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borisvp

EPR mode does not work with FFRATS

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Hello dear fellow RFP pilots,as you see in the topic, there must be something I miss. I do as described in the manual, I followed all the procedures I found in similar topics in the forum, and still - the EPR mode does not work.Here is what happens:FFRATS to TOD, EPR mode, EPR set to auto (1,50 or less if derated), A/T on.Throttle (I have a PFC quadrant) slowly all the way forward to max.EPR also goes to max (1,68) and is further controlled only by the hardware throttles. No automatic whatsoever. No difference whether FFRATS is in TOD or CLB. No difference whether I move the throttle slowly or fast.Only speed mode works. When I set FFRATS to CRZ and SPEED mode, the autothrottle kicks in and holds the selected speed.What am I doing wrong here?ThanksBoris

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hi,I'll describe how the FFRATS(TRC for Boeing)should work.On the EPR indicators there's on right bottom the EPR LIMIT setting button.By this button it's possible to set the EPR limit in automatic or manual mode.Clicking on the button using the little blank Hand the Limit indicator goes to the EPR limit indicated on the TAT/EPR LIMIT indicator.Clicking on the button using the little hand with the signs - or + it's possible to set the EPR Limit manually to the desired value.With the FFRATS(TRC) on TOD/EPR mode at TO, after having positioned the throttles in vertical position, you switch on the A/T.The engines will be accelerated to the value already set on the EPR indicators.After TO when you turn the FFRATS(TRC)selector to CLIMB the EPR LIMITindicators will be reduced to the CLIMB value indicated on the TAT/EPR LIMIT indicator and the engines power should be reduced accordingly.Following the right procedure you should be able to use the CLIMB THRUST in EPR mode varying the VERTICAL SPEED until the cruising level is reached but....The RFP software hasn't be made properly and the CLIMB THRUST with altitude growing isn't sufficient to support the plane climb.On the contrary using the FFRATS(TRC) in SPEED MODE the plane receive the proper thrust and can maintain the climb speed without any problem.We have to consider that the usage the FFRATS(TRC) in speed mode during climb is very wrong but the RFP community to reach the cruising level has not different chance.cheers

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Actually, Gianfranco, the offenders is the FS9 autopilot and the rather exaggerated changes that it makes to the trim settings when using EPR modes. It simply is just too sensitive and makes too many changes too quickly, this is why the plane tends to porpoise.You can use EPR Climb mode over FL100 IF you climb to above that altitude, get your speed bugs centered and wait until everything is stable at the selected altitude (I use FL110 or FL120 and 320KIAS depending on desired course). At that point, I engage the EPR Climb mode and it usually does just fine. The centering of the speedbug on the ASI seems to be critical to making it work.Hope that's of some use.EdEd GreenKCLT


http://www.oncourse-software.co.uk/forum_images/fdc_beta.jpg

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Hi ED,I supposed something like this and I assigned a key to center all flight surfaces but with no result:growing the Altitude the EPR calculated by the thrust computer evidently is too low and the speed decreases even with very low vertical rate of climb.I think that a patch should be necessary to get the thrust computerworking proper.I know that a RFP B742 v4 revision is in the RFP Team intentions but I don't know when and I don't know also if the FFRATS is included in the planned revision.Cheers

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Well, thanks for your help, but it doesn't work for me. EPR simply doesn't become active, no matter what I do. Speed mode works fine, though.RegardsBoris

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