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Post by johnhinson on Mar 21, 2024 20:07:05 GMT -5
I loaded up the V810 to see what happens and the problem seems entirely due to the delayed throttle response which may or may not be realistic, I don't know. Table 511 doesn't look too different from the stock King Air's. It takes 24% throttle to start rolling on concrete but when reducing to say 18% the actual engine thrust keeps on falling and so the aircraft eventually stops. There's another useful tool which allows you to observe the throttle/thrust relationship and the settings that table 511 is using. Look for AFSD_portable.exe. It only runs when an aircraft is loaded and it needs a separate window from FS. I note Tom's comments but I'll try to find out what controls that power delay. Bill Thanks, Bill, yes what you are experiencing with the Viscount sums up what I experience but in better words. I have found the file AFSD_portable.exe at aero.sors.fr/designer_pilot_utilities1.html - this looks useful for all sorts of things, thanks for the tip. John PS - I also note Tom's comments but it seems UK developers focus on in-air behaviour too!
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Post by Defender on Mar 22, 2024 6:23:19 GMT -5
John,
Our friend Luis Pallas from the Connie team has come up with the following advice.
The parameter in aircraft.cfg dealing with throttle gain is fuel_flow_gain. With the original FS9 settings for KingAir 350, the value was 0.011. I have increased it to 0.018. With higher values you get a quicker response to throttle, but there is a relevant overshot on torque with throttle movements, very nasty. In other turboprops I am using even lower values, to avoid torque oscillations, as:
Embraer 120: 0.021
C130H: 0.0046
C130J: 0.0055
L1249: 0.0035
In all this cases, response to throttle inputs is quite slow, but there is no oscillations nor overshoots. You should move throttle a little and wait for a while. With practice, you can get it. It seems to be an inherent problem with FS9 FDE for turboprops.
So I see that the JBK Britannia which handles quite well uses 0.003 whereas the Viscount is 0.01. You need to try a range of values up or down and see what you get. Yes, AFSD is useful for watching how the thrust changes.
I recall reading that when pilots were converting from piston to jet there was some concern about the jet's delayed throttle response, particularly at a go around. I think whoever set the aircraft.cfg values had in mind creating a realistic delay in setting take off power despite the effect on taxi power.
Best of luck
Bill
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Post by johnhinson on Mar 22, 2024 7:20:31 GMT -5
Sounds good! I will definitely explore that when time permits - have a busy weekend ahead though.
Hopefully that is the solution. I will report back.
Very best regards, and thank you so much for putting the time into this,
John
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Post by Defender on Mar 22, 2024 14:42:31 GMT -5
Hopefully it will work John although probably no one size fits all.
I never use the Viscounts as I'm a VC fan but having tried them today I've already learned why Luis says to wait a while after setting power. If I use say 24% throttle to start moving from parking nothing seems to happen so there's a temptation to add more throttle. Bad move because if the first setting is right then the aircraft will start to move after a few seconds. Any more throttle and the aircraft shoots away and you start chasing the throttle. So it helps to know the throttle settings you need for that aircraft, moving off and then nice taxi speed.
But I'm sure you and other turbo prop users might know that.
Bill
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Post by Tom/CalClassic on Mar 22, 2024 20:42:21 GMT -5
I’m not a big turboprop user, the F-27 is the one I use most.
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Post by johnhinson on Mar 22, 2024 20:46:17 GMT -5
That will be fine for me if I can get them set up like that. I keep a crib card with settings like that noted down for each aircraft.
I plan to make a start on this next week.
John
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Post by johnhinson on Mar 25, 2024 8:03:00 GMT -5
First report . . .
Following Bill's instructions, I now have the Viscount 700 performing excellently.
Interestingly, I had a private note from somebody suggesting another way to achieve this - by adjusting the centre column of the graph in section 1508 in the Air file "Turbine Turboprop Torque vs N2" from 0.40 to 0.30. This produces almost identical results to Bill's method so there seem to be two ways of achieving the desired result.
I'm now working on the F27 but this seems a little "livelier" than the Viscount and I'm still meddling with the numbers - in fact currently trying a combination of both settings.
I won't post individually for each aircraft but will make a list when all are done, if I am successful.
Best regards,
John
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Post by Defender on Mar 25, 2024 14:08:11 GMT -5
Glad you're getting results John. I take it you added section 508? Haven't got that. Some might be concerned to know whether a 508 change affects other performance areas, take off, cruise speed etc. Also we all find that FS aircraft lose speed on turning during taxi which usually needs a throttle response. Does that torque/N2 change make that worse?
What I did find is that doubling the fuel_flow_gain value had much the same result as halving it but both helped. Another thing I did to assist taxi was to reduce the brake scalar. I found that the Viscount's release setting lost you about 5 knots each click of the controller so it's now a 3 knot drop. Less throttle work. It might vary between different controllers however.
Either way I now find taxying the Viscount not much harder that most pistons.
Best regards
Bill
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Post by Defender on Mar 25, 2024 14:56:40 GMT -5
Sorry I see you meant table 1508, not 508!
Bill
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Post by johnhinson on Mar 26, 2024 11:12:33 GMT -5
Glad you're getting results John. I take it you added section 508? Haven't got that. Some might be concerned to know whether a 508 change affects other performance areas, take off, cruise speed etc. Also we all find that FS aircraft lose speed on turning during taxi which usually needs a throttle response. Does that torque/N2 change make that worse? So far I am finding that changing these settings does not appear to impact overall performance - I'm still flying the various aircraft to the same figures and all seems well. Nor does it seem to make much difference to the issue of losing speed turning during taxi (although I don't find that too much of a problem) and I also find you need to set slightly above the optimum throttle setting to get most aircraft to start moving, then throttling back to the desired RPM once they are going. I would think this kind of precision setting might be difficult for those without the luxury of a yoke, though. But it is such a pleasure to be able to taxi smoothly - I am thoroughly enjoying the testing! John
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Post by Defender on Mar 26, 2024 14:48:36 GMT -5
You can ignore my comments about turning etc. I can see that table 1508 is quite a different thing although I'm a bit puzzled by your reference to "changing from 0.40 to 0.30". Do you mean changing the X axis from 40 to 30 in which case you get more torque from lower N1 settings? I can see that would help matters. I agree folk will have difficulty setting throttle levels without visible percentage readings or marks on the controller. Another completely unrelated question. Do you know how the doors/exits work in Rick Piper's Viscount 800?. They seem automatically linked to the engine status, rear door opening when inboards shut down, forward door linked to the outboards. I can't find any guidance Best regards Bill PS I suspect it would be quite easy to create a little gauge to show percentage throttle but still beyond me.
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Post by johnhinson on Mar 26, 2024 20:00:31 GMT -5
You can ignore my comments about turning etc. I can see that table 1508 is quite a different thing although I'm a bit puzzled by your reference to "changing from 0.40 to 0.30". Do you mean changing the X axis from 40 to 30 in which case you get more torque from lower N1 settings? I can see that would help matters. Hi Bill, You can adjust settings on the graph on 1508 with the keyboard arrow keys. Right arrow takes you to the middle column in the graph, then up and down arrows adjust it. (I'm sorry, proper mathematics isn't me, not sure which is x or y axis . . .) I don't know about the doors on the RP Viscount, it is quite an old model but I haven't ever studied them closely. Incidentally, you mentioned preferring Virtual Cockpits. The Jens B Kristensen one has a VC, although it is a bit basic. I haven't tried it, personally I prefer the detail and realism of the Fraser Mackay panels. Nor do I know how realistic the JBK performance is - all of mine have been set to work with FM's modifications. John
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Post by johnhinson on Apr 30, 2024 11:57:39 GMT -5
I have finally completed my tests after modifying my collection of turboprop aircraft. My guidance and recommended settings can now be downloaded as a PDF file at Flightsim.com - search for "turboprop taxi" to find it.
Best regards,
John
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