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Old 03-13-2018, 01:04 PM   #111
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Like others repeating the same.

Nothing new under the sun
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Old 03-13-2018, 01:22 PM   #112
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Quote:
Originally Posted by Vatikus View Post
+1

And what most people are ignoring is credibility of their next module which sole purpose is to fly on its extremes where there is no empirical documentation available should be somehow a peak in GA sim than mig21 which has it, yet they are unable to code it.

So true !
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Old 03-13-2018, 02:45 PM   #113
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Quote:
Originally Posted by Esac_mirmidon View Post
How can you measure "actual" AoA to be 100% off if cockpit readings are ok?

What are you using for "actual" measurements?
Ctrl + Y gives you an info bar with everything from TAS (Ctrl+y x2) to true AoA.
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Old 03-13-2018, 02:48 PM   #114
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Quote:
Originally Posted by Esac_mirmidon View Post
Like others repeating the same.

Nothing new under the sun
Do you honestly believe that the MiG21, a delta, has a significantly lower critical AoA than a MiG-15?

If so I'd seriously recommend taking a basic aerodynamics course. NASA has their own online one you can take. After completing this you should realize how completely effed up the ingame MiG21's flyable AoA range is.
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Old 03-13-2018, 04:41 PM   #115
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Thanks for the recommendation.

What i.m trying to said is:

Real Mig-21Bis manual:

Max permissible AoA is 28º, as indicated by the YYA-1. Stall is 33º as indicated by YYA-1. So all references must use instrument readings, not external views. Thats the only source for flying correctly the Mig-21. On board instruments. In my oppinion of course. And the real manual says the same, use the YYA-1 pointer indications.

The YYA-1 shows the current AoA to the pilot and the scale is calibrated in degrees of local angel of attack ( corresponding to deflection angles of the vane of transmmiter DUA-3 ). The yellow-black sector ( covering from 21º to 28º ) is intended to warn the pilot of approaching the limit angles of attack.

It is permitted to fly inside this limits and and at these AoA maximum use is made of the aircraft maneuverability, but flying requires greater attention of the pilot.

The red-black sector ( covering from 28º to 35º ) indicates the zone of AoA wich is dangerous for flying, because the aircraft may stall. 28º is the maximum permissible, assuming a lift coeficient of 0.85, corresponding to Mach 0.85 or higher. The margins increasing at lower Mach numbers.

AoA exceeding 33º, as read by the indicator, correspond to the aircraft stall conditions, so the safety margin is at least 5º to 8º.

With the AoA changing at the minimum possible rate, the warning unit operates at 26º. As the rate of AoA variations increase, the warning unit operate at lower AoA. WIth maximum rate changes in AoA the warning is at 22º.

So the warning is working 11º to 12º units ahead of the stall regime.

At this point all my tests to check this AoA values according to YYA-1 readings are correct inside DCS. Maybe some minor marginal differences ( for sure because my own fault flying ) but overall my tests results are coincident with the manual.


Now, again Manual taking as reference:

During take off, readings from the instrument are stable at IAS 200-300 Km/h, after the nose wheel clears the ground. Keeping the recommended unstick AoA makes the aircraft unsticks at the required speed irrespective of the aircrafts takeoff weight and external load variant. Keeping 11º-13º AoA during take off is the correct value.

Manual reference:

After unsticking the indicator pointer oscillation do not exceed +-1º and at speeds higher than 400-500 the pointer oscillation must stop.

Manual reference:

In level flight at airspeeds of 500 Km/h and higher the YYA-1 pointer is in almost horizontal position.


Manual reference:

In acceleration and deceleration in level flight the readings are constant while the aircraft is passing transonic speed range, irrespective of the altitude or external loads.


While the aircraft is being flown at angles of attack corresponding to Cy of initial stall warning buffeting, the readings are between 16º to 18º, the warning unit would not operate.

Manual reference:

To accomplish a descent at optimum airspeed according to maximum glide distance keep AoA to 5º-7º and make the final turn at 7º-9º. To obtain the rquired glide speed on the leg from the final turn to the outer beacon keep AoA 6º-7º, irrespective of the aircraft landing weight and external loads. Corrections should be made by engine thrust.


After overflying hte outer beacon the AoA should increase to 11º-12º with the BLC disengage or 9º-10º with the BLC engaged, irrespective of loading.


As the BLC engages the readings should be 2º-2.5º less. With BLC enganged the pointer oscillations should be in the 1º-4.5º range.


So my point is the AoA instrument readings of the Mig-21 inside DCS are correct as far as we use the real manual as reference. I was trying to reproduce all this things inside DCS and overall, the Mig-21 is flying like that, some minor differences in some aspects but i cant find anything wrong according to the manual taking the YYA-1 readings as references ALWAYS.

So thats what i´ve to say.
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Old 03-13-2018, 06:08 PM   #116
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Quote:
Originally Posted by Hummingbird View Post
Ctrl + Y gives you an info bar with everything from TAS (Ctrl+y x2) to true AoA.
With experience you'll learn to not trust this info bar. At first you will notice that it's not TAS but EAS that is displayed. Then you'll discover that any AoA value reading except from the cockpit instrument presents an offset and a coefficient with this module. Better use the instrument only.
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Old 03-13-2018, 06:13 PM   #117
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Indeed
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Old 03-14-2018, 02:57 AM   #118
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The info bar provides accurate information provided you understand what is being shown. Speeds given are "IAS" and "TS", true speed is simply the geometric velocity magnitude through the coordinate space (ground speed). The IAS is a notional indicated airspeed for a theoretically perfect instrument so there is no difference between IAS and CAS since there is no calibration required for a perfect instrument.

The F2 "IAS" shown is probably also EAS as it is likely to be calculated as the TAS times the square root of the air density ratio (vs standard SL) which is dynamic pressure equivalence to that TAS at sea level standard air density.

Given "AOA" figure is geometric relationship between air mass and airframe orientation. Gauge will be different as it is mounted on the body and local flow around the sensor is disturbed. Realize that pre-production testing is always done with very long air data probe booms to place sensor well ahead of the airplane to get essentially perfect AOA. Testing airplane also carries production sensor so an equivalence relationship can be recorded.

If you find CL-alpha diagram for TsAGI-12 aerofoil you will see peak CL at ~15 degrees true but this is not representative of total airplane lift as vortex effect is not considered by simple 2D aerofoil plots.

Also UUA-1 meter showing 33 degrees on gauge is only equal to CL max for a small range of Mach ~0.80-0.95. At less Mach there is CL increases beyond 33 on the gauge. For example at 0.6M CLmax should not be reached until maybe 40 degrees by the gauge. MiG falling like a rock when gauge is >33 at all Mach (especially low) is fiction.

When speaking of aerodynamics do not talk about the UUA-1 gauge until it is verified that UUA-1 gauge relationship to geometrical AOA or local flow around wing or sensor is anything close to reality.
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Old 03-14-2018, 12:09 PM   #119
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This MiG-21 has gone through so many extreme (and opposing) changes in its FM, at each stage labelled as "the most realistic", that it's just impossible to trust these devs on FM anymore.

Is it realistic now that it falls like a rock? Was it realistic then, when you could cruise all day long at 50º AoA? Same thing applies to aileron rolls, stalls etc.
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Old 03-14-2018, 12:20 PM   #120
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Read the real manual, compare to DCS and make your own conclusions. I can link two useful ones.

Or post a track, vídeo, data.
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