bkthunder Posted October 20, 2014 Share Posted October 20, 2014 Just wondering 'cause I've had this problem with the P-51 since day 1: I uncage the AI when I'm on the runway, checking that the vacuum gauge is in the green. Soon after I take off, the AI is all wrong and slacking off big time, even though the vacuum was always in the green. It's like the gyro isn't spun up properly, but I haven't seen this happen on any aircraft (in RL) unless there is a drop in vacuum pressure. Any thoughts? Windows 10 - Intel i7 7700K 4.2 Ghz (no OC) - Asus Strix GTX 1080 8Gb - 16GB DDR4 (3000 MHz) - SSD 500GB + WD Black FZEX 1TB 6Gb/s Link to comment Share on other sites More sharing options...
MVSokie Posted October 20, 2014 Share Posted October 20, 2014 +1 [sIGPIC][/sIGPIC] Link to comment Share on other sites More sharing options...
Whiplash Posted October 20, 2014 Share Posted October 20, 2014 I've noticed this too. It's gotten to the point where I don't even bother uncaging it until after I am airborne which is less than ideal. [sIGPIC][/sIGPIC] "Adulthood is like looking both ways before you cross the street and then getting hit by an airplane." Dogs of War Dedicated WWII Server Thread Link to comment Share on other sites More sharing options...
kontiuka Posted October 20, 2014 Share Posted October 20, 2014 I've noticed this too. It's gotten to the point where I don't even bother uncaging it until after I am airborne which is less than ideal.same here. I find it invaluable for rocket and bomb attacks so it's important that it be pretty aligned. Link to comment Share on other sites More sharing options...
OutOnTheOP Posted October 20, 2014 Share Posted October 20, 2014 I *think* it is correct behavior: say you uncage on the ground, pointing north. The artificial horizon gyro "thinks" that it is level, but it is in fact tilted up (in the north) some 15-20 degrees, because the airplane is not at a level stance on the ground. If you then take off and turn to the east, the gyro will be tilted some 15-20 degrees to the right. As best I can tell, the artificial horizon is a ball with a slightly weighted bottom (to force it to level), and the gyro is just there to steady it and prevent it from tumbling. This means that if you continue to fly generally level, it will slowly settle into level. It also means that violent maneuvering will cause it to drift out of level. Both appear to be reflected in how the simulation seems to do it. If you're impatient, just go wings level and momentarily cage it, and it'll be good to go. Link to comment Share on other sites More sharing options...
Mike Busutil Posted October 20, 2014 Share Posted October 20, 2014 (edited) If you're impatient, just go wings level and momentarily cage it, and it'll be good to go. But if the Artificial Horizon is incorrect how do you know you are level??? :D Edited October 20, 2014 by Mike Busutil [sIGPIC][/sIGPIC] Checkout my user files here: https://www.digitalcombatsimulator.com/en/files/?CREATED_BY=Mike%20Busutil&set_filter=Y Link to comment Share on other sites More sharing options...
ff4life4 Posted October 20, 2014 Share Posted October 20, 2014 I don't recall this happening on the dora, which I'm going to guess is a very similar system. I also find it to be a pain on the 51. But at least it holds its calibration consistently. I'd crash if I was in a cloud having to rely on the ka50 backup horizon Link to comment Share on other sites More sharing options...
Buzzles Posted October 20, 2014 Share Posted October 20, 2014 But if the Artificial Horizon is incorrect how do you know you are level??? :D That's why those clever designers gave us a bank/slip indicator and a vertical velocity meter :) Fancy trying Star Citizen? Click here! Link to comment Share on other sites More sharing options...
OutOnTheOP Posted October 20, 2014 Share Posted October 20, 2014 But if the Artificial Horizon is incorrect how do you know you are level??? :D You don't know exactly; you get it close. Like I said, it still drifts to level... you're just helping it out by getting it closer. Link to comment Share on other sites More sharing options...
bkthunder Posted October 21, 2014 Author Share Posted October 21, 2014 I *think* it is correct behavior: say you uncage on the ground, pointing north. The artificial horizon gyro "thinks" that it is level, but it is in fact tilted up (in the north) some 15-20 degrees, because the airplane is not at a level stance on the ground. If you then take off and turn to the east, the gyro will be tilted some 15-20 degrees to the right. As best I can tell, the artificial horizon is a ball with a slightly weighted bottom (to force it to level), and the gyro is just there to steady it and prevent it from tumbling. This means that if you continue to fly generally level, it will slowly settle into level. It also means that violent maneuvering will cause it to drift out of level. Both appear to be reflected in how the simulation seems to do it. If you're impatient, just go wings level and momentarily cage it, and it'll be good to go. I don't mean to sound harsh or anything, but you actually got it all wrong. Nice read here: http://www.pilotfriend.com/training/flight_training/fxd_wing/attitude.htm Windows 10 - Intel i7 7700K 4.2 Ghz (no OC) - Asus Strix GTX 1080 8Gb - 16GB DDR4 (3000 MHz) - SSD 500GB + WD Black FZEX 1TB 6Gb/s Link to comment Share on other sites More sharing options...
Art-J Posted October 21, 2014 Share Posted October 21, 2014 This topic pops up every now and then, should be made sticky :D. Explanation why it works as it works here: http://forums.eagle.ru/showthread.php?t=87919 Not sure it it's not overdone a bit, though, 'because right now I almost don't bother to use it at all! 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...
bkthunder Posted October 21, 2014 Author Share Posted October 21, 2014 Well that topic only goes to prove my point (and yours maybe): it is WAY overdone. As others have stated, I have never ever seen that effect in RL, certainly not after 30 seconds from gear up, flying straight..... What I noticed the other day is actually the opposite of the gyro precession described in that topic, that is, the AI drifted down and right as I was in a slight right turn, according to the topic it should have done the opposite. To me the problem looks like bad vacuum pressure / worn out gimbals. The pressure gauge was steadily in the green though, and I'm not sure they simulated worn out gimbals, especially after a 1 minute flight... Windows 10 - Intel i7 7700K 4.2 Ghz (no OC) - Asus Strix GTX 1080 8Gb - 16GB DDR4 (3000 MHz) - SSD 500GB + WD Black FZEX 1TB 6Gb/s Link to comment Share on other sites More sharing options...
bkthunder Posted October 23, 2014 Author Share Posted October 23, 2014 *bump* Windows 10 - Intel i7 7700K 4.2 Ghz (no OC) - Asus Strix GTX 1080 8Gb - 16GB DDR4 (3000 MHz) - SSD 500GB + WD Black FZEX 1TB 6Gb/s Link to comment Share on other sites More sharing options...
Echo38 Posted May 23, 2015 Share Posted May 23, 2015 I don't understand how I'm supposed to use this for IFR flying. It accumulates more and more error at a rapid rate, even when I'm flying more or less straight & level and more or less coordinated. If I were trying to fly in clouds, I'd lose use of this thing within a couple of minutes, and have no way to realign it ('coz I have no good way to know when I'm actually level, if horizon isn't visible and the gyro horizon isn't reliable). I know I could technically use the turn & bank indicator to more-or-less align it, but if I'm constantly (every few minutes) having to us the turn & bank indicator because the gyro horizon is off again by as much as 20 degrees, then I might as well be stuck with just the turn & bank indicator. I know I never experienced this effect (that is, of the gyro horizon gaining ~20% error within 15 minutes of normal flying) in the Cessnas I flew IRL. Hour-long flights with circles-around-a-point and S-turns over a line didn't result in any noticeable errors. I must question if this effect isn't overdone in DCS, since I can't think of a reason why the P-51's gyro horizon would behave differently than a modern one. Link to comment Share on other sites More sharing options...
98abaile Posted May 23, 2015 Share Posted May 23, 2015 I'm at the point where I don't even uncage it anymore. If I want to do level flight I use the VVI and bank and slip indicator. Link to comment Share on other sites More sharing options...
Echo38 Posted May 24, 2015 Share Posted May 24, 2015 Same here. I leave it caged from engine startup to engine shutdown. I find it difficult to believe that the instrument would have been included if it were unreliable to this extreme. Link to comment Share on other sites More sharing options...
msalama Posted May 24, 2015 Share Posted May 24, 2015 Color me weird, but it seems that if you reset the AH by pressing & momentarily holding the caging knob 2 or 3 times within, say, 30 minutes from startup, it'll eventually start to behave itself. Maybe the gyro just needs time to spinup / stabilize properly? The DCS Mi-8MTV2. The best aviational BBW experience you could ever dream of. Link to comment Share on other sites More sharing options...
Diemos Posted May 24, 2015 Share Posted May 24, 2015 What would happen if you were to adjust the pitch knob to match the ACTUAL pitch up of the plane while sitting on the ground? Could it be that the errors are accumulating so radically from the original 5 - 10 degree pitch error of a taildragger to ground "level"? Haven't tried it myself... Just spitballing... Link to comment Share on other sites More sharing options...
Echo38 Posted May 25, 2015 Share Posted May 25, 2015 Another thing that occurred to me--maybe, just maybe, something's happening with the vibration of the aircraft on the ground? My accelerometer always shows +-0.5G before I even get to the runway, even when I reset it several times (after startup, after warmup, and before takeoff). I wonder if the gyro is being effected by this heavy vibration. Just a shot in the dark. Link to comment Share on other sites More sharing options...
Teapot Posted May 25, 2015 Share Posted May 25, 2015 Color me weird, but it seems that if you reset the AH by pressing & momentarily holding the caging knob 2 or 3 times within, say, 30 minutes from startup, it'll eventually start to behave itself. Maybe the gyro just needs time to spinup / stabilize properly? This is my solution as well. Seems to work. "A true 'sandbox flight sim' requires hi-fidelity flyable non-combat utility/support aircraft." Wishlist Terrains - Bigger maps Wishlist Modules - A variety of utility aircraft to better reflect the support role. E.g. Flying the Hornet ... big yawn ... flying a Caribou on a beer run to Singapore? Count me in. Extracting a Recon Patrol from a hastily prepared landing strip at a random 6 figure grid reference? Now yer talking! Link to comment Share on other sites More sharing options...
Eros Posted May 25, 2015 Share Posted May 25, 2015 Well, i think this video is great for P-51 flyers! Always a pleasure to watch and the checklist he follows is pretty similar to D model. You can see the moment he uncage the A.H. and when he resets it. 335th_GREros [sIGPIC][/sIGPIC] Link to comment Share on other sites More sharing options...
NeilWillis Posted May 25, 2015 Share Posted May 25, 2015 I also think that he resets it again when the clip has been cut too. Just check out the position of the AH when the clip jumps forwards during the warm up phase. I personally have absolutely no doubt that during the engine warm up phase, variation in vaccuum will cause progression, as would any bumps and G variation during the take off roll. These are highly sensitive instruments, and although they are useful, they're only useful when used in combination with ALL the other flight instruments. I for one think the P-51D is a work of art. The fact that giro progression is modelled is why we're having this debate. Welcome to reality! Link to comment Share on other sites More sharing options...
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