R-27ER update?

[Harker]

This is DCS. Your jammer emits constantly, it's not a an SPJ-like jammer (And in fact DCS known nothing about how your radar is tuned - this information just doesn't exist) so with the bandit radar gone, you'd expect the SPJ to have nothing to repeat after 5 sec (imagining perfect timing where the SPJ 'listened' just before the radar stopped emitting, then tried to do its thing for 5 sec) ... so it would just go silent.

 

THis doesn't happen in DCS, it's just a constant source of noise that the missile can home in on. However, missiles should be flying pure pursuit at this point, so if you got hit it's sort of on you.

 

Also, turn off your jammer once you're inside 20-25nm.

Indeed that's true for FC3, but some modules do have ASPJ functionality (or at least appear to have), such as the Harrier.

But my question was about the missile. Is a FOX1 missile supposed to be able to switch from STT tracking to HOJ mid-flight, if illumination is lost? Or does it need to be launched in either STT or HOJ from the beginning?

[GGTharos]

Who knows :) HoJ switch in mid-flight implies you're getting at least jammed on the same channel. In game all jamming is on all channels :)

[nighthawk2174]

Yeah pretty much, ECM in DCS is incredibly basic, wouldn't surprise me if the code is from the flanker days back in the early 2000's.

[Max1mus]

I see, the ER unlocked will "track" the target, but it will only do 1.5g (including countering gravity). It does not really follow the target, it just turns whenever the target turns.

 

But still the missile will never hit the target.

I tried firing an R-27ER, watched the missile in F6 going directly to the maneuvering target. Moments before the imact I turned the radar off and watched the missile instantly turn away from the intercept hitting and flying far in front of the target.

 

This non-radar ER guidance is nothing but a "visual effect". It is not actually going for the target as a object in 3d space, but somehow its movement correlates with the target movement.

 

In fact all Fox 1 in DCS are plagued by this bug, which means that in almost all cases losing lock even for a split second will mean that the missile will magically turn away from its last intercept course into a chaff: https://forums.eagle.ru/showthread.php?t=253434

 

So on a server where players use chaff you should never see ER's "guiding" without lock, as without lock they are instantly trashed due to the bug.

 

I want to add that the ER also doesnt just keep following its course towards last known intercept point even WITHOUT chaff OR Jamming. This means that the missile can not hit a slightly flanking, not maneuvering target (with it being unsupported inbetween) even though it easily could if it just kept flying ballistically.

 

I know that fixing the AIM-120 satisfies more customers, but in a simulator both sides need missiles modeled to the same level realisticially, or else DCS will be at the same level as a certain F-16 turkey shoot adventure.

 

PLEASE fix this bug, unless the missile going pure when unsupported on a flanking target is intended.

Edited February 21, 2020 by Max1mus

[SgtPappy]

R-27ER, R-27ET, R-27EP

 

 

I read through this whole thread in a couple days, and I'm finding it very interesting but I am a little confused here. Someone correct my interpretation.

 

It says the R-27ER max launch range at 1 km altitude against a head on target where both launch and target aircraft are at Mach 0.9 is only just under 30 km but the AIM-7F datasheet gives 20 nm (37 km) at sea level? I always thought the R-27ER and ET have much better flyout performance than any AIM-7.

 

[BlackPixxel]

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.

[SgtPappy]

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.

 

I noticed these things as well - yet it appears that they are both "official" documentation. My brain needs an explanation! :D

[BlackPixxel]

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

[Fri13]

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?

 

What difference does the "distance" and "range" do with each others in the AIM-7 graph?

 

The R-27 graph is very easy to understand and read. But I just can't make out what difference is between "distance" and "range" in the context with left/right etc.

 

As it doesn't even make sense as up-down view that AIM-7 could be launched at target that is 10 nmi forward and 20 nmi side of you (almost 60 degree) as the missile would fly well over 20 nmi after pulling serious G's on launch, but it can't get over 22 nmi in straight head-on?

[draconus]

As it doesn't even make sense as up-down view that AIM-7 could be launched at target that is 10 nmi forward and 20 nmi side of you (almost 60 degree) as the missile would fly well over 20 nmi after pulling serious G's on launch, but it can't get over 22 nmi in straight head-on?

 

No. It indicates target aspect. The shoot is meant to be optimal intercept course.

[nighthawk2174]

Something else to keep in mind the AIM-7's charts Rmax is limited due to seeker performance not kinematic performance to 22Nmi. That is why you see all the max ranges limited to this number. The chart is for a relatively weak CW signal not a PD signal which the 7F and up could home in on or even just a more powerfull CW signal.

Edited February 27, 2020 by nighthawk2174

[SgtPappy]

Something else to keep in mind the AIM-7's charts Rmax is limited due to seeker performance not kinematic performance to 22Nmi. That is why you see all the max ranges limited to this number. The chart is for a relatively weak CW signal not a PD signal which the 7F and up could home in on or even just a more powerfull CW signal.

 

Oh right, that makes a lot more sense... hence the 2m^2 target indication.

 

As I understand, the R-27R has a datalink so it can be launched beyond the SARH seeker's ability to "see" the reflected signal. However, I would expect a greater range then. Does the Russian chart only show range for the distance at which the seeker can pick up the reflection? Even if so, where is the R-27T chart?

[AnarchyZG]

I'd like to know more about that Russian chart, I mean those certainly aren't Raero and are pretty short, also unexpected ER/ET having the same range as they have both different guidance and aerodynamics.

 

40nm for a head on high subsonic shot at 30k feet seems rather short for 27ER...

 

EDIT:

Official data

 

http://eng.ktrv.ru/production/military_production/air-to-air_missiles/r-27r1_-_r-27er1.html

 

Type Range vs fighter type vs other (probably less manuverable, larger, slower)

R-27R1 50-60km <75km

R-27ER1 60-62,5 <100km

 

R-27T1 65km head-on

R-27ET1 80km head-on

 

Chart seems to be based on manufacturer's data for head-on launch ranges vs fighter type target at high alt, co-alt (30k, M0.9 parameters specified in the chart) for R/ER and head-on shots vs unspecified target for T/ET (presumably also high alt 30k feet).

Small difference between R/ER vs fighter type targets is interesting (maybe data link/illumination radar limit?) and kind of explains why russian fighters usually carry R-27R rather then ER

 

I doubt you can get to those ranges in DCS

 

As for AIM-7(F) the range data is rather optimistic as it assumes head-on engagement with launch aircraft speed of M2.0 @40k feet, I wonder which parameters are used when specifying other US missile ranges like AMRAAM as this is sort of best-case scenario

Edited February 28, 2020 by AnarchyZG

[BlackPixxel]

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.

[Fri13]

No. It indicates target aspect. The shoot is meant to be optimal intercept course.

 

So what is difference between "Range" and "Distance"?

[Coxy_99]

So what is difference between "Range" and "Distance"?

 

Dysnc or missiles disappearing not sure which yet :)

[GGTharos]

So what is difference between "Range" and "Distance"?

 

Range is the distance between you and the target at the time of the shot, but this will change with time.

 

Distance is point x to point y. The actual distance that the missile will fly, which is different from range.

 

If a missile launched at speed x and altitude y, will fly to distance w from the point of launch before it's not longer effective, the shot range itself is affected by target parameters - aspect, altitude, speed, etc.

 

This is why ranges tend to be calculated based on time-of-flight ... time-of-flight and distance are the same thing.

 

Your missile will behave the same way for the same TOF (excepting defensive maneuvers for now), so for example a head-on TOF of 20s has the same capability of tail-on TOF 20s but the range is obviously different.

[AnarchyZG]

Just did a quick test in 2.5.6, I conclude that R-27ER in DCS has maximum aerodynamic range under conditions specified in the chart below slightly less then max range for fighter type target according to manufacturer's data. Target was flying level, directly head on at ~M0.9, not defending, I was doing M1+.

 

Hit can be achievend in DCS at about 60km

 

R-27ER in DCS has shorter absolute max range then real R-27R by about 15km and about 40km shorter then real R-27ER.

 

In line with manufacturer's data, chart below seems to represent max recommended range when engaging fighter type target

 

[nighthawk2174]

Yeah pretty much lined up with my results the ER/ET are more likely than not just a touch to draggy. The R/T are quite a bit worse.

[Fri13]

Range is the distance between you and the target at the time of the shot, but this will change with time.

 

Explain why AIM-7 has distance of 2 nmi when launched from range of 20 nmi?

Or why it has 20 nmi distance when launched from range of 10 nmi?

 

Both at same Mach 2 head-on (4 mach Vc)

 

Or in tail-on, launch range is 9.8 nmi but distance is only 1 nmi? (0 Vc)

[Fri13]

RANGE

(1): the horizontal distance to which a projectile can be propelled

(2): the horizontal distance between a weapon and target

 

DISTANCE

measure the distance between point A and point B

the degree or amount of separation between two points, lines, surfaces, or objects

 

Question is not what those means, but what does that AIM-7 graph illustrate? How are range and distance suppose to be read in that scale when target is 2^m in size?

 

The airplane figure is the target, not the launching aircraft.

[nighthawk2174]

As I understand it the chart is a launch zone chart with the target as the reference. with the rmax being defined as something alone the lines of 6-8 g for like 3-6 seconds (been quite a while since I read the definition). In addition to the seeker range limit.

[GGTharos]

The missile has limitations beyond just rocket/aerodynamic, and the 2m^2 has to do with seeker sensitivity to that sort of target given that the AIM-7 needs to home-all-the-way.

[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.

Edited February 29, 2020 by BlackPixxel

[AnarchyZG]

R-27 family is currently terribly undermodelled, practically useless for both kinematic and sensor reasons (chaff and flares).

 

ED is not in a hurry to do anything about it since AMRAAM equipped modules are the cash cows and multiplayer was never high on priority list (wake up, it is not 2001 any more)