R-27ER update?

[JunMcKill]

Ahh, and another interesting thing I didn't notice when looking at the charts before.

 

The same chart is used for both ER and ET, and since the ET has worst aerodynamic properties then the ER, the limiting factor for range might not be propulsion, but the power source life time like stated before.

 

And that the ET chases a lit cigar if you throw it out the window! :megalol:

[JunMcKill]

AIM-120 in Russian MiG-29 combat manual

 

 

But this chart is for defensive purposes, give the possible use of an enemy AIM-120 if the target is visible in PPS (frontal) or ZPS (behind) radar modes, depending on maximum and minimum launcher speeds

[GGTharos]

It makes a significant difference; it makes that weight difference irrelevant; that missile should not be able to reach the same top speed as its radar-guided counter-part.

This is why you'll find heat seekers that want to fly longer ranges adopting a more pointy sort of design.

 

 

 

Does the round nose instead of the cone make such a big difference that it would require a second chart? Since they are propably just a rough guideline, a kilometer here or there should not matter. The ET is also a little bit lighter, which would mean faster acceleration (but also deacceleration due to drag) and reduced drag because a lower AOA is required to keep the altitute.

[nighthawk2174]

Does the round nose instead of the cone make such a big difference that it would require a second chart? Since they are propably just a rough guideline, a kilometer here or there should not matter. The ET is also a little bit lighter, which would mean faster acceleration (but also deacceleration due to drag) and reduced drag because a lower AOA is required to keep the altitute.

 

Yes it makes a big difference, there was this one doc that clearly expressed this but I can't find it anymore :doh:

 

So maybe the R27 family in DCS need better kinematics but have a battery life both like the 530D has in DCS.

 

This is my opinion as well, if i were a betting man the DLZ for the 27 as shown above, is based either off of PK (my personal pick) or based off of the 60 sec life time of the R27 (IIRC this is how long the missile fins are able to move for). Hence why earlier I said having these charts are nice but its far better just to either find a doc with flyout data or to CFD the missile as they can be misleading. As we have seen with the missile mod many missiles have too much drag in DCS, in fact almost all of them besides the AIM-9's.

Edited March 29, 2019 by nighthawk2174

[Chizh]

@Chizh, is the EP in use anywhere, or was it ever?

No. We have not found any evidence of the use of this missile.

[Max1mus]

AIM-120 in Russian MiG-29 combat manual

 

 

Not really related to the R-27, but i found that the rMax of the DCS AIM-120C fits at least the frontal aspect ranges shown in the chart. If it would loft, the current DCS AIM-120C would surpass some of the ranges shown in the chart, as for example at 5000m. Have not tested at higher altitudes, but it seems highly likely that even the official 105km maximum range would be surpassed then. Does this mean that the chart does not take lofting into account, or is the DCS AIM-120 currently overperforming in some areas to make up for the missing loft? Or does the AIM-120C (block 5 im assuming) and 120B not loft at all?

Edited April 2, 2019 by Max1mus

[nighthawk2174]

Both missiles are capable of lofting again this is a Russian (estimation?) of the AIM-120's performance and is unlikely to match up with actual capabilities, especially considering it does not seem RMax is defined in the chart its kinda meaningless to deducing its performance at above ranges.

 

 

https://drive.google.com/file/d/1Fl8D2n1YW1ANCybeL44G9ouq-xZ_ABiK/view?usp=sharing

 

I always like to point people towards IASTAG's work in this regard.

Edited April 2, 2019 by nighthawk2174

[Max1mus]

rMax is defined in the chart at least in the headon section. It shows all POSSIBLE launches of AIM-120 against a slow or fast target.

 

But even when ignoring it, it still does not add up. If our 120C is a -5, it should have a maximum range of 105km. With lofting with current DCS drag however, this can possibly be extended beyond that, making the maximum ranges at high altitudes lean more into 120D range.

 

As far as IASTAGs work is concerned, he does not have more knowledge about missiles than ED and does not provide any clues about how the actual 120C-5 lofts, but instead tests specific scenarios and what ranges and results could be achieved. And his results provide a similar problem - the maximum range of 105km for the 120C5 would be greatly extended if the missile was modified to fit his imaginations.

[Schmidtfire]

The whole issue is about missile navigation and guidance in DCS. Missile pull crazy amount of G’s at launch or everytime target do a barrel-roll. Wasting a lot of energy at long range to target.

 

Most bvr air-air missiles in DCS can be defeated by basic aircraft maneuvering. Even if lock is held and no chaff/ecm is used, missiles can rather easy be outflown by pilot.

 

Regarding the R-27ER. I never duobted ED charts, they look good. But does it track and behave similar the real thing?

Edited April 2, 2019 by Schmidtfire

[GGTharos]

The chart is for 120A/B. The 120C5 will exceed those ranges easily.

 

The maximum range of 105km being mentioned is completely meaningless.

 

As for what IASGATG knows ... He did the CFD. ED did not. The knowledge regarding the 120 is preferred together from many sources.

[Max1mus]

The chart is for 120A/B. The 120C5 will exceed those ranges easily.

 

The maximum range of 105km being mentioned is completely meaningless.

 

As for what IASGATG knows ... He did the CFD. ED did not. The knowledge regarding the 120 is preferred together from many sources.

 

How do you know the chart is for the A/B? It would certainly make sense to brief MiG-29 pilots to expect the most modern versions, even if they are perhabs still in development at the time (which would be the case for the 90s).

 

EDs point of view on the issue seems to be that the chart represents the 120C5 since the DCS missile exactly meets the rMaxes shown in the chart.

[falcon_120]

How do you know the chart is for the A/B? It would certainly make sense to brief MiG-29 pilots to expect the most modern versions, even if they are perhabs still in development at the time (which would be the case for the 90s).

 

EDs point of view on the issue seems to be that the chart represents the 120C5 since the DCS missile exactly meets the rMaxes shown in the chart.

 

Why would you put a chart for something under development? Based on what? Nor even Raytheon engineers could know which range they were going to get until it could be tested. The only plausible scenario is to put a graph to help you defeat weapons your potential enemies are carrying under their wings, right?

Edited April 2, 2019 by falcon_120

[GGTharos]

How do you know the chart is for the A/B?

 

Because I asked :)

 

It would certainly make sense to brief MiG-29 pilots to expect the most modern versions, even if they are perhabs still in development at the time (which would be the case for the 90s).

 

That chart is very old, and I don't see them briefing for versions that did not yet exist.

 

EDs point of view on the issue seems to be that the chart represents the 120C5 since the DCS missile exactly meets the rMaxes shown in the chart.

 

No, EDs point of view is that it represents A/B. Like I said, I asked.

[nighthawk2174]

rMax is defined in the chart at least in the headon section. It shows all POSSIBLE launches of AIM-120 against a slow or fast target.

 

But even when ignoring it, it still does not add up. If our 120C is a -5, it should have a maximum range of 105km. With lofting with current DCS drag however, this can possibly be extended beyond that, making the maximum ranges at high altitudes lean more into 120D range.

 

As far as IASTAGs work is concerned, he does not have more knowledge about missiles than ED and does not provide any clues about how the actual 120C-5 lofts, but instead tests specific scenarios and what ranges and results could be achieved. And his results provide a similar problem - the maximum range of 105km for the 120C5 would be greatly extended if the missile was modified to fit his imaginations.

 

I should have clarified in my post it doesn't define what Rmax means in the way that it doesn't say what the current state of the missile is. As I said earlier: "Each country has its own definitions of Rmax it could be the max range the missile will fly before stalling out, it could be the range at which the missile will be able to pull xg's for x seconds, it could be limited by battery/hydrolic reservoir life (Super 530D for example its capable of going further than Rmax may indicate but its battery will run dry before then), sensor sensitivity, or it could be defined by PK (so at this range you have a PK of .2), etc etc etc. Hopefully as you can see there are a huge number of ways to define Rmax and without this definition these charts although cool and nice to have for system creations aren't the most helpful with the generation of a realistic missile flight model. What you need for an effective flight model is the motor burn times and thrust, CD, CM, and CL. From these you can run the Drag, Lift and Moment equations (with regards to moment there is more to this in particular but lets keep it simple for now). "

 

Additionally since this is a Russian source and not an american one you got to ask if their number were right? Did they take into account lofting? Did they overestimate or underestimate the drag on the missile body/ thrust on the rocket motor?

[GGTharos]

The answer is that we don't know.

[nighthawk2174]

^

[3G0]

[GGTharos]

Is there a translation? :)

[Ironhand]

Is there a translation? :)

 

This is my own, so it may not be exact:

 

[GGTharos]

Thanks, this is actually in line with what I was expecting :)

 

#4,5 is altitude separation.

[Dudikoff]

This is the chart from the Su-27SK manual, it was already translated.

[Ironhand]

This is the chart from the Su-27SK manual, it was already translated.

Yes, though the only translation I've seen looks like it was done through Google Translate or somesuch. If there's an excellent translation out there, I'd love a link to it. OTOH, translating it myself helps me to learn a bit more technical Russian.

[FoxAlfa]

Hello,

 

I did some more tests and need your help understanding the results.

I was trying to figure out the maneuverability of the missiles and the R-27r again managed to surprise me.

 

The setup is simple fire a missile at a parallel flying non-maneuvering Yak-40, 45' to the right and 6 km away.

 

 

here are the results table:

 

 

Graphs:

 

R-27r:

 

Aim-7:

 

Aim-120:

 

R-77:

 

 

I will compare only R-27r and Aim-7m since they are same aero configuration with R-27r being more advanced and developed with the full knowledge of the aero of Aim-7E.

 

Basically, the weight difference is neglactable here since R-27r burns much faster.

And even since R-27 is going faster the speed quickly drops to the similar speed to the Aim-7 so higher speed can not enplane such big differences in performance.

The speed loss can be explained since the R-27r is maneuvering all the time and not able to get on the target but other differences in performance is stunning.

 

If you look the results Aim-7m was able to have ~30-40% higher turn rate with ~55% shorter turn radius, pulling 3x times AoA (thus much much larger drag) with a much lower speed loss ( 9% vs 39%).

 

What gives? I can't find any logical reason why the R-27r would have such bad turing performance...

Edited April 17, 2019 by FoxAlfa

[GGTharos]

The AIM-7 has a sustainer motor that will maintain its speed for about 15 seconds total.

 

 

 

Your shot is not valid - even though missiles CAN hit, a 45deg OBS shot is typically not a valid shot.

 

 

Finally, while the AIM-7M has demonstrated to intercept a target from 6nm in tail-chase in RL, but that was a straight-line shot. Here, as you see from the page presented above, you're just below the range limit for that shot, and you're forcing the missile to maneuver.

 

 

Now, to answer your other questions - I think some aero values (possibly lift, max AoA) need to be tuned for this missile. Your shot is still technically not valid. :)

 

 

The graphs being scaled differently is annoying, it makes them more difficult to compare accurately, but I get where you're going. The R-27 has both slowed down significantly (maybe M1.5) compared to the other missiles, but it has also given up tracking - this is evident by the 0 deg turn rate. You have not marked the point at which is gets closest to target however.

Edited April 17, 2019 by GGTharos

[FoxAlfa]

Of course the shot is not valid, again the idea was to force missiles to maneuver at same parameters so to be able to compare them.

 

The range wasn't 6nm, but 6 km, check the setup picture.

 

And Aim-7 parameters seam quite good and accurate also compared well to the Aim-120 and R-77 and make complete sense.

 

the R-27r is again the black sheep that doesn't make sense.