Ракеты в DCS

[alessander]

Вот читаю тут "общение" Чижа с потриотами и какое-то дежавю возникает...

Но напягши память вспоминаю себя на месте его оппонентов, и как я с пеной у рта доказывал что нашежи лучше патамушта наше.

 

А потом была работа в спецэкспорте и общение с вооруженцами (лучшими из них, других в эту контору не брали), и реальные истории из частей, как в совковом вооружении все что на бумаге вообще не соответствовало реальности, как падал МиГ-27 от залпа из своей же пушки, как отказывало оборудование у Су-27 после включения сорбций, как наспех скопированные у амеров ракеты вообще никуда не наводились и не попадали, и что пресловутые С-300 вообще не предназначались для борьбы с высокоманевренными целями, и сами нуждаются в эшелонированной защите ПВО. А потом были пьянки с иностранными делегациями на предприятиях производивших все это неимеющееаналогов вооружение, и как приходилось следить за подвыпившими инженерами, что бы они не проболтались потенциальному покупателю о том, каким хламом на самом деле есть весь наш товар. Ну, а самым интересным, было выдумывание обоснований для отмазок на письма-рекламации от покупателей, которым все же впарили совецкий металлолом и который нифига не мог подтвердить свои ТТХ.

 

 

Наверное все же стоить признать, что был тогда давно не прав...

[GGTharos]

8 hours ago, AAK said:

If you say this in relation to 7E2, yes, it was, on the ground, the rocket could turn on the dogfight mod for 25G, or leave the limitation at 15G. 7E1 was limited to 15G with no possibility of increasing congestion.

 

The dogfight mode does not 'enable 25g'. The missile overall was modified to be capable of 25g by adding power to the hydraulics and modifying the wings (they were so large that they created too much resistance for the hydraulics to achieve 25g at speed).

 

What the dogfight mode does is shorten the trigger-to-eject time, it enables full maneuver capability immediately at launch and activates the fuze after a minimum time of flight.

Without this mode the missile is launched in 'long range' mode, which will delay enabling of the fuze and try to preserve hydraulics for a long flight, but it will still enable full maneuvering when close to target (about 4.5nm).

 

After E-2 this would be done electronically onboard the missile, and didn't have to be set on the ground.

 

8 hours ago, AAK said:

 

 

Here it is necessary to stipulate that this applies specifically to the 9L / M, which are the next generation missiles after the R-60. The 9J has a weak engine from 9B, which operates EMNIP for no more than 2 seconds, I suspect it may have an even worse flight time at peak G-forces than the R-60, while its peak G-forces are most likely 1.5 -2 times less (I simply did not see the exact figures for the available P-60 loadings in the documents, so I cannot say 100% for sure). Well, naval Sidewinders with powerful engines have smaller Gs, as far as I remember, 18Gs, so they also do not compete with the P-60 in highly maneuverable combat.

 

 

As a technical detail, the 2 second engine is quite powerful, about twice the thrust of the engine on today's sidewinders in thrust per second. Probably a little less total impulse, but not weak.   I'm not sure what the AIM-9B used ... I'm only familiar with the more modern variants of these engines.

Edited August 31, 2021 by GGTharos

[GGTharos]

1 minute ago, ААК said:

Ok, interesting details, it means everything is even more complicated. In the dogfight fashion for launching 7E2, long distance runs the risk of leading to a loss of pressure in the hydraulic system at the right time? Those. in fact, in dogfight fashion 7E2 risks becoming a short-range missile?

 

This is correct.  The hydraulics in the AIM-7 are open-loop to this day (maybe ESSM is different), so whatever fluid is used for flight control is thrown outside

 

Heavy maneuvering will deplete the hydraulic reservoir, so the missile has well programmed ways of preventing this.  But for E-2, you made a choice, long range or short range dogfight (still more range than sidewinder, but not by a lot - this AIM-7 used a 2.8 second high thrust motor).

[Max1mus]

8 hours ago, Chizh said:

We do not ignore documents, we use them.

You intentionally do not follow R-27ER documentation, but follow the same R-27R one. What would you call that?

[NineLine]

This thread was created 8 years ago, anything been solved yet?

[GGTharos]

Interesting question.  The answer is yes ... unless it is no

[milit]

7 часов назад, GGTharos сказал:

 

This is correct.  The hydraulics in the AIM-7 are open-loop to this day (maybe ESSM is different), so whatever fluid is used for flight control is thrown outside

 

Heavy maneuvering will deplete the hydraulic reservoir, so the missile has well programmed ways of preventing this.  But for E-2, you made a choice, long range or short range dogfight (still more range than sidewinder, but not by a lot - this AIM-7 used a 2.8 second high thrust motor).

So if a target performs an S-maneuvers... how fast will the AIM-7 drop all the fluid? If it was set to a long range mode and was fired from max distance.

[NineLine]

14 minutes ago, GGTharos said:

Interesting question.  The answer is yes ... unless it is no

So maybe :D, carry on. 

[Airhunter]

2 hours ago, Max1mus said:

You intentionally do not follow R-27ER documentation, but follow the same R-27R one. What would you call that?

 

What documentation? That one possible launch envelope which has been thrown around a thousand times by now? There have been adjustments to the ER as of late which made it more in line with it. 

[GGTharos]

36 minutes ago, milit said:

So if a target performs an S-maneuvers... how fast will the AIM-7 drop all the fluid? If it was set to a long range mode and was fired from max distance.

 

I don't know, I believe that it would not be possible for the target to exhaust the reservoir of any sparrow after AIM-7E2 except for very marginal circumstances.   For max distance, the AIM-7 can perform an intercept as far as 53nm away without loft (AIM-7F) which it must achieve within 75 seconds (maximum powered flight time).

 

The missile is programmed to restrict any maneuvering until it is close to its target, so I expect it would have enough hydraulic fluid for all of its needs.   S-turns would not be effective for this reason.  At max distance, S-Turns would simply run the missile out of speed as well.

Edited August 31, 2021 by GGTharos

[FoxAlfa]

1 hour ago, NineLine said:

This thread was created 8 years ago, anything been solved yet?

Well, R-27R got improved, so I guess that is yes... for the R-27ER and other I guess we will have to wait 8 more years.... just kidding, looks like more good stuff is on the way...

[tavarish palkovnik]

53 nmi is aerodynamic range at 12,2km altitude at 2,5M ... allegedlly

 

Have you tried to calculate some figures by yourself about this AIM-7F?

 

 

 

 

Boost phase thrust 5750 Lb ... it is 2608 kg or 25585 N for 4,5 seconds.

Fuel is regular composite and it is about 52 Lb or 23,5 kg. Impuse of such composite is known as 2500 Ns/kg or something.

So ... 25585 * 4,5 / 23,5 = 4900 Ns/kg !??

 

Impuls is increasing with inner pressure and altitude (external pressure) ... for how much in this case 

Can this confidental, unclassified document can be taken for real or not, with all its data?

 

OK...let's say nozzle neck is 40mm ... p = 25585 *4 / 3,14 / 40 /40 / 1,6 = 12,7 MPa

Let's see for how much impulse will increase for this pressure and let's take almost full vacuum...

0,96*2500+190,3+76*12,7-3,058*12,7*12,7-7000*0,0001+25484*0,0001*0,0001 = 3062 s ... not even close

 

 

 

 

 

 

[tavarish palkovnik]

With 5750 Lb (4,5s) ; 1018 Lb (11s) ; 2,5 M ; 19,5 deg theta ; 12,2 km ; i58 act = 1,35 ; i58 pas = 1,6

 

 

 

US made is always the best only sometimes you need to close one or both eyes

 

Кстати ... максимальная перегрузка ракеты Р-60МК по данным Yugoimport Сербия составляет 30 ед.

 

Edited September 1, 2021 by tavarish palkovnik

[nighthawk2174]

1 hour ago, tavarish palkovnik said:

53 nmi is aerodynamic range at 12,2km altitude at 2,5M ... allegedlly

 

Have you tried to calculate some figures by yourself about this AIM-7F?

 

 

 

 

Boost phase thrust 5750 Lb ... it is 2608 kg or 25585 N for 4,5 seconds.

Fuel is regular composite and it is about 52 Lb or 23,5 kg. Impuse of such composite is known as 2500 Ns/kg or something.

So ... 25585 * 4,5 / 23,5 = 4900 Ns/kg !??

 

Impuls is increasing with inner pressure and altitude (external pressure) ... for how much in this case 

Can this confidental, unclassified document can be taken for real or not, with all its data?

 

OK...let's say nozzle neck is 40mm ... p = 25585 *4 / 3,14 / 40 /40 / 1,6 = 12,7 MPa

Let's see for how much impulse will increase for this pressure and let's take almost full vacuum...

0,96*2500+190,3+76*12,7-3,058*12,7*12,7-7000*0,0001+25484*0,0001*0,0001 = 3062 s ... not even close

Flip the fuel weights for boost and sustain and the math makes a lot more sense.  Additionally its likely that it is only at the listed thrust for part of the 4.5 and 11sec with a small transition period where the thrust is either increasing or decreasing.  This also makes the math make more sense.  The exact math ED used is somewhere in this thread and is largely from a AIAA document about how you calculate a lot of this stuff, where they used the AIM-7 as an example.

[tavarish palkovnik]

Thanks @nighthawk2174 ... good points 

It makes sense now, not only 4900 s was absolute fiction but also 1325 s for second phase which is under any normality.

 

2608*9,81*4,5/37,6=3062 s ... wow ... what a coincidence, same in single digit   

[Chizh]

14 часов назад, Max1mus сказал:

You intentionally do not follow R-27ER documentation, but follow the same R-27R one. What would you call that?

Earlier, I have explained more than once what and why.

[GGTharos]

4 hours ago, tavarish palkovnik said:

Thanks @ nighthawk2174 ... good points 

It makes sense now, not only 4900 s was absolute fiction but also 1325 s for second phase which is under any normality.

 

2608 * 9.81 * 4.5 / 37.6 = 3062 s ... wow ... what a coincidence, same in single digit   

 

The 4.5 second is incorrect. It's 3.5. Check the ISP, you'll see it can't be that way.

 

And there is absolutely no loft function for the 7F .

 

The maximum range conditions are Mach 2 shooter/target, 50000' altitude.

Edited September 1, 2021 by GGTharos

[tavarish palkovnik]

2 hours ago, GGTharos said:

The 4.5 second is incorrect. It's 3.5. Check the ISP, you'll see it can't be that way.

2609*9,81*3,5/23,5=3812 -> not correct, too much

 

2609*9,81*3,5/37,6=2382 -> seams correct but not for composite with aluminum in it. This rate is more for good nitrocellulose-nitroglycerin double based fuel grades.

 

Whit converting this Isp to nominal or specific or удельный at ratio 40:1 atmospheres as usually fuel data are given it drops to 2255 Ns/kg.

Widely used double based RNDSI-5K is given with 2186 for comparison.

 

If you have layout, cutoff drawing of this motor we can go in other direction and by geometry, burning rate and by common criterium to determine seconds. 

[GGTharos]

Unfortunately I do not have this sort of documentation.

[tavarish palkovnik]

Until internal ballistic and attempt to understand thrust data of AIM-7F get finished some about external.

This is from serious source and thrust diagram is as it is.

 

 

Good thing is that M f (time) is included as well and passive flight isochore says it is trajectory with kinematic overload or horizontal flight H=const.

 

My algorithm gives very close results 

 

And accordingly kilometers in function of time looks like this

 

Is it close to DCS or respectively is DCS close to this?

 

[GGTharos]

It looks reasonably close but I would have to run a test to be certain.  The thrust is 1 second too long (what is the serious source?   The ISP doesn't match if we give the boost motor 4.5 sec) and the sustainer thrust is a too low - should be more than 1000lbf.

 

I know that the DCS missile is a little too slow (no, I have no source to provide, so feel free to not believe me obviously) but it's close.   I'll get you results ASAP.

[tavarish palkovnik]

Thanks GGTharos, it is not about trust or believing, just about my unexplainable love, wish and needs of turning twist around numbers of various kinds 

 

I hope internal ballistic analysis of this motor will be successful, momentarily there are several “walls” and bricks in head but I’m kind of stubborn and several bricks can’t stop me

 

[GGTharos]

Thanks

 

Very quick test:

 

I launched from M0.95 at 40000', the missile was in a slight descent.   Peak speed was 0.4M lower than your graph, and distance flown at 75sec (maximum time of flight for this missile) was 20nm at which point speed was again M0.95.

 

So your missile gains +0.4M and +10km distance.  I'll get you more information on 7F when I am able, 7M is ... more mysterious although technically it uses the same motor.

[tavarish palkovnik]

This is kind of huge difference especially when take my launch speed 250m/s even under yours (M=0,85)

 

[tavarish palkovnik]

Rough method but most probably that Mk-58 motor burns this way

 

 

 

 

 

With more precise dimension and of course proper step of integrations function should be in line to what expected but even as it is gives direction that described and specified in literature should be correct and without doubts