BlackPixxel

Fri13, I think the labeling of the graph is just a little weird, and range and distance are just the x- and y-components of the distance vector to the target from a top down view. Basically just read it like the R-27 chart above. Also note how the 40k ft co-altitute chart of the Aim-7 is a perfect circle with a ~22nm radius until the target aspect is about ~50°, which shows the seeker limitation. Only when the target aspect is above the ~50° the launch range is reduced due to energy limitations.

Here are some other ranges for ukrainian R-27 from Artem. http://www.artem.ua/en/produktsiya/aviation-means-of-attack-and-defense/air-to-air-missiles-r-27er1 They make more sense, with reasonable range advantage for the R/ER over T/ET as well as ER vs R. But of course it is unclear what the conditions for those ranges are. Certainly we shoud get more range than we have right now. The R-27ER carries 135 KG of fuel vs the 50 KG of the Aim-120C5. It has more drag and more weight to accelerate, but also significantly more energy. And when the motor stops burning the weight helps it to keep its speed against the air resistance. For comparison: The big Phoenix has 163 KG of fuel (longer burntime though). The DLZ we have access to are for the very early R-27 / prototypes. The rocket motors have been updated several times since. Here is also something interesting to read, but nothing official (use google translate): https://www.mycity-military.com/Avioni/MiG-29-Fulcrum_2545.html One user talks about updated R-27 with increased weight (370 KG instead of 350 KG) and increased burntime of 14 seconds. Pretty much the same amount of fuel as in the phoenix, but with a much more narrow missile body. If you look for R-27ER drawings you will also find that there are variants with 4.7m length and ones with even longer motor with 4.78m length. The current R-27 ranges and speeds of the R-27 in DCS are a joke, I am sure we will see big improvements once ED reworked them. It should outrange any Aim-120 below Aim-120D.

It would make alot more sense if it was 10nm head on instead of 20nm. Then the overall shape of the chart would be similar to the 40,000ft one. Could be an error. The launch zone chart for the R-24 missile from the MiG-23 also has an error :D

This AIM-7 graph does not make alot of sense. Why is the head on co-altitude launch range on the ground with mach 0.9 almost the same as the launch range at 40,000ft with mach 2.0? For the R-27 chart: It is unlikely that those are the aerodynamic ranges for two reasons: ET, ER and EP all have different weight and nose shapes. They will have different aerodynamic ranges before they stall. But on the chart the ranges are identical. The manual says for engaging maneuvering fighters to launch one rocket at the max allowed launch range and the second at the second launch range ("no escape zone"). If the max allowed launch range was the same as the aerodynamic range then firing the first missile would not make any sense, because it would be no threat and never be able to hit.

[100☭] BlackPixxel - Ka-50

What is your argument that this is wrong? Do you have any facts or evidence that the missile should kill under those conditions? If you want to have a missile that has good kinematics, then wait for the R-27ER/ET update. It should turn into a monster if ED does realistic. Aim-120 is a small missile that does not carry a lot of energy.

The inverse square law applies for radars as well as for any(?) other antenna. It is just that you always have to be at the same azimuth/elevation in the antenna diagramm when you make the simple power calculation.

When the chaff is dropped in the notch the missile cannot differentiate between real target and chaff, because the monopulse seeker receives a mix of target and chaff return, and in the notch they are within the same frequency and range. So the monopulse seeker does not see two independend targets where he can decide which one to take, the seeker sees just one target that is a mix of both targets the same time.

I understood, I should have called them launchers not rails.

Thank you, the difference between the two launch rails is something I did not consider. I specifically mean breaking the lock of the missile with the last part. When chasing targets and launching R-27, they can simply defeat the missile by dropping 1-5 chaff while flying away, not notching. When the missile only uses its own seeker at a much closer range to the target (3.125 km), then the first chaffs will not be seen. Su-27 has at least a better radar than the R-27, so it should have less troubles than the missile seeker in this situation.

Warning: Google Translated R-27ER / ET маневрирует только в DCS через 1,5 с после взлета. R-27R / T маневрирует гораздо раньше. Для реального R-27R время для маневра безопасности составляет 0,4 с. Есть ли доказательства того, что это время для R-27ER / ET более чем в три раза больше? R-27ER/ET in DCS don't maneuver for 1.5 s after launch. R-27R/T in DCS maneuver much earlier. In the MiG-29 manuals the time for this "safetey maneuver" is defined as 0.4 s for the R-27R. Is there any reason/evidence why the R-27ER/ET in DCS have a value more than 3 times as much? Видоискатель реального R-27R начинает работать только с расстояния 25 км до места назначения. (Размер цели истребителя) При преследовании цели на высоте менее 1 км видоискатель включается только на расстоянии менее 3,125 км. Может ли это поведение быть реализовано в DCS? Вот как ведет себя настоящий R-27. Это сделало бы ракету намного более надежной в ЗПС. Real R-27 use their seeker for medium sized targets only within ranges less than 25 km (beyond that they use radio correction or inertial guidance). When a target is engaged in medium PRF (ЗПС) with a target altitude less than 1 km, the range at which the missile seeker will start searching drops down to just 3.125 km. This means that any action that the target does before to defeat the lock of the missile is not effective. Only when the missile is within 3.125 km it can be chaffed/notched. Could such a behaviour be implemented in DCS? Maybe with the upcoming R-27 update? This is how the real missile behaves, and this is how it should behave in DCS as well.

Nothing is as awaited as a full fidelity modern Flanker!

One issue with the russian missiles in DCS is that ED reads the charts from the manuals as maximum aerodynamic range. But those are the maximum launch zones. In the R-24 manual it is recommended to fire one R-24R at maximum range and another closer. The maximum range shot would be completely useless if it was the maximum aerodynamic range. With a slight headwind the missile would not be able to reach the target if it flew 100% straight. Another issue is that the R-27 charts are very old ones, the missiles have been upgraded several times since. But all ED has access to is old hand-drawn charts from old manuals. R-27ER and ET carry twice as much rocket motor fuel as an Aim-120C5. Against the Aim-120 in BVR the R-27ER should hit the target when the seeker of the Aim-120 is not even active, defeating the ARH advantage. If the empty weight of 214.5 Kg posted above is correct, then the ER carries about 135 Kg of fuel. The Aim-54A carries 163 Kg. Sure, the Phoenix burns the fuel slower and does a loft, but the ER is a much thinner missile. Certainly the current range seems very odd for a missile that has so much energy. I am very curious how the R-27 will perform once ED updated them, they said they want to work on the R-27 this month.

Let's take a look at the AN/APG-63 from the F-15C: There are two horn antennas. The orange one at the top, and the grey one at the bottom. Note how the bottom one is pointing downwards. If the F-15 is using this downward pointing antenna for sidelobe compensation, then it will face EXACTLY THE SAME situation as our MiG-29 with DCS logic. Is the F-15C radar roll stabilized? What are the gimbal limits? The top horn antenna seems to be pointing straight ahead. Height is about 3.27 cm, width is about 4.1 cm. Enter these values on the following page: https://www.rfwireless-world.com/calculators/Horn-Antenna-Calculator.html The radar is X-Band, so with a frequency of about 10 GHz we end up with a horizontal 3dB- beamwidth of about 50° (+/-25°) and a vertical 3dB-beamwidth of about 48° (+/-24°). The lower horn antenna is not fully visible in the image, but its dimensions appear to be the same. So, the guard antenna(s) of the F-15 radar already have a very wide beam. Now looking at the MiG-29 radar the guard antenna is significantly smaller. The dimensions of the opening are barely any wider than the waveguide itself. With horn antennas a smaller width/height equals to a wider beam. So the MiG-29's compensation antenna covers significantly more in azimuth and elevation than that of the F-15C. This makes alot of sense, as the compensation antenna of the MiG does not follow the main beam as the compensation antenna on the APG-63 does. The downtilt of the compensation antenna on the MiG-29 is very small, it looks like it is in the order of about or less than 10°. With a vertical beamwidth of significantly more than 48° there is almost no difference in coverage, whether the MiG is flying level or inverted. It is time for ED to remove that unrealistic restriction for russian/soviet aircraft from the game. Or to come up with an explanation that makes sense. Bonus: Downward pointing fixed compensation antennas on F-15 AESA without roll stabilisation. Inverted radar loss confirmed by Eagle Dynamics Logic!

Su-33 please!

In BVR mode for roll angles smaller than 120° the main antenna and the sidelobe suppression antenna will both be fully aligned with the horizon, there should be no degradation at all, so here DCS is correct (but there it ends). For roll angles above 120° the compensation antenna will rotate with the plane, so it will no longer point at the center below the main radar beam but in the direction that the aircraft rolls. The amount of left/right shift depends on how much the plane rolls beyond 120°. For smaller angles above 120° there will not be a big change, it will still cover almost all of the area. But in DCS the radar is unable to do anything at any roll angle beyond 120°. Even for larger angles (largest angle is 60° when the plane is exactly inverted) the compensation antenna is still covering much of the ground. If we had a better image of that horn antenna we could even calculate the beamwidth. It is very likely that it has a rather high one, as it looks like the diameter of the antenna is not really larger than the actual waveguide itself, which results in a large beamwidth. The higher the beamwidth is, the less the roll angle will cause issues. To me it seems likely that the compensation channel is only really usefull when scanning, so less false targets will appear on the radar scope. Once a proper target has been locked it is unlikely that it gets lost because the sidelobe return would have to match the target in azimuth, elevation, speed, flight direction and signal strength. Pretty unlikely. In all the close combat modes where the targets are not shown on any scope but selected automatically (vertical scan) or by pointing the beam directly at it (helmet mode, optical mode) the sidelobe returns are less of an issue as the radar is looking at the target directly. On the real MiG-29 the compensation channel is only used when the pilot enables it via a switch. It will then use some of the radar resources (filter etc.) that would otherwise be used for the main channel, thus resulting in a slight degradation of radar performance. And for the SU-27 it is not even clear where the compensation antenna is. Very likely it is different than the MiG, because it cannot be seen on any image. Maybe it is incorporated into the main antenna? The IFF channel also has a sidelobe compensation channel in the Su-27 for more accurate IFF direction finding. Question is whether it is using the same compensation antenna as for the radar operation or a different one. Still the Su-27 suffers from the same problem, without any explanation by ED. Edit: The IFF sidelobe suppression works quite interesting on the Su-27: The sidelobe suppression antenna (wherever it is) and then the main antenna are emmiting IFF signals seperated in time, and the target is then comparing their signal strengths. Only when the pulse from the main antenna is stronger than the one from the sidelobe suppression antenna it will respond. So here the sidelobe detection is actually done by the target. Clever and simple! The IFF sidelobe suppression antenna has to cover the whole azimuth and elevation range to work properly (it is intended to increase azimuth accuracy of IFF during the scanning mode. Elevation accuracy is less important, as targets will not be seperated by altitude on the radar topdown view anyway, but even in elevation it performs the sidelobe suppression by exactly the same prinicples as in azimuth). This all means that the sidelobe compensation antenna used for IFF has to have a wide beamwidth OR its beam is moving with the main beam, otherwise it could not be used in BVR scan mode. And if the IFF is using the same antenna for sidelobe compensation as the radar is, then the radar's sidelobe comensation will not really be affected by rolling at all due to the high beamwidth OR because it is moving with the main antenna!

I finally found where the compensation antenna is located on the MiG-29: The long yellow part in the top under the cover is the waveguide, and on the circular end of the cover (where the fixed reflector of the main antenna sits) you can see the yellow end of the waveguide peeking out forming a horn antenna. Here is an image without the cover, where the waveguide + horn antenna are removed. You can still see the yellow part of the waveguide where it all attaches to, with a red rectangular cover to protect it: Now, that was the MiG-29. But what about the Su-27? Here is a side view, the whole radar is slightly rolled towards the camera, so we can see a little from the top of the radar cover. This means that a horn antenna on the front of the cover like on the MiG-29 radar would be seen in this image. But there is none. The horn antenna could of course sit behind the radio transparent cover. Another image: Here the cover is removed, and the radar is tilted in such a way that we can see through the slow in the moveable reflector (where the waveguide for the main antenna sits). If the radar was build the same way as the N019, then we would see the waveguide for the guard channel throug the whole, and extending beyond the reflector. But it is not there: Maybe the waveguide was temporarily removed in this case like on the N019 in the one image above? But there would need to be a slot in the moveable reflector for the waveguide to pass through. The reflectors diameter is as much as the cover, so there is no space for the waveguide to fit between reflector and cover without a cut in the reflector. For example like in this MiG-radar, where you can see a rectangular cut in the top of the reflector (and the open waveguide in yellow where the compensation antenna would attaches to). And last but not least, even the DCS model of the Su-27 does not have a seperate horn antenna for the compensation channel above the moveable reflector: With the MiG-23 for examples some versions had the seperate horn antenna as on the MiG-29, but some variants had the compensation antenna pointed on the movable refector, according to some forum. Maybe this is the case with the N001 of the Flanker. With either of the two locations for the compensation antenna, it is clear that the guard horn follows the main antenna on roll. So in BVR mode, the compensation antenna will START to tilt away from the ground only when the roll angle is beyond 120°. As the antenna will have a very wide beam, the sidelobe compensation will not instantly be ruined, as it is right now in DCS. The maximum angle that the compensation antenna will be turned away from the ground is 60° anyway. So it is still mostly pointing on the ground. Also on the MiG-29 the compensation antenna does not follow the main antenna elevation or azimuth, from which we can expect that the beamwidth is propably wide enough to cover the whole azimuth and the negative elevation range of the main antenna. As the radar will be locked on roll in close combat modes (vertical scan on the MiG for example locks any target in a range of up to 10 km), it is very likely that the compensation antenna beamwidth is wide enough to work during maneuvering (with a locked roll axis, the comensation antenna is never perfectly aligned unless the bank angle is exactly 0°). The current behaviour in DCS of losing any radar function when rolling just 1° beyond 120° in BVR STT is just wrong. Both antennas will be rotated by 1° in this case, so there is almost no difference. In DCS there is a big difference though: instant loss of the complete radar function. And even ith a max tilt of 60° when flying inverted the guard channel will still point on the ground, but a little more to one side than to the other. Still the sidelobe compensation will not be fully broken, just to a certain extend. And with a target that is flying towards the fighter the compensation antenna position should not play any role, as ground returns do not really matter in this case.

In DCS at the end of every engagement that startet with BVR. The high altitude R-27ER shots will always get chaffed, and you end up in low altitudes closer to the target, where the best thing you can do after firing a missile is going inverted and pulling towards the ground into the thicker air. With the current radar behaviour it means broken radar lock + trashed R-27ER, because due to the Fox 1 bug it will go for a chaff as soon as the radar stops emitting for a splitsecond. I am not sure how loss of radar tracking while keeping IRST tracking works when guiding SARH missiles with the real Flanker. The pulses for the missiles and the pulses that the radar emitts for its own tracking purposes are different ones and multiplexed in time. There is a good chance that the radar can still emit the missile pulses while being slaved to the IRST, and at the same time still trying to regain the lock. A lock that will not be broken by just rolling inverted aganist a head on target in the first place.

It all depends on where the compensation antenna is exactly. When it is fixed to the fuselage then all modes will suffer the same way from rolling and will have the same amount of sidelobe compensation degradation at certain degrees of roll angle (This does of course not mean that the radar will lose tracking, especially when the target is in front aspect). When the compensation antenna is somewhere on the roll gimbal, then it will not suffer from worse sidelobe compensation in BVR mode at roll angles below 120°, but it will suffer in close combat modes on any roll angle above 0°. The amount of degradation of course depends on the roll angle and also on the beamwidth of the compensation antenna. Maybe it still covers the ground when inverted, but with less gain? I don't see why the radar would be roll stabilized at all when the compensation antenna is not mounted somewhere on the moving radar. But maybe it wants to keep the the polarisation of the radiowaves optimal (either horizontal or vertical) for long range engagements for an improved range and detection.

What do you mean with the compensation horn in front of the target? The compensation antenna is not blocking radio waves from entering the main radar. It is a seperate antenna with a very wide beamwidth, but with a very low gain in the area of the main antennas beamwidth. The radar then compares the signals received from the main channel and from the compensation channel. When a certain return is strong just in the main channel but weak in the compensation channel, then this is a valid signal from the main lobe. When a signal stronger in the compensation channel, then it is not a valid return as it is coming from a sidelobe. The radar processing will then ignore this combination of time delay and frequency. It is using a seperate receiver. It is not just like sunglasses blocking the radar returns of a certain area.

What is still here? Sidelobe returns? Yes they are, but as I wrote multiple times and as you can even see in the MiG-29B document, the ground return that comes in through the sidelobes is in a different spectrum in this case. This is what you have a bank of bandpass filters for, or FFT in the digital computer of the plane. Frequencies that you don't want get removed, either via analog or digital filtering.

Because when the target is not flying towards the radar then the spectra from ground reflections and the target itself will overlap. There you want to minimize any return that is not coming directly from the direction of the target.

As long as the target is flying towards the radar faster than the ground the compensation antenna can point wherever it wants, the frequency range of target and ground return is completely different. Even the F-15C manual says the compensation antenna issue happens with fleeing targets. Imagine locking an approaching target when flying level. Now the radar knows the frequency of the closing target and sets its filters to only pass frequencies in this region. If you now go inverted, it still only looks for frequencies in that region, anything else will be ignored. Yes, when the target is flying away the lock will be less stable and can be broken by rolling. But not when you are engaging a head on bandit. And in DCS the radar 100% shuts off independend from the target aspect when going inverted <1500m.

We are aware of the gimbal limits of the radar. It does not mean that the radar is unable to work when it is inverted, it just means that it is no longer aligned with the horizon on roll. That is all. And in all modes except for BVR mode the radar does not even use the roll stabilisation at all, it is locked as if there was no roll gimbal.

So the radar in the MiG-29/Su-27 has to be aligned with the horizon on roll otherwise it cannot track? The radar is locked on roll into its place without any stabilisation in any mode except the BVR mode. This would mean that a target locked in any other mode would be lost as soon as you bank more than 0° (because then the radar has the same roll angle as it has when you tilt more than 120° in BVR mode). In general it would be nice to have an image of the compensation antenna, or at least the location. I would really like to know where it is exactly.