REL Posted March 10, 2011 Posted March 10, 2011 Is it my bad or the HSI current heading is not correct ? Here I'm alined with the runway at Batumi but the Course Arrow is not alined with the Aircraft Symbol ... why ?
Nate--IRL-- Posted March 10, 2011 Posted March 10, 2011 Someone mentioned Magnetic Variance to me before, but I can't be certain that was the cause. Nate Ka-50 AutoPilot/stabilisation system description and operation by IvanK- Essential Reading
Avilator Posted March 10, 2011 Posted March 10, 2011 Is it my bad or the HSI current heading is not correct ? Here I'm alined with the runway at Batumi but the Course Arrow is not alined with the Aircraft Symbol ... why ? [ATTACH]48775[/ATTACH] You can turn the course arrow with the knob at the lower right corner of the instrument. You have it set at 130(top right of the HSI) and you are flying heading 120. I only respond to that little mechanical voice that says "Terrain! Terrain! Pull Up! Pull Up!" Who can say what is impossible, for the dream of yesterday is the hope of today and the reality of tomorrow. -Robert Goddard "A hybrid. A car for enthusiasts of armpit hair and brown rice." -Jeremy Clarkson "I swear by my pretty floral bonet, I will end you." -Mal from Firefly
REL Posted March 10, 2011 Author Posted March 10, 2011 So what is the correct heading to Batumi - I thought it was 130 ?
636_Castle Posted March 10, 2011 Posted March 10, 2011 (edited) Alright, lets see if I can put my theory into words this time: Since the HSI runs off of the EGI system, I'll blame that, assuming you were using the EGI as your primary navigation source. The EGI can run off of either an INS system, or a GPS system, or both (blended). Typically the driver of the EGI is set to blended, but I have looked at the CDU before and seen it running off of the INS. Correct me if I'm wrong, but INS systems tend to drift, the same way gyros tend to precess. (Which is why you have to sit there and align your EGI before taxi). Additionally, Batumi's runway course is 125, not 130 as you have set. With that said, could it be possible you were using the INS as your flight driver, it drifted slightly, and you compensated by setting an incorrect final approach course, canceling out the two and making it appear as if you were lined up? Edited March 10, 2011 by 636_Castle [sIGPIC][/sIGPIC] How To Fix Your X-52's Rudder!
636_Castle Posted March 10, 2011 Posted March 10, 2011 I suppose it's impossible to know if my theory is correct or not unless you know which flight driver you were using, and know what it's figure of merit was. [sIGPIC][/sIGPIC] How To Fix Your X-52's Rudder!
S77th-konkussion Posted March 10, 2011 Posted March 10, 2011 Batumi / or the avionics modeling Batumi was bugged in beta.. might still be. http://forums.eagle.ru/showthread.php?t=64672&highlight=batumi Actual heading is 130.7 (!) http://worldaerodata.com/wad.cgi?runway=GG0000731 [sIGPIC]http://forums.eagle.ru/attachment.php?attachmentid=43337&d=1287169113[/sIGPIC]
REL Posted March 10, 2011 Author Posted March 10, 2011 Alright, lets see if I can put my theory into words this time: Since the HSI runs off of the EGI system, I'll blame that, assuming you were using the EGI as your primary navigation source. The EGI can run off of either an INS system, or a GPS system, or both (blended). Typically the driver of the EGI is set to blended, but I have looked at the CDU before and seen it running off of the INS. Correct me if I'm wrong, but INS systems tend to drift, the same way gyros tend to precess. (Which is why you have to sit there and align your EGI before taxi). Additionally, Batumi's runway course is 125, not 130 as you have set. With that said, could it be possible you were using the INS as your flight driver, it drifted slightly, and you compensated by setting an incorrect final approach course, canceling out the two and making it appear as if you were lined up? I was using the INS
636_Castle Posted March 10, 2011 Posted March 10, 2011 Actual heading is 130.7 (!) http://worldaerodata.com/wad.cgi?runway=GG0000731 Runway courses are derived from magnetic heading, not true heading. [sIGPIC][/sIGPIC] How To Fix Your X-52's Rudder!
636_Castle Posted March 10, 2011 Posted March 10, 2011 I was using the INS That might have been your problem then. Any idea what the figure of merit was? [sIGPIC][/sIGPIC] How To Fix Your X-52's Rudder!
REL Posted March 10, 2011 Author Posted March 10, 2011 That might have been your problem then. Any idea what the figure of merit was? Figure of merit ? Oops ... I lost you there buddy :(
REL Posted March 10, 2011 Author Posted March 10, 2011 Found it EGI INS Figure of Merit (FOM), L8. FOM indicates the quality performance of a device. In this case, it is used to indicate the accuracy of INS derived navigation data. This can range from 1 to 9 and represents accuracy of 26 m to 5,000 m. As such, the lower the FOM, the greater the accuracy of the INS derived data. An asterisk (*) symbol indicates that the FOM is unknown. Just learned somthing new so ...
effte Posted March 10, 2011 Posted March 10, 2011 (edited) 1) Runway HEADINGS are magnetic. 2) The HSI should run off a gyro corrected to magnetic from a flux gate valve - a sensor registering the magnetic field. Edit: Confirmed from docs. Runs off the HARS and a remote compass sensor. 3) Batumi is correctly aligned @ 131 deg true. 4) Mag var is 5E, so you should see 126 on the HSI. 5) Last I checked, the HSI said 121 or so when lined up at Batumi. Conclusion: DCS heading reference system broken, subtracting mag var twice. I think this has been acknowledged by ED. The course selector is not a factor here. Edited March 10, 2011 by effte 1 ----- Introduction to UTM/MGRS - Trying to get your head around what trim is, how it works and how to use it? - DCS helos vs the real world.
REL Posted March 10, 2011 Author Posted March 10, 2011 Conclusion: DCS heading reference system broken, subtracting mag var twice. I think this has been acknowledged by ED. I wish someone from ED can confirm that ...
636_Castle Posted March 10, 2011 Posted March 10, 2011 (edited) 1) Runway HEADINGS are magnetic. 2) The HSI should run off a gyro corrected to magnetic from a flux gate valve - a sensor registering the magnetic field. Edit: Confirmed from docs. Runs off the HARS and a remote compass sensor. The HSI will run off of the HARS if your NMSP is set to HARS. At that point you can go to the HARS control panel and select either compass slave mode (magnetic mode as you described) or DG. HARS is a backup legacy system. The EGI should be passing data to both the ADI and HSI. This is why both gauges read "off" until your EGI has been aligned. I think we'll need to hear from ED if it's a bug or something mechanical in the simulator that's causing the inaccurate readings from the EGI though. I'll go into the simulator and see if I can play around with it. Edited March 10, 2011 by 636_Castle [sIGPIC][/sIGPIC] How To Fix Your X-52's Rudder!
636_Castle Posted March 10, 2011 Posted March 10, 2011 After messing with it myself, something does seem bugged. The true runway heading at Batumi should be 130 degrees, yet it appears to be 120 degrees in the simulator. [sIGPIC][/sIGPIC] How To Fix Your X-52's Rudder!
Bvoiash Posted March 10, 2011 Posted March 10, 2011 (edited) I too noticed the discrepancy while doing the take off and landing tutorial missions. So either it's a bug or probably one of the tutorial missions needs to be slightly modified to explain the discrepancy. Edited March 10, 2011 by Bvoiash
effte Posted March 10, 2011 Posted March 10, 2011 (edited) You should see 126 deg mag on the HSI at Batumi. When you have an INS feeding the HSI, it typically looks in a database to find the mag var in order to present the mag heading. The true runway heading at Batumi is 131 degrees. Verified through checking coordinates. The error is not in the terrain but somewhere in the systems. Castle: Reading the DCS manual, yes, the EGI seems to feed the HSI unless you deliberately switch it to HARS. I only had the A model manual when posting before. Edited March 10, 2011 by effte ----- Introduction to UTM/MGRS - Trying to get your head around what trim is, how it works and how to use it? - DCS helos vs the real world.
Recommended Posts