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Guest BeaverDriver

Speed & Temp Issues

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Just saying thanks to all you guys trying to fix this issue.
Yes, indeed - your efforts to improve this (otherwise very nice) plane are very much appreciated :(

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Disregard

Edited by Fede80

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Thanks Guys. here was my initial settings and I was not too far off fede80's numbers, so at this stage I will go with fed's numbers as he has proven record, even though my settings already produced a more suitable 208.empty_weight_pitch_MOI = 13500 //8890empty_weight_roll_MOI = 9100 //6012empty_weight_yaw_MOI = 16000 //12025[flight_tuning]parasite_drag_scalar = 0.9 //1.5elevator_effectiveness = 1.1 //1.2[GeneralEngineData]fuel_flow_scalar = 1.155 //1.1[propeller]thrust_scalar = 1.25 //1.0prop_tc = 0.0004 //0.004gear_reduction_ratio = 17.4 //17.1[TurbineEngineData]fuel_flow_gain = 0.03 //0.011static_thrust = 150 //85 [Flaps.0]extending-time =10 //5.7lift_scalar =1.1 //1.3 drag_scalar =1.0 //1.1 [brakes]toe_brakes_scale = 0.85 //1.0

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Blink, why have you lowered the lift value with flaps? It seemed already too low to me

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Guest BeaverDriver
I have some spare time today, I'll be playing with the ITT value and see if I can find the correct value. I'll use the takeoff power chart to get it.Anyway, the ITT is just a visual problem, I guess, as it doesn't affect the torque produced. It's all a matter of torque or drag, but I'm more prone to the drag, as the takeoff roll and climb are ok.Glen, I can't understand one thing: how can the induced drag affect the high speed cruise? And wasn't the rule that Di=(sqCl / 3.14 x A) x (p SqV S) / 2? The sentence you wrote seems to mean the opposite. But it's been a while since the ATPL, I should take a read at my book again to refresh laugh.gif It's true that induced drag plays a role in total drag, though, but at high speed it's the parasite drag to play a major role. Induced drag is caused by the high coefficient of lift, so with a high angle of attack at slow speed (clean and slow, strong wingtip vortices, etc): I think if you're going to alter that value it will take forever to land, and it will have an instant vertical speed at takeoff. As it is now that seems fine, I played at some short field, about the length of the required take off roll, to see if I could barely make it, and in fact I could take off at the very end of the runway, and having the correct climbout with a slow increase of speed after airborne. What do you think?I'll report later if I can find a useful number for the ITT (oh, and fuel flow, too)CheersP.S. For the flaps, they have their own value of drag
OK, I can see your point here. I will bow to your greater level of training and understanding on this one (and that's said with envy and respect, not with any malice whatsoever :(). I'm going to give your numbers posted below this post a go, but it sounds like you've got it nailed pretty good. Can't tell you how much I appreciate that! Thanks, and more thanks for this. Off to do a flight and will be back in a bit. Again much appreciated :(

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Thank you Glen. I very much appreciate it.I've been trying again, but there's a point I can't understand. Is there a value to be set in the cfg to make the torque available decrease quicker with altitude? You know, like the critical altitude for turbo piston engines. It seems the torque availabel remains a bit too high during the climb...

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Guest BeaverDriver
Thank you Glen. I very much appreciate it.I've been trying again, but there's a point I can't understand. Is there a value to be set in the cfg to make the torque available decrease quicker with altitude? You know, like the critical altitude for turbo piston engines. It seems the torque availabel remains a bit too high during the climb...
Boy, not sure on that one. I'm reasonably familiar with piston pounders but turbines are a bit of a different story for me. I think the service ceiling is pretty far up there so it may be that it doesn't matter much, even in the mountains, but it still should be tweaked if it needs. I'll keep my eyes open for something here, but I'm not too familiar with turboprops as I say.Just installed your tweaks and will give it a go in about another hour. I'll let you know how it goes (I operate from a cooler climate so that might be interesting), but I have every confidence it will work beautifully. Back in a bit... .

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I may have found it, reading now :)

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I got it! Now I have to find the values.. :)

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One of the problems we have is that FSX has a terrible turboprop model...you should see ITT increase as you climb, not decrease. ITT is affected by outside air temp but also by air density; as the air gets less dense, there's less cooling airflow into the turbine, so ITT increases.I'm headed home now to try out the stuff Federico did this afternoon...I'll let you know my results.


Best Regards,

Kurt "Yoda" Kalbfleisch

Pinner, Middx, UK

Beta tester for PMDG J41, NGX, and GFO, Flight1 Super King Air B200, Flight1 Cessna Citation Mustang, Flight1 Cessna 182, Flight1 Cessna 177B, Aeroworx B200

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I know Kurt, but I go as far as I can, I can't reprogram FSX! :)Ok guys, I have a solution to my latest problem. Unfortunately there isn't a single value to be changed, we have to use the airfile editor. Line 1548, the very last one, atmospheric density on shaft torque (why the things I need are always at the bottom? :) ). It's a graph, X Y simple one. You'll see the X axis is locked, leave it locked. Work on the Y. I'll make a sort of table below with the X value and the corresponding Y value to be changed.X= 0.00204 / 0.00175 / 0.00149 / 0.00126 / 0.00114 / 0.00089Y= 0.99 / / / / 0.94 / / / / 0.81 / / / / 0.74 / / / / 0.69 / / / / 0.61I checked until 20000 feet. Believe me, you won't go higher with this plane, but it should work higher too. Things I said earlier are still valid: when you see you are at full throttle, don't decrese the RPM unless you are looking for a slower cruise with lower settings of both torque and RPM. I can't reproduce the increase in torque due to the reduction of RPM...This should be ok. I'll wait for your resultsCheers

Edited by Fede80

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TEST RESULTSFirst thing, I'll tell you what I changed:Aircraft.cfg[GeneralEngineData]fuel_flow_scalar = 1.18 [turboprop_engine]maximum_torque = 2040[flight_tuning]parasite_drag_scalar = 0.8Air file (I use Aircraft Airfile manager v2.2.)Entry 1526ITT scale factor 0.95LIMITATIONSAs you all well know, FS has some limitations, so I had to tweak by reaching a good balance with the numbers.EXPLANATIONWhy did I decrease the torque scalar and increased the maximum torque? FIrst I increased the torque value to 2040, as it is a value "unreachable" by the aircraft if not sitting still. We need a 1970 torque during cruise, though. Do you see the red line "TO" at 1865, and then another one at 1970 on the torque gauge? Well ,that's the one. But setting the torque limit at 1865 wouldn't allow us to reach 1970. Setting it at 1970 neither. We need that value, during cruise, at cruise speed with full throttle you won't go over 1970 torque, setting the limit at 2040 in the cfg. Ok.I had to lower the scalar, though, or the climb (and the cruise as well) would be way too fast. Keep in mind I had the manual in front of me, it's not a random number. If you look at the "cruise climb" page you'll see it reaches 12000 feet. Because after that we can't reach 1865 torque any more, so you just keep full throttle and keep climbing. I managed to use that value, 0.85 (it was 0.83 originally, but it seems a bit too low), because in the cruise page I checked the values of torque at different altitudes (ISA cond), and as you can see there are strange numbers, like 1428 at 14000 feet, those seem to be absolute maximum values. But the values for lower RPM are higher! Simply because reducing the RPM will produce a higher torque, but not in FS (or not here, at least). So, if you climb above 10000 feet (about), and you want to cruise fast, just keep full throttle and 1900 RPM. If you want to slow your cruise, you can use lower settings of torque and RPM, but at least our speeds and performance aren't compromised.So remember: climb at 1865 torque and 1900 RPM until you can, monitoring the ITT, of course. Don't use full throttle from sea level, it would be unrealistic. ITT, you need to open the airfile, it's an easy step, just change that value, save and close. I tested it at 42°C at sea level, then 50° sea level with 1700 torque, as per the book. It works. ;) I think it could be lowered a little more, like 0.94 maybe, but 0.95 looks more challenging. And after all, how many times do you take off with 42°? Unless you always fly in the desert...This setting will also control the ITT during climb and cruise, where limits are at 765° and 740°.Fuel flow parameter. Not much to explain here, it was too low, this is the optimal value I could find for all altitudes. My tests were run at different RPM and torque settings at 4000, 8000, 12000 and 16000 feet.Parasite drag remains as yesterday tests, at 0.8, cruise speeds are just fine.CONCLUSIONSYou will get a balanced plane overall. If you are looking to change these values to make the plane as real as you can, you won't cheat. Yes, because you can. Increasing the torque will give you more power available, but it's not our purpose. You will fly it as it supposed to be flown. So take off at 1865 torque (be very careful when incresing the power to TO, or you'll stress the engine), take a close look at ITT temperatures during all critical phases of flight, such as takeoff and climb out. Be within the limits, and you'll have a very nice bird to fly. Gauges are just plain perfect, Carenado style. You have everything you need, so now go fly it!CheersFedeP.S. This was the result of a whole afternoon of testing, we may tweak a little more the numbers, just try it this way, and let me know
Federico, I think you've nailed it! This airplane was visually perfect before, now it's also got a great FDE to go along with it. Well done, sir!

Best Regards,

Kurt "Yoda" Kalbfleisch

Pinner, Middx, UK

Beta tester for PMDG J41, NGX, and GFO, Flight1 Super King Air B200, Flight1 Cessna Citation Mustang, Flight1 Cessna 182, Flight1 Cessna 177B, Aeroworx B200

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Federico, one thing that bugs me is that the C208B's prop is governed to 1900 RPM. It should never go higher than that if the prop governor is working. I can't seem to find a limit variable for prop speed, though.


Best Regards,

Kurt "Yoda" Kalbfleisch

Pinner, Middx, UK

Beta tester for PMDG J41, NGX, and GFO, Flight1 Super King Air B200, Flight1 Cessna Citation Mustang, Flight1 Cessna 182, Flight1 Cessna 177B, Aeroworx B200

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Guest BeaverDriver
I know Kurt, but I go as far as I can, I can't reprogram FSX! :)Ok guys, I have a solution to my latest problem. Unfortunately there isn't a single value to be changed, we have to use the airfile editor. Line 1548, the very last one, atmospheric density on shaft torque (why the things I need are always at the bottom? :) ). It's a graph, X Y simple one. You'll see the X axis is locked, leave it locked. Work on the Y. I'll make a sort of table below with the X value and the corresponding Y value to be changed.X= 0.00204 / 0.00175 / 0.00149 / 0.00126 / 0.00114 / 0.00089Y= 0.99 / / / / 0.94 / / / / 0.81 / / / / 0.74 / / / / 0.69 / / / / 0.61I checked until 20000 feet. Believe me, you won't go higher with this plane, but it should work higher too. Things I said earlier are still valid: when you see you are at full throttle, don't decrese the RPM unless you are looking for a slower cruise with lower settings of both torque and RPM. I can't reproduce the increase in torque due to the reduction of RPM...This should be ok. I'll wait for your resultsCheers
Well Sir, you sure did nail it!! NICE WORK!!! I have to put in the data you list here, but the previous tweaks really nailed this thing down near perfect. Fantastic job, and thank you.Off to do these latest tweaks then.

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Federico,I am in the middle of my first flight using your Atmospheric Density on Shaft Torque mods, and here's what I'm seeing:Altitude 8000 ftAltimeter 29.80OAT 22oCTQ 1400RPM 1900ITT 727oC137 KIAS (160 KTAS)Fuel Flow 333 PPHThat's an astonishing 1 KTAS and 4 PPH difference from the charted performance!Still better, ITT increased during the climb.Yep. You nailed it.Now to fix that prop governor!


Best Regards,

Kurt "Yoda" Kalbfleisch

Pinner, Middx, UK

Beta tester for PMDG J41, NGX, and GFO, Flight1 Super King Air B200, Flight1 Cessna Citation Mustang, Flight1 Cessna 182, Flight1 Cessna 177B, Aeroworx B200

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