Jakey-Poo Posted May 19, 2021 Share Posted May 19, 2021 (edited) After talking with several members of the community (more knowledgeable than myself) the common consensus for the problem with the artificial horizon drifting constantly is due to low suction in the vacuum system. After comparing this to readings on the suction gauge during flight this checks out. The problem then becomes why is the suction consistently below operational range even while in climb power? Is there a fix for this that I have not stumbled across, or is this a bug? Edited February 11, 2022 by Jakey-Poo Updated info Link to comment Share on other sites More sharing options...
Nozzle Posted May 19, 2021 Share Posted May 19, 2021 The vacuum-based attitude systems on these aircraft were never able to maintain a stable reference for the entire flight even when working perfectly. Really the best a pilot could hope for was a somewhat stable horizon reference during a cloud layer penetration when absolutely necessary to land. The expectation was the pilot would have been flying straight and level for enough time before penetration for the vacuum to provide a somewhat reliable reference during the time the pilot had no visual horizon. Important to remember these fighter aircraft were only marginally IFR capable by today's standards. 1 Link to comment Share on other sites More sharing options...
Jakey-Poo Posted May 19, 2021 Author Share Posted May 19, 2021 21 minutes ago, Nozzle said: The vacuum-based attitude systems on these aircraft were never able to maintain a stable reference for the entire flight even when working perfectly. Really the best a pilot could hope for was a somewhat stable horizon reference during a cloud layer penetration when absolutely necessary to land. The expectation was the pilot would have been flying straight and level for enough time before penetration for the vacuum to provide a somewhat reliable reference during the time the pilot had no visual horizon. Important to remember these fighter aircraft were only marginally IFR capable by today's standards. Is it normal then for the suction gauge to be consistently below the operational range, and I'm just tweaking? I figured there was something that I was missing or operating incorrectly to have these results be the norm. Link to comment Share on other sites More sharing options...
grafspee Posted May 19, 2021 Share Posted May 19, 2021 (edited) Looks like at least 3.8" is required to proper operation of gyro-horizon . I also has impression that gyro-horyzons drifts a bit too quick, not only in P-47 other warbrids as well. I expect to loose gyro coordination after sudden maneuvers, but i have this problem in level flight as well. Edited May 19, 2021 by grafspee 3 System specs: I7 14700KF, Gigabyte Z690 Aorus Elite, 64GB DDR4 3600MHz, Gigabyte RTX 4090,Win 11, 48" OLED LG TV + 42" LG LED monitor Link to comment Share on other sites More sharing options...
Nealius Posted May 19, 2021 Share Posted May 19, 2021 Oddly, I find the P-51 and Spitfire to have fairly reliable gyros. They drift after hard maneuvering, but given a few minutes of stable flight they sort themselves out. The P-47's, however, is a functioning alcoholic. Some consistency needs to be applied here. 2 Link to comment Share on other sites More sharing options...
Jakey-Poo Posted May 19, 2021 Author Share Posted May 19, 2021 (edited) 13 hours ago, grafspee said: Looks like at least 3.8" is required to proper operation of gyro-horizon . I also has impression that gyro-horyzons drifts a bit too quick, not only in P-47 other warbrids as well. I expect to loose gyro coordination after sudden maneuvers, but i have this problem in level flight as well. 9 hours ago, Nealius said: Oddly, I find the P-51 and Spitfire to have fairly reliable gyros. They drift after hard maneuvering, but given a few minutes of stable flight they sort themselves out. The P-47's, however, is a functioning alcoholic. Some consistency needs to be applied here. After flying the P-51 this morning I'm getting more and more the feeling that this has to do with inadequate suction in the vacuum system in the P-47, as opposed to the gyro itself. While in the P-51 I had no problem keeping the suction gauge within the operational range (although admittedly on the lower side), and, I would assume correspondingly, had no problem with the ADI during "normal" flight. This is a completely different experience than the Jug. If this is modeled accurately, and the jug had particular problems with the vacuum system, then fine. I'm just looking for info. Edited May 19, 2021 by Jakey-Poo verbiage Link to comment Share on other sites More sharing options...
Jakey-Poo Posted January 30, 2022 Author Share Posted January 30, 2022 Has there been any headway on this? Haven't flown the jug in a few months, came back and this is still an issue (at least for me). Link to comment Share on other sites More sharing options...
Jakey-Poo Posted February 6, 2022 Author Share Posted February 6, 2022 After further testing in Instant Action missions where the suction gauge is reading within normal operating parameters, it’s pretty obvious at this point that the artificial horizon acting up is a symptom of inadequate suction in the vac system. I’m going to be testing more with the compass, but haven’t noticed anything obvious. Link to comment Share on other sites More sharing options...
ED Team NineLine Posted July 27, 2022 ED Team Share Posted July 27, 2022 Please supply a track of the issue if you are still seeing it. Thanks 1 Forum Rules • My YouTube • My Discord - NineLine#0440• **How to Report a Bug** Link to comment Share on other sites More sharing options...
Aernov Posted November 7, 2022 Share Posted November 7, 2022 Here are two screenshots, taken in flight after cold start, Channel map: 1) Max. continuous power in climb, suction gauge needle is barely over the bottom red line 2) Max economy in almost level flight, suction is at or slightly below bottom red line Shouldn't it be firmly in "green" zone even at idle power? 1 Link to comment Share on other sites More sharing options...
cw4ogden Posted November 16, 2022 Share Posted November 16, 2022 (edited) This is still a problem. Tend to agree with the original poster, the poor gyro is linked to low vacuum. As is, the plane would be on a red X, awaiting the crewchief to get his duct tape. Edited November 16, 2022 by cw4ogden 1 Link to comment Share on other sites More sharing options...
Jakey-Poo Posted November 18, 2022 Author Share Posted November 18, 2022 On 11/16/2022 at 6:40 AM, cw4ogden said: This is still a problem. Tend to agree with the original poster, the poor gyro is linked to low vacuum. As is, the plane would be on a red X, awaiting the crewchief to get his duct tape. If you or anyone else knows how, and would be willing to post a track file for this, it would help me out a ton - I’m computer illiterate; I just fly imaginary airplanes. This got flagged for missing info, and I’m assuming per NL’s response above that the track files are what they need. Link to comment Share on other sites More sharing options...
Aernov Posted March 12 Share Posted March 12 (edited) P-47D-40 suction on the ground.trk P-47D-40 suction climb 2700 RPM.trk Here are two short tracks with P-47D-40 (hot start on parking and in air, I haven't noticed a difference with cold started plane in these tests). At 900 RPM suction stays at about 3 in Hg, with RPM increase it starts to rise (beginning at around 1100 RPM) and gets to about 3.8 (low red line on the gauge) and stops there, never rising above low redline. One test was done on the ground, other - in air at military limit (2700 RPM, 52'' MP), both on Caucasus with "DCS default" weather. Same results were obtained with P-47D-30. There was an outlier case where suction rose to 4,2 in Hg in flight at high altitude (see screenshot) (P-47D-30 early, Normandy, clod start at Azeville ALG)... Edit: I've got 4.2 in Hg of suction again with D-30 early on Normandy after an air start, this time at low altitude: P-47D-30 early suction 4,2.trk Even if vacuum pump has 1:1 engine-pump RPM ratio (I don't know real ratio, but kinda doubt it is 1:1), it should still provide adequate pressure difference at 2500+ RPM. Also, aren't external tanks pressurized by vacuum pump exhaust? Edited March 12 by Aernov Link to comment Share on other sites More sharing options...
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