312_Lobo Posted March 1, 2015 Share Posted March 1, 2015 I'm not able to reach max speed at sea level at MIL settings. Attached is a track and mission and also TacView record. In DCSW v1.2.15 P-51 TAS at sea level at MIL power seems to be only 348mph which does not match the expected value (~364mph) stated in this post http://forums.eagle.ru/showpost.php?p=1577405&postcount=7 . Weather: Default, Temp 15°C, no wind. Plane condition: Clean aircraft, wings tanks full (67% fuel), radiator auto Steps to repro: Spawn at altitude, decent to approx 25m AGL, set Military power (3000 RPM and 61") fly straight and level for about 5 minutes. Observed: After 5 minutes TAS stabilizes around 560km/h (348mph). Expected: According to TSCEP5E-1908 (http://www.wwiiaircraftperformance.org/mustang/p51d-15342.html) at MIL power settings TAS at SL should be 364mph which is ~585km/h. Difference is ~25km/h (16mph).SPEED_TEST-p-51.mizspeedtest-p51SL.trkTacview.zip Link to comment Share on other sites More sharing options...
Crumpp Posted March 1, 2015 Share Posted March 1, 2015 348 mph IAS + 12 mph PEC = 360mph TAS 4/364 = 1.1% error That is excellent agreement with known data. Answers to most important questions ATC can ask that every pilot should memorize: 1. No, I do not have a pen. 2. Indicating 250 Link to comment Share on other sites More sharing options...
USARStarkey Posted March 1, 2015 Share Posted March 1, 2015 348 mph IAS + 12 mph PEC = 360mph TAS 4/364 = 1.1% error That is excellent agreement with known data. His TAS was already 348mph. Unless you for some reason think DCS doesnt calculate TAS correctly. [sIGPIC][/sIGPIC]Weed Be gone Needed Link to comment Share on other sites More sharing options...
RoflSeal Posted March 1, 2015 Share Posted March 1, 2015 You might need to have radiator set to closed position rather then auto. 1 Link to comment Share on other sites More sharing options...
gavagai Posted March 1, 2015 Share Posted March 1, 2015 Yo-yo confirmed that the P-51D is slower than it was at release in 2012. No explanation offered yet, but they'll fix it soon I hope. P-51D | Fw 190D-9 | Bf 109K-4 | Spitfire Mk IX | P-47D | WW2 assets pack | F-86 | Mig-15 | Mig-21 | Mirage 2000C | A-10C II | F-5E | F-16 | F/A-18 | Ka-50 | Combined Arms | FC3 | Nevada | Normandy | Straight of Hormuz | Syria Link to comment Share on other sites More sharing options...
Crumpp Posted March 1, 2015 Share Posted March 1, 2015 His TAS was already 348mph. Unless you for some reason think DCS doesnt calculate TAS correctly. His airspeed indicator was reading 350 mph IAS...watch the track. Answers to most important questions ATC can ask that every pilot should memorize: 1. No, I do not have a pen. 2. Indicating 250 Link to comment Share on other sites More sharing options...
Crumpp Posted March 1, 2015 Share Posted March 1, 2015 Yo-yo confirmed that the P-51D is slower than it was at release in 2012. No explanation offered yet, but they'll fix it soon I hope. He may not have fixed it yet then. It is strange that the Indicated airspeed read in the cockpit exactly matches the real aircraft when the Position Error Correction is applied. Even playing with CEC and PEC I can't get it outside the 3% tolerance. Answers to most important questions ATC can ask that every pilot should memorize: 1. No, I do not have a pen. 2. Indicating 250 Link to comment Share on other sites More sharing options...
312_Lobo Posted March 1, 2015 Author Share Posted March 1, 2015 (edited) His airspeed indicator was reading 350 mph IAS...watch the track. PEC is apparently not modelled for P-51 in DCS. F2 view or F10 view shows TAS for given plane. When I tested A-10 and switched airspeed indicator on HUD to TAS it showed 350 KTAS on HUD and at the same time object speed in F2/F10 views showed 648km/h (~350KTAS). For P-51 at ~350mph IAS F2/F10 view shows 560 km/h TAS (~348mph) which des not explain the measured difference within measurement tolerance. Edited March 1, 2015 by do.st Link to comment Share on other sites More sharing options...
Crumpp Posted March 1, 2015 Share Posted March 1, 2015 For P-51 at ~350mph IAS F2/F10 view shows 560 km/h TAS (~348mph) which des not explain the measured difference within measurement tolerance. Ok, In testing the Dora's climb rate, there were issues with the F2 values in the game. Answers to most important questions ATC can ask that every pilot should memorize: 1. No, I do not have a pen. 2. Indicating 250 Link to comment Share on other sites More sharing options...
312_Lobo Posted March 1, 2015 Author Share Posted March 1, 2015 I think that example with A-10c demonstrated that F2 shows TAS quite accurately close to SL ... unless A-10c has same error as p-51. Well, I think OP shows that there is quite good chance that P-51 speed is off. It would be great to know whether it's been reported or not. Link to comment Share on other sites More sharing options...
Crumpp Posted March 1, 2015 Share Posted March 1, 2015 It would be great to know whether it's been reported or not. It was a known issue as gavagai points out. Answers to most important questions ATC can ask that every pilot should memorize: 1. No, I do not have a pen. 2. Indicating 250 Link to comment Share on other sites More sharing options...
Lib Posted March 2, 2015 Share Posted March 2, 2015 348 mph IAS + 12 mph PEC = 360mph TAS What is PEC and where does that value come from please ? Link to comment Share on other sites More sharing options...
MiloMorai Posted March 2, 2015 Share Posted March 2, 2015 What is PEC and where does that value come from please ? position error correction Link to comment Share on other sites More sharing options...
Derbysieger Posted March 2, 2015 Share Posted March 2, 2015 I was always under the impression that F2 shows GS, not TAS. At least in the A-10C, GS on the TAD or the CDU is always equal or very close to the speed shown in the F2 view and TAS often differs quite a bit from what is shown in F2. Same in the MiG-21, TAS needle often shows different values than F2. Proof: Look at the TAS on the POS Page and then the GS shown on the TAD. Compare to the F2 view. As you can see GS is only off by 2kn whereas TAS is off by 10kn! CPU: AMD Ryzen 9 5900X | Mobo: Gigabyte X570 Aorus Pro | RAM: 64GB DDR4 3600 G.Skill TridentZ | GPU: Palit RTX3080 Ti 12GB | SSDs: 2xSabrent Rocket 1TB M.2 | Samsung Pro 256GB | Samsung EVO 850 500GB | Samsung QVO 1TB Peripherals: Warthog HOTAS | TrackIR 5 | MFG Crosswinds | 3xTM Cougar MFDs | HP Reverb G2 Link to comment Share on other sites More sharing options...
msalama Posted March 2, 2015 Share Posted March 2, 2015 You're right Derby. F2 shows GS and I'm pretty sure this has been acknowledged by the devs as well. The DCS Mi-8MTV2. The best aviational BBW experience you could ever dream of. Link to comment Share on other sites More sharing options...
Derbysieger Posted March 2, 2015 Share Posted March 2, 2015 Well F2 showing GS instead of TAS isn't necessarily a bug but since people in this thread were taking F2 as TAS I thought I should make them aware that it's actually GS. Doesn't matter too much if they're testing at sea level with no wind but nonetheless... CPU: AMD Ryzen 9 5900X | Mobo: Gigabyte X570 Aorus Pro | RAM: 64GB DDR4 3600 G.Skill TridentZ | GPU: Palit RTX3080 Ti 12GB | SSDs: 2xSabrent Rocket 1TB M.2 | Samsung Pro 256GB | Samsung EVO 850 500GB | Samsung QVO 1TB Peripherals: Warthog HOTAS | TrackIR 5 | MFG Crosswinds | 3xTM Cougar MFDs | HP Reverb G2 Link to comment Share on other sites More sharing options...
Echo38 Posted March 2, 2015 Share Posted March 2, 2015 (edited) What is PEC and where does that value come from please ? Some aircraft had the pitot tube located in a position where the airflow through it was unusually altered by an unintended source. For example, the P-38's pitot tube was too close to one of the engines, and the propwash was affecting the tube, causing the ASI to display a very incorrect airspeed. Hence calibrated IAS. IIRC, there's a chart in the P-38 handbook with a table for calibration. I think this is what Crumpp is talking about with PEC. Edited March 2, 2015 by Echo38 Link to comment Share on other sites More sharing options...
Kwiatek Posted March 2, 2015 Share Posted March 2, 2015 Doubt really if any combat simulator simulate position error of pitot :) Link to comment Share on other sites More sharing options...
msalama Posted March 2, 2015 Share Posted March 2, 2015 isn't necessarily a bug Sorry, my bad, didn't mean it was. Should've said that AFAIK the devs have stated that it shows GS, not TAS :) The DCS Mi-8MTV2. The best aviational BBW experience you could ever dream of. Link to comment Share on other sites More sharing options...
msalama Posted March 2, 2015 Share Posted March 2, 2015 simulate position error of pitot :) If the planes are accurately modelled, then the plane-specific error must've been taken into account - and I'm pretty sure this is the case here. The DCS Mi-8MTV2. The best aviational BBW experience you could ever dream of. Link to comment Share on other sites More sharing options...
Echo38 Posted March 2, 2015 Share Posted March 2, 2015 (edited) If the planes are accurately modelled, then the plane-specific error must've been taken into account - and I'm pretty sure this is the case here. Our DCS-level aircraft are exquisitely modelled, of course, but they aren't entirely complete, nor always entirely accurate. For example, engine idle behavior is not currently modelled in the WWII birds, virtual pilot head limitations are not accurately modelled (i.e. the virtual head/camera is allowed to go through the canopy when it is closed, allowing you to see things you would not be able to in real life), enemy aircraft are unrealistically audible over the sound of your own ~1800 hp. engine, and so on. As good as the sim is, it's a WIP. I don't know if pitot tube error is modelled or not; the sim is detailed enough to model such things, and it usually does, but there are still some of these things which haven't been addressed yet. I'm hoping that, after the last of the five scheduled WWII fighters is released, the team will have a bit more time to go back and look at some of these things, but right now, I'd wager that they've got their hands more than full. Edited March 2, 2015 by Echo38 Link to comment Share on other sites More sharing options...
Art-J Posted March 2, 2015 Share Posted March 2, 2015 Since noone seems to be 100% sure, could somebody just take any airplane in the air and dive perpendicular towards the ground? Then F2 would tell us if it's GS or TAS. I'm not at my gaming rig right now, so can't do it at the moment :). 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...
USARStarkey Posted March 2, 2015 Share Posted March 2, 2015 its TAS....... [sIGPIC][/sIGPIC]Weed Be gone Needed Link to comment Share on other sites More sharing options...
Crumpp Posted March 2, 2015 Share Posted March 2, 2015 I was always under the impression that F2 shows GS, not TAS. I agree. Answers to most important questions ATC can ask that every pilot should memorize: 1. No, I do not have a pen. 2. Indicating 250 Link to comment Share on other sites More sharing options...
Derbysieger Posted March 2, 2015 Share Posted March 2, 2015 Since noone seems to be 100% sure, could somebody just take any airplane in the air and dive perpendicular towards the ground? Then F2 would tell us if it's GS or TAS. I'm not at my gaming rig right now, so can't do it at the moment :). Just look at the pics I posted. They clearly show that it's GS ;) http://forums.eagle.ru/showpost.php?p=2334782&postcount=14 I paused the game and then took the two screenshots: ~220kn IAS, TAD with GS (234kn) and PosInfo with TAS (226kn) on the CDU page. F2 view shows 236kn ... Wind is coming from about east, my heading is roughly 295. CPU: AMD Ryzen 9 5900X | Mobo: Gigabyte X570 Aorus Pro | RAM: 64GB DDR4 3600 G.Skill TridentZ | GPU: Palit RTX3080 Ti 12GB | SSDs: 2xSabrent Rocket 1TB M.2 | Samsung Pro 256GB | Samsung EVO 850 500GB | Samsung QVO 1TB Peripherals: Warthog HOTAS | TrackIR 5 | MFG Crosswinds | 3xTM Cougar MFDs | HP Reverb G2 Link to comment Share on other sites More sharing options...
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