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Old 05-06-2020, 03:24 AM   #11
kontiuka
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Quote:
Originally Posted by frumpy View Post
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.
The positive rate of climb isn't due to the vertical lift component of the wings. It's due to the fact that the nose is now above the horizon. Therefore, the thrust of the engine is pushing the aircraft slightly upward.

And remember, in some aircraft (not the C-101), you can do a knife edge pass using just the rudder. In that case, the wings are providing zero lift.

As an aside, I just tried the F-5E and this phenomenon is actually quite pronounced in it.
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Old 05-07-2020, 12:47 PM   #12
Vibora
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Regarding positive rate of climb when deflecting ailerons:
We use real aircraft data in our flight model, and that includes a positive pitch as well as a negative lift when deflecting ailerons. We've just checked that this agrees with NASA documentation regarding asymmetrical deflection of ailerons causing pitch and lift variations. There are many other flight mechanics effects included in our simulation that are not the case now. But, be sure that, as I told you, our simulation is at a high professional level.
In any case, I've tested it again and that effect is there but it's really negligible. Please check this video. I use just aileron and no elevator, to get to that scenario I use just arrow keys corresponding to ailerons, without deflecting arrow keys corresponding to elevator or joystick.
Hope this ends up the discussion because I would rather prefer to spend time developing what's missing in our simulation, than testing and researching stuff that is already working correctly, I'm sure most users will agree.
Nevertheless, I appreciate your feedback as it helped to improve ADI and HSI indications. Just recommend you to report stuff that you are absolutely sure is wrong.
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Old 05-08-2020, 06:57 AM   #13
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Quote:
Originally Posted by Vibora View Post
We've just checked that this agrees with NASA documentation regarding asymmetrical deflection of ailerons causing pitch and lift variations.
Do you have a link for these NASA docs? After a quick search I only found TM X-3231.
Thanx in advance
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Old 05-08-2020, 01:44 PM   #14
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Yes, That one serves for the purpose.
https://ntrs.nasa.gov/archive/nasa/c...9830002803.pdf
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Old 05-08-2020, 07:41 PM   #15
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Thanx: Although I'm not sure if the results from this highly swept high aspect ratio wing with its supercritical airfoil can be applied to the short straight CASA wing.

Last edited by bbrz; 05-08-2020 at 07:43 PM.
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Old 05-08-2020, 10:49 PM   #16
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Obviously.
That's just an example.
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Last edited by Vibora; 05-08-2020 at 10:54 PM.
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Old 05-24-2020, 09:47 AM   #17
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I feel if a 10° tilted oval fuselage creates more lift than a 10° tilted wing, then aerodynamics have to get a second thought. Okay, it's only a small effect, so lets leave it.







One thing I noticed when following the procedure of retracting the flaps at 120-125 kts (4800kg) the AOA will rise suddenly and will activate the stall warning if the pilot is not reacting quickly. Not nice being close to the ground in a low powered aircraft, especially in a trainer aircraft.

I compared the AOA of the L39 (4500kg, due to smaller wing area) with the C101. While the AOA with flaps retracted is pretty similar in both modules above 240 km/h, the AOA of the C101 is significantly higher with flaps in takeoff position. I am not completly sure on how to interpret this, but it seems like they are not generating enough lift?




There seems to be something with the thrust vector. When at 250 kts, increasing the thrust will lower the nose, while lowering the thrust will lift the nose. I think it should be the other way around, since the engine is below the airplanes CoG.




Is there a public bug list? The is a thread from 2015, but I cannot find a list there. Vibora, you wrote something like the pitch axis is being worked on, what are the symptoms that you are working on? I am interested in helping to improve the flight dynamics, perhaps there is something I can do



Thanks,


Olli
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Old 05-25-2020, 01:51 PM   #18
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Quote:
Originally Posted by frumpy View Post
One thing I noticed when following the procedure of retracting the flaps at 120-125 kts (4800kg) the AOA will rise suddenly and will activate the stall warning if the pilot is not reacting quickly. Not nice being close to the ground in a low powered aircraft, especially in a trainer aircraft.
This is known from long time ago and already solved, will probably be in next update.
Quote:
I compared the AOA of the L39 (4500kg, due to smaller wing area) with the C101. While the AOA with flaps retracted is pretty similar in both modules above 240 km/h, the AOA of the C101 is significantly higher with flaps in takeoff position. I am not completly sure on how to interpret this, but it seems like they are not generating enough lift?
Why would L-39 flaps be similar to C-101 flaps, even angle of extention? Our module shows precisely the flight model of the real aircraft. See the attached screenshot comparing a real situation with our simulation, showing around 3º of pitch with flaps at takeoff. Of course weight and other parameters can make data vary slightly, but this shows you that parameters fit.


Quote:
There seems to be something with the thrust vector. When at 250 kts, increasing the thrust will lower the nose, while lowering the thrust will lift the nose. I think it should be the other way around, since the engine is below the airplanes CoG.
I'll try to give an answer soon.


Quote:
Is there a public bug list? The is a thread from 2015, but I cannot find a list there. Vibora, you wrote something like the pitch axis is being worked on, what are the symptoms that you are working on? I am interested in helping to improve the flight dynamics, perhaps there is something I can do
We don't publish bug lists, we manage it internally. We fixed an error in the FM code some time ago, we are not working on anything else regarding flight model right now.
Txs for your reports.
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