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Luis Hernandez

Time compression: why some planes don't work OK with it...

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I usually like to fly short hops in FS (up to 45-75 minutes, I usually don't have more time) so I limit my flights to short ones, but sometimes I fell bored and try a longer one... using time compression. I did some time ago a "world tour" with Posky's 767-200 and Lonny Payne's panel, and I didn't have any problem flying at 16x.However, if I try a payware aircraft like the PMDG 737, the PSS A340 or the Level-D 767 (or use iFly's 744), I'll get some mild oscillations in altitude at 8x, and very violent oscillations at 16x (except Level-D: The aircraft's autopilot doesn't support time compression that high), no matter if the skies are clear or if I use real weather. For comparison, I flew yesterday a longhaul between LFPG and SKBO with Camil Vaquette's 787 at 16x... no problem at all. Try it with the PSS A340... oscillations.I see people that report flying the PSS 777 at 16x with no problem (I uninstalled it because of the oscillations), so there should be something wrong with my FS, but I can't find what could be. What could be the problem, and how could I fix it?Best regards from ColombiaLuis Miguel

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Hi Luis,16X!!! :-eek Try limiting it to 4X and you'll be fine. I believe that advice is in the FS help guide. 16X is asking a lot when you consider it equates to Mach 12.6 (assuming M.79 cruise at normal speed).I appreciate time may be limited but you're killing the realism with time acceleration and having spent your money on the PMDG737 and LDS767 they deserve to be flown 'correctly' ;-)Cheers,

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LOL, I know LDS767 and PMDG deserve to be flown "correctly"... but sometimes I feel a little bit unrealistic sending a big plane on a route worth of an RJ. Anyway, I only accelerate time at cruise, because I don't know a "correct" way of flying it ;)(yes, please, someone teach me) and so I'll prefer to skip it. Climb (from 10000 ft) and descent, 1x; take-off (up to 10000 ft) and final approach, hand-flown.

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Simple answer - the aircraft you have problems with use custom autopilots, hence the erratic behaviour at high compression rates. Highly suggest you consult the developer-provided tutorials - they really are your best basis for learning.regards,Markhttp://www.dreamfleet2000.com/a320/custbanner2.jpgPC Power Silencer 470/3.2HT/2048mb/ATI X1950pro/SB Audigy

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Hi,<>There's nothing wrong with flying a large jet on a short flight. 747s and Concorde often had short reposition flights and they were flown correctly. Just make sure you load the right amount of fuel.;)(yes, please, someone teach me) >>If you're going to time accelerate that severely make sure the route is fairly straight and you might get away with it. Didn't those aircraft packages come with tutorial flights?Cheers,

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Why not try this, (and I'm in no way saying you are doing anything wrong your way) if you want to do a long trip, once you have flown as long as you want to, then save the flight, and pick it up where you left off your next flight. That way you can remain true to the realism and not have to us any time compression and you still get to see the world.

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Hola Luis, The answer to why some aircraft perform well at high accel multipliers and others do not has to do with both the design of the autopilot feedback loop in the panel software, and the FDE. Most developers work hard to make sure the A/P and FDE are a good match at 1X speeds so that the oscillations inherent in the FDE are well-damped by the automatic flight controls. But at accelerated rates, the frequency of the oscillation changes, and what may have been well-damped at 1X may be less stable, neutrally stable, or even dynamically unstable at higher accel rates. Generally, I don't think most developers test for stability at rates above 4X, some probably not even above 1X. Getting the FDE and A/P feedback loop params tweaked to perform well at multiple accel rates is a challenge, too. I pulled my hair out for days trying to get my A330-340 FDE to play nice with the PSS panel at 4X and 8X. That said, you might try varying the loading to shift the CG on the model...you can often find a CG range that keeps the pitch stable at some or all of the higher accel rates...and once you know where that CG value is, you can load the jet accordingly on those flights where acceleration is planned.SaludosBob ScottATP IMEL Gulfstream II-III-IV-VSantiago de Chile

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