And one more thing i want to say about limitation is, based on Su-27SK manual, Su-27 has Vne of 1400 which in game value should have Vne of 1470 than 1540
While other aircrafts have 5% margain but why Su-27 alone have 10% margain?
Sukhoi Su-27/30/33/35/37 Flanker series & Su-34 Fullback - History, Design, Performance & Dissection
It’s based on the max allowed normal forces. As told by the manual, for M < 0.85, the normal force experienced by the aircraft should not exceed 171000 kgf. And max allowed Ny = max allowed normal force / mass, with a cap of 9g.
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Su 27 SK manual.
7.2. Боковая устойчивость и управляемость.
Для повышения запаса путевой устойчивости в систему бокового канала СДУ введен автомат путевой устойчивости – демпфер курса. Путевая статическая устойчивость самолета сохраняется во всем диапазоне чисел М. Зависимость коэффициентов путевой и поперечной статической устойчивости от угла атаки myв=f(α) и mxв=f(α) приведена на рис. 3. На скоростях Vпр более 800 км/ч и числах М=0,7-1,0 самолет обладает повышенной чувствительностью к созданию боковой перегрузки на отклонение педалей. Реакция самолета по крену на отклонение педалей на всех режимах полета при Пу ≥ 1,0 – прямая вплоть до углов атаки сваливания.
Для обеспечения поперечной управляемости используется совместное отклонение флаперонов и дифференциальное отклонение стабилизатора, последнее используется и для демпфирования по крену.
Балансировка при координированных скольжениях в горизонтальном полете отмечается малым расходом ручки по крену.
Для обеспечения поперечной управляемости на больших углах атаки в путевой канал СДУ введена перекрестная связь руля направления с поперечным отклонением ручки управления, а для увеличения угла атаки сваливания (α свал.) в систему поперечного управления на углах атаки более 25° введено механическое ограничение поперечного отклонения ручки на 1/3 хода в виде пружинного упора с усилием 7 кгс. При отказе демпфера крена и демпфера курса обеспечиваются достаточные для завершения полета и выполнения посадки характеристики боковой управляемости, при этом α доп.=10°.
Для обеспечения хороших характеристик маневренности во всем допустимом диапазоне углов атаки на дозвуковых скоростях полета введены системы автоматического управления носками крыла и флаперонами по сигналу угла атаки. С увеличением угла атаки характеристики боковой устойчивости и управляемости сохраняются удовлетворительными, вплоть α доп.
На скоростях менее 400 км/ч и α ≥ 24° самолет обладает пониженной поперечной управляемостью. При выводе из крена на скоростях менее 400 км/ч во время выполнения маневров по границе срабатывания ОПР возможен заброс угла атаки более α доп.
Поэтому при выводе из крена контролировать угол атаки, не допуская превышения αдоп.
*На углах атаки α > 28° вплоть до сваливания управляемость самолета отсутствует.*
Аэродинамическая тряска возникает на углах атаки α=9°-5° при числах М=0,5-0,9 соответственно. При увеличении угла атаки интенсивность тряски возрастает и через Δα=2°-3° стабилизируется.
Характер тряски мягкий. Во всем диапазоне углов атаки тряска пилотирование не затрудняет и предупредительным признаком о приближении к α доп. служить не может.
При отключенной и отказавшей системе управления носками крыла пилотирование безопасно и особенностей не имеет до α доп. =10°.
Поведение самолета с отклоненными носками на 30° (шасси убраны, флапероны убраны) особенностей не имеет. Отказ управления носками и флаперонами на дозвуковых скоростях не вызывает эволюций самолета, требующих вмешательства летчика. Максимальное приращение перегрузки при этом ΔПу ≈ 0,5. Располагаемая угловая скорость по крену при увеличении угла атаки уменьшается, но остается достаточной до α доп. (более 20°/сек). Эффективность поперечного управления в горизонтальном полете обеспечивает угловую скорость крена ωх ≥ 1,5°/сек.
На взлетно-посадочных режимах с выпущенной механизацией крыла и шасси обеспечивается угловая скорость ω 1,0°/сек.
Характеристики устойчивости и управляемости самолета без подвесок и со всеми вариантами ракетного вооружения сохраняются приемлемыми до углов атаки:
7.2 Lateral stability and controllability.
In order to increase the margin of lateral stability in the lateral channel system of the SRS, a course damper is introduced. The track static stability of the aircraft is maintained over the entire range of numbers M. The dependence of the track and lateral static stability coefficients on the angle of attack myv=f(α) and mxv=f(α) is shown in Fig. 3. 3. At speeds Vpr more than 800 km/h and numbers M=0.7-1.0, the aircraft has increased sensitivity to the creation of lateral overload on pedal deflection. The roll response to pedal deflection at all flight modes at Pu ≥ 1.0 is straight up to stall angles of attack.
To ensure lateral controllability, joint flaperon deflection and differential stabiliser deflection are used, the latter also for roll damping.
Balancing during coordinated glideslopes in horizontal flight is noted by the low roll rate of the knob.
To ensure transverse controllability at large angles of attack in the track channel of the SRS introduced cross-link rudder direction with the transverse deflection of the control knob, and to increase the angle of attack of stall (α stall.) in the system of transverse control at angles of attack of more than 25 ° introduced a mechanical limitation of the transverse deflection of the knob at 1/3 of the stroke in the form of a spring stop with a force of 7 kgf. In case of roll damper and heading damper failure, lateral control characteristics sufficient for flight completion and landing are provided, with α extra =10°.
To ensure good manoeuvrability characteristics in the entire permissible range of angles of attack at subsonic flight speeds, systems of automatic control of wingtips and flaperons on the signal of the angle of attack are introduced. As the angle of attack increases, the lateral stability and controllability characteristics remain satisfactory, up to α dop.
At speeds below 400 km/h and α ≥ 24°, the aircraft has reduced lateral controllability. When climbing out of roll at speeds less than 400 km/h during manoeuvres at the edge of the ERP response, it is possible for the angle of attack to be greater than α dop.
Therefore, when climbing out of a roll, control the angle of attack to ensure that αdop is not exceeded.
**At angles of attack α > 28° up to stall the aircraft is uncontrollable.
Aerodynamic shaking occurs at angles of attack α=9°-5° at M=0.5-0.9, respectively. As the angle of attack increases, the intensity of the shake increases and stabilises after Δα=2°-3°.
The nature of the shaking is soft. Over the entire range of angles of attack, shaking does not impede piloting and cannot serve as a warning sign of approaching α extra.
When the wingtip control system is switched off and fails, piloting is safe and has no peculiarities up to α ∼10°.
The behaviour of the aircraft with deflected toes at 30° (landing gear retracted, flaperons retracted) has no peculiarities. Failure of nosecone and flaperon control at subsonic speeds does not cause aircraft evolutions requiring pilot intervention. The maximum incremental overload at this ΔPu ≈ 0.5. The available roll angular velocity decreases with increasing angle of attack, but remains sufficient up to α extra (more than 20°/sec). The efficiency of lateral control in horizontal flight provides a roll angular velocity ωx ≥ 1.5°/sec.
At take-off and landing modes with released wing and landing gear mechanisation provides angular velocity ω 1.0°/sec.
Characteristics of stability and controllability of the aircraft without hangers and with all variants of missile armament remain acceptable up to angles of attack:
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There is an error in the Operating Manual, there is no transverse controllability at AoA over 28 degrees for Flaperon, and not a complete loss of control
However, roll control is maintained through cross-linking
Is the error in the Russian manual or in the translation ? Do you have another source that says otherwise ?
As a matter of interest,
In the F-15, at 20 AoA the ailerons become ineffective ( rolling manoeuvres are done with stabilators), at 25 AoA the rudder becomes ineffective.
Yes, I have another source.
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Can you please provide a source or link ? Because manuals are usually not wrong, or I have never found a mistake in such important pilot manuals.
So in your sources, above 24 AoA there is no deterioration in lateral stability of the aircraft and above 28 AoA the aircraft is not laterally uncontrollable. Is that correct ?
The turn and the rising barrel of the Su-27UB at low altitude… Вираж и восходящая бочка Су-27 – смотреть видео онлайн в Моем Мире | Пётр Каракай (mail.ru)
Flight specifications of the Su-27 aircraft
Track stability is deteriorating, but not to zero.But the control of flaperons after 28 AoA is not possible
The manual says that
**At angles of attack α > 28° until stall, the aircraft is uncontrollable ( laterally).
It doesn’t specify what stops working, if flaperons or stabilizers or rudders but it literally says the aircraft is uncontrollable. That’s important.
Is there somewhere to get your sources or, would you at least send a picture, perhaps in a private message ?
TsAGI paper suggests that the success of the Cobra is the rapid attainment of the Cobra maneuver. Staying in a position of 30-40 degrees AoA creates large lateral instability and oscillations and causes departure. To Cobra you must surpass this and go to the point of flow separation over the wing with little lateral movements for the maneuver to be a success.
Now, to further your point… the Su-27 has been seen doing great lateral motions in its’ maneuvers and recovering with ease and full control. This would be a better example for comparison;
Here, the MiG-29M2 has a slight loss of track stability
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It is not my intention to argue, but to find the truth.
Sorry but the video is not of a Su 27, but a Su 35 with vectored nozzles, completely different digital FbW and a significantly different airframe. I am attaching the video and a picture of the aircraft for comparison.
The first Su 27, the one in WT and DCS, does not do this "Su 35 Super version of Cobra. “Classic Su 27” Cobra is a post stall maneuver. The point is that longitudinally the aircraft can get dynamically above 100 AoA (if the pilot has the balls to do it, that is with a very good pilot, because the safety constraints of AoA and G are turned off, the Cobra maneuver can kill weaker pilots).
But laterally, above 28AoA it is uncontrollable ( according to the manual for the SK version.
Su 27, the original one in the game and in DCS can do this :
Here performed by excellent test and demonstration pilots.
For those who don’t know, here performed by Sweden’s Drakken.
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so…did the you give up on fixing the flanker stupid speed bleed? or the r73 going crazy at low speeds and not tracking a target even with afterburner on(gripen) just cause he is flaring like a maniac
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It’s back to position because of inercia and because of coefficient drag to lift go sky hi above ~18 AoA and it’s not existent around ~30 AoA (basically 0 lift> movement Vector stay the same as inercia Vector) . It’s have nothing comon with control flying. Pilot is passenger above point where plane going into deep stall (according definition what some one post for you)
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I’m not reporting anything for war thunder anymore. I’ve shifted my focus towards other games.
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wise decision
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