-1.9, zoom at 15-20 degrees angle up to 19500m with speed dropping to Mach 1.7-1.6, AB off, airbrakes deployed, descent. "Our" MiG doesn't match these figures exactly (yet), but as I said, I'm not sure if these are for Bis. Nevertheless, we're getting beyond 20k and strato flights are fun :D. Edited November 13, 2014 by Art-J i7 9700K @ stock speed, single GTX1070, 32 gigs of RAM, TH Warthog, MFG Crosswind, Win10. Link to comment Share on other sites More sharing options...
Frischi234 Posted November 13, 2014 Share Posted November 13, 2014 Manual: Link to comment Share on other sites More sharing options...
FishBike Posted November 14, 2014 Author Share Posted November 14, 2014 I haven't tried it after the most recent update, but before that it was possible to get to almost 80,000 feet (over 24 km) in a zoom climb. I think with enough practice to get the technique just right, it should be possible to do just a little better than that even. The best way I found so far is to accelerate to maximum speed at about 10km altitude, then do about a 4G pull up to 60 degrees nose up. Hold that attitude as long as you can and then just keep as much nose up as you can without stalling. The real trick is surviving the experience--I found if I stalled up there, I would fall out of the sky with the plane level but falling straight down, faster and faster until the G-forces make it explode. So if you try it, just make sure you don't stall (watch the AoA gauge and keep it out of the red zone). Don't pull up too much past 60 degrees or you may not be able to avoid a stall even with full forward stick at the top of the climb. I'm looking forward to trying this again in the next few days once I have some time and have installed the latest update. Link to comment Share on other sites More sharing options...
Vinny002 Posted November 15, 2014 Share Posted November 15, 2014 Hi, guys! Since the update today, I got the DCS Mig-21bis up to an altitude of 19,500 meters or 19.5 kilometers and sustained level flight at that altitude!! Please see attached. Thanks! Cheers, Vincent Link to comment Share on other sites More sharing options...
Vinny002 Posted November 15, 2014 Share Posted November 15, 2014 And the screenshot of the DCS Mig-21bis flying at mach 2.04 at the altitude of 19,500 meters or 19.5 kilometers high! Please see attached. Thanks! Cheers, Vincent Link to comment Share on other sites More sharing options...
Art-J Posted November 15, 2014 Share Posted November 15, 2014 Cool. Didn't try level flights at such altitudes after latest update, but If it can be done, I'm happy. i7 9700K @ stock speed, single GTX1070, 32 gigs of RAM, TH Warthog, MFG Crosswind, Win10. Link to comment Share on other sites More sharing options...
Recommended Posts