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Old 04-26-2020, 07:33 PM   #1
frumpy
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Hi there,


I feel the C101 is a fun module, good job.



However, I feel there may be a few discrepacies for IFR turning: Using the 4 min turn coordinator, I should turn at about 22° bank at 230 IAS. Doing this, I'll get about 3:40 for a full turn, so its a bit fast.



Doing a bank = TAS/10 + 7 (30° at 230 kts) I'll get around 2:20, so its a bit slow.


Also I noticed when in level flight, doing a bank from one side to another, there is a slight pitchup. This pitchup can even be used for climbing: once I stop waving the wings, the v/s goes to 0. I have never seen a (simulated) aircraft climb when being banked. Maybe thats a feature due to the design of the aircraft, I have no idea.



I attached both turns and banking issue as a video, the banking is at the very end.
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File Type: trk c101 climb.trk (1.54 MB, 11 views)
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Old 04-26-2020, 09:55 PM   #2
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We'll take a look at it. Txs for your report.
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Old 04-28-2020, 12:48 AM   #3
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Regarding a bank initiating a slight climb, this might just be the adverse yaw from uncoordinated turns l. I see the same thing with the F-14.
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Old 04-28-2020, 03:50 PM   #4
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You are using IAS instead of TAS. I guess you did your tests at around 6000ft.
In that case, flying at 6000 ft, if you set 230 kts of IAS and a bank of 30º it will take the time you say to turn 360º, around 2 min 20 sec.
You should set an IAS of around 190 kts, equivalent to around 215 kts of TAS, which is the true airspeed you have to use for a coordinated 2 minutes standard turn. Take into account that the formula you use is just a rule of thumb and it's not precise. If you use the real formula, you have to set the IAS I told you for 30º of bank. You can check it in this web page from Luis Monteiro:
http://www.luizmonteiro.com/Article_...d_Rate_05.aspx

Regarding the climbing issue when banking, i don't see such effect. But if there would be any it could be caused by the adverse yaw as kengou said.
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Old 04-28-2020, 04:50 PM   #5
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Quote:
Originally Posted by Vibora View Post
Regarding the climbing issue when banking, i don't see such effect. But if there would be any it could be caused by the adverse yaw as kengou said.
It is there and has been there pretty much since day 1. Even in the SFM. I've always wondered about it but this is the first time I've seen someone else mention it. It only lasts a few seconds into the turn before the aircraft starts descending. Possibly because of the adverse yaw.
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Old 04-28-2020, 06:34 PM   #6
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You men the adverse yaw effect then. In fact, it is only a very brief climb indication. It shouldn't affect your IFR flying as the aircraft will soon start descending. If you want to do a coordinated turn you should apply some rudder while the ailerons are deflected to keep the ball centred.
BTW, SFM has nothing to do with AFM, if you had seen such effect in the SFM then you would have seen it in any other DCS module with SFM.
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Old 05-01-2020, 10:07 AM   #7
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Hi Vibora,

thanks for taking a look at it. Check out the video in the first post, just at the end I blocked my pitch axis and just rolled left and right and got the positive vertical speed. You can also see this effect when pointing the nose at a ground target and correct only left and right. I don't see how adverse yaw should have any positive effect on pitch. (Just by yawing in level flight I'll get a slight descent rate, which is correct.)



I did some testflights again. This time at about ISA and flew 1000 ft (mission file attached). 230 TAS is about 227 IAS, which I tried to keep as good as possible.

4 minute turn using the bank indicator is 3:50min left and right, so if pointer indication is increased by a factor of 1.04, it should be pretty much dead on.
I noticed left turns at 1000', 227 IAS and 30° are 2:14min left, 2:21min right (did each turn twice to average the time). I am not sure about the precision of the TAS/10+7 rule so *maybe* the C101 turns a bit slow in general. I checked this in other sims too, the rule of thumb was pretty much dead on.
But why are the left turns quicker than right turns?
Well, I noticed that the bank scale for a right turn is a bit off. It displays 30° bank, but the DCS value (F2 view) is 29°. It's correct on the right side (left turn).



I know this is a bit picky, as this is a consumer and not a professioinal product. I bought this module yesterday, as the overall experience convinced me and I want to support the developers for their art. I believe most things are not that hard to correct and I would appreciate if the devs could take care of it.


Thank you!
Attached Files
File Type: miz C-101 EB Testflight ISA CAVOK.miz (7.8 KB, 7 views)

Last edited by frumpy; 05-01-2020 at 10:11 AM.
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Old 05-01-2020, 11:56 AM   #8
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Regarding adverse yaw, if you bank left without coordinating rudder, the nose will drift right a bit, but since you’re banked left, that means the nose drifts above the horizon, inducing a slight climb briefly before the nose settles again.
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Old 05-04-2020, 11:10 PM   #9
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Hi frumpy,
Nose up tendency during roll: kengou already answered this. There is a vertical component of adverse yaw effect when you are in a bank.
Coordinated standard two minutes turn: You keep making the same error. That rule of thumb is not precise enough. You should use the real formula, or you can find the bank angle for a certain rate of turn and TAS in this link:
http://www.aviationwebdevelopment.co...alculator.aspx
I made the test in our C-101 and in the F-5 with same correct results.
The TAS for a 2 minutes turn at a 30° bank angle is 210 kts.
At 1000 ft with ISA (29.92 inHg, 15°C) a TAS of 210 kts corresponds to 206 kts IAS.
You can check it here:
http://www.indoavis.co.id/main/tas.html
Flying with those parameters, I get a standard two minutes turn with precision enough. It took me 2:02 min to complete a 360 to the right, and 1:58 to compete it to the left. We have to take into account pilot error, as keeping exact bank angle, speed and altitude is not easy.
Check the attached screenshots.
Bank scale: we have already corrected it, thanks.
BTW, in a second attempt after correcting bank indexes, I got the opposite results, 1:58 right and 2:02 left, which could confirm that these minor deviations can be due to pilot error.
Bank indicator: please do it the other way around, set the correct bank angle for a certain turn rate and check the indicator, you will see that there is no error. Take into account that there are induced pilot errors in the tests.
Check the attached screenshot, keeping 206 KTS of IAS at 1000ft, ISA, and 16° of bank angle, which is the one that corresponds for a 4 minutes turn, the turn and slip indicator show a correct indication, needle on the mark.
We consider our simulation is at a high professional level, we have used the real aircraft data and our developers are aerospace engineers. Of course, there can always be some unwanted bugs, including graphic glitches as the one you reported with several banking marks displaced 1 degree.
Attached Files
File Type: rar Screenshots.rar (3.25 MB, 12 views)
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Old 05-05-2020, 02:12 PM   #10
frumpy
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Hi Vibora,


Thanks for the link on bank angle. I knew the TAS/10+7 rule is a rule of
thumb, but now I know exactly how much bank is needed.
It's great to hear the turn rate is spot on!



I am not sure about the nose-up attitude on rolling. Where do you think
does the vertical component of adverse yaw come from? After all, with a
bank we are losing a part of the vertical lift. Since the ailerons of the C101
are deflected in a differential way (-17/+24°) this should minimize adverse
yaw anyway.
I mean after all it would mean that when I'll lose the elevator, I can control
altitude by the means of inducing adverse yaw?

I also had contact with a senior flight model developer, asking him about the
climb. He said there is no lift component and due to design adverse yaw
should be very little, if any.


Thank you.
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