Hi! I'm trying to write a program that simulates IRS drift. I remember seeing a mathematical model that reflected IRS drift rate to an extent. I know you can't predict drifts, as otherwise it wouldn't exist , but nevertheless I'm looking for a model or tables that show the drift (either GS or position offset) after different time intervalls. Does anyone know of something like this? Thanks, Mark

Mark,First I need to know if you are one of the developers of the PIC V2, if so could you help PMDG with there IRS. They not yet sure about the IRS thing. If you one of the developers let me know.Ramon

Ramon,I am sorry to disappoint you but my wild guess is that the PIC team have enough work in their own project to "lend a hand" for IRS development for the PMDG bird.*:-*Tero

Ramon,well I am a 767 sim developer, just not 767PIC, nor am I working with them in any way.Regarding PMDG, I did propose to help them during early beta testing, but they didn't seem interested. Anyway, the IRS isn't THAT hard ;-), it does take a little time and you need quite a few good manuals (which was the hardest task for us).Other than that it comes down to your understanding of the system..Anyway, I am still looking for some drift info. The only thing I have deals with residual GS limits (A340) so that doesn't really help a lot.Regards,Mark

Ok, well I could try it anyway.Good luck with your drift of IRS.Ramon

LOL ok Mark. Maybe you should rephase that remark to "It's not that hard to make a so called IRS system in FS" because if it's anything life like it is not easy by anymeans..[h4]Best Wishes,Randy J. Smithhttp://www.precisionmanuals.com/images/forum/betaimg.jpg

That depends on wat you are.For a pro. developer it is no problem but you just a BETA tester.PS. How do you get a BETA tester?Ramon

Randy,It's not rocket science - several other developers, including of course the 767PIC team, have modeled IRS systems with a very appreciable degree of fidelity. I would have to say the the current 767PIC panel models inertial nav quite well overall, including initial alignment, drift, map shift, IRS failure, quick align, and attitude restoration after loss of alignment. IRS modeling obviously can be done and done well.

Guys, let me say a few things.To Randy:"LOL ok Mark"Not a very respectful way of starting a discussion, right?"Maybe you should rephase that remark to "It's not that hard to make a so called IRS system in FS"Well I have no idea how hard it is to develop under MSFS, as we are not using FS as our base - just too many limitations. Therefore, maybe it is extremely difficult to do something like this, but other developers have succeeded before... ( and no, not 767PIC, but rather the INS project that is available as freeware!)"because if it's anything life like it is not easy by anymeans.."Are you a programmer or just repeating things other developers have said?To Ramon:"That depends on wat you are.For a pro. developer it is no problem"Well, we aren't by any means pros. We just try until we succeed :-)" but you just a BETA tester."Beta testers are very valuable! Without 'em no flight simulation software (or any software product actually!) would be that what it is!" PS. How do you get a BETA tester?"Was that a question for me?To Mike:"It's not rocket science - several other developers, including of course the 767PIC team, have modeled IRS systems with a very appreciable degree of fidelity."I think I can agree with that. But remember, a real IRS, is very well more than rocket science! (That is if you actually model an IRS 100%, with all mathematical equations, integrals and differentials and the doppler effect) But if you do that, you better buy a second computer just to compute those equations every 50 milliseconds. Luckily, with flightsimming, you can cheat as you always know where the aircraft is and only calculate a drift offset and a groundspeed offset. (or a heading drift if in ATT mode). I'm pretty sure all flightsim developers, taht actually designed IRU's, took this approach. Anything else would be (in my opinion) overkill, as it takes too long and uses too much CPU for a very small difference in _feeling_.Even real sims (level D sims) use this approach."I would have to say the the current 767PIC panel models inertial nav quite well overall, including initial alignment, drift, map shift, IRS failure, quick align, and attitude restoration after loss of alignment. "While it is pretty nice, there are a few short commings. But if you remember that 767PIC was developed over 4 years ago, the first flight sim product for MSFS that actually HAD an IRS, and still beats most commercial addons, it is simply amazing. Who knows, with 4 years' time of deveopment, maybe 767PIC 2.0 will blow the first 767PIC right out of the water with a more realistic overhead.Regards,Mark

I wonder if modelling an IRS is harder than linking an image to your forum sig. Hmmmmmm.Luhiss