ED Team Yo-Yo Posted November 17, 2014 ED Team Share Posted November 17, 2014 @Alfa Exactly strong stuff there :) When I translated the russian DCS forum (topic Su-27) with google translate, I found out that Yo-Yo said, he hasn't got a sausage and his samurai skills are to blame hahahhaha. I'm sure google mixed up, with or without advertising!! But who can be sure about that??? :P Please do not smoke this hahahha substance too much! :) Ніщо так сильно не ранить мозок, як уламки скла від розбитих рожевих окулярів There is nothing so hurtful for the brain as splinters of broken rose-coloured spectacles. Ничто так сильно не ранит мозг, как осколки стекла от разбитых розовых очков (С) Me Link to comment Share on other sites More sharing options...
blkspade Posted November 17, 2014 Share Posted November 17, 2014 I don't know if the two things are connected in some way with state of the PFM ground handling, but at times the Eagle will actually continue to accelerate on the ground at idle power. http://104thphoenix.com/ Link to comment Share on other sites More sharing options...
L0op8ack Posted November 17, 2014 Share Posted November 17, 2014 (edited) ^^^ Where from can I get such telemetry? +1 Tacview? Just lines of script. Export data with export.lua, pretty easy way for precise in-game data. No eyeball-metering:) 1. Backup your C:\Users\[YOUR NAME]\Saved Games\DCS\Scripts\export.lua Put files in Scripts.zip to dir C:\Users\[YOUR NAME]\Saved Games\DCS\Scripts Then you can start mission and do the flight test. Test mission: Su27_TurnTest.miz When you exit the mission, flight data will be logged in file: C:\Users\[YOUR NAME]\Saved Games\DCS\Logs\FlightData-YYYYMMDD-HHMMSS.log 2. Extract graphic_Flighdata.zip Open the top .html (with MS.IE please) in the dir Click 'CHOOSE LOG FILE', choose your flight data log file Click 'draw me' button Now there it is. Edited November 17, 2014 by L0op8ack 2 Link to comment Share on other sites More sharing options...
Bucic Posted November 17, 2014 Share Posted November 17, 2014 Just lines of script. Export data with export.lua, pretty easy way for precise in-game data. No eyeball-metering:) 1. Backup your C:\Users\[YOUR NAME]\Saved Games\DCS\Scripts\export.lua Put files in [ATTACH]107597[/ATTACH] to dir C:\Users\[YOUR NAME]\Saved Games\DCS\Scripts Then you can start mission and do the flight test. Test mission: [ATTACH]107600[/ATTACH] When you exit the mission, flight data will be logged in file: C:\Users\[YOUR NAME]\Saved Games\DCS\Logs\FlightData-YYYYMMDD-HHMMSS.log 2. Extract graphic_Flighdata.zip Open the top .html (with MS.IE please) in the [ATTACH]107598[/ATTACH] Click 'CHOOSE LOG FILE', choose your flight data log file Click 'draw me' button Now there it is. Thanks! https://akaagar.github.io/briefing-room-for-dcs/ F-5E simpit project https://forum.dcs.world/topic/318106-f-5e-simpit-cockpit-dimensions-and-flight-controls/ Link to comment Share on other sites More sharing options...
Fox One Posted November 18, 2014 Author Share Posted November 18, 2014 L0op8ack, many thanks! My DCS videos Link to comment Share on other sites More sharing options...
Robin_Hood Posted December 2, 2014 Share Posted December 2, 2014 I am sorry to bring this topic again, but it still seems very strange to me, so I would like to confirm that the behaviour is realistic. The thrust with open nozzles is apparently immensely less than with nozzles open, and it doesn't seem to really increase with RPMs (which is to say, 70% or 78% doesn't seem to make any difference in thrust). I did a little acceleration testing (in flight, so nothing about wheels friction here) to illustrate what I mean, using an export script. I maintained 7 000 m during the whole maneuver. What I did was start idle, and advance the throttle slowly (by increments), until 85%, then retard the throttle slowly back to 70%, all the while recording the time, IAS (in m/s) and RPM (left engine). Here are the results: As you can see: - the aircraft (nozzles open) starts at 70% and decelerating. - as the throttle advances from 70% to 79% it keeps decelerating at a steady pace, as if RPM didn't matter. - when when reaching about 80%, nozzles close* and thrust kicks in, instantly resulting in a significant acceleration. - as the throttles is advanced to 85, the aicraft accelerates faster and faster - with the RPM going back, acceleration decreases slowly until speed as approximately constant at about 75% RPM - when RPM goes under 74%, nozzles open* and the aircraft immediately starts decelerating at a great pace - once again, as the throttle is retarded from 4% to 70%, no change in the pace of deceleration is noticed. * I suppose What I would gather from that is that it would seem as if thrust was kept constant at idle thrust in the whole region where nozzles are open. I may be interpreting this wrong, of course, and maybe the engine model is absolutely allright, but I wanted to share this tests with you so that a confirmation could be made that this is realistic for the Su-27. Note: I did not made this tests in the new Open Beta, so if things have changed, I will redo them later with the new version. 2nd French Fighter Squadron Link to comment Share on other sites More sharing options...
Robin_Hood Posted December 6, 2014 Share Posted December 6, 2014 Just for information, the 1.12 gives the same results: 2nd French Fighter Squadron Link to comment Share on other sites More sharing options...
Svend_Dellepude Posted December 6, 2014 Share Posted December 6, 2014 I don't know if the two things are connected in some way with state of the PFM ground handling, but at times the Eagle will actually continue to accelerate on the ground at idle power. That would be in extreme cold temperatures i think. [sIGPIC][/sIGPIC] Win10 64, Asus Maximus VIII Formula, i5 6600K, Geforce 980 GTX Ti, 32 GB Ram, Samsung EVO SSD. Link to comment Share on other sites More sharing options...
Robin_Hood Posted December 7, 2014 Share Posted December 7, 2014 That would be in extreme cold temperatures i think. Could be, I guess. I noticed Idle RPM are dependent on the temperature. Here's a little chart I made shortly after the PFM was released. Although this is quite off-topic 2nd French Fighter Squadron Link to comment Share on other sites More sharing options...
Robin_Hood Posted December 8, 2014 Share Posted December 8, 2014 Ok, so. After a couple more flight tests, I have come to the conclusion that the (current) engine always produce the same thrust when the nozzles are open, ie. having your RPM at 70% or 78% produces exactly the same thrust if the nozzles are open. See attached charts with a comparison of speed* and acceleration** against time (also, for reference, altitude* and left engine RPM*). * extracted by export script ** computed by derivation of the velocity For all the parameters (except obviously RPM), both curves are pretty much exactly superimposed, indicating that the 8.5% difference in RPM does not change anything. I might try plotting the same for 80% and 88%, for comparison purposes, although I strongly expect it would show a much better acceleration for 88% than for 80%. Note that I have tested on a light aircraft in order to have a better sensivity to thrust. I know I may seem obsessed about the matter, but I'm simply intrigued by the current behaviour (also, I like to do flight tests and charts). Also, note that I am not at all trying to belittle the huge work that was done on the Su-27 flight model, which is very impressive. 2nd French Fighter Squadron Link to comment Share on other sites More sharing options...
nickexists Posted December 12, 2014 Share Posted December 12, 2014 From the DCS SU-27 manual: "When the landing gear is extended, the nozzles partially closed in order to preserve the power margin and to avoid nozzle contact with the runway during the touchdown. Due to this, the thrust is increased when on the glide path. In order to decelerate, the speedbrake should be used." Has anyone observed this behavior in DCS? Link to comment Share on other sites More sharing options...
Bimbac Posted December 17, 2014 Share Posted December 17, 2014 Yes, it's there. Could someone help me to explain the taxiing technique with the new PFM? When the nozzles close (going above 78%), the thrust increase seems to be very significant (which I think is not entirely correct), but the thrust doesn't decrease when you throttle down, until the nozzles open again. I have noticed on some videos that Flanker pilots sometimes taxi by using just one engine, but if anybody among testers or developers could shed some light into this, I'd be extremely grateful. Link to comment Share on other sites More sharing options...
Robin_Hood Posted April 14, 2015 Share Posted April 14, 2015 I am happy to report that the issue has been fixed in the latest update (1.2.16.38741), as you can see by comparing the quick test I just did with the earlier ones (like post #32): Now you can see that before, when the nozzles were open, the velocity decreased in a straight line, no matter the RPM, indicating no change in thrust. But now, the acceleration can clearly be seen to depend upon the RPM. Thank you for fixing the issue. By the way, this has also fixed the taxiing problem (where the aircraft would suddenly jump forward at 80% RPM), so now taxi will be a lot easier. 1 2nd French Fighter Squadron Link to comment Share on other sites More sharing options...
black27 Posted August 25, 2015 Share Posted August 25, 2015 Hi, it was interesting to watch you to solve the problem of idle thrust. In fact the accuracy of idle thrust doesn't bother me at all. What I suppose not to be accurate is the idle thrust at low temperatures. Try to simulate siberia conditions with temp around -20°C. The idle thrust is so high, that the aircraft accelerates on idle. What i would like to be solved is high fuel consumption of Su-27. According to engine charts and aircraft datas it seemed to be approx. 20% higher in the whole envelope. Does someone know, how to fixed it? Link to comment Share on other sites More sharing options...
Svend_Dellepude Posted August 25, 2015 Share Posted August 25, 2015 They are probably working on it if its an issue. Still BETA, remember.. [sIGPIC][/sIGPIC] Win10 64, Asus Maximus VIII Formula, i5 6600K, Geforce 980 GTX Ti, 32 GB Ram, Samsung EVO SSD. Link to comment Share on other sites More sharing options...
UVPMechan Posted August 25, 2015 Share Posted August 25, 2015 (edited) Hi, it was interesting to watch you to solve the problem of idle thrust. In fact the accuracy of idle thrust doesn't bother me at all. What I suppose not to be accurate is the idle thrust at low temperatures. Try to simulate siberia conditions with temp around -20°C. The idle thrust is so high, that the aircraft accelerates on idle. What i would like to be solved is high fuel consumption of Su-27. According to engine charts and aircraft datas it seemed to be approx. 20% higher in the whole envelope. Does someone know, how to fixed it? It's alright. It is realistic. The higher the temperature difference upstream of the engine and the output power increases. Edited August 25, 2015 by UVP/Mechan Link to comment Share on other sites More sharing options...
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