Ракеты в DCS

[Max1mus]

The Su-27 in a other category, it is a simplified LOCKON-level project, not hi-fidelity.

 

What else should we fly, MiG-21?

[Chizh]

I think thread is going off-topic a bit, so how about on-topic question. Can we get maybe get dual calculations for R-27 guidance? One for Datalink phase and other for SARH phase?

 

P.S. Thank you so much for the drag changes, it is a great stopgap measure till CFD

I think yes, when we do new flight dynamics and autopilot.

[BlackPixxel]

Why do you think that this is a diagram of AIM-120B?

 

I am not saying that the diagram is an Aim-120B.

 

But isn't the Aim-120B using the same motor and the same shape as the Aim-120A, with the big change of introducing loft?

 

I fired the missile without loft, so the straight line performance should match that of the Aim-120A.

[BlackPixxel]

Not correct. For the LOKON level we make simplified systems and, of course, not everything that is in a real prototype.

 

If we'll do high fidelity, then everything will be there.

 

It just seems so odd with the plane to plane link.

It is fully working in singeplayer, all that would be different in multiplayer is that the position and the targets of 3 other players will be taken instead of from AI.

[GGTharos]

But isn't the Aim-120B using the same motor and the same shape as the Aim-120A, with the big change of introducing loft?

 

I fired the missile without loft, so the straight line performance should match that of the Aim-120A.

 

Do you know what the termination parameters are for that graph?

 

The big difference between A and B is a re-programmable processor - we don't really know about loft or no loft etc.

[FoxAlfa]

I think yes, when we do new flight dynamics and autopilot.

 

Yeah, it makes sense to do it then. Excellent, thank you!

[Сладенький]

В эфиопско-эритрейском военном конфликте (1999-2000 годы) ВВС Эфиопии выставили истребители Су-27, оснащенных ракетами Р-27 и Р-73 (последние применялись крайне редко) против эритрейских МиГ-29. В общей сложности всеми видами оружия было сбито три МиГ-29. Сомалийские самолеты выпустили по эритрейским истребителям 24 ракеты Р-27, но лишь один МиГ-29 получил повреждения, и разбился при выполнении посадки на свой аэродром.

 

Таким образом, боевая эффективность Р-27 составила всего лишь 4%, что сопоставимо с результатами применения во вьетнамской войне уже устаревших к тому времени американских ракет воздушного боя AIM-4 Falcon.

 

Во время войны с Эритреей один из российских пилотов-наемников пожаловался, что Р-27 имеет весьма невысокую надежность бортовых систем и недостаточную эффективность управляющих поверхностей для перехвата маневрирующих целей. Кроме того, присутствовало плохое техническое обслуживание ракет до подвески на самолет, и, наконец, весьма несовершенная импульсно-допплеровская полуактивная головка самонаведения ракеты оказалась весьма уязвимой для систем радиоэлектронного подавления.

Р-27 сейчас в DCS сильно переапаны.

Как AIM-120 просто разрывали эти недостижимые для Р-27 МиГ-29 в Югославии можете сами найти.

[TaxDollarsAtWork]

Р-27 сейчас в DCS сильно переапаны.

Как AIM-120 просто разрывали эти недостижимые для Р-27 МиГ-29 в Югославии можете сами найти.

Those are interesting numbers, one can't fail to acknowledge the impact of crew training and how well the missiles were maintained (As shown by this 1974 report of AIM effectiveness in Viet-nam https://apps.dtic.mil/dtic/tr/fulltext/u2/a486826.pdf), the latter being inescapable even for the world's most modern and lethal SRAAM, the AIM-9X, which is going with a Pk 50% at the minute as a result of poor maintenance and was an issue for AIM-54s as well in USN service.

 

 

If some one could find the numbers for AA-10/11 launches broken up by side in the EE war I'm sure the findings would be very telling.

[Max1mus]

Извините, я забыл, что имею в виду режим памяти, который вы к 120B и C добавили. Когда 120 в 5-секундном режиме памяти, она по моему взгляду полности диполи игнорирует.

Нет. Диполи по прежнему могут оказать влияние. Но для этого нужно чтобы радиальная скорость цели была близка к нулю.

 

Если да, откуда ракета знает, что цель потеряла и видит диполи? Р-27/AIM-7/R-77 этот режим памяти в DCS получют?

Р-77 получит.

Когда сделаем полноценную ИНС этот режим будет работать не как память, а как экстраполяция траектории по последним измерениям параметров цели.

Edited August 26, 2020 by Chizh

[BBCRF]

Р-27 сейчас в DCS сильно переапаны.

Как AIM-120 просто разрывали эти недостижимые для Р-27 МиГ-29 в Югославии можете сами найти.

чего там кто разрывал сказки не рассказывай

[FoxAlfa]

Р-27 сейчас в DCS сильно переапаны.

Как AIM-120 просто разрывали эти недостижимые для Р-27 МиГ-29 в Югославии можете сами найти.

 

Hm... no, Yugo MiG-29 didn't have working radars due to not being able to maintain them due to sanctions, that was part of the well documented scandal after regime change... hard to launch R-27R without radar... but R-27s seam to do quite alright in Yemen from 0 km/h ground launches

[Кош]

Hm... no, Yugo MiG-29 didn't have working radars due to not being able to maintain them due to sanctions, that was part of the well documented scandal after regime change... hard to launch R-27R without radar... but R-27s seam to do quite alright in Yemen from 0 km/h ground launches

 

Don't feed the troll. Also, read about R-23 use by Iraqis.

[Tone_Picky]

Hm... no, Yugo MiG-29 didn't have working radars due to not being able to maintain them due to sanctions, that was part of the well documented scandal after regime change... hard to launch R-27R without radar... but R-27s seam to do quite alright in Yemen from 0 km/h ground launches

 

That beautiful Houthi launch was done via T-model.

 

[DronneR]

Chizh said that the stupid R-27 does not have variable PN guidance.

 

This is not entirely true.

 

It appears to have fixed PN coefficients during the stage where the seeker is in semi active homing mode, which starts when the missile is 25 km from the target when a typical fighter jet is engaged. The required overload of the missile calculates as follows:

 

 

If the missile is launched at the target between 25 km and 1.5 * 25 km (37.5), then the initial flight of the missile will be done using inertial navigation. During this stage, the overload calculation is done differently:

 

 

Note how the navigation factor of 4 gets divided by the term T*. T* is a time that is depending on the speed of approach between missile and to the target, the estimated range between missile and target and the seeker lock on range (25 km).

For a fighter sized target, this term will basically calculate the estimated time that the missile still has left until it gets within 0.8*seeker range = 20 km to the target.

The division by the term results in the missile gets commanded to pull less and less g, the further it is away from the target.

 

 

For launch ranges beyond 37.5 km for a fighter sized target, the weapon system of the launch aicraft will support the missile with radio correction updates until the missile is estimated to have reached the range of 25 km to the target.

 

The formula (4.3) is used again. (Note that it looks as if the top left of the first term would say "4 D". It is actually 4 times the derivative of D, the dot is just overlapping with the text above).

 

 

Note how the text is basically saying:

 

"The first term should be interpreted as a navigation constant for the proportional guidance method depending on the range D."

 

We have a range (and rate of change of range = speed of approach) dependent term that will cause the missile to pull less g the further away it is from the target.

The amount of g that the missile will be asked to pull increases the closer it gets to the target.

When it is 20-25 km to the target, it will switch back to the larger, fixed navigation constant of 4 that is seen in formula (4.2).

 

 

Conclusion:

 

For long range shots, the missile will effectively use variable PN coefficients, which will result in less speed loss due to the missile doing smoother turns with less g-loadings.

So in contrast to what we hear from Chizh, the R-27 does have variable PN.

 

This is not entirely true.

 

This kind of variable PN will be used only for shots between 25 and 38km. At ranges further than 38km it will use INS+Correction guidance. If you read this document more carefully (or find an actual technical description of K-27 missile family somwhere), you'll notice the requirement of seeker to be pointed right on target at the moment of its activation, and that seeker is not allowed to move during INS stage due to the fact, that its antenna gyro and accelerometers together compose an inertial platform, and moving it will destroy all the calculations of target position. And if you calculate this navigational constant between max and min ranges, you'll see that it tends to infinity at minimum range (D=>0.8lrz). Navigational constant equals to infinity when the lead point guidance is used, and in that case target will not be in the seeker FOV at all. So variable PN only for 25km<D<38km , for other cases - fixed PN coefficient.

 

Also note that for the moment of seeker activation, changing the navigational constant from infinity to 4 will lead to huge loss of speed due to instantaneous change of overload and further oscillations of trajectory.

[BlackPixxel]

This is not entirely true.

 

This kind of variable PN will be used only for shots between 25 and 38km. At ranges further than 38km it will use INS+Correction guidance. If you read this document more carefully (or find an actual technical description of K-27 missile family somwhere), you'll notice the requirement of seeker to be pointed right on target at the moment of its activation, and that seeker is not allowed to move during INS stage due to the fact, that its antenna gyro and accelerometers together compose an inertial platform, and moving it will destroy all the calculations of target position. And if you calculate this navigational constant between max and min ranges, you'll see that it tends to infinity at minimum range (D=>0.8lrz). Navigational constant equals to infinity when the lead point guidance is used, and in that case target will not be in the seeker FOV at all. So variable PN only for 25km<D<38km , for other cases - fixed PN coefficient.

 

Also note that for the moment of seeker activation, changing the navigational constant from infinity to 4 will lead to huge loss of speed due to instantaneous change of overload and further oscillations of trajectory.

 

The seeker, when launched from 25 to 37,5 km, will already point at the estimated target position that it will have when the rocket is estimated to reach 25 km to target. But the missile can be lanched of boresight, and the variable PN during this INS stage will cause the missile to do a smooth instead of a sharp turn.

 

Variable PN will also be used during the radio corrected portion of the flight when the missile is launched beyond 37,5 km, as you can see in the document (Why do you think it would not be used? Just look at the third picture I posted, it is about the radio correction stage).

 

Also, the navigation constant will of course not reach infinity, as the fighter will transition to radar homing when the missile is estimaged to be 25 km from the target.

 

So it will be (25 km - 0.8* 25km), which means the 4 gets divided by 5, not zero.

Edited August 26, 2020 by BlackPixxel

[DronneR]

The seeker, when launched from 25 to 37,5 km, will already point at the estimated target position that it will have when the rocket is estimated to reach 25 km to target. But the missile can be lanched of boresight, and the variable PN during this INS stage will cause the missile to do a smooth instead of a sharp turn.

 

Variable PN will also be used during the radio corrected portion of the flight when the missile is launched beyond 37,5 km, as you can see in the document (Why do you think it would not be used? Just look at the third picture I posted, it is about the radio correction stage).

 

The third picture is about INS without correction. On page 232 it is clearly pointed out that during SARH stage and INS+Correction stage control system employs equiaions 4.1 with overload calculated by 4.2 (constant PN coefficient) or by 4.4 and 4.5 with constant lead angle (wich is basically similar to constant PN). Since INS+Correction stage is used only at ranges more than 37.5km, as pointed out on page 200, INS+Correction stage will not use equiation 4.3.

 

Also, the navigation constant will of course not reach infinity, as the fighter will transition to radar homing when the missile is estimaged to be 25 km from the target.

 

So it will be (25 km - 0.8* 25km), which means the 4 gets divided by 5, not zero.

 

SARH starts, when timer Ty* reaches zero. And it reaches zero when lx=0.8lrz.

[BlackPixxel]

Please read the first sentence in my third picture.

 

It says that if the radio correction system is used, then the first term in equation 4.3 (which is the one with the variable coefficient) equals another one, where some symbols are replaced with some approximations, but it is essentially similar to the one in 4.3.

 

It is super clear that in the radio correction phase variable PN will be used.

 

 

And you really think they will allow for the PN coefficient to grow to an infinite value when the missile is still far from the target?

It would also mean that the missile would use its seeker only 20 km from the target. So fire at 25 km and seeker goes on directly after launch. Fire at 25.1 km and the missile flies 5.1 km with INS and uses its seeker 20 km from launch.

 

In my opinion, the 0,8 factor is used so the time does NOT reach zero when the missile is 25 km from target, to keep the variable coefficient low.

Edited August 26, 2020 by BlackPixxel

[Маэстро]

How comes that the DCS Aim-120B fired WITHOUT loft exceeds its estimated straight line performance by 33% (240 m/s shooter + target) and by 50% (500 m/s shooter + target)?

 

I doubt that the soviet rocket scienists made such huge mistakes?

 

They did't. In DCS For Vf=Vt=500m/s range is 61km w/o loft. Terminal condition is Vm=Vt.

[BlackPixxel]

Seems good, my terminal condition was the missile being able to hit the target, regardless of its speed.

[DronneR]

Please read the first sentence in my third picture.

 

It says that if the radio correction system is used, then the first term in equation 4.3 (which is the one with the variable coefficient) equals another one, where some symbols are replaced with some approximations, but it is essentially similar to the one in 4.3.

 

It is super clear that in the radio correction phase variable PN will be used.

 

It says that IF it is used, you can assume some of terms as different ones. But it will be implemented when fired from between 25 and 37.5km, which means without correction. Also, there is no need to use Ty* in such a manner during correction stage, because seeker activates on command from the plane, and its activation time is calculated by the launcher. Well, maybe there are some misunderstandings there due to some descriptional errors, but I see it like this.

 

And you really think they will allow for the PN coefficient to grow to an infinite value when the missile is still far from the target?

It would also mean that the missile would use its seeker only 20 km from the target. So fire at 25 km and seeker goes on directly after launch. Fire at 25.1 km and the missile flies 5.1 km with INS and uses its seeker 20 km from launch.

 

This is what is written there. Exactly. In a mathematical way.

 

In my opinion, the 0,8 factor is used so the time does NOT reach zero when the missile is 25 km from target, to keep the variable coefficient low.

 

If timer will not reach zero, how the hell would the missile understand it needs to activate the seeker? It may not need this timer with correction commands, but without them - no way. It MUST reach zero.

[BlackPixxel]

It says that IF it is used, you can assume some of terms as different ones. But it will be implemented when fired from between 25 and 37.5km, which means without correction. Also, there is no need to use Ty* in such a manner during correction stage, because seeker activates on command from the plane, and its activation time is calculated by the launcher. Well, maybe there are some misunderstandings there due to some descriptional errors, but I see it like this.

 

Where does it say that 4.3 will only be implemented when the missile is fired between 25 and 37,5 km?

 

First it says that this formula is used when the missile is aimed using INS, and INS is used in both pure INS stage as well as in INS + radio correction (launch from 1.5 to 2.5*lrz).

 

The sentence "If radio correction is used, then the first term in (4.3) will become XYZ" is saying that during the radio corrected phase formula 4.3 with a slight modification is used. And those modifications are just that the speed of the missile projected on the LOS vector is approximated with the closure speed of missile and target. So not a drastic change. And d = lx is not even an approximation, those are identical.

 

 

This is what is written there. Exactly. In a mathematical way.

 

If timer will not reach zero, how the hell would the missile understand it needs to activate the seeker? It may not need this timer with correction commands, but without them - no way. It MUST reach zero.

 

This time does not have to be the same timer that the launch aircraft uses when it decides that it will start transmitting SARH pulses. It is just a term to make the navigation coefficient variable with distance, with an arbitrarily factor to avoid the term reaching 0.

For the aircraft, it will propably be T=(lx-lrz)/(derivative of lp).

Why would you delay the time where the aircraft starts painting by an additional 5 km for no reason by having this 0.8 factor?

Edited August 26, 2020 by BlackPixxel

[Max1mus]

Нет. Диполи по прежнему могут оказать влияние. Но для этого нужно чтобы радиальная скорость цели была близка к нулю.

 

 

Р-77 получит.

Когда сделаем полноценную ИНС этот режим будет работать не как память, а как экстраполяция траектории по последним измерениям параметров цели.

 

@Chizh

 

memorymode_chaffimune.trk

 

Ракета диполи здесь игнорирует, пока 5сек не прошли, даже если их в 2.5 раз больше чем во втором .TRK .

after_5s_normally_chaffed.trk

 

Если не баг, почему Р-27 и AIM-7 не получют? И что с другими активными ракетами, как AIM-54?

[DronneR]

Where does it say that 4.3 will only be implemented when the missile is fired between 25 and 37,5 km?

 

I definetely misunderstood it, because in 200-201 there are implemented guidance methods defined by the range, and 233-234 states that guidance calculations of SARH and INS+Corrections are same (4.1+4.2). I understood it as the same equiations. My bad.

 

 

This time is does not have to be the same timer that the launch aircraft uses when it decides that it will start transmitting SARH pulses. It is just a term to make the navigation coefficient variable with distance, with an arbitrarily factor to avoid the term reaching 0.

 

This is true for INS+Correction phase. But we still have the no-correction INS launch between 1*lrz and 1.5*lrz.

 

Why would you delay the time where the aircraft starts painting by an additional 5 km for no reason by having this 0.8 factor?

 

Ask those who created this algorithm, why would they do so. But without seeker activation signal from the launcher, the internal will tick down to zero.

[BlackPixxel]

Is there even a dedicated seeker activation signal?

 

The missile knows the time diagramm of the launch aircrafts radar, and it knows its "channel" (so it either looks for the pulses/radio corrections for channel 1 or channel 2). Maybe it is already enough to simply receive the homing pulses from the correct time channel via its reference antennas to cause its seeker to "wake up".

 

 

I would think the SARH homing starts before that "timer" in that formula goes down to 0.

Edited August 26, 2020 by BlackPixxel

[Chizh]

@Chizh

 

[ATTACH]245831[/ATTACH]

 

Ракета диполи здесь игнорирует, пока 5сек не прошли, даже если их в 2.5 раз больше чем во втором .TRK .

[ATTACH]245830[/ATTACH]

 

Если не баг, почему Р-27 и AIM-7 не получют? И что с другими активными ракетами, как AIM-54?

Пожалуйста делайте треки с ярлыками и разрешенными внешними видами.