Tigerclaw 31 Posted September 1, 2011 Share Posted September 1, 2011 Hi guys, I find myself in need of some help with regards to the Gyro compass and the amount of drift I'm seeing. When it comes to the technical side of gyro drift, I'm afraid I'm a bit of a div. For those that aren't English, div means stupid, a dunce, a thicko. So there you have it, I'm stupid. Anyway, can someone please explain why I appear to be getting excessive drift in the Katana? When I say excessive, I, me personally, feel it's excessive, but is it? I do know a gyro compass will drift very badly when doing sharp hard turns, aerobatics etc, but I'm not doing those things. I'm flying straight and level, mostly, with a bit of turbulence I'd guess,. But the compass drifts as much as 180 degrees. I seem be readjusting it every couple of minutes, is this normal? I can't exactly compare this to anything else, because quite frankly, there's nothing else like the Katana for realism, but I've not noticed such a huge drift before. I was wondering if it was linked to a sound I'm hearing repeated over and over again all through my flights. The sound starts when you turn batteries on and the artificial horizon initiates, then it repeats at regular intervals throughout the flight. The drift "appears" to happen each time that sound restarts, but that may well be a coincidence. Anyone have any ideas? Link to comment Share on other sites More sharing options...
Voyager30 0 Posted September 2, 2011 Share Posted September 2, 2011 Hi Tigerclaw If you experience a drift that much I would definatelly say that something is wrong. When I helped beta test the Sibwings Saab Safir did I have a discussion with a IRL Safir pilot and he told me that in a Safir was a gyro drift of 1 degree / 4-5 min not uncommon - but the DG in that particular aircraft is driven by pneumatic pressure and possible 30+ years The DG in a Katana is electric though so the first that comes to my mind is - have you checked that all circuit breakers are in ? //Gerth Link to comment Share on other sites More sharing options...
Tigerclaw 31 Posted September 2, 2011 Author Share Posted September 2, 2011 Yes all circuit breakers are in, but now I know it may be a possible fault I can start "replacing" or "repairing" parts of the electronics in the aircraft to see if there is a fault not showing up in the maintenance hanger. If I do them one at a time, I might find something. If not then I'll await other replies and go from there. Thank you for taking the time to answer Link to comment Share on other sites More sharing options...
Snave 466 Posted September 2, 2011 Share Posted September 2, 2011 Yeah, that does sound like an aircraft fault - a maintenance issue. The sound you refer to is only heard when the avionics are spooling up, so something must be cycling in-flight. I think in the Kat4X it is deliberately set as a `startup` sound rather than background continuous for CPU-cycle reasons - in real life you don't hear it against the rest of the hubbub and you can save the extra `voice` for other incidental and consistent noises. IIRC the gyro for the heading indicator is vacuum driven, so possibly check for blockage. When started up from cold, it can show quite a variation from magnetic as it kind of `remembers` it's last heading. But it doesn't normally need excessive amounts of re-alignment in flight. 2-3 degrees an hour, although I used to align it (against the GPS in this case) every fifteen minutes, as that's what I was taught to do in older aircraft. If you are constantly hearing that startup sound then it sounds like there is a maintenance issue that needs attending to with the avionics cycling. Certainly the drift is nothing like what you are describing in the real deal. Link to comment Share on other sites More sharing options...
Tigerclaw 31 Posted September 2, 2011 Author Share Posted September 2, 2011 Thank you for the reply. I did, and always do check the "maintenance hanger" and the "Service sheet" too, and so far nothing has indicated there is a problem. I'll replace a few items and see if that fixes the problem. I would like to say though, that this is occurring even with a complete reset of the data file. The start up sound is recycling every 2-3 minutes, and the drift also is moving far in excess of 30 degrees every couple of minute or so. It really does seem linked to that sound cycling, but that may just be me Question on procedure: When you flick the switch for battery and the Artificial horizon initiates, should you wait until it finishes before carrying on with the starting of the engine? If you start the engine BEFORE it's finished, could that be causing the issue? Edit update: I think I fixed my drifting issue by "replacing" the Avionics. That's the only thing I replaced, but I DID wait until the Artificial horizon had initiated before starting the engine. I did a very brief flight, it had to be brief because I couldn't get above 60 knots again, and the gyro drift was negligible. No wild fluctuations, and if there was any drift at all over the short flight, I didn't notice it. So I can say I'm happy with that, and a bit of knowledge has been obtained. What I'm not happy about is that stupid engine power again. But that's something I'll have to work with until I get it right Link to comment Share on other sites More sharing options...
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