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Post by Falcon on Feb 22, 2012 16:27:37 GMT
Recently, when I turn off the auto pilot on the CV-990 it does a quick bank to the left and the nose starts down. I never experienced this before, but then I don't think I had flown it much. Any suggestions? FSX, Vista  Falcon |
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Post by aerofoto - HJG Admin on Feb 22, 2012 16:53:41 GMT
You say "RECENTLY" .... suggesting this didn´t happen before ?
I can only say our CV990´s all fly as stable as every other aircraft we offer (just a lot faster .... with exception of the CONCORDE of course) .... both in AP and in manual flight control modes.
Of course I´m referring to my many years of experience with this simulation in FS2004 .... but even so .... there´s no such known issue with any of our CV990´s in FSX either .... at least none that I´ve heard of before now.
In do recall another poster reporting that he had experienced a similar issue with our B707´s .... but again .... which we/I couldn´t ever replicate the problem. As I recall .... I think his particular issue was eventually traced back to something, or other, to to with his controller device configuration/calibration .... BUT .... I don´t, now, recall the actual solution/specifics.
Mark C
BOG/CO
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Post by aerofoto - HJG Admin on Feb 22, 2012 18:25:56 GMT
In the light of your report, I had time, today, to do a quick test flight using our CV990-A in FS2004 .... and using our standard CV990-A version panel too. Our 2 CV990 panel/s (along with those for the CV880 also) are compatible with both FS2004 and FSX .... as are their respective FDE´s too (which haven´t been edited (no need to) since mid 2008). In fact the only difference between the CV990 FS2004 and FSX version FDE´s are the "FSX specific" smoke effects data which applies to that sim version only. ANYWAY ....  I took my CV990-A up to FL310. I purposely flew it overweight (without any of the normal fuel adjustments I usually apply in order to set any simulation at/near its MGTOW) .... because I felt, if there was any stability problem (which I already knew wasn´t the case) then this condition would likely tend to be hilighted during an overweight high altitude and high speed cruise condition . My CV990-A´s AP controlled flight cruise performance at FL310 was noted as follows .... MACH 96.7 (just below the CV990´s max cruise speed of MACH 97.0)
IAS 386 KIAS
TAS 567 MPH
EPR 1.81 (this isn´t a power setting)
FAN RPM (forwad fan section - this isn´t an N1 indication) 90.1%
EGT 510
FAN RPM (aft fan section - this isn´t an N2 indication) 90.2%.... and that´s going "B-A-L-L-S TO T-H-E W-A-LL".... almost as fast as the thing/CV990-A can safely go without "ringing the bell" The earlier version of this aircraft (the standard CV990 .... which we also represent here) can´t go this fast as was the problem with the original version of these realworld aircraft too and essentially why the CV990 was eventually modified to become the CV990-A .... which met the aircrafts promised speed performance, but, only at the expence of excessive fuel burn .... and which combined with its lower payload/PAX capacity (compared with the B707 and DC8) due to its narrower fusdelage cross-section ensured that the CV990 became a real commercial failure. MOVING ON THOUGH .... :  My AP controlled high altitude and high speed cruise flight performance was observed to be "PERFECTLY STABLE". The only observation probably worthy of being noted/commented regarding is that the CV990 does appear to be just "a-tiny-we-bit" more difficult to trim, using the AP TRIM THUMB WHEEL, than is the case with the DC8 .... and despite the fact that both simulations use the same type of AP .... but .... this particular observation could just be a reflection of how this simulation performs on "THIS" PC (here in Colombia) and using the mouse pointing/selecting device (ours is terrible) which we have here, because I don´t recall this ever being an issue on my procinple PC (in New Zealand) otherwise I´d have commented accordingly within my CONVAIR PANEL INSTALLATION & HANDLING notes which are located on the ABOUT HJG AIRCRAFT forum page. Continuing to cruise at FL310 .... I then .... disengaged the AP SERVO tab .... leaving it set at its "YAW DAMPER" postion .... and my cruise flight performance was again noted to remain "ABSOLUTELY P-E-R-F-E-C-T-L-Y STABLE" for the duration of my non-AP controlled cruise/flight test. Getting bored with all of this .... I then turned around went back home .... landing at KSEA .... and put the airplane/simulation to bed again I wonder if your particular experience "might" be caused by either one of the following 2 possibilities ....   - Fuel imbalance .... which would induce a banked attitude at least and which could, possibly develop into a worse condition once the AP is disengaged !
- The trim setting control on your controller device may be in need of recalibration .... or .... complete recalibration of all of your controller device axis which "might" (at the moment) be causing your trim settings to slip/change uncommandedly when the AP is disengage !I can´t really think of anything else "FALCON" Mark C BOG/CO |
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Post by Falcon on Feb 23, 2012 15:26:57 GMT
thanks again Mark. I'm going to try (which I should have done in the first place) this in another aircraft to see if it happens, then I can tell if my devices need recalibration. Secondly, I turned the AP off entirely, did not leave it in YAW Damper postion.
Falcon
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Post by Falcon on Feb 24, 2012 23:43:14 GMT
Hey Mark, I tried the CV-990 again today, and when I turned the AP off with the lever on the AP to Yaw Damper mode, everything was fine. It's only when I turn it off completely with the key command. I would imagine it would be hard to control with no Yaw Damper on in real life at that speed and altitude. Thanks again. It was no big deal, and the key was the Yaw Damper.
Falcon/Denny
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Post by aerofoto - HJG Admin on Feb 25, 2012 19:42:44 GMT
You´re welcome "FALCON" .... our pleasure !  I´m glad the CV990 solution, for you, was "that simple" She´s a very fast bird indeed .... and (apart from the CONCORDE) .... I/we hope you really enjoy flying her Mark C BOG/CO |
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