R-27ER update?

Saying 'why this? why that?' is not an argument. Reality doesn't care about your whys, just about theirs. Economy and manufacturing went in the drain for quite some time; production of the parts may have been in a location which was no longer considered desirable, and ramping up new manufacturing is no small feat. Etc.

 

 

The R-27 family works reasonably, but it's no longer competitive with newer weapons. It doesn't mean they're not dangerous; it means they're not as good.

I don't care about your theories....

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I usually post from my phone so please excuse any typos, inappropriate punctuation and capitalization, missing words and general lack of cohesion and sense in my posts.....

Ok, I have two conclusions based on these results.

Conclusion 1:

The DCS R-27ER when its speed reaches 800 km/h (around the missile stall speed) it would reach the range of ~18km at 1000m and ~21 km at 5000m in around ~40 sec. the plane traveling 1100 kmh would travel a ~12km. So all in all the engagement range would be 30 km at 1000m and 33 km at 5000m

If we compared the engagement range of the R-27ER to the one provided by GGTharos from the Sukhoi manual and our charts that give us the range of 29 km at 1000m and 39 at 5000m.

We can see that the missile is in the ballpark at 1000m but around 6km off on 5000m.

I think the R-27ER only needs small tweaks

Conclusion 2:

The performance of the R-27r is a bit odd. Its graphs (burn time, speed, range...) have much more in common with the R-73 than R-27ER. It's performance often is more the 50% off the R-27ER which is hard to account for by just a bigger rocket engine.

And in the end, if we take into account that R-27R bleeds much more speed in turn that R-73 the effective range difference for a maneuvering target between them becomes neglectable.

And these missiles were developed at the same time for the same planes.

I can't image a Soviet rocket Scientist going to a Military Officer and saying well it will have maybe 20% bigger range if you are above the 5000m and if the target doesn't turn and if the radar doesn't drop a lock and it will cost more and you can only have two on your Front line fighter since it is 2.5 times heavier with all the added cost of logistics and maintenance... and the Officer goes, yes please, give me those 20% please... It doesn't pass the common sense test...

To conclude I think the R-27r is underperforming and it needs another look from the ED.

Conclusion 2:

The performance of the R-27r is a bit odd. Its graphs (burn time, speed, range...) have much more in common with the R-73 than R-27ER. It's performance often is more the 50% off the R-27ER which is hard to account for by just a bigger rocket engine.

Fuel fraction plays an enormous role here. Look at how AIM-7 behaves, then come back to this.

The R-27ER has more than twice the weight of fuel compared to R-27R, and it is also in a boost-sustain configuration. So the rocket engine is not similar at all - not even a little. Different amount of fuel, different diameter, etc.

Fuel fraction plays an enormous role here. Look at how AIM-7 behaves, then come back to this.

Come on, you can do better than that... go play Kerbal Space Program a bit... maxing out DeltaV isn't just get a bigger rocket...

Please provide the data and the charts since you were asking for them.

This data is old history - I've already provided you with some information. The R-27ER contains 135Kg of fuel in boost-sustain configuration, the R-27R 60Kg in all-boost configuration.

The rocket diameter is different, this you can tell literally by looking at the two missiles.

Chizh can give you better sources, and he probably has them handy - they're also in Russian, so you can read them from source if he tells you where to find them. There's a huge missile thread on the Russian forum where all of this was presented.

Guys, let's calm down a bit. Arguing about behavior of a simulated missile in the simulator is entirely pointless. If anyone would ever make a simulator which would take into account a realistic atmospheric model along with detailed physics simulation and a realistic simulation of the electronic environment, only then we could get the results which could be considered relevant. I believe ED would like to do it all but there are hurdles to overcome, like security clearances, time, and money. If any of you is willing to pay $1'000 for a software like that, then we're talking! ;)

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This data is old history - I've already provided you with some information. The R-27ER contains 135Kg of fuel in boost-sustain configuration, the R-27R 60Kg in all-boost configuration.

The rocket diameter is different, this you can tell literally by looking at the two missiles.

 

 

 

Chizh can give you better sources, and he probably has them handy - they're also in Russian, so you can read them from source if he tells you where to find them. There's a huge missile thread on the Russian forum where all of this was presented.

Ok, you are saying that R-27R as is, passes my common sense test in your opinion?

In my opinion you're dealing with way too many technical details in terms of missile construction to attempt anything resembling 'common sense test'. Back of the envelope calculation as a starting point, yes, 'common sense', no. That's a great way to go down the wrong path quickly.

You have a feeling that something is wrong - that's fair. Now verify that something is wrong by doing the math ... which means obtaining the details for those missiles. Fortunately, the details for rocket motors in the game are the corresponding RL values for R-27 and R-73 family, as well as R-77, AIM-9/7/120.

Ok, now for the math, the R-27R weights 253 kg, R-27ER weights 350 kg, aerodynamic they are quite similar only the small diameter change on the R-27ER and the additional lateral due to length but I won't take that in an account.

To accelerate the R-27R to 2800 kmh from 1100 kmh in 4 seconds as per graph it will need an acceleration of 118.06 m/s*s using a net force 29869.2 N

The R-27ER acceleration to 3500 kmh from 1100 kmh in 2 seconds as per graph it will need an acceleration of 347.2 m/s*s using a net force 121520 N

The specific impulse between the R-27R and R-27ER is close since of the diameter of the nozzle limiting the flow and both missiles are flying in the atmosphere.

Basically what you are saying is that in the 2 times the propellant you would have to store 4 times the energy and provide 4 times amount of thrust and delivery 4 times the acceleration to achieve those stats. And that doesn't seem possible in my book.

The data was the same before for Aim-120, R-77, AiM-7 but they got updated and their performance changed. The R-27 was left in the old format and now it shows a lot, and the only thing few of us here are asking is for ED to take a look at the R-27 since now it look, feels and performs odd comparing to the other missiles.

It's burning the booster section (60kg of it or however much of it there is) in 2 sec, the rest is in lower thrust sustain configuration.

It's not the first missile to do something like this.

Ok, now for the math, the R-27R weights 253 kg, R-27ER weights 350 kg, aerodynamic they are quite similar only the small diameter change on the R-27ER.

 

To accelerate the R-27R to 2800 kmh from 1100 kmh in 4 seconds as per graph it will need an acceleration of 118.06 m/s*s using a net force 29869.2 N

 

The R-27ER acceleration to 3500 kmh from 1100 kmh in 2 seconds as per graph it will need an acceleration of 347.2 m/s*s using a net force 121520 N

It's burning the booster section (60kg of it or however much of it there is) in 2 sec, the rest is in lower thrust sustain configuration.

It's not the first missile to do something like this.

The efficiency of the rocket is gauged by the Specific Impuls, and the range for all the rockets is around ~250 to ~350 at sea level for all rockets humanity ever created, it can not account for the difference off 2 times.

If flight manuals, in-game data, and even high schools physics, says something is wrong.... something is wrong.

And I don't think its done on purpose or with bad faith, on the contrary, the DCS is phenomenal and I can't believe that we are getting this kind of fidelity and I much appreciate the work ED has put in it. I only think that some of the stats got outdated as the sim progressed and need another look.

There's no change in efficiency. The rocket is burning a lot more fuel mass per unit time for the boost phase.

Again, absolutely nothing strange or new about this. It's not the first missile to do this.

The efficiency of the rocket is gauged by the Specific Impuls, and the range for all the rockets is around ~250 to ~350 at sea level for all rockets humanity ever created, it can not account for the difference off 2 times.

There's no change in efficiency. The rocket is burning a lot more fuel mass per unit time for the boost phase.

Again, absolutely nothing strange or new about this. It's not the first missile to do this.

You can not fit a 4l of Cola in a 2l bottle, no matter if you pour it drop by drop all teleport it all at once...

You have a 135kg bottle and you're pouring the first half of it out as fast you can go, then you slow to a trickle. Are we still on the level of 'it's the same rocket motor'? It isn't. At all.

And I will reiterate yet again, this is not the first missile to do such a thing.

You can not fit a 4l of Cola in a 2l bottle, no matter if you pour it drop by drop all teleport it all at once...

You have a 135kg bottle and you're pouring the first half of it out as fast you can go, then you slow to a trickle. Are we still on the level of 'it's the same rocket motor'? It isn't. At all.

And I will reiterate yet again, this is not the first missile to do such a thing.

Ok, I am giving up, you are correct. Since getting 270kg worth of the propltion of a 135kg propellant looks correct to you, it must be correct to me too... and thank you for derailing the topic...

The table for the R-27R:

Rocket operating time(s):      6.0
Mass used every second(kg/s):  11.3
Thrust (N):                    25620.0

This gives an ISP of about 231, and the total impulse is 153720N

For the R-27ER:

[b]Boost:[/b]

Rocket operating time(s):      3.0
Mass used every second(kg/s):  31.9
Thrust (N):                    73500.0


[b]Sustain:[/b]
Rocket operating time(s):      7.0
Mass used every second(kg/s):  6.32
Thrust (N):                    14560.0

This gives ISPs of 235 for both boost and sustain sections, and a total impulse of 322420N.

I don't see the problem.

The table for the R-27R:

 

 

Rocket operating time(s):      6.0
Mass used every second(kg/s):  11.3
Thrust (N):                    25620.0

This gives an ISP of about 231, and the total impulse is 153720N

 

 

For the R-27ER:

 

 

[b]Boost:[/b]

Rocket operating time(s):      3.0
Mass used every second(kg/s):  31.9
Thrust (N):                    73500.0


[b]Sustain:[/b]
Rocket operating time(s):      7.0
Mass used every second(kg/s):  6.32
Thrust (N):                    14560.0

This gives ISPs of 235 for both boost and sustain sections, and a total impulse of 322420N.

 

 

I don't see the problem.

Ok, this is my last post, since this is getting pointless... I am trying to prove that something wrong and needs another look, you are trying to prove that everything is correct. We must agree that my bar is much lower than yours.

Let's start here with the calculation... 6 * 11.3 kg... gives 67.8 kg... not 60kg... 3 * 31.9 + 7 * 6.32 = 95.7 + 44.24 = 139.94kg not 135kg... in the game the missile burns for 12 sec and not 10 sec... so still haven't account for those 2 secs... if we use your total impulse of both missiles and calculate velocity change of both missiles according to their mass, the velocity change difference is ~30% not over 50% like in-game performance... in the end I think the bar for something is wrong is met...

I still remain with my two conclusions based on manuals, in-game data and calculation... and they are R-27ER is in the ballpark but could use a small range extension based on the flight manual data... the R-27r is underperforming by around 20-30% in range...

Am I wrong in saying the best approach to check DCS would be to use a cfd program and use that to build the drag and lift curves like what HB did with the phoenix?

You don't need anything as deep and incredibly expensive as a CFD.

Why not? It would be the most accurate model you could create without actual missile flight tests or wind tunnel tests.

Because the available data is enough for modeling. If I wanted to model an R-27 and assuming I did ALL the work by myself (which I'm not qualified to do), I'd be paying at least $3000 to run that CFD. If I needed to pay people to get me a high quality CFD I wouldn't be surpised to run it up to $10000.

So the question is, what's the problem with the existing data available for this family of missiles?

Why not? It would be the most accurate model you could create without actual missile flight tests or wind tunnel tests.

So the question is, what's the problem with the existing data available for this family of missiles?

Because some people say that someone have it, but no one else can get it or it should be just accepted as is.

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I usually post from my phone so please excuse any typos, inappropriate punctuation and capitalization, missing words and general lack of cohesion and sense in my posts.....

I don't know what to tell you, there's plenty of data available to the public. It's not complete, yes it could be better, but it's also quite good.

If you want more, you can pay for said CFD.

Because some people say that someone have it, but no one else can get it or it should be just accepted as is.

Ok, this is my last post, since this is getting pointless... I am trying to prove that something wrong and needs another look, you are trying to prove that everything is correct. We must agree that my bar is much lower than yours.

 

Let's start here with the calculation... 6 * 11.3 kg... gives 67.8 kg... not 60kg... 3 * 31.9 + 7 * 6.32 = 95.7 + 44.24 = 139.94kg not 135kg... in the game the missile burns for 12 sec and not 10 sec... so still haven't account for those 2 secs... if we use your total impulse of both missiles and calculate velocity change of both missiles according to their mass, the velocity change difference is ~30% not over 50% like in-game performance... in the end I think the bar for something is wrong is met...

 

I still remain with my two conclusions based on manuals, in-game data and calculation... and they are R-27ER is in the ballpark but could use a small range extension based on the flight manual data... the R-27r is underperforming by around 20-30% in range...

^^

That's great, but he's wrong just like he was wrong with his original estimates. Bring this to ED, and see what happens. If you're on the ball they'll listen.